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Merge remote-tracking branch 'upstream/master' into rustup

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18
.github/workflows/clippy.yml vendored
View file

@ -27,6 +27,7 @@ env:
jobs:
base:
# NOTE: If you modify this job, make sure you copy the changes to clippy_bors.yml
runs-on: ubuntu-latest
steps:
@ -50,11 +51,16 @@ jobs:
- name: Build
run: cargo build --features deny-warnings,internal-lints
- name: Test "--fix -Zunstable-options"
run: cargo run --features deny-warnings,internal-lints --bin cargo-clippy -- clippy --fix -Zunstable-options
- name: Test
run: cargo test --features deny-warnings,internal-lints
- name: Test Workspace
run: cargo test --all --features deny-warnings,internal-lints
- name: Test clippy_lints
run: cargo test --features deny-warnings,internal-lints
working-directory: clippy_lints
- name: Test rustc_tools_util
run: cargo test --features deny-warnings
working-directory: rustc_tools_util
- name: Test clippy_dev
run: cargo test --features deny-warnings
@ -64,6 +70,10 @@ jobs:
run: ../target/debug/cargo-clippy
working-directory: clippy_workspace_tests
- name: Test cargo-clippy --fix
run: ../target/debug/cargo-clippy clippy --fix -Zunstable-options
working-directory: clippy_workspace_tests
- name: Test clippy-driver
run: bash .github/driver.sh
env:

24
.github/workflows/clippy_bors.yml vendored
View file

@ -72,6 +72,7 @@ jobs:
runs-on: ${{ matrix.os }}
# NOTE: If you modify this job, make sure you copy the changes to clippy.yml
steps:
# Setup
- uses: rust-lang/simpleinfra/github-actions/cancel-outdated-builds@master
@ -112,8 +113,16 @@ jobs:
- name: Build
run: cargo build --features deny-warnings,internal-lints
- name: Test Workspace
run: cargo test --all --features deny-warnings,internal-lints
- name: Test
run: cargo test --features deny-warnings,internal-lints
- name: Test clippy_lints
run: cargo test --features deny-warnings,internal-lints
working-directory: clippy_lints
- name: Test rustc_tools_util
run: cargo test --features deny-warnings
working-directory: rustc_tools_util
- name: Test clippy_dev
run: cargo test --features deny-warnings
@ -123,11 +132,22 @@ jobs:
run: ../target/debug/cargo-clippy
working-directory: clippy_workspace_tests
- name: Test cargo-clippy --fix
run: ../target/debug/cargo-clippy clippy --fix -Zunstable-options
working-directory: clippy_workspace_tests
- name: Test clippy-driver
run: bash .github/driver.sh
env:
OS: ${{ runner.os }}
- name: Test cargo dev new lint
run: |
cargo dev new_lint --name new_early_pass --pass early
cargo dev new_lint --name new_late_pass --pass late
cargo check
git reset --hard HEAD
integration_build:
needs: changelog
runs-on: ubuntu-latest

2
CHANGELOG.md
View file

@ -2104,6 +2104,7 @@ Released 2018-09-13
[`if_not_else`]: https://rust-lang.github.io/rust-clippy/master/index.html#if_not_else
[`if_same_then_else`]: https://rust-lang.github.io/rust-clippy/master/index.html#if_same_then_else
[`ifs_same_cond`]: https://rust-lang.github.io/rust-clippy/master/index.html#ifs_same_cond
[`implicit_clone`]: https://rust-lang.github.io/rust-clippy/master/index.html#implicit_clone
[`implicit_hasher`]: https://rust-lang.github.io/rust-clippy/master/index.html#implicit_hasher
[`implicit_return`]: https://rust-lang.github.io/rust-clippy/master/index.html#implicit_return
[`implicit_saturating_sub`]: https://rust-lang.github.io/rust-clippy/master/index.html#implicit_saturating_sub
@ -2134,6 +2135,7 @@ Released 2018-09-13
[`invisible_characters`]: https://rust-lang.github.io/rust-clippy/master/index.html#invisible_characters
[`items_after_statements`]: https://rust-lang.github.io/rust-clippy/master/index.html#items_after_statements
[`iter_cloned_collect`]: https://rust-lang.github.io/rust-clippy/master/index.html#iter_cloned_collect
[`iter_count`]: https://rust-lang.github.io/rust-clippy/master/index.html#iter_count
[`iter_next_loop`]: https://rust-lang.github.io/rust-clippy/master/index.html#iter_next_loop
[`iter_next_slice`]: https://rust-lang.github.io/rust-clippy/master/index.html#iter_next_slice
[`iter_nth`]: https://rust-lang.github.io/rust-clippy/master/index.html#iter_nth

13
Cargo.toml
View file

@ -1,13 +1,7 @@
[package]
name = "clippy"
version = "0.1.52"
authors = [
"Manish Goregaokar <manishsmail@gmail.com>",
"Andre Bogus <bogusandre@gmail.com>",
"Georg Brandl <georg@python.org>",
"Martin Carton <cartonmartin@gmail.com>",
"Oliver Schneider <clippy-iethah7aipeen8neex1a@oli-obk.de>"
]
authors = ["The Rust Clippy Developers"]
description = "A bunch of helpful lints to avoid common pitfalls in Rust"
repository = "https://github.com/rust-lang/rust-clippy"
readme = "README.md"
@ -42,6 +36,7 @@ tester = "0.9"
clippy-mini-macro-test = { version = "0.2", path = "mini-macro" }
serde = { version = "1.0", features = ["derive"] }
derive-new = "0.5"
regex = "1.4"
# A noop dependency that changes in the Rust repository, it's a bit of a hack.
# See the `src/tools/rustc-workspace-hack/README.md` file in `rust-lang/rust`
@ -55,3 +50,7 @@ rustc_tools_util = { version = "0.2.0", path = "rustc_tools_util" }
deny-warnings = []
integration = ["tempfile"]
internal-lints = ["clippy_lints/internal-lints"]
[package.metadata.rust-analyzer]
# This package uses #[feature(rustc_private)]
rustc_private = true

1
README.md
View file

@ -202,7 +202,6 @@ the lint(s) you are interested in:
```terminal
cargo clippy -- -A clippy::all -W clippy::useless_format -W clippy::...
```
Note that if you've run clippy before, this may only take effect after you've modified a file or ran `cargo clean`.
### Specifying the minimum supported Rust version

3
clippy_dev/Cargo.toml
View file

@ -1,10 +1,9 @@
[package]
name = "clippy_dev"
version = "0.0.1"
authors = ["Philipp Hansch <dev@phansch.net>"]
authors = ["The Rust Clippy Developers"]
edition = "2018"
[dependencies]
bytecount = "0.6"
clap = "2.33"

14
clippy_dev/lintcheck_crates.toml
View file

@ -14,10 +14,22 @@ bitflags = {name = "bitflags", versions = ['1.2.1']}
libc = {name = "libc", versions = ['0.2.81']}
log = {name = "log", versions = ['0.4.11']}
proc-macro2 = {name = "proc-macro2", versions = ['1.0.24']}
puffin = {name = "puffin", git_url = "https://github.com/EmbarkStudios/puffin", git_hash = "02dd4a3"}
quote = {name = "quote", versions = ['1.0.7']}
rand = {name = "rand", versions = ['0.7.3']}
rand_core = {name = "rand_core", versions = ['0.6.0']}
regex = {name = "regex", versions = ['1.3.2']}
syn = {name = "syn", versions = ['1.0.54']}
unicode-xid = {name = "unicode-xid", versions = ['0.2.1']}
# some more of dtolnays crates
anyhow = {name = "anyhow", versions = ['1.0.38']}
async-trait = {name = "async-trait", versions = ['0.1.42']}
cxx = {name = "cxx", versions = ['1.0.32']}
ryu = {name = "ryu", version = ['1.0.5']}
serde_yaml = {name = "serde_yaml", versions = ['0.8.17']}
thiserror = {name = "thiserror", versions = ['1.0.24']}
# some embark crates, there are other interesting crates but
# unfortunately adding them increases lintcheck runtime drastically
cfg-expr = {name = "cfg-expr", versions = ['0.7.1']}
puffin = {name = "puffin", git_url = "https://github.com/EmbarkStudios/puffin", git_hash = "02dd4a3"}
rpmalloc = {name = "rpmalloc", versions = ['0.2.0']}
tame-oidc = {name = "tame-oidc", versions = ['0.1.0']}

2
clippy_dev/src/lib.rs
View file

@ -530,7 +530,7 @@ fn test_gen_deprecated() {
#[should_panic]
fn test_gen_deprecated_fail() {
let lints = vec![Lint::new("should_assert_eq2", "group2", "abc", None, "module_name")];
let _ = gen_deprecated(lints.iter());
let _deprecated_lints = gen_deprecated(lints.iter());
}
#[test]

457
clippy_dev/src/lintcheck.rs
View file

@ -5,20 +5,30 @@
// positives.
#![cfg(feature = "lintcheck")]
#![allow(clippy::filter_map)]
#![allow(clippy::filter_map, clippy::collapsible_else_if)]
use crate::clippy_project_root;
use std::collections::HashMap;
use std::process::Command;
use std::sync::atomic::{AtomicUsize, Ordering};
use std::{env, fmt, fs::write, path::PathBuf};
use std::{collections::HashMap, io::ErrorKind};
use std::{
env, fmt,
fs::write,
path::{Path, PathBuf},
};
use clap::ArgMatches;
use rayon::prelude::*;
use serde::{Deserialize, Serialize};
use serde_json::Value;
const CLIPPY_DRIVER_PATH: &str = "target/debug/clippy-driver";
const CARGO_CLIPPY_PATH: &str = "target/debug/cargo-clippy";
const LINTCHECK_DOWNLOADS: &str = "target/lintcheck/downloads";
const LINTCHECK_SOURCES: &str = "target/lintcheck/sources";
/// List of sources to check, loaded from a .toml file
#[derive(Debug, Serialize, Deserialize)]
struct SourceList {
@ -86,7 +96,7 @@ impl std::fmt::Display for ClippyWarning {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
writeln!(
f,
r#"{}-{}/{}:{}:{} {} "{}""#,
r#"target/lintcheck/sources/{}-{}/{}:{}:{} {} "{}""#,
&self.crate_name, &self.crate_version, &self.file, &self.line, &self.column, &self.linttype, &self.message
)
}
@ -99,15 +109,13 @@ impl CrateSource {
fn download_and_extract(&self) -> Crate {
match self {
CrateSource::CratesIo { name, version, options } => {
let extract_dir = PathBuf::from("target/lintcheck/crates");
let krate_download_dir = PathBuf::from("target/lintcheck/downloads");
let extract_dir = PathBuf::from(LINTCHECK_SOURCES);
let krate_download_dir = PathBuf::from(LINTCHECK_DOWNLOADS);
// url to download the crate from crates.io
let url = format!("https://crates.io/api/v1/crates/{}/{}/download", name, version);
println!("Downloading and extracting {} {} from {}", name, version, url);
let _ = std::fs::create_dir("target/lintcheck/");
let _ = std::fs::create_dir(&krate_download_dir);
let _ = std::fs::create_dir(&extract_dir);
create_dirs(&krate_download_dir, &extract_dir);
let krate_file_path = krate_download_dir.join(format!("{}-{}.crate.tar.gz", name, version));
// don't download/extract if we already have done so
@ -140,7 +148,7 @@ impl CrateSource {
options,
} => {
let repo_path = {
let mut repo_path = PathBuf::from("target/lintcheck/crates");
let mut repo_path = PathBuf::from(LINTCHECK_SOURCES);
// add a -git suffix in case we have the same crate from crates.io and a git repo
repo_path.push(format!("{}-git", name));
repo_path
@ -182,25 +190,23 @@ impl CrateSource {
use fs_extra::dir;
// simply copy the entire directory into our target dir
let copy_dest = PathBuf::from("target/lintcheck/crates/");
let copy_dest = PathBuf::from(format!("{}/", LINTCHECK_SOURCES));
// the source path of the crate we copied, ${copy_dest}/crate_name
let crate_root = copy_dest.join(name); // .../crates/local_crate
if !crate_root.exists() {
println!("Copying {} to {}", path.display(), copy_dest.display());
dir::copy(path, &copy_dest, &dir::CopyOptions::new()).expect(&format!(
"Failed to copy from {}, to {}",
path.display(),
crate_root.display()
));
} else {
if crate_root.exists() {
println!(
"Not copying {} to {}, destination already exists",
path.display(),
crate_root.display()
);
} else {
println!("Copying {} to {}", path.display(), copy_dest.display());
dir::copy(path, &copy_dest, &dir::CopyOptions::new()).unwrap_or_else(|_| {
panic!("Failed to copy from {}, to {}", path.display(), crate_root.display())
});
}
Crate {
@ -219,16 +225,17 @@ impl Crate {
/// issued
fn run_clippy_lints(
&self,
cargo_clippy_path: &PathBuf,
cargo_clippy_path: &Path,
target_dir_index: &AtomicUsize,
thread_limit: usize,
total_crates_to_lint: usize,
fix: bool,
) -> Vec<ClippyWarning> {
// advance the atomic index by one
let index = target_dir_index.fetch_add(1, Ordering::SeqCst);
// "loop" the index within 0..thread_limit
let target_dir_index = index % thread_limit;
let perc = ((index * 100) as f32 / total_crates_to_lint as f32) as u8;
let thread_index = index % thread_limit;
let perc = (index * 100) / total_crates_to_lint;
if thread_limit == 1 {
println!(
@ -238,7 +245,7 @@ impl Crate {
} else {
println!(
"{}/{} {}% Linting {} {} in target dir {:?}",
index, total_crates_to_lint, perc, &self.name, &self.version, target_dir_index
index, total_crates_to_lint, perc, &self.name, &self.version, thread_index
);
}
@ -246,7 +253,18 @@ impl Crate {
let shared_target_dir = clippy_project_root().join("target/lintcheck/shared_target_dir");
let mut args = vec!["--", "--message-format=json", "--", "--cap-lints=warn"];
let mut args = if fix {
vec![
"-Zunstable-options",
"--fix",
"-Zunstable-options",
"--allow-no-vcs",
"--",
"--cap-lints=warn",
]
} else {
vec!["--", "--message-format=json", "--", "--cap-lints=warn"]
};
if let Some(options) = &self.options {
for opt in options {
@ -260,7 +278,7 @@ impl Crate {
// use the looping index to create individual target dirs
.env(
"CARGO_TARGET_DIR",
shared_target_dir.join(format!("_{:?}", target_dir_index)),
shared_target_dir.join(format!("_{:?}", thread_index)),
)
// lint warnings will look like this:
// src/cargo/ops/cargo_compile.rs:127:35: warning: usage of `FromIterator::from_iter`
@ -276,6 +294,23 @@ impl Crate {
);
});
let stdout = String::from_utf8_lossy(&all_output.stdout);
let stderr = String::from_utf8_lossy(&all_output.stderr);
if fix {
if let Some(stderr) = stderr
.lines()
.find(|line| line.contains("failed to automatically apply fixes suggested by rustc to crate"))
{
let subcrate = &stderr[63..];
println!(
"ERROR: failed to apply some suggetion to {} / to (sub)crate {}",
self.name, subcrate
);
}
// fast path, we don't need the warnings anyway
return Vec::new();
}
let output_lines = stdout.lines();
let warnings: Vec<ClippyWarning> = output_lines
.into_iter()
@ -283,10 +318,73 @@ impl Crate {
.filter(|line| filter_clippy_warnings(&line))
.map(|json_msg| parse_json_message(json_msg, &self))
.collect();
warnings
}
}
#[derive(Debug)]
struct LintcheckConfig {
// max number of jobs to spawn (default 1)
max_jobs: usize,
// we read the sources to check from here
sources_toml_path: PathBuf,
// we save the clippy lint results here
lintcheck_results_path: PathBuf,
// whether to just run --fix and not collect all the warnings
fix: bool,
}
impl LintcheckConfig {
fn from_clap(clap_config: &ArgMatches) -> Self {
// first, check if we got anything passed via the LINTCHECK_TOML env var,
// if not, ask clap if we got any value for --crates-toml <foo>
// if not, use the default "clippy_dev/lintcheck_crates.toml"
let sources_toml = env::var("LINTCHECK_TOML").unwrap_or_else(|_| {
clap_config
.value_of("crates-toml")
.clone()
.unwrap_or("clippy_dev/lintcheck_crates.toml")
.to_string()
});
let sources_toml_path = PathBuf::from(sources_toml);
// for the path where we save the lint results, get the filename without extension (so for
// wasd.toml, use "wasd"...)
let filename: PathBuf = sources_toml_path.file_stem().unwrap().into();
let lintcheck_results_path = PathBuf::from(format!("lintcheck-logs/{}_logs.txt", filename.display()));
// look at the --threads arg, if 0 is passed, ask rayon rayon how many threads it would spawn and
// use half of that for the physical core count
// by default use a single thread
let max_jobs = match clap_config.value_of("threads") {
Some(threads) => {
let threads: usize = threads
.parse()
.unwrap_or_else(|_| panic!("Failed to parse '{}' to a digit", threads));
if threads == 0 {
// automatic choice
// Rayon seems to return thread count so half that for core count
(rayon::current_num_threads() / 2) as usize
} else {
threads
}
},
// no -j passed, use a single thread
None => 1,
};
let fix: bool = clap_config.is_present("fix");
LintcheckConfig {
max_jobs,
sources_toml_path,
lintcheck_results_path,
fix,
}
}
}
/// takes a single json-formatted clippy warnings and returns true (we are interested in that line)
/// or false (we aren't)
fn filter_clippy_warnings(line: &str) -> bool {
@ -310,19 +408,6 @@ fn filter_clippy_warnings(line: &str) -> bool {
false
}
/// get the path to lintchecks crate sources .toml file, check LINTCHECK_TOML first but if it's
/// empty use the default path
fn lintcheck_config_toml(toml_path: Option<&str>) -> PathBuf {
PathBuf::from(
env::var("LINTCHECK_TOML").unwrap_or(
toml_path
.clone()
.unwrap_or("clippy_dev/lintcheck_crates.toml")
.to_string(),
),
)
}
/// Builds clippy inside the repo to make sure we have a clippy executable we can use.
fn build_clippy() {
let status = Command::new("cargo")
@ -336,10 +421,7 @@ fn build_clippy() {
}
/// Read a `toml` file and return a list of `CrateSources` that we want to check with clippy
fn read_crates(toml_path: Option<&str>) -> (String, Vec<CrateSource>) {
let toml_path = lintcheck_config_toml(toml_path);
// save it so that we can use the name of the sources.toml as name for the logfile later.
let toml_filename = toml_path.file_stem().unwrap().to_str().unwrap().to_string();
fn read_crates(toml_path: &Path) -> Vec<CrateSource> {
let toml_content: String =
std::fs::read_to_string(&toml_path).unwrap_or_else(|_| panic!("Failed to read {}", toml_path.display()));
let crate_list: SourceList =
@ -399,7 +481,7 @@ fn read_crates(toml_path: Option<&str>) -> (String, Vec<CrateSource>) {
// sort the crates
crate_sources.sort();
(toml_filename, crate_sources)
crate_sources
}
/// Parse the json output of clippy and return a `ClippyWarning`
@ -428,7 +510,7 @@ fn parse_json_message(json_message: &str, krate: &Crate) -> ClippyWarning {
}
/// Generate a short list of occuring lints-types and their count
fn gather_stats(clippy_warnings: &[ClippyWarning]) -> String {
fn gather_stats(clippy_warnings: &[ClippyWarning]) -> (String, HashMap<&String, usize>) {
// count lint type occurrences
let mut counter: HashMap<&String, usize> = HashMap::new();
clippy_warnings
@ -441,63 +523,69 @@ fn gather_stats(clippy_warnings: &[ClippyWarning]) -> String {
// to not have a lint with 200 and 2 warnings take the same spot
stats.sort_by_key(|(lint, count)| format!("{:0>4}, {}", count, lint));
stats
let stats_string = stats
.iter()
.map(|(lint, count)| format!("{} {}\n", lint, count))
.collect::<String>()
.collect::<String>();
(stats_string, counter)
}
/// check if the latest modification of the logfile is older than the modification date of the
/// clippy binary, if this is true, we should clean the lintchec shared target directory and recheck
fn lintcheck_needs_rerun(toml_path: Option<&str>) -> bool {
fn lintcheck_needs_rerun(lintcheck_logs_path: &Path) -> bool {
if !lintcheck_logs_path.exists() {
return true;
}
let clippy_modified: std::time::SystemTime = {
let mut times = ["target/debug/clippy-driver", "target/debug/cargo-clippy"]
.iter()
.map(|p| {
std::fs::metadata(p)
.expect("failed to get metadata of file")
.modified()
.expect("failed to get modification date")
});
// the lates modification of either of the binaries
let mut times = [CLIPPY_DRIVER_PATH, CARGO_CLIPPY_PATH].iter().map(|p| {
std::fs::metadata(p)
.expect("failed to get metadata of file")
.modified()
.expect("failed to get modification date")
});
// the oldest modification of either of the binaries
std::cmp::max(times.next().unwrap(), times.next().unwrap())
};
let logs_modified: std::time::SystemTime = std::fs::metadata(lintcheck_config_toml(toml_path))
let logs_modified: std::time::SystemTime = std::fs::metadata(lintcheck_logs_path)
.expect("failed to get metadata of file")
.modified()
.expect("failed to get modification date");
// if clippys modification time is bigger (older) than the logs mod time, we need to rerun lintcheck
clippy_modified > logs_modified
// time is represented in seconds since X
// logs_modified 2 and clippy_modified 5 means clippy binary is older and we need to recheck
logs_modified < clippy_modified
}
/// lintchecks `main()` function
///
/// # Panics
///
/// This function panics if the clippy binaries don't exist.
pub fn run(clap_config: &ArgMatches) {
let config = LintcheckConfig::from_clap(clap_config);
println!("Compiling clippy...");
build_clippy();
println!("Done compiling");
let clap_toml_path = clap_config.value_of("crates-toml");
// if the clippy bin is newer than our logs, throw away target dirs to force clippy to
// refresh the logs
if lintcheck_needs_rerun(clap_toml_path) {
if lintcheck_needs_rerun(&config.lintcheck_results_path) {
let shared_target_dir = "target/lintcheck/shared_target_dir";
match std::fs::metadata(&shared_target_dir) {
Ok(metadata) => {
if metadata.is_dir() {
println!("Clippy is newer than lint check logs, clearing lintcheck shared target dir...");
std::fs::remove_dir_all(&shared_target_dir)
.expect("failed to remove target/lintcheck/shared_target_dir");
}
},
Err(_) => { // dir probably does not exist, don't remove anything
},
// if we get an Err here, the shared target dir probably does simply not exist
if let Ok(metadata) = std::fs::metadata(&shared_target_dir) {
if metadata.is_dir() {
println!("Clippy is newer than lint check logs, clearing lintcheck shared target dir...");
std::fs::remove_dir_all(&shared_target_dir)
.expect("failed to remove target/lintcheck/shared_target_dir");
}
}
}
let cargo_clippy_path: PathBuf = PathBuf::from("target/debug/cargo-clippy")
let cargo_clippy_path: PathBuf = PathBuf::from(CARGO_CLIPPY_PATH)
.canonicalize()
.expect("failed to canonicalize path to clippy binary");
@ -508,7 +596,7 @@ pub fn run(clap_config: &ArgMatches) {
cargo_clippy_path.display()
);
let clippy_ver = std::process::Command::new("target/debug/cargo-clippy")
let clippy_ver = std::process::Command::new(CARGO_CLIPPY_PATH)
.arg("--version")
.output()
.map(|o| String::from_utf8_lossy(&o.stdout).into_owned())
@ -517,15 +605,18 @@ pub fn run(clap_config: &ArgMatches) {
// download and extract the crates, then run clippy on them and collect clippys warnings
// flatten into one big list of warnings
let (filename, crates) = read_crates(clap_toml_path);
let crates = read_crates(&config.sources_toml_path);
let old_stats = read_stats_from_file(&config.lintcheck_results_path);
let counter = AtomicUsize::new(1);
let clippy_warnings: Vec<ClippyWarning> = if let Some(only_one_crate) = clap_config.value_of("only") {
// if we don't have the specified crate in the .toml, throw an error
if !crates.iter().any(|krate| {
let name = match krate {
CrateSource::CratesIo { name, .. } => name,
CrateSource::Git { name, .. } => name,
CrateSource::Path { name, .. } => name,
CrateSource::CratesIo { name, .. } | CrateSource::Git { name, .. } | CrateSource::Path { name, .. } => {
name
},
};
name == only_one_crate
}) {
@ -541,52 +632,51 @@ pub fn run(clap_config: &ArgMatches) {
.into_iter()
.map(|krate| krate.download_and_extract())
.filter(|krate| krate.name == only_one_crate)
.map(|krate| krate.run_clippy_lints(&cargo_clippy_path, &AtomicUsize::new(0), 1, 1))
.flatten()
.flat_map(|krate| krate.run_clippy_lints(&cargo_clippy_path, &AtomicUsize::new(0), 1, 1, config.fix))
.collect()
} else {
let counter = std::sync::atomic::AtomicUsize::new(0);
if config.max_jobs > 1 {
// run parallel with rayon
// Ask rayon for thread count. Assume that half of that is the number of physical cores
// Use one target dir for each core so that we can run N clippys in parallel.
// We need to use different target dirs because cargo would lock them for a single build otherwise,
// killing the parallelism. However this also means that deps will only be reused half/a
// quarter of the time which might result in a longer wall clock runtime
// Ask rayon for thread count. Assume that half of that is the number of physical cores
// Use one target dir for each core so that we can run N clippys in parallel.
// We need to use different target dirs because cargo would lock them for a single build otherwise,
// killing the parallelism. However this also means that deps will only be reused half/a
// quarter of the time which might result in a longer wall clock runtime
// This helps when we check many small crates with dep-trees that don't have a lot of branches in
// order to achive some kind of parallelism
// This helps when we check many small crates with dep-trees that don't have a lot of branches in
// order to achive some kind of parallelism
// by default, use a single thread
let num_cpus = match clap_config.value_of("threads") {
Some(threads) => {
let threads: usize = threads
.parse()
.expect(&format!("Failed to parse '{}' to a digit", threads));
if threads == 0 {
// automatic choice
// Rayon seems to return thread count so half that for core count
(rayon::current_num_threads() / 2) as usize
} else {
threads
}
},
// no -j passed, use a single thread
None => 1,
};
// by default, use a single thread
let num_cpus = config.max_jobs;
let num_crates = crates.len();
let num_crates = crates.len();
// check all crates (default)
crates
.into_par_iter()
.map(|krate| krate.download_and_extract())
.map(|krate| krate.run_clippy_lints(&cargo_clippy_path, &counter, num_cpus, num_crates))
.flatten()
.collect()
// check all crates (default)
crates
.into_par_iter()
.map(|krate| krate.download_and_extract())
.flat_map(|krate| {
krate.run_clippy_lints(&cargo_clippy_path, &counter, num_cpus, num_crates, config.fix)
})
.collect()
} else {
// run sequential
let num_crates = crates.len();
crates
.into_iter()
.map(|krate| krate.download_and_extract())
.flat_map(|krate| krate.run_clippy_lints(&cargo_clippy_path, &counter, 1, num_crates, config.fix))
.collect()
}
};
// if we are in --fix mode, don't change the log files, terminate here
if config.fix {
return;
}
// generate some stats
let stats_formatted = gather_stats(&clippy_warnings);
let (stats_formatted, new_stats) = gather_stats(&clippy_warnings);
// grab crashes/ICEs, save the crate name and the ice message
let ices: Vec<(&String, &String)> = clippy_warnings
@ -595,9 +685,9 @@ pub fn run(clap_config: &ArgMatches) {
.map(|w| (&w.crate_name, &w.message))
.collect();
let mut all_msgs: Vec<String> = clippy_warnings.iter().map(|warning| warning.to_string()).collect();
let mut all_msgs: Vec<String> = clippy_warnings.iter().map(ToString::to_string).collect();
all_msgs.sort();
all_msgs.push("\n\n\n\nStats\n\n".into());
all_msgs.push("\n\n\n\nStats:\n".into());
all_msgs.push(stats_formatted);
// save the text into lintcheck-logs/logs.txt
@ -607,7 +697,132 @@ pub fn run(clap_config: &ArgMatches) {
ices.iter()
.for_each(|(cratename, msg)| text.push_str(&format!("{}: '{}'", cratename, msg)));
let file = format!("lintcheck-logs/{}_logs.txt", filename);
println!("Writing logs to {}", file);
write(file, text).unwrap();
println!("Writing logs to {}", config.lintcheck_results_path.display());
write(&config.lintcheck_results_path, text).unwrap();
print_stats(old_stats, new_stats);
}
/// read the previous stats from the lintcheck-log file
fn read_stats_from_file(file_path: &Path) -> HashMap<String, usize> {
let file_content: String = match std::fs::read_to_string(file_path).ok() {
Some(content) => content,
None => {
return HashMap::new();
},
};
let lines: Vec<String> = file_content.lines().map(ToString::to_string).collect();
// search for the beginning "Stats:" and the end "ICEs:" of the section we want
let start = lines.iter().position(|line| line == "Stats:").unwrap();
let end = lines.iter().position(|line| line == "ICEs:").unwrap();
let stats_lines = &lines[start + 1..end];
stats_lines
.iter()
.map(|line| {
let mut spl = line.split(' ');
(
spl.next().unwrap().to_string(),
spl.next().unwrap().parse::<usize>().unwrap(),
)
})
.collect::<HashMap<String, usize>>()
}
/// print how lint counts changed between runs
fn print_stats(old_stats: HashMap<String, usize>, new_stats: HashMap<&String, usize>) {
let same_in_both_hashmaps = old_stats
.iter()
.filter(|(old_key, old_val)| new_stats.get::<&String>(&old_key) == Some(old_val))
.map(|(k, v)| (k.to_string(), *v))
.collect::<Vec<(String, usize)>>();
let mut old_stats_deduped = old_stats;
let mut new_stats_deduped = new_stats;
// remove duplicates from both hashmaps
same_in_both_hashmaps.iter().for_each(|(k, v)| {
assert!(old_stats_deduped.remove(k) == Some(*v));
assert!(new_stats_deduped.remove(k) == Some(*v));
});
println!("\nStats:");
// list all new counts (key is in new stats but not in old stats)
new_stats_deduped
.iter()
.filter(|(new_key, _)| old_stats_deduped.get::<str>(&new_key).is_none())
.for_each(|(new_key, new_value)| {
println!("{} 0 => {}", new_key, new_value);
});
// list all changed counts (key is in both maps but value differs)
new_stats_deduped
.iter()
.filter(|(new_key, _new_val)| old_stats_deduped.get::<str>(&new_key).is_some())
.for_each(|(new_key, new_val)| {
let old_val = old_stats_deduped.get::<str>(&new_key).unwrap();
println!("{} {} => {}", new_key, old_val, new_val);
});
// list all gone counts (key is in old status but not in new stats)
old_stats_deduped
.iter()
.filter(|(old_key, _)| new_stats_deduped.get::<&String>(&old_key).is_none())
.for_each(|(old_key, old_value)| {
println!("{} {} => 0", old_key, old_value);
});
}
/// Create necessary directories to run the lintcheck tool.
///
/// # Panics
///
/// This function panics if creating one of the dirs fails.
fn create_dirs(krate_download_dir: &Path, extract_dir: &Path) {
std::fs::create_dir("target/lintcheck/").unwrap_or_else(|err| {
if err.kind() != ErrorKind::AlreadyExists {
panic!("cannot create lintcheck target dir");
}
});
std::fs::create_dir(&krate_download_dir).unwrap_or_else(|err| {
if err.kind() != ErrorKind::AlreadyExists {
panic!("cannot create crate download dir");
}
});
std::fs::create_dir(&extract_dir).unwrap_or_else(|err| {
if err.kind() != ErrorKind::AlreadyExists {
panic!("cannot create crate extraction dir");
}
});
}
#[test]
fn lintcheck_test() {
let args = [
"run",
"--target-dir",
"clippy_dev/target",
"--package",
"clippy_dev",
"--bin",
"clippy_dev",
"--manifest-path",
"clippy_dev/Cargo.toml",
"--features",
"lintcheck",
"--",
"lintcheck",
"--crates-toml",
"clippy_dev/test_sources.toml",
];
let status = std::process::Command::new("cargo")
.args(&args)
.current_dir("../" /* repo root */)
.status();
assert!(status.unwrap().success());
}

3
clippy_dev/src/main.rs
View file

@ -77,7 +77,8 @@ fn get_clap_config<'a>() -> ArgMatches<'a> {
.short("j")
.long("jobs")
.help("number of threads to use, 0 automatic choice"),
);
)
.arg(Arg::with_name("fix").help("runs cargo clippy --fix and checks if all suggestions apply"));
let app = App::new("Clippy developer tooling")
.subcommand(

4
clippy_dev/test_sources.toml Normal file
View file

@ -0,0 +1,4 @@
[crates]
cc = {name = "cc", versions = ['1.0.67']}
home = {name = "home", git_url = "https://github.com/brson/home", git_hash = "32044e53dfbdcd32bafad3109d1fbab805fc0f40"}
rustc_tools_util = {name = "rustc_tools_util", versions = ['0.2.0']}

2
clippy_dummy/Cargo.toml
View file

@ -1,7 +1,7 @@
[package]
name = "clippy_dummy" # rename to clippy before publishing
version = "0.0.303"
authors = ["Manish Goregaokar <manishsmail@gmail.com>"]
authors = ["The Rust Clippy Developers"]
edition = "2018"
readme = "crates-readme.md"
description = "A bunch of helpful lints to avoid common pitfalls in Rust."

15
clippy_lints/Cargo.toml
View file

@ -3,12 +3,7 @@ name = "clippy_lints"
# begin automatic update
version = "0.1.52"
# end automatic update
authors = [
"Manish Goregaokar <manishsmail@gmail.com>",
"Andre Bogus <bogusandre@gmail.com>",
"Georg Brandl <georg@python.org>",
"Martin Carton <cartonmartin@gmail.com>"
]
authors = ["The Rust Clippy Developers"]
description = "A bunch of helpful lints to avoid common pitfalls in Rust"
repository = "https://github.com/rust-lang/rust-clippy"
readme = "README.md"
@ -29,10 +24,10 @@ smallvec = { version = "1", features = ["union"] }
toml = "0.5.3"
unicode-normalization = "0.1"
semver = "0.11"
rustc-semver="1.1.0"
rustc-semver = "1.1.0"
# NOTE: cargo requires serde feat in its url dep
# see <https://github.com/rust-lang/rust/pull/63587#issuecomment-522343864>
url = { version = "2.1.0", features = ["serde"] }
url = { version = "2.1.0", features = ["serde"] }
quote = "1"
syn = { version = "1", features = ["full"] }
@ -40,3 +35,7 @@ syn = { version = "1", features = ["full"] }
deny-warnings = []
# build clippy with internal lints enabled, off by default
internal-lints = ["clippy_utils/internal-lints"]
[package.metadata.rust-analyzer]
# This crate uses #[feature(rustc_private)]
rustc_private = true

2
clippy_lints/src/assign_ops.rs
View file

@ -209,7 +209,7 @@ fn lint_misrefactored_assign_op(
diag.span_suggestion(
expr.span,
&format!(
"Did you mean `{} = {} {} {}` or `{}`? Consider replacing it with",
"did you mean `{} = {} {} {}` or `{}`? Consider replacing it with",
snip_a,
snip_a,
op.node.as_str(),

3
clippy_lints/src/async_yields_async.rs
View file

@ -50,8 +50,7 @@ impl<'tcx> LateLintPass<'tcx> for AsyncYieldsAsync {
let body_id = BodyId {
hir_id: body.value.hir_id,
};
let def_id = cx.tcx.hir().body_owner_def_id(body_id);
let typeck_results = cx.tcx.typeck(def_id);
let typeck_results = cx.tcx.typeck_body(body_id);
let expr_ty = typeck_results.expr_ty(&body.value);
if implements_trait(cx, expr_ty, future_trait_def_id, &[]) {

2
clippy_lints/src/attrs.rs
View file

@ -640,7 +640,7 @@ fn check_mismatched_target_os(cx: &EarlyContext<'_>, attr: &Attribute) {
diag.span_suggestion(span, "try", sugg, Applicability::MaybeIncorrect);
if !unix_suggested && is_unix(os) {
diag.help("Did you mean `unix`?");
diag.help("did you mean `unix`?");
unix_suggested = true;
}
}

19
clippy_lints/src/await_holding_invalid.rs
View file

@ -97,8 +97,7 @@ impl LateLintPass<'_> for AwaitHolding {
let body_id = BodyId {
hir_id: body.value.hir_id,
};
let def_id = cx.tcx.hir().body_owner_def_id(body_id);
let typeck_results = cx.tcx.typeck(def_id);
let typeck_results = cx.tcx.typeck_body(body_id);
check_interior_types(
cx,
&typeck_results.generator_interior_types.as_ref().skip_binder(),
@ -116,20 +115,20 @@ fn check_interior_types(cx: &LateContext<'_>, ty_causes: &[GeneratorInteriorType
cx,
AWAIT_HOLDING_LOCK,
ty_cause.span,
"this MutexGuard is held across an 'await' point. Consider using an async-aware Mutex type or ensuring the MutexGuard is dropped before calling await.",
"this MutexGuard is held across an 'await' point. Consider using an async-aware Mutex type or ensuring the MutexGuard is dropped before calling await",
ty_cause.scope_span.or(Some(span)),
"these are all the await points this lock is held through",
);
}
if is_refcell_ref(cx, adt.did) {
span_lint_and_note(
cx,
AWAIT_HOLDING_REFCELL_REF,
ty_cause.span,
"this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await.",
ty_cause.scope_span.or(Some(span)),
"these are all the await points this ref is held through",
);
cx,
AWAIT_HOLDING_REFCELL_REF,
ty_cause.span,
"this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await",
ty_cause.scope_span.or(Some(span)),
"these are all the await points this ref is held through",
);
}
}
}

2
clippy_lints/src/bytecount.rs
View file

@ -28,7 +28,7 @@ declare_clippy_lint! {
/// &vec.iter().filter(|x| **x == 0u8).count(); // use bytecount::count instead
/// ```
pub NAIVE_BYTECOUNT,
perf,
pedantic,
"use of naive `<slice>.filter(|&x| x == y).count()` to count byte values"
}

7
clippy_lints/src/case_sensitive_file_extension_comparisons.rs
View file

@ -1,12 +1,11 @@
use crate::utils::paths::STRING;
use crate::utils::{match_def_path, span_lint_and_help};
use crate::utils::span_lint_and_help;
use if_chain::if_chain;
use rustc_ast::ast::LitKind;
use rustc_hir::{Expr, ExprKind, PathSegment};
use rustc_lint::{LateContext, LateLintPass};
use rustc_middle::ty;
use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_span::{source_map::Spanned, Span};
use rustc_span::{source_map::Spanned, symbol::sym, Span};
declare_clippy_lint! {
/// **What it does:**
@ -59,7 +58,7 @@ fn check_case_sensitive_file_extension_comparison(ctx: &LateContext<'_>, expr: &
return Some(span);
},
ty::Adt(&ty::AdtDef { did, .. }, _) => {
if match_def_path(ctx, did, &STRING) {
if ctx.tcx.is_diagnostic_item(sym::string_type, did) {
return Some(span);
}
},

87
clippy_lints/src/casts/cast_lossless.rs Normal file
View file

@ -0,0 +1,87 @@
use rustc_errors::Applicability;
use rustc_hir::{Expr, ExprKind};
use rustc_lint::LateContext;
use rustc_middle::ty::{self, FloatTy, Ty};
use crate::utils::{in_constant, is_isize_or_usize, snippet_opt, span_lint_and_sugg};
use super::{utils, CAST_LOSSLESS};
pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>, cast_op: &Expr<'_>, cast_from: Ty<'_>, cast_to: Ty<'_>) {
if !should_lint(cx, expr, cast_from, cast_to) {
return;
}
// The suggestion is to use a function call, so if the original expression
// has parens on the outside, they are no longer needed.
let mut applicability = Applicability::MachineApplicable;
let opt = snippet_opt(cx, cast_op.span);
let sugg = opt.as_ref().map_or_else(
|| {
applicability = Applicability::HasPlaceholders;
".."
},
|snip| {
if should_strip_parens(cast_op, snip) {
&snip[1..snip.len() - 1]
} else {
snip.as_str()
}
},
);
span_lint_and_sugg(
cx,
CAST_LOSSLESS,
expr.span,
&format!(
"casting `{}` to `{}` may become silently lossy if you later change the type",
cast_from, cast_to
),
"try",
format!("{}::from({})", cast_to, sugg),
applicability,
);
}
fn should_lint(cx: &LateContext<'_>, expr: &Expr<'_>, cast_from: Ty<'_>, cast_to: Ty<'_>) -> bool {
// Do not suggest using From in consts/statics until it is valid to do so (see #2267).
if in_constant(cx, expr.hir_id) {
return false;
}
match (cast_from.is_integral(), cast_to.is_integral()) {
(true, true) => {
let cast_signed_to_unsigned = cast_from.is_signed() && !cast_to.is_signed();
let from_nbits = utils::int_ty_to_nbits(cast_from, cx.tcx);
let to_nbits = utils::int_ty_to_nbits(cast_to, cx.tcx);
!is_isize_or_usize(cast_from)
&& !is_isize_or_usize(cast_to)
&& from_nbits < to_nbits
&& !cast_signed_to_unsigned
},
(true, false) => {
let from_nbits = utils::int_ty_to_nbits(cast_from, cx.tcx);
let to_nbits = if let ty::Float(FloatTy::F32) = cast_to.kind() {
32
} else {
64
};
from_nbits < to_nbits
},
(_, _) => {
matches!(cast_from.kind(), ty::Float(FloatTy::F32)) && matches!(cast_to.kind(), ty::Float(FloatTy::F64))
},
}
}
fn should_strip_parens(cast_expr: &Expr<'_>, snip: &str) -> bool {
if let ExprKind::Binary(_, _, _) = cast_expr.kind {
if snip.starts_with('(') && snip.ends_with(')') {
return true;
}
}
false
}

54
clippy_lints/src/casts/cast_possible_truncation.rs Normal file
View file

@ -0,0 +1,54 @@
use rustc_hir::Expr;
use rustc_lint::LateContext;
use rustc_middle::ty::{self, FloatTy, Ty};
use crate::utils::{is_isize_or_usize, span_lint};
use super::{utils, CAST_POSSIBLE_TRUNCATION};
pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>, cast_from: Ty<'_>, cast_to: Ty<'_>) {
let msg = match (cast_from.is_integral(), cast_to.is_integral()) {
(true, true) => {
let from_nbits = utils::int_ty_to_nbits(cast_from, cx.tcx);
let to_nbits = utils::int_ty_to_nbits(cast_to, cx.tcx);
let (should_lint, suffix) = match (is_isize_or_usize(cast_from), is_isize_or_usize(cast_to)) {
(true, true) | (false, false) => (to_nbits < from_nbits, ""),
(true, false) => (
to_nbits <= 32,
if to_nbits == 32 {
" on targets with 64-bit wide pointers"
} else {
""
},
),
(false, true) => (from_nbits == 64, " on targets with 32-bit wide pointers"),
};
if !should_lint {
return;
}
format!(
"casting `{}` to `{}` may truncate the value{}",
cast_from, cast_to, suffix,
)
},
(false, true) => {
format!("casting `{}` to `{}` may truncate the value", cast_from, cast_to)
},
(_, _) => {
if matches!(cast_from.kind(), &ty::Float(FloatTy::F64))
&& matches!(cast_to.kind(), &ty::Float(FloatTy::F32))
{
"casting `f64` to `f32` may truncate the value".to_string()
} else {
return;
}
},
};
span_lint(cx, CAST_POSSIBLE_TRUNCATION, expr.span, &msg);
}

44
clippy_lints/src/casts/cast_possible_wrap.rs Normal file
View file

@ -0,0 +1,44 @@
use rustc_hir::Expr;
use rustc_lint::LateContext;
use rustc_middle::ty::Ty;
use crate::utils::{is_isize_or_usize, span_lint};
use super::{utils, CAST_POSSIBLE_WRAP};
pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>, cast_from: Ty<'_>, cast_to: Ty<'_>) {
if !(cast_from.is_integral() && cast_to.is_integral()) {
return;
}
let arch_64_suffix = " on targets with 64-bit wide pointers";
let arch_32_suffix = " on targets with 32-bit wide pointers";
let cast_unsigned_to_signed = !cast_from.is_signed() && cast_to.is_signed();
let from_nbits = utils::int_ty_to_nbits(cast_from, cx.tcx);
let to_nbits = utils::int_ty_to_nbits(cast_to, cx.tcx);
let (should_lint, suffix) = match (is_isize_or_usize(cast_from), is_isize_or_usize(cast_to)) {
(true, true) | (false, false) => (to_nbits == from_nbits && cast_unsigned_to_signed, ""),
(true, false) => (to_nbits <= 32 && cast_unsigned_to_signed, arch_32_suffix),
(false, true) => (
cast_unsigned_to_signed,
if from_nbits == 64 {
arch_64_suffix
} else {
arch_32_suffix
},
),
};
if should_lint {
span_lint(
cx,
CAST_POSSIBLE_WRAP,
expr.span,
&format!(
"casting `{}` to `{}` may wrap around the value{}",
cast_from, cast_to, suffix,
),
);
}
}

51
clippy_lints/src/casts/cast_precision_loss.rs Normal file
View file

@ -0,0 +1,51 @@
use rustc_hir::Expr;
use rustc_lint::LateContext;
use rustc_middle::ty::{self, FloatTy, Ty};
use crate::utils::{is_isize_or_usize, span_lint};
use super::{utils, CAST_PRECISION_LOSS};
pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>, cast_from: Ty<'_>, cast_to: Ty<'_>) {
if !cast_from.is_integral() || cast_to.is_integral() {
return;
}
let from_nbits = utils::int_ty_to_nbits(cast_from, cx.tcx);
let to_nbits = if let ty::Float(FloatTy::F32) = cast_to.kind() {
32
} else {
64
};
if !(is_isize_or_usize(cast_from) || from_nbits >= to_nbits) {
return;
}
let cast_to_f64 = to_nbits == 64;
let mantissa_nbits = if cast_to_f64 { 52 } else { 23 };
let arch_dependent = is_isize_or_usize(cast_from) && cast_to_f64;
let arch_dependent_str = "on targets with 64-bit wide pointers ";
let from_nbits_str = if arch_dependent {
"64".to_owned()
} else if is_isize_or_usize(cast_from) {
"32 or 64".to_owned()
} else {
utils::int_ty_to_nbits(cast_from, cx.tcx).to_string()
};
span_lint(
cx,
CAST_PRECISION_LOSS,
expr.span,
&format!(
"casting `{0}` to `{1}` causes a loss of precision {2}(`{0}` is {3} bits wide, \
but `{1}`'s mantissa is only {4} bits wide)",
cast_from,
if cast_to_f64 { "f64" } else { "f32" },
if arch_dependent { arch_dependent_str } else { "" },
from_nbits_str,
mantissa_nbits
),
);
}

81
clippy_lints/src/casts/cast_ptr_alignment.rs Normal file
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use rustc_hir::{Expr, ExprKind, GenericArg};
use rustc_lint::LateContext;
use rustc_middle::ty::{self, Ty};
use rustc_span::symbol::sym;
use rustc_target::abi::LayoutOf;
use if_chain::if_chain;
use crate::utils::{is_hir_ty_cfg_dependant, span_lint};
use super::CAST_PTR_ALIGNMENT;
pub(super) fn check(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
if let ExprKind::Cast(ref cast_expr, cast_to) = expr.kind {
if is_hir_ty_cfg_dependant(cx, cast_to) {
return;
}
let (cast_from, cast_to) = (
cx.typeck_results().expr_ty(cast_expr),
cx.typeck_results().expr_ty(expr),
);
lint_cast_ptr_alignment(cx, expr, cast_from, cast_to);
} else if let ExprKind::MethodCall(method_path, _, args, _) = expr.kind {
if_chain! {
if method_path.ident.name == sym!(cast);
if let Some(generic_args) = method_path.args;
if let [GenericArg::Type(cast_to)] = generic_args.args;
// There probably is no obvious reason to do this, just to be consistent with `as` cases.
if !is_hir_ty_cfg_dependant(cx, cast_to);
then {
let (cast_from, cast_to) =
(cx.typeck_results().expr_ty(&args[0]), cx.typeck_results().expr_ty(expr));
lint_cast_ptr_alignment(cx, expr, cast_from, cast_to);
}
}
}
}
fn lint_cast_ptr_alignment<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'_>, cast_from: Ty<'tcx>, cast_to: Ty<'tcx>) {
if_chain! {
if let ty::RawPtr(from_ptr_ty) = &cast_from.kind();
if let ty::RawPtr(to_ptr_ty) = &cast_to.kind();
if let Ok(from_layout) = cx.layout_of(from_ptr_ty.ty);
if let Ok(to_layout) = cx.layout_of(to_ptr_ty.ty);
if from_layout.align.abi < to_layout.align.abi;
// with c_void, we inherently need to trust the user
if !is_c_void(cx, from_ptr_ty.ty);
// when casting from a ZST, we don't know enough to properly lint
if !from_layout.is_zst();
then {
span_lint(
cx,
CAST_PTR_ALIGNMENT,
expr.span,
&format!(
"casting from `{}` to a more-strictly-aligned pointer (`{}`) ({} < {} bytes)",
cast_from,
cast_to,
from_layout.align.abi.bytes(),
to_layout.align.abi.bytes(),
),
);
}
}
}
/// Check if the given type is either `core::ffi::c_void` or
/// one of the platform specific `libc::<platform>::c_void` of libc.
fn is_c_void(cx: &LateContext<'_>, ty: Ty<'_>) -> bool {
if let ty::Adt(adt, _) = ty.kind() {
let names = cx.get_def_path(adt.did);
if names.is_empty() {
return false;
}
if names[0] == sym::libc || names[0] == sym::core && *names.last().unwrap() == sym!(c_void) {
return true;
}
}
false
}

28
clippy_lints/src/casts/cast_ref_to_mut.rs Normal file
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use rustc_hir::{Expr, ExprKind, MutTy, Mutability, TyKind, UnOp};
use rustc_lint::LateContext;
use rustc_middle::ty;
use if_chain::if_chain;
use crate::utils::span_lint;
use super::CAST_REF_TO_MUT;
pub(super) fn check(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
if_chain! {
if let ExprKind::Unary(UnOp::Deref, e) = &expr.kind;
if let ExprKind::Cast(e, t) = &e.kind;
if let TyKind::Ptr(MutTy { mutbl: Mutability::Mut, .. }) = t.kind;
if let ExprKind::Cast(e, t) = &e.kind;
if let TyKind::Ptr(MutTy { mutbl: Mutability::Not, .. }) = t.kind;
if let ty::Ref(..) = cx.typeck_results().node_type(e.hir_id).kind();
then {
span_lint(
cx,
CAST_REF_TO_MUT,
expr.span,
"casting `&T` to `&mut T` may cause undefined behavior, consider instead using an `UnsafeCell`",
);
}
}
}

70
clippy_lints/src/casts/cast_sign_loss.rs Normal file
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use rustc_hir::{Expr, ExprKind};
use rustc_lint::LateContext;
use rustc_middle::ty::{self, Ty};
use if_chain::if_chain;
use crate::consts::{constant, Constant};
use crate::utils::{method_chain_args, sext, span_lint};
use super::CAST_SIGN_LOSS;
pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>, cast_op: &Expr<'_>, cast_from: Ty<'_>, cast_to: Ty<'_>) {
if should_lint(cx, cast_op, cast_from, cast_to) {
span_lint(
cx,
CAST_SIGN_LOSS,
expr.span,
&format!(
"casting `{}` to `{}` may lose the sign of the value",
cast_from, cast_to
),
);
}
}
fn should_lint(cx: &LateContext<'_>, cast_op: &Expr<'_>, cast_from: Ty<'_>, cast_to: Ty<'_>) -> bool {
match (cast_from.is_integral(), cast_to.is_integral()) {
(true, true) => {
if !cast_from.is_signed() || cast_to.is_signed() {
return false;
}
// Don't lint for positive constants.
let const_val = constant(cx, &cx.typeck_results(), cast_op);
if_chain! {
if let Some((Constant::Int(n), _)) = const_val;
if let ty::Int(ity) = *cast_from.kind();
if sext(cx.tcx, n, ity) >= 0;
then {
return false;
}
}
// Don't lint for the result of methods that always return non-negative values.
if let ExprKind::MethodCall(ref path, _, _, _) = cast_op.kind {
let mut method_name = path.ident.name.as_str();
let allowed_methods = ["abs", "checked_abs", "rem_euclid", "checked_rem_euclid"];
if_chain! {
if method_name == "unwrap";
if let Some(arglist) = method_chain_args(cast_op, &["unwrap"]);
if let ExprKind::MethodCall(ref inner_path, _, _, _) = &arglist[0][0].kind;
then {
method_name = inner_path.ident.name.as_str();
}
}
if allowed_methods.iter().any(|&name| method_name == name) {
return false;
}
}
true
},
(false, true) => !cast_to.is_signed(),
(_, _) => false,
}
}

42
clippy_lints/src/casts/char_lit_as_u8.rs Normal file
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@ -0,0 +1,42 @@
use rustc_ast::LitKind;
use rustc_errors::Applicability;
use rustc_hir::{Expr, ExprKind};
use rustc_lint::LateContext;
use rustc_middle::ty::{self, UintTy};
use if_chain::if_chain;
use crate::utils::{snippet_with_applicability, span_lint_and_then};
use super::CHAR_LIT_AS_U8;
pub(super) fn check(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
if_chain! {
if let ExprKind::Cast(e, _) = &expr.kind;
if let ExprKind::Lit(l) = &e.kind;
if let LitKind::Char(c) = l.node;
if ty::Uint(UintTy::U8) == *cx.typeck_results().expr_ty(expr).kind();
then {
let mut applicability = Applicability::MachineApplicable;
let snippet = snippet_with_applicability(cx, e.span, "'x'", &mut applicability);
span_lint_and_then(
cx,
CHAR_LIT_AS_U8,
expr.span,
"casting a character literal to `u8` truncates",
|diag| {
diag.note("`char` is four bytes wide, but `u8` is a single byte");
if c.is_ascii() {
diag.span_suggestion(
expr.span,
"use a byte literal instead",
format!("b{}", snippet),
applicability,
);
}
});
}
}
}

37
clippy_lints/src/casts/fn_to_numeric_cast.rs Normal file
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@ -0,0 +1,37 @@
use rustc_errors::Applicability;
use rustc_hir::Expr;
use rustc_lint::LateContext;
use rustc_middle::ty::{self, Ty, UintTy};
use crate::utils::{snippet_with_applicability, span_lint_and_sugg};
use super::{utils, FN_TO_NUMERIC_CAST};
pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>, cast_expr: &Expr<'_>, cast_from: Ty<'_>, cast_to: Ty<'_>) {
// We only want to check casts to `ty::Uint` or `ty::Int`
match cast_to.kind() {
ty::Uint(_) | ty::Int(..) => { /* continue on */ },
_ => return,
}
match cast_from.kind() {
ty::FnDef(..) | ty::FnPtr(_) => {
let mut applicability = Applicability::MaybeIncorrect;
let from_snippet = snippet_with_applicability(cx, cast_expr.span, "x", &mut applicability);
let to_nbits = utils::int_ty_to_nbits(cast_to, cx.tcx);
if (to_nbits >= cx.tcx.data_layout.pointer_size.bits()) && (*cast_to.kind() != ty::Uint(UintTy::Usize)) {
span_lint_and_sugg(
cx,
FN_TO_NUMERIC_CAST,
expr.span,
&format!("casting function pointer `{}` to `{}`", from_snippet, cast_to),
"try",
format!("{} as usize", from_snippet),
applicability,
);
}
},
_ => {},
}
}

39
clippy_lints/src/casts/fn_to_numeric_cast_with_truncation.rs Normal file
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@ -0,0 +1,39 @@
use rustc_errors::Applicability;
use rustc_hir::Expr;
use rustc_lint::LateContext;
use rustc_middle::ty::{self, Ty};
use crate::utils::{snippet_with_applicability, span_lint_and_sugg};
use super::{utils, FN_TO_NUMERIC_CAST_WITH_TRUNCATION};
pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>, cast_expr: &Expr<'_>, cast_from: Ty<'_>, cast_to: Ty<'_>) {
// We only want to check casts to `ty::Uint` or `ty::Int`
match cast_to.kind() {
ty::Uint(_) | ty::Int(..) => { /* continue on */ },
_ => return,
}
match cast_from.kind() {
ty::FnDef(..) | ty::FnPtr(_) => {
let mut applicability = Applicability::MaybeIncorrect;
let from_snippet = snippet_with_applicability(cx, cast_expr.span, "x", &mut applicability);
let to_nbits = utils::int_ty_to_nbits(cast_to, cx.tcx);
if to_nbits < cx.tcx.data_layout.pointer_size.bits() {
span_lint_and_sugg(
cx,
FN_TO_NUMERIC_CAST_WITH_TRUNCATION,
expr.span,
&format!(
"casting function pointer `{}` to `{}`, which truncates the value",
from_snippet, cast_to
),
"try",
format!("{} as usize", from_snippet),
applicability,
);
}
},
_ => {},
}
}

407
clippy_lints/src/casts/mod.rs Normal file
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mod cast_lossless;
mod cast_possible_truncation;
mod cast_possible_wrap;
mod cast_precision_loss;
mod cast_ptr_alignment;
mod cast_ref_to_mut;
mod cast_sign_loss;
mod char_lit_as_u8;
mod fn_to_numeric_cast;
mod fn_to_numeric_cast_with_truncation;
mod ptr_as_ptr;
mod unnecessary_cast;
mod utils;
use rustc_hir::{Expr, ExprKind};
use rustc_lint::{LateContext, LateLintPass, LintContext};
use rustc_middle::lint::in_external_macro;
use rustc_semver::RustcVersion;
use rustc_session::{declare_tool_lint, impl_lint_pass};
use crate::utils::is_hir_ty_cfg_dependant;
declare_clippy_lint! {
/// **What it does:** Checks for casts from any numerical to a float type where
/// the receiving type cannot store all values from the original type without
/// rounding errors. This possible rounding is to be expected, so this lint is
/// `Allow` by default.
///
/// Basically, this warns on casting any integer with 32 or more bits to `f32`
/// or any 64-bit integer to `f64`.
///
/// **Why is this bad?** It's not bad at all. But in some applications it can be
/// helpful to know where precision loss can take place. This lint can help find
/// those places in the code.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// let x = u64::MAX;
/// x as f64;
/// ```
pub CAST_PRECISION_LOSS,
pedantic,
"casts that cause loss of precision, e.g., `x as f32` where `x: u64`"
}
declare_clippy_lint! {
/// **What it does:** Checks for casts from a signed to an unsigned numerical
/// type. In this case, negative values wrap around to large positive values,
/// which can be quite surprising in practice. However, as the cast works as
/// defined, this lint is `Allow` by default.
///
/// **Why is this bad?** Possibly surprising results. You can activate this lint
/// as a one-time check to see where numerical wrapping can arise.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// let y: i8 = -1;
/// y as u128; // will return 18446744073709551615
/// ```
pub CAST_SIGN_LOSS,
pedantic,
"casts from signed types to unsigned types, e.g., `x as u32` where `x: i32`"
}
declare_clippy_lint! {
/// **What it does:** Checks for casts between numerical types that may
/// truncate large values. This is expected behavior, so the cast is `Allow` by
/// default.
///
/// **Why is this bad?** In some problem domains, it is good practice to avoid
/// truncation. This lint can be activated to help assess where additional
/// checks could be beneficial.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// fn as_u8(x: u64) -> u8 {
/// x as u8
/// }
/// ```
pub CAST_POSSIBLE_TRUNCATION,
pedantic,
"casts that may cause truncation of the value, e.g., `x as u8` where `x: u32`, or `x as i32` where `x: f32`"
}
declare_clippy_lint! {
/// **What it does:** Checks for casts from an unsigned type to a signed type of
/// the same size. Performing such a cast is a 'no-op' for the compiler,
/// i.e., nothing is changed at the bit level, and the binary representation of
/// the value is reinterpreted. This can cause wrapping if the value is too big
/// for the target signed type. However, the cast works as defined, so this lint
/// is `Allow` by default.
///
/// **Why is this bad?** While such a cast is not bad in itself, the results can
/// be surprising when this is not the intended behavior, as demonstrated by the
/// example below.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// u32::MAX as i32; // will yield a value of `-1`
/// ```
pub CAST_POSSIBLE_WRAP,
pedantic,
"casts that may cause wrapping around the value, e.g., `x as i32` where `x: u32` and `x > i32::MAX`"
}
declare_clippy_lint! {
/// **What it does:** Checks for casts between numerical types that may
/// be replaced by safe conversion functions.
///
/// **Why is this bad?** Rust's `as` keyword will perform many kinds of
/// conversions, including silently lossy conversions. Conversion functions such
/// as `i32::from` will only perform lossless conversions. Using the conversion
/// functions prevents conversions from turning into silent lossy conversions if
/// the types of the input expressions ever change, and make it easier for
/// people reading the code to know that the conversion is lossless.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// fn as_u64(x: u8) -> u64 {
/// x as u64
/// }
/// ```
///
/// Using `::from` would look like this:
///
/// ```rust
/// fn as_u64(x: u8) -> u64 {
/// u64::from(x)
/// }
/// ```
pub CAST_LOSSLESS,
pedantic,
"casts using `as` that are known to be lossless, e.g., `x as u64` where `x: u8`"
}
declare_clippy_lint! {
/// **What it does:** Checks for casts to the same type, casts of int literals to integer types
/// and casts of float literals to float types.
///
/// **Why is this bad?** It's just unnecessary.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// let _ = 2i32 as i32;
/// let _ = 0.5 as f32;
/// ```
///
/// Better:
///
/// ```rust
/// let _ = 2_i32;
/// let _ = 0.5_f32;
/// ```
pub UNNECESSARY_CAST,
complexity,
"cast to the same type, e.g., `x as i32` where `x: i32`"
}
declare_clippy_lint! {
/// **What it does:** Checks for casts, using `as` or `pointer::cast`,
/// from a less-strictly-aligned pointer to a more-strictly-aligned pointer
///
/// **Why is this bad?** Dereferencing the resulting pointer may be undefined
/// behavior.
///
/// **Known problems:** Using `std::ptr::read_unaligned` and `std::ptr::write_unaligned` or similar
/// on the resulting pointer is fine. Is over-zealous: Casts with manual alignment checks or casts like
/// u64-> u8 -> u16 can be fine. Miri is able to do a more in-depth analysis.
///
/// **Example:**
/// ```rust
/// let _ = (&1u8 as *const u8) as *const u16;
/// let _ = (&mut 1u8 as *mut u8) as *mut u16;
///
/// (&1u8 as *const u8).cast::<u16>();
/// (&mut 1u8 as *mut u8).cast::<u16>();
/// ```
pub CAST_PTR_ALIGNMENT,
pedantic,
"cast from a pointer to a more-strictly-aligned pointer"
}
declare_clippy_lint! {
/// **What it does:** Checks for casts of function pointers to something other than usize
///
/// **Why is this bad?**
/// Casting a function pointer to anything other than usize/isize is not portable across
/// architectures, because you end up losing bits if the target type is too small or end up with a
/// bunch of extra bits that waste space and add more instructions to the final binary than
/// strictly necessary for the problem
///
/// Casting to isize also doesn't make sense since there are no signed addresses.
///
/// **Example**
///
/// ```rust
/// // Bad
/// fn fun() -> i32 { 1 }
/// let a = fun as i64;
///
/// // Good
/// fn fun2() -> i32 { 1 }
/// let a = fun2 as usize;
/// ```
pub FN_TO_NUMERIC_CAST,
style,
"casting a function pointer to a numeric type other than usize"
}
declare_clippy_lint! {
/// **What it does:** Checks for casts of a function pointer to a numeric type not wide enough to
/// store address.
///
/// **Why is this bad?**
/// Such a cast discards some bits of the function's address. If this is intended, it would be more
/// clearly expressed by casting to usize first, then casting the usize to the intended type (with
/// a comment) to perform the truncation.
///
/// **Example**
///
/// ```rust
/// // Bad
/// fn fn1() -> i16 {
/// 1
/// };
/// let _ = fn1 as i32;
///
/// // Better: Cast to usize first, then comment with the reason for the truncation
/// fn fn2() -> i16 {
/// 1
/// };
/// let fn_ptr = fn2 as usize;
/// let fn_ptr_truncated = fn_ptr as i32;
/// ```
pub FN_TO_NUMERIC_CAST_WITH_TRUNCATION,
style,
"casting a function pointer to a numeric type not wide enough to store the address"
}
declare_clippy_lint! {
/// **What it does:** Checks for casts of `&T` to `&mut T` anywhere in the code.
///
/// **Why is this bad?** It’s basically guaranteed to be undefined behaviour.
/// `UnsafeCell` is the only way to obtain aliasable data that is considered
/// mutable.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust,ignore
/// fn x(r: &i32) {
/// unsafe {
/// *(r as *const _ as *mut _) += 1;
/// }
/// }
/// ```
///
/// Instead consider using interior mutability types.
///
/// ```rust
/// use std::cell::UnsafeCell;
///
/// fn x(r: &UnsafeCell<i32>) {
/// unsafe {
/// *r.get() += 1;
/// }
/// }
/// ```
pub CAST_REF_TO_MUT,
correctness,
"a cast of reference to a mutable pointer"
}
declare_clippy_lint! {
/// **What it does:** Checks for expressions where a character literal is cast
/// to `u8` and suggests using a byte literal instead.
///
/// **Why is this bad?** In general, casting values to smaller types is
/// error-prone and should be avoided where possible. In the particular case of
/// converting a character literal to u8, it is easy to avoid by just using a
/// byte literal instead. As an added bonus, `b'a'` is even slightly shorter
/// than `'a' as u8`.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust,ignore
/// 'x' as u8
/// ```
///
/// A better version, using the byte literal:
///
/// ```rust,ignore
/// b'x'
/// ```
pub CHAR_LIT_AS_U8,
complexity,
"casting a character literal to `u8` truncates"
}
declare_clippy_lint! {
/// **What it does:**
/// Checks for `as` casts between raw pointers without changing its mutability,
/// namely `*const T` to `*const U` and `*mut T` to `*mut U`.
///
/// **Why is this bad?**
/// Though `as` casts between raw pointers is not terrible, `pointer::cast` is safer because
/// it cannot accidentally change the pointer's mutability nor cast the pointer to other types like `usize`.
///
/// **Known problems:** None.
///
/// **Example:**
///
/// ```rust
/// let ptr: *const u32 = &42_u32;
/// let mut_ptr: *mut u32 = &mut 42_u32;
/// let _ = ptr as *const i32;
/// let _ = mut_ptr as *mut i32;
/// ```
/// Use instead:
/// ```rust
/// let ptr: *const u32 = &42_u32;
/// let mut_ptr: *mut u32 = &mut 42_u32;
/// let _ = ptr.cast::<i32>();
/// let _ = mut_ptr.cast::<i32>();
/// ```
pub PTR_AS_PTR,
pedantic,
"casting using `as` from and to raw pointers that doesn't change its mutability, where `pointer::cast` could take the place of `as`"
}
pub struct Casts {
msrv: Option<RustcVersion>,
}
impl Casts {
#[must_use]
pub fn new(msrv: Option<RustcVersion>) -> Self {
Self { msrv }
}
}
impl_lint_pass!(Casts => [
CAST_PRECISION_LOSS,
CAST_SIGN_LOSS,
CAST_POSSIBLE_TRUNCATION,
CAST_POSSIBLE_WRAP,
CAST_LOSSLESS,
CAST_REF_TO_MUT,
CAST_PTR_ALIGNMENT,
UNNECESSARY_CAST,
FN_TO_NUMERIC_CAST,
FN_TO_NUMERIC_CAST_WITH_TRUNCATION,
CHAR_LIT_AS_U8,
PTR_AS_PTR,
]);
impl<'tcx> LateLintPass<'tcx> for Casts {
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
if expr.span.from_expansion() {
return;
}
if let ExprKind::Cast(ref cast_expr, cast_to) = expr.kind {
if is_hir_ty_cfg_dependant(cx, cast_to) {
return;
}
let (cast_from, cast_to) = (
cx.typeck_results().expr_ty(cast_expr),
cx.typeck_results().expr_ty(expr),
);
if unnecessary_cast::check(cx, expr, cast_expr, cast_from, cast_to) {
return;
}
fn_to_numeric_cast::check(cx, expr, cast_expr, cast_from, cast_to);
fn_to_numeric_cast_with_truncation::check(cx, expr, cast_expr, cast_from, cast_to);
if cast_from.is_numeric() && cast_to.is_numeric() && !in_external_macro(cx.sess(), expr.span) {
cast_possible_truncation::check(cx, expr, cast_from, cast_to);
cast_possible_wrap::check(cx, expr, cast_from, cast_to);
cast_precision_loss::check(cx, expr, cast_from, cast_to);
cast_lossless::check(cx, expr, cast_expr, cast_from, cast_to);
cast_sign_loss::check(cx, expr, cast_expr, cast_from, cast_to);
}
}
cast_ref_to_mut::check(cx, expr);
cast_ptr_alignment::check(cx, expr);
char_lit_as_u8::check(cx, expr);
ptr_as_ptr::check(cx, expr, &self.msrv);
}
extract_msrv_attr!(LateContext);
}

52
clippy_lints/src/casts/ptr_as_ptr.rs Normal file
View file

@ -0,0 +1,52 @@
use std::borrow::Cow;
use rustc_errors::Applicability;
use rustc_hir::{Expr, ExprKind, Mutability, TyKind};
use rustc_lint::LateContext;
use rustc_middle::ty::{self, TypeAndMut};
use rustc_semver::RustcVersion;
use if_chain::if_chain;
use crate::utils::sugg::Sugg;
use crate::utils::{meets_msrv, span_lint_and_sugg};
use super::PTR_AS_PTR;
const PTR_AS_PTR_MSRV: RustcVersion = RustcVersion::new(1, 38, 0);
pub(super) fn check(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, msrv: &Option<RustcVersion>) {
if !meets_msrv(msrv.as_ref(), &PTR_AS_PTR_MSRV) {
return;
}
if_chain! {
if let ExprKind::Cast(cast_expr, cast_to_hir_ty) = expr.kind;
let (cast_from, cast_to) = (cx.typeck_results().expr_ty(cast_expr), cx.typeck_results().expr_ty(expr));
if let ty::RawPtr(TypeAndMut { mutbl: from_mutbl, .. }) = cast_from.kind();
if let ty::RawPtr(TypeAndMut { ty: to_pointee_ty, mutbl: to_mutbl }) = cast_to.kind();
if matches!((from_mutbl, to_mutbl),
(Mutability::Not, Mutability::Not) | (Mutability::Mut, Mutability::Mut));
// The `U` in `pointer::cast` have to be `Sized`
// as explained here: https://github.com/rust-lang/rust/issues/60602.
if to_pointee_ty.is_sized(cx.tcx.at(expr.span), cx.param_env);
then {
let mut applicability = Applicability::MachineApplicable;
let cast_expr_sugg = Sugg::hir_with_applicability(cx, cast_expr, "_", &mut applicability);
let turbofish = match &cast_to_hir_ty.kind {
TyKind::Infer => Cow::Borrowed(""),
TyKind::Ptr(mut_ty) if matches!(mut_ty.ty.kind, TyKind::Infer) => Cow::Borrowed(""),
_ => Cow::Owned(format!("::<{}>", to_pointee_ty)),
};
span_lint_and_sugg(
cx,
PTR_AS_PTR,
expr.span,
"`as` casting between raw pointers without changing its mutability",
"try `pointer::cast`, a safer alternative",
format!("{}.cast{}()", cast_expr_sugg.maybe_par(), turbofish),
applicability,
);
}
}
}

106
clippy_lints/src/casts/unnecessary_cast.rs Normal file
View file

@ -0,0 +1,106 @@
use rustc_ast::{LitFloatType, LitIntType, LitKind};
use rustc_errors::Applicability;
use rustc_hir::{Expr, ExprKind, Lit, UnOp};
use rustc_lint::{LateContext, LintContext};
use rustc_middle::lint::in_external_macro;
use rustc_middle::ty::{self, FloatTy, InferTy, Ty};
use if_chain::if_chain;
use crate::utils::{numeric_literal::NumericLiteral, snippet_opt, span_lint, span_lint_and_sugg};
use super::UNNECESSARY_CAST;
pub(super) fn check(
cx: &LateContext<'_>,
expr: &Expr<'_>,
cast_expr: &Expr<'_>,
cast_from: Ty<'_>,
cast_to: Ty<'_>,
) -> bool {
if let Some(lit) = get_numeric_literal(cast_expr) {
let literal_str = snippet_opt(cx, cast_expr.span).unwrap_or_default();
if_chain! {
if let LitKind::Int(n, _) = lit.node;
if let Some(src) = snippet_opt(cx, lit.span);
if cast_to.is_floating_point();
if let Some(num_lit) = NumericLiteral::from_lit_kind(&src, &lit.node);
let from_nbits = 128 - n.leading_zeros();
let to_nbits = fp_ty_mantissa_nbits(cast_to);
if from_nbits != 0 && to_nbits != 0 && from_nbits <= to_nbits && num_lit.is_decimal();
then {
let literal_str = if is_unary_neg(cast_expr) { format!("-{}", num_lit.integer) } else { num_lit.integer.into() };
lint_unnecessary_cast(cx, expr, &literal_str, cast_from, cast_to);
return true
}
}
match lit.node {
LitKind::Int(_, LitIntType::Unsuffixed) if cast_to.is_integral() => {
lint_unnecessary_cast(cx, expr, &literal_str, cast_from, cast_to);
},
LitKind::Float(_, LitFloatType::Unsuffixed) if cast_to.is_floating_point() => {
lint_unnecessary_cast(cx, expr, &literal_str, cast_from, cast_to);
},
LitKind::Int(_, LitIntType::Unsuffixed) | LitKind::Float(_, LitFloatType::Unsuffixed) => {},
_ => {
if cast_from.kind() == cast_to.kind() && !in_external_macro(cx.sess(), expr.span) {
span_lint(
cx,
UNNECESSARY_CAST,
expr.span,
&format!(
"casting to the same type is unnecessary (`{}` -> `{}`)",
cast_from, cast_to
),
);
return true;
}
},
}
}
false
}
fn lint_unnecessary_cast(cx: &LateContext<'_>, expr: &Expr<'_>, literal_str: &str, cast_from: Ty<'_>, cast_to: Ty<'_>) {
let literal_kind_name = if cast_from.is_integral() { "integer" } else { "float" };
span_lint_and_sugg(
cx,
UNNECESSARY_CAST,
expr.span,
&format!("casting {} literal to `{}` is unnecessary", literal_kind_name, cast_to),
"try",
format!("{}_{}", literal_str.trim_end_matches('.'), cast_to),
Applicability::MachineApplicable,
);
}
fn get_numeric_literal<'e>(expr: &'e Expr<'e>) -> Option<&'e Lit> {
match expr.kind {
ExprKind::Lit(ref lit) => Some(lit),
ExprKind::Unary(UnOp::Neg, e) => {
if let ExprKind::Lit(ref lit) = e.kind {
Some(lit)
} else {
None
}
},
_ => None,
}
}
/// Returns the mantissa bits wide of a fp type.
/// Will return 0 if the type is not a fp
fn fp_ty_mantissa_nbits(typ: Ty<'_>) -> u32 {
match typ.kind() {
ty::Float(FloatTy::F32) => 23,
ty::Float(FloatTy::F64) | ty::Infer(InferTy::FloatVar(_)) => 52,
_ => 0,
}
}
fn is_unary_neg(expr: &Expr<'_>) -> bool {
matches!(expr.kind, ExprKind::Unary(UnOp::Neg, _))
}

25
clippy_lints/src/casts/utils.rs Normal file
View file

@ -0,0 +1,25 @@
use rustc_middle::ty::{self, IntTy, Ty, TyCtxt, UintTy};
/// Returns the size in bits of an integral type.
/// Will return 0 if the type is not an int or uint variant
pub(super) fn int_ty_to_nbits(typ: Ty<'_>, tcx: TyCtxt<'_>) -> u64 {
match typ.kind() {
ty::Int(i) => match i {
IntTy::Isize => tcx.data_layout.pointer_size.bits(),
IntTy::I8 => 8,
IntTy::I16 => 16,
IntTy::I32 => 32,
IntTy::I64 => 64,
IntTy::I128 => 128,
},
ty::Uint(i) => match i {
UintTy::Usize => tcx.data_layout.pointer_size.bits(),
UintTy::U8 => 8,
UintTy::U16 => 16,
UintTy::U32 => 32,
UintTy::U64 => 64,
UintTy::U128 => 128,
},
_ => 0,
}
}

2
clippy_lints/src/comparison_chain.rs
View file

@ -117,7 +117,7 @@ impl<'tcx> LateLintPass<'tcx> for ComparisonChain {
expr.span,
"`if` chain can be rewritten with `match`",
None,
"Consider rewriting the `if` chain to use `cmp` and `match`.",
"consider rewriting the `if` chain to use `cmp` and `match`",
)
}
}

5
clippy_lints/src/default_numeric_fallback.rs
View file

@ -130,10 +130,9 @@ impl<'a, 'tcx> Visitor<'tcx> for NumericFallbackVisitor<'a, 'tcx> {
}
},
ExprKind::Struct(qpath, fields, base) => {
ExprKind::Struct(_, fields, base) => {
if_chain! {
if let Some(def_id) = self.cx.qpath_res(qpath, expr.hir_id).opt_def_id();
let ty = self.cx.tcx.type_of(def_id);
let ty = self.cx.typeck_results().expr_ty(expr);
if let Some(adt_def) = ty.ty_adt_def();
if adt_def.is_struct();
if let Some(variant) = adt_def.variants.iter().next();

9
clippy_lints/src/derive.rs
View file

@ -1,6 +1,6 @@
use crate::utils::paths;
use crate::utils::{
get_trait_def_id, is_allowed, is_automatically_derived, is_copy, match_def_path, match_path, span_lint_and_help,
get_trait_def_id, is_allowed, is_automatically_derived, is_copy, match_def_path, span_lint_and_help,
span_lint_and_note, span_lint_and_then,
};
use if_chain::if_chain;
@ -294,7 +294,12 @@ fn check_ord_partial_ord<'tcx>(
/// Implementation of the `EXPL_IMPL_CLONE_ON_COPY` lint.
fn check_copy_clone<'tcx>(cx: &LateContext<'tcx>, item: &Item<'_>, trait_ref: &TraitRef<'_>, ty: Ty<'tcx>) {
if match_path(&trait_ref.path, &paths::CLONE_TRAIT) {
if cx
.tcx
.lang_items()
.clone_trait()
.map_or(false, |id| Some(id) == trait_ref.trait_def_id())
{
if !is_copy(cx, ty) {
return;
}

6
clippy_lints/src/doc.rs
View file

@ -329,9 +329,9 @@ fn lint_for_missing_headers<'tcx>(
if_chain! {
if let Some(body_id) = body_id;
if let Some(future) = cx.tcx.lang_items().future_trait();
let def_id = cx.tcx.hir().body_owner_def_id(body_id);
let mir = cx.tcx.optimized_mir(def_id.to_def_id());
let ret_ty = mir.return_ty();
let typeck = cx.tcx.typeck_body(body_id);
let body = cx.tcx.hir().body(body_id);
let ret_ty = typeck.expr_ty(&body.value);
if implements_trait(cx, ret_ty, future, &[]);
if let ty::Opaque(_, subs) = ret_ty.kind();
if let Some(gen) = subs.types().next();

8
clippy_lints/src/drop_forget_ref.rs
View file

@ -98,13 +98,13 @@ declare_clippy_lint! {
}
const DROP_REF_SUMMARY: &str = "calls to `std::mem::drop` with a reference instead of an owned value. \
Dropping a reference does nothing.";
Dropping a reference does nothing";
const FORGET_REF_SUMMARY: &str = "calls to `std::mem::forget` with a reference instead of an owned value. \
Forgetting a reference does nothing.";
Forgetting a reference does nothing";
const DROP_COPY_SUMMARY: &str = "calls to `std::mem::drop` with a value that implements `Copy`. \
Dropping a copy leaves the original intact.";
Dropping a copy leaves the original intact";
const FORGET_COPY_SUMMARY: &str = "calls to `std::mem::forget` with a value that implements `Copy`. \
Forgetting a copy leaves the original intact.";
Forgetting a copy leaves the original intact";
declare_lint_pass!(DropForgetRef => [DROP_REF, FORGET_REF, DROP_COPY, FORGET_COPY]);

32
clippy_lints/src/eta_reduction.rs
View file

@ -10,6 +10,8 @@ use crate::utils::{
implements_trait, is_adjusted, iter_input_pats, snippet_opt, span_lint_and_sugg, span_lint_and_then,
type_is_unsafe_function,
};
use clippy_utils::higher;
use clippy_utils::higher::VecArgs;
declare_clippy_lint! {
/// **What it does:** Checks for closures which just call another function where
@ -74,7 +76,10 @@ impl<'tcx> LateLintPass<'tcx> for EtaReduction {
match expr.kind {
ExprKind::Call(_, args) | ExprKind::MethodCall(_, _, args, _) => {
for arg in args {
check_closure(cx, arg)
// skip `foo(macro!())`
if arg.span.ctxt() == expr.span.ctxt() {
check_closure(cx, arg)
}
}
},
_ => (),
@ -87,6 +92,23 @@ fn check_closure(cx: &LateContext<'_>, expr: &Expr<'_>) {
let body = cx.tcx.hir().body(eid);
let ex = &body.value;
if ex.span.ctxt() != expr.span.ctxt() {
if let Some(VecArgs::Vec(&[])) = higher::vec_macro(cx, ex) {
// replace `|| vec![]` with `Vec::new`
span_lint_and_sugg(
cx,
REDUNDANT_CLOSURE,
expr.span,
"redundant closure",
"replace the closure with `Vec::new`",
"std::vec::Vec::new".into(),
Applicability::MachineApplicable,
);
}
// skip `foo(|| macro!())`
return;
}
if_chain!(
if let ExprKind::Call(ref caller, ref args) = ex.kind;
@ -107,11 +129,11 @@ fn check_closure(cx: &LateContext<'_>, expr: &Expr<'_>) {
if compare_inputs(&mut iter_input_pats(decl, body), &mut args.iter());
then {
span_lint_and_then(cx, REDUNDANT_CLOSURE, expr.span, "redundant closure found", |diag| {
span_lint_and_then(cx, REDUNDANT_CLOSURE, expr.span, "redundant closure", |diag| {
if let Some(snippet) = snippet_opt(cx, caller.span) {
diag.span_suggestion(
expr.span,
"remove closure as shown",
"replace the closure with the function itself",
snippet,
Applicability::MachineApplicable,
);
@ -141,8 +163,8 @@ fn check_closure(cx: &LateContext<'_>, expr: &Expr<'_>) {
cx,
REDUNDANT_CLOSURE_FOR_METHOD_CALLS,
expr.span,
"redundant closure found",
"remove closure as shown",
"redundant closure",
"replace the closure with the method itself",
format!("{}::{}", name, path.ident.name),
Applicability::MachineApplicable,
);

4
clippy_lints/src/excessive_bools.rs
View file

@ -1,7 +1,5 @@
use crate::utils::{attr_by_name, in_macro, match_path_ast, span_lint_and_help};
use rustc_ast::ast::{
AssocItemKind, Extern, FnKind, FnSig, ImplKind, Item, ItemKind, TraitKind, Ty, TyKind,
};
use rustc_ast::ast::{AssocItemKind, Extern, FnKind, FnSig, ImplKind, Item, ItemKind, TraitKind, Ty, TyKind};
use rustc_lint::{EarlyContext, EarlyLintPass};
use rustc_session::{declare_tool_lint, impl_lint_pass};
use rustc_span::Span;

2
clippy_lints/src/fallible_impl_from.rs
View file

@ -133,7 +133,7 @@ fn lint_impl_body<'tcx>(cx: &LateContext<'tcx>, impl_span: Span, impl_items: &[h
move |diag| {
diag.help(
"`From` is intended for infallible conversions only. \
Use `TryFrom` if there's a possibility for the conversion to fail.");
Use `TryFrom` if there's a possibility for the conversion to fail");
diag.span_note(fpu.result, "potential failure(s)");
});
}

6
clippy_lints/src/float_literal.rs
View file

@ -145,11 +145,7 @@ fn count_digits(s: &str) -> usize {
.take_while(|c| *c != 'e' && *c != 'E')
.fold(0, |count, c| {
// leading zeros
if c == '0' && count == 0 {
count
} else {
count + 1
}
if c == '0' && count == 0 { count } else { count + 1 }
})
}

4
clippy_lints/src/format.rs
View file

@ -28,11 +28,11 @@ declare_clippy_lint! {
/// ```rust
///
/// // Bad
/// # let foo = "foo";
/// let foo = "foo";
/// format!("{}", foo);
///
/// // Good
/// format!("foo");
/// foo.to_owned();
/// ```
pub USELESS_FORMAT,
complexity,

4
clippy_lints/src/functions.rs
View file

@ -317,9 +317,7 @@ impl<'tcx> LateLintPass<'tcx> for Functions {
let attr = must_use_attr(attrs);
if let Some(attr) = attr {
check_needless_must_use(cx, &sig.decl, item.hir_id(), item.span, fn_header_span, attr);
} else if is_public
&& !is_proc_macro(cx.sess(), attrs)
&& trait_ref_of_method(cx, item.hir_id()).is_none()
} else if is_public && !is_proc_macro(cx.sess(), attrs) && trait_ref_of_method(cx, item.hir_id()).is_none()
{
check_must_use_candidate(
cx,

18
clippy_lints/src/implicit_return.rs
View file

@ -1,4 +1,4 @@
use crate::utils::{fn_has_unsatisfiable_preds, match_panic_def_id, snippet_opt, span_lint_and_then};
use crate::utils::{match_panic_def_id, snippet_opt, span_lint_and_then};
use if_chain::if_chain;
use rustc_errors::Applicability;
use rustc_hir::intravisit::FnKind;
@ -133,19 +133,13 @@ impl<'tcx> LateLintPass<'tcx> for ImplicitReturn {
span: Span,
_: HirId,
) {
let def_id = cx.tcx.hir().body_owner_def_id(body.id());
// Building MIR for `fn`s with unsatisfiable preds results in ICE.
if fn_has_unsatisfiable_preds(cx, def_id.to_def_id()) {
if span.from_expansion() {
return;
}
let mir = cx.tcx.optimized_mir(def_id.to_def_id());
// checking return type through MIR, HIR is not able to determine inferred closure return types
// make sure it's not a macro
if !mir.return_ty().is_unit() && !span.from_expansion() {
expr_match(cx, &body.value);
let body = cx.tcx.hir().body(body.id());
if cx.typeck_results().expr_ty(&body.value).is_unit() {
return;
}
expr_match(cx, &body.value);
}
}

3
clippy_lints/src/inconsistent_struct_constructor.rs
View file

@ -66,8 +66,7 @@ impl LateLintPass<'_> for InconsistentStructConstructor {
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) {
if_chain! {
if let ExprKind::Struct(qpath, fields, base) = expr.kind;
if let Some(def_id) = cx.qpath_res(qpath, expr.hir_id).opt_def_id();
let ty = cx.tcx.type_of(def_id);
let ty = cx.typeck_results().expr_ty(expr);
if let Some(adt_def) = ty.ty_adt_def();
if adt_def.is_struct();
if let Some(variant) = adt_def.variants.iter().next();

12
clippy_lints/src/indexing_slicing.rs
View file

@ -132,13 +132,13 @@ impl<'tcx> LateLintPass<'tcx> for IndexingSlicing {
}
let help_msg = match (range.start, range.end) {
(None, Some(_)) => "Consider using `.get(..n)`or `.get_mut(..n)` instead",
(Some(_), None) => "Consider using `.get(n..)` or .get_mut(n..)` instead",
(Some(_), Some(_)) => "Consider using `.get(n..m)` or `.get_mut(n..m)` instead",
(None, Some(_)) => "consider using `.get(..n)`or `.get_mut(..n)` instead",
(Some(_), None) => "consider using `.get(n..)` or .get_mut(n..)` instead",
(Some(_), Some(_)) => "consider using `.get(n..m)` or `.get_mut(n..m)` instead",
(None, None) => return, // [..] is ok.
};
span_lint_and_help(cx, INDEXING_SLICING, expr.span, "slicing may panic.", None, help_msg);
span_lint_and_help(cx, INDEXING_SLICING, expr.span, "slicing may panic", None, help_msg);
} else {
// Catchall non-range index, i.e., [n] or [n << m]
if let ty::Array(..) = ty.kind() {
@ -153,9 +153,9 @@ impl<'tcx> LateLintPass<'tcx> for IndexingSlicing {
cx,
INDEXING_SLICING,
expr.span,
"indexing may panic.",
"indexing may panic",
None,
"Consider using `.get(n)` or `.get_mut(n)` instead",
"consider using `.get(n)` or `.get_mut(n)` instead",
);
}
}

6
clippy_lints/src/infinite_iter.rs
View file

@ -89,11 +89,7 @@ impl Finiteness {
impl From<bool> for Finiteness {
#[must_use]
fn from(b: bool) -> Self {
if b {
Infinite
} else {
Finite
}
if b { Infinite } else { Finite }
}
}

2
clippy_lints/src/inherent_to_string.rs
View file

@ -139,7 +139,7 @@ fn show_lint(cx: &LateContext<'_>, item: &ImplItem<'_>) {
self_type.to_string()
),
None,
&format!("remove the inherent method from type `{}`", self_type.to_string())
&format!("remove the inherent method from type `{}`", self_type.to_string()),
);
} else {
span_lint_and_help(

2
clippy_lints/src/integer_division.rs
View file

@ -39,7 +39,7 @@ impl<'tcx> LateLintPass<'tcx> for IntegerDivision {
expr.span,
"integer division",
None,
"division of integers may cause loss of precision. consider using floats.",
"division of integers may cause loss of precision. consider using floats",
);
}
}

166
clippy_lints/src/len_zero.rs
View file

@ -1,11 +1,17 @@
use crate::utils::{get_item_name, snippet_with_applicability, span_lint, span_lint_and_sugg};
use crate::utils::{
get_item_name, get_parent_as_impl, is_allowed, snippet_with_applicability, span_lint, span_lint_and_sugg,
span_lint_and_then,
};
use if_chain::if_chain;
use rustc_ast::ast::LitKind;
use rustc_data_structures::fx::FxHashSet;
use rustc_errors::Applicability;
use rustc_hir::def_id::DefId;
use rustc_hir::{AssocItemKind, BinOpKind, Expr, ExprKind, Impl, ImplItemRef, Item, ItemKind, TraitItemRef};
use rustc_hir::{
def_id::DefId, AssocItemKind, BinOpKind, Expr, ExprKind, FnRetTy, ImplItem, ImplItemKind, ImplicitSelfKind, Item,
ItemKind, Mutability, Node, TraitItemRef, TyKind,
};
use rustc_lint::{LateContext, LateLintPass};
use rustc_middle::ty;
use rustc_middle::ty::{self, AssocKind, FnSig};
use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_span::source_map::{Span, Spanned, Symbol};
@ -113,14 +119,38 @@ impl<'tcx> LateLintPass<'tcx> for LenZero {
return;
}
match item.kind {
ItemKind::Trait(_, _, _, _, ref trait_items) => check_trait_items(cx, item, trait_items),
ItemKind::Impl(Impl {
of_trait: None,
items: ref impl_items,
..
}) => check_impl_items(cx, item, impl_items),
_ => (),
if let ItemKind::Trait(_, _, _, _, ref trait_items) = item.kind {
check_trait_items(cx, item, trait_items);
}
}
fn check_impl_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx ImplItem<'_>) {
if_chain! {
if item.ident.as_str() == "len";
if let ImplItemKind::Fn(sig, _) = &item.kind;
if sig.decl.implicit_self.has_implicit_self();
if cx.access_levels.is_exported(item.hir_id());
if matches!(sig.decl.output, FnRetTy::Return(_));
if let Some(imp) = get_parent_as_impl(cx.tcx, item.hir_id());
if imp.of_trait.is_none();
if let TyKind::Path(ty_path) = &imp.self_ty.kind;
if let Some(ty_id) = cx.qpath_res(ty_path, imp.self_ty.hir_id).opt_def_id();
if let Some(local_id) = ty_id.as_local();
let ty_hir_id = cx.tcx.hir().local_def_id_to_hir_id(local_id);
if !is_allowed(cx, LEN_WITHOUT_IS_EMPTY, ty_hir_id);
then {
let (name, kind) = match cx.tcx.hir().find(ty_hir_id) {
Some(Node::ForeignItem(x)) => (x.ident.name, "extern type"),
Some(Node::Item(x)) => match x.kind {
ItemKind::Struct(..) => (x.ident.name, "struct"),
ItemKind::Enum(..) => (x.ident.name, "enum"),
ItemKind::Union(..) => (x.ident.name, "union"),
_ => (x.ident.name, "type"),
}
_ => return,
};
check_for_is_empty(cx, sig.span, sig.decl.implicit_self, ty_id, name, kind)
}
}
}
@ -202,40 +232,94 @@ fn check_trait_items(cx: &LateContext<'_>, visited_trait: &Item<'_>, trait_items
}
}
fn check_impl_items(cx: &LateContext<'_>, item: &Item<'_>, impl_items: &[ImplItemRef<'_>]) {
fn is_named_self(cx: &LateContext<'_>, item: &ImplItemRef<'_>, name: &str) -> bool {
item.ident.name.as_str() == name
&& if let AssocItemKind::Fn { has_self } = item.kind {
has_self && cx.tcx.fn_sig(item.id.def_id).inputs().skip_binder().len() == 1
} else {
false
}
/// Checks if the given signature matches the expectations for `is_empty`
fn check_is_empty_sig(cx: &LateContext<'_>, sig: FnSig<'_>, self_kind: ImplicitSelfKind) -> bool {
match &**sig.inputs_and_output {
[arg, res] if *res == cx.tcx.types.bool => {
matches!(
(arg.kind(), self_kind),
(ty::Ref(_, _, Mutability::Not), ImplicitSelfKind::ImmRef)
| (ty::Ref(_, _, Mutability::Mut), ImplicitSelfKind::MutRef)
) || (!arg.is_ref() && matches!(self_kind, ImplicitSelfKind::Imm | ImplicitSelfKind::Mut))
},
_ => false,
}
}
let is_empty = if let Some(is_empty) = impl_items.iter().find(|i| is_named_self(cx, i, "is_empty")) {
if cx.access_levels.is_exported(is_empty.id.hir_id()) {
return;
}
"a private"
} else {
"no corresponding"
/// Checks if the given type has an `is_empty` method with the appropriate signature.
fn check_for_is_empty(
cx: &LateContext<'_>,
span: Span,
self_kind: ImplicitSelfKind,
impl_ty: DefId,
item_name: Symbol,
item_kind: &str,
) {
let is_empty = Symbol::intern("is_empty");
let is_empty = cx
.tcx
.inherent_impls(impl_ty)
.iter()
.flat_map(|&id| cx.tcx.associated_items(id).filter_by_name_unhygienic(is_empty))
.find(|item| item.kind == AssocKind::Fn);
let (msg, is_empty_span, self_kind) = match is_empty {
None => (
format!(
"{} `{}` has a public `len` method, but no `is_empty` method",
item_kind,
item_name.as_str(),
),
None,
None,
),
Some(is_empty)
if !cx
.access_levels
.is_exported(cx.tcx.hir().local_def_id_to_hir_id(is_empty.def_id.expect_local())) =>
{
(
format!(
"{} `{}` has a public `len` method, but a private `is_empty` method",
item_kind,
item_name.as_str(),
),
Some(cx.tcx.def_span(is_empty.def_id)),
None,
)
},
Some(is_empty)
if !(is_empty.fn_has_self_parameter
&& check_is_empty_sig(cx, cx.tcx.fn_sig(is_empty.def_id).skip_binder(), self_kind)) =>
{
(
format!(
"{} `{}` has a public `len` method, but the `is_empty` method has an unexpected signature",
item_kind,
item_name.as_str(),
),
Some(cx.tcx.def_span(is_empty.def_id)),
Some(self_kind),
)
},
Some(_) => return,
};
if let Some(i) = impl_items.iter().find(|i| is_named_self(cx, i, "len")) {
if cx.access_levels.is_exported(i.id.hir_id()) {
let ty = cx.tcx.type_of(item.def_id);
span_lint(
cx,
LEN_WITHOUT_IS_EMPTY,
item.span,
&format!(
"item `{}` has a public `len` method but {} `is_empty` method",
ty, is_empty
),
);
span_lint_and_then(cx, LEN_WITHOUT_IS_EMPTY, span, &msg, |db| {
if let Some(span) = is_empty_span {
db.span_note(span, "`is_empty` defined here");
}
}
if let Some(self_kind) = self_kind {
db.note(&format!(
"expected signature: `({}self) -> bool`",
match self_kind {
ImplicitSelfKind::ImmRef => "&",
ImplicitSelfKind::MutRef => "&mut ",
_ => "",
}
));
}
});
}
fn check_cmp(cx: &LateContext<'_>, span: Span, method: &Expr<'_>, lit: &Expr<'_>, op: &str, compare_to: u32) {

72
clippy_lints/src/lib.rs
View file

@ -182,6 +182,7 @@ mod booleans;
mod bytecount;
mod cargo_common_metadata;
mod case_sensitive_file_extension_comparisons;
mod casts;
mod checked_conversions;
mod cognitive_complexity;
mod collapsible_if;
@ -586,6 +587,18 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
&bytecount::NAIVE_BYTECOUNT,
&cargo_common_metadata::CARGO_COMMON_METADATA,
&case_sensitive_file_extension_comparisons::CASE_SENSITIVE_FILE_EXTENSION_COMPARISONS,
&casts::CAST_LOSSLESS,
&casts::CAST_POSSIBLE_TRUNCATION,
&casts::CAST_POSSIBLE_WRAP,
&casts::CAST_PRECISION_LOSS,
&casts::CAST_PTR_ALIGNMENT,
&casts::CAST_REF_TO_MUT,
&casts::CAST_SIGN_LOSS,
&casts::CHAR_LIT_AS_U8,
&casts::FN_TO_NUMERIC_CAST,
&casts::FN_TO_NUMERIC_CAST_WITH_TRUNCATION,
&casts::PTR_AS_PTR,
&casts::UNNECESSARY_CAST,
&checked_conversions::CHECKED_CONVERSIONS,
&cognitive_complexity::COGNITIVE_COMPLEXITY,
&collapsible_if::COLLAPSIBLE_ELSE_IF,
@ -769,11 +782,13 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
&methods::FLAT_MAP_IDENTITY,
&methods::FROM_ITER_INSTEAD_OF_COLLECT,
&methods::GET_UNWRAP,
&methods::IMPLICIT_CLONE,
&methods::INEFFICIENT_TO_STRING,
&methods::INSPECT_FOR_EACH,
&methods::INTO_ITER_ON_REF,
&methods::ITERATOR_STEP_BY_ZERO,
&methods::ITER_CLONED_COLLECT,
&methods::ITER_COUNT,
&methods::ITER_NEXT_SLICE,
&methods::ITER_NTH,
&methods::ITER_NTH_ZERO,
@ -941,28 +956,16 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
&types::ABSURD_EXTREME_COMPARISONS,
&types::BORROWED_BOX,
&types::BOX_VEC,
&types::CAST_LOSSLESS,
&types::CAST_POSSIBLE_TRUNCATION,
&types::CAST_POSSIBLE_WRAP,
&types::CAST_PRECISION_LOSS,
&types::CAST_PTR_ALIGNMENT,
&types::CAST_REF_TO_MUT,
&types::CAST_SIGN_LOSS,
&types::CHAR_LIT_AS_U8,
&types::FN_TO_NUMERIC_CAST,
&types::FN_TO_NUMERIC_CAST_WITH_TRUNCATION,
&types::IMPLICIT_HASHER,
&types::INVALID_UPCAST_COMPARISONS,
&types::LET_UNIT_VALUE,
&types::LINKEDLIST,
&types::OPTION_OPTION,
&types::PTR_AS_PTR,
&types::RC_BUFFER,
&types::REDUNDANT_ALLOCATION,
&types::TYPE_COMPLEXITY,
&types::UNIT_ARG,
&types::UNIT_CMP,
&types::UNNECESSARY_CAST,
&types::VEC_BOX,
&undropped_manually_drops::UNDROPPED_MANUALLY_DROPS,
&unicode::INVISIBLE_CHARACTERS,
@ -1073,6 +1076,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
store.register_late_pass(move || box use_self::UseSelf::new(msrv));
store.register_late_pass(move || box missing_const_for_fn::MissingConstForFn::new(msrv));
store.register_late_pass(move || box needless_question_mark::NeedlessQuestionMark::new(msrv));
store.register_late_pass(move || box casts::Casts::new(msrv));
store.register_late_pass(|| box size_of_in_element_count::SizeOfInElementCount);
store.register_late_pass(|| box map_clone::MapClone);
@ -1084,7 +1088,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
store.register_late_pass(|| box main_recursion::MainRecursion::default());
store.register_late_pass(|| box lifetimes::Lifetimes);
store.register_late_pass(|| box entry::HashMapPass);
store.register_late_pass(|| box types::Casts);
let type_complexity_threshold = conf.type_complexity_threshold;
store.register_late_pass(move || box types::TypeComplexity::new(type_complexity_threshold));
store.register_late_pass(|| box minmax::MinMaxPass);
@ -1105,7 +1108,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
store.register_late_pass(|| box panic_unimplemented::PanicUnimplemented);
store.register_late_pass(|| box strings::StringLitAsBytes);
store.register_late_pass(|| box derive::Derive);
store.register_late_pass(|| box types::CharLitAsU8);
store.register_late_pass(|| box get_last_with_len::GetLastWithLen);
store.register_late_pass(|| box drop_forget_ref::DropForgetRef);
store.register_late_pass(|| box empty_enum::EmptyEnum);
@ -1173,7 +1175,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
store.register_late_pass(|| box slow_vector_initialization::SlowVectorInit);
store.register_late_pass(|| box unnecessary_sort_by::UnnecessarySortBy);
store.register_late_pass(|| box unnecessary_wraps::UnnecessaryWraps);
store.register_late_pass(|| box types::RefToMut);
store.register_late_pass(|| box assertions_on_constants::AssertionsOnConstants);
store.register_late_pass(|| box transmuting_null::TransmutingNull);
store.register_late_pass(|| box path_buf_push_overwrite::PathBufPushOverwrite);
@ -1275,7 +1276,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
store.register_late_pass(|| box strings::StringToString);
store.register_late_pass(|| box zero_sized_map_values::ZeroSizedMapValues);
store.register_late_pass(|| box vec_init_then_push::VecInitThenPush::default());
store.register_late_pass(move || box types::PtrAsPtr::new(msrv));
store.register_late_pass(|| box case_sensitive_file_extension_comparisons::CaseSensitiveFileExtensionComparisons);
store.register_late_pass(|| box redundant_slicing::RedundantSlicing);
store.register_late_pass(|| box from_str_radix_10::FromStrRadix10);
@ -1341,7 +1341,15 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
LintId::of(&await_holding_invalid::AWAIT_HOLDING_LOCK),
LintId::of(&await_holding_invalid::AWAIT_HOLDING_REFCELL_REF),
LintId::of(&bit_mask::VERBOSE_BIT_MASK),
LintId::of(&bytecount::NAIVE_BYTECOUNT),
LintId::of(&case_sensitive_file_extension_comparisons::CASE_SENSITIVE_FILE_EXTENSION_COMPARISONS),
LintId::of(&casts::CAST_LOSSLESS),
LintId::of(&casts::CAST_POSSIBLE_TRUNCATION),
LintId::of(&casts::CAST_POSSIBLE_WRAP),
LintId::of(&casts::CAST_PRECISION_LOSS),
LintId::of(&casts::CAST_PTR_ALIGNMENT),
LintId::of(&casts::CAST_SIGN_LOSS),
LintId::of(&casts::PTR_AS_PTR),
LintId::of(&checked_conversions::CHECKED_CONVERSIONS),
LintId::of(&copies::SAME_FUNCTIONS_IN_IF_CONDITION),
LintId::of(&copy_iterator::COPY_ITERATOR),
@ -1380,6 +1388,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
LintId::of(&matches::SINGLE_MATCH_ELSE),
LintId::of(&methods::FILTER_MAP),
LintId::of(&methods::FILTER_MAP_NEXT),
LintId::of(&methods::IMPLICIT_CLONE),
LintId::of(&methods::INEFFICIENT_TO_STRING),
LintId::of(&methods::MAP_FLATTEN),
LintId::of(&methods::MAP_UNWRAP_OR),
@ -1400,18 +1409,11 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
LintId::of(&strings::STRING_ADD_ASSIGN),
LintId::of(&trait_bounds::TRAIT_DUPLICATION_IN_BOUNDS),
LintId::of(&trait_bounds::TYPE_REPETITION_IN_BOUNDS),
LintId::of(&types::CAST_LOSSLESS),
LintId::of(&types::CAST_POSSIBLE_TRUNCATION),
LintId::of(&types::CAST_POSSIBLE_WRAP),
LintId::of(&types::CAST_PRECISION_LOSS),
LintId::of(&types::CAST_PTR_ALIGNMENT),
LintId::of(&types::CAST_SIGN_LOSS),
LintId::of(&types::IMPLICIT_HASHER),
LintId::of(&types::INVALID_UPCAST_COMPARISONS),
LintId::of(&types::LET_UNIT_VALUE),
LintId::of(&types::LINKEDLIST),
LintId::of(&types::OPTION_OPTION),
LintId::of(&types::PTR_AS_PTR),
LintId::of(&unicode::NON_ASCII_LITERAL),
LintId::of(&unicode::UNICODE_NOT_NFC),
LintId::of(&unnecessary_wraps::UNNECESSARY_WRAPS),
@ -1455,7 +1457,11 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
LintId::of(&blocks_in_if_conditions::BLOCKS_IN_IF_CONDITIONS),
LintId::of(&booleans::LOGIC_BUG),
LintId::of(&booleans::NONMINIMAL_BOOL),
LintId::of(&bytecount::NAIVE_BYTECOUNT),
LintId::of(&casts::CAST_REF_TO_MUT),
LintId::of(&casts::CHAR_LIT_AS_U8),
LintId::of(&casts::FN_TO_NUMERIC_CAST),
LintId::of(&casts::FN_TO_NUMERIC_CAST_WITH_TRUNCATION),
LintId::of(&casts::UNNECESSARY_CAST),
LintId::of(&collapsible_if::COLLAPSIBLE_ELSE_IF),
LintId::of(&collapsible_if::COLLAPSIBLE_IF),
LintId::of(&collapsible_match::COLLAPSIBLE_MATCH),
@ -1576,6 +1582,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
LintId::of(&methods::INTO_ITER_ON_REF),
LintId::of(&methods::ITERATOR_STEP_BY_ZERO),
LintId::of(&methods::ITER_CLONED_COLLECT),
LintId::of(&methods::ITER_COUNT),
LintId::of(&methods::ITER_NEXT_SLICE),
LintId::of(&methods::ITER_NTH),
LintId::of(&methods::ITER_NTH_ZERO),
@ -1695,15 +1702,10 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
LintId::of(&types::ABSURD_EXTREME_COMPARISONS),
LintId::of(&types::BORROWED_BOX),
LintId::of(&types::BOX_VEC),
LintId::of(&types::CAST_REF_TO_MUT),
LintId::of(&types::CHAR_LIT_AS_U8),
LintId::of(&types::FN_TO_NUMERIC_CAST),
LintId::of(&types::FN_TO_NUMERIC_CAST_WITH_TRUNCATION),
LintId::of(&types::REDUNDANT_ALLOCATION),
LintId::of(&types::TYPE_COMPLEXITY),
LintId::of(&types::UNIT_ARG),
LintId::of(&types::UNIT_CMP),
LintId::of(&types::UNNECESSARY_CAST),
LintId::of(&types::VEC_BOX),
LintId::of(&undropped_manually_drops::UNDROPPED_MANUALLY_DROPS),
LintId::of(&unicode::INVISIBLE_CHARACTERS),
@ -1736,6 +1738,8 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
LintId::of(&attrs::BLANKET_CLIPPY_RESTRICTION_LINTS),
LintId::of(&blacklisted_name::BLACKLISTED_NAME),
LintId::of(&blocks_in_if_conditions::BLOCKS_IN_IF_CONDITIONS),
LintId::of(&casts::FN_TO_NUMERIC_CAST),
LintId::of(&casts::FN_TO_NUMERIC_CAST_WITH_TRUNCATION),
LintId::of(&collapsible_if::COLLAPSIBLE_ELSE_IF),
LintId::of(&collapsible_if::COLLAPSIBLE_IF),
LintId::of(&collapsible_match::COLLAPSIBLE_MATCH),
@ -1832,8 +1836,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
LintId::of(&tabs_in_doc_comments::TABS_IN_DOC_COMMENTS),
LintId::of(&to_digit_is_some::TO_DIGIT_IS_SOME),
LintId::of(&try_err::TRY_ERR),
LintId::of(&types::FN_TO_NUMERIC_CAST),
LintId::of(&types::FN_TO_NUMERIC_CAST_WITH_TRUNCATION),
LintId::of(&unsafe_removed_from_name::UNSAFE_REMOVED_FROM_NAME),
LintId::of(&unused_unit::UNUSED_UNIT),
LintId::of(&upper_case_acronyms::UPPER_CASE_ACRONYMS),
@ -1849,6 +1851,8 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
LintId::of(&assign_ops::MISREFACTORED_ASSIGN_OP),
LintId::of(&attrs::DEPRECATED_CFG_ATTR),
LintId::of(&booleans::NONMINIMAL_BOOL),
LintId::of(&casts::CHAR_LIT_AS_U8),
LintId::of(&casts::UNNECESSARY_CAST),
LintId::of(&double_comparison::DOUBLE_COMPARISONS),
LintId::of(&double_parens::DOUBLE_PARENS),
LintId::of(&duration_subsec::DURATION_SUBSEC),
@ -1881,6 +1885,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
LintId::of(&methods::FILTER_NEXT),
LintId::of(&methods::FLAT_MAP_IDENTITY),
LintId::of(&methods::INSPECT_FOR_EACH),
LintId::of(&methods::ITER_COUNT),
LintId::of(&methods::MANUAL_FILTER_MAP),
LintId::of(&methods::MANUAL_FIND_MAP),
LintId::of(&methods::OPTION_AS_REF_DEREF),
@ -1924,10 +1929,8 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
LintId::of(&transmute::TRANSMUTE_PTR_TO_PTR),
LintId::of(&transmute::TRANSMUTE_PTR_TO_REF),
LintId::of(&types::BORROWED_BOX),
LintId::of(&types::CHAR_LIT_AS_U8),
LintId::of(&types::TYPE_COMPLEXITY),
LintId::of(&types::UNIT_ARG),
LintId::of(&types::UNNECESSARY_CAST),
LintId::of(&types::VEC_BOX),
LintId::of(&unnecessary_sort_by::UNNECESSARY_SORT_BY),
LintId::of(&unwrap::UNNECESSARY_UNWRAP),
@ -1945,6 +1948,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
LintId::of(&bit_mask::BAD_BIT_MASK),
LintId::of(&bit_mask::INEFFECTIVE_BIT_MASK),
LintId::of(&booleans::LOGIC_BUG),
LintId::of(&casts::CAST_REF_TO_MUT),
LintId::of(&copies::IFS_SAME_COND),
LintId::of(&copies::IF_SAME_THEN_ELSE),
LintId::of(&derive::DERIVE_HASH_XOR_EQ),
@ -1997,7 +2001,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
LintId::of(&transmute::WRONG_TRANSMUTE),
LintId::of(&transmuting_null::TRANSMUTING_NULL),
LintId::of(&types::ABSURD_EXTREME_COMPARISONS),
LintId::of(&types::CAST_REF_TO_MUT),
LintId::of(&types::UNIT_CMP),
LintId::of(&undropped_manually_drops::UNDROPPED_MANUALLY_DROPS),
LintId::of(&unicode::INVISIBLE_CHARACTERS),
@ -2010,7 +2013,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
]);
store.register_group(true, "clippy::perf", Some("clippy_perf"), vec![
LintId::of(&bytecount::NAIVE_BYTECOUNT),
LintId::of(&entry::MAP_ENTRY),
LintId::of(&escape::BOXED_LOCAL),
LintId::of(&large_const_arrays::LARGE_CONST_ARRAYS),

20
clippy_lints/src/lifetimes.rs
View file

@ -1,5 +1,4 @@
use crate::utils::paths;
use crate::utils::{get_trait_def_id, in_macro, span_lint, trait_ref_of_method};
use crate::utils::{in_macro, span_lint, trait_ref_of_method};
use rustc_data_structures::fx::{FxHashMap, FxHashSet};
use rustc_hir::intravisit::{
walk_fn_decl, walk_generic_param, walk_generics, walk_item, walk_param_bound, walk_poly_trait_ref, walk_ty,
@ -8,8 +7,8 @@ use rustc_hir::intravisit::{
use rustc_hir::FnRetTy::Return;
use rustc_hir::{
BareFnTy, BodyId, FnDecl, GenericArg, GenericBound, GenericParam, GenericParamKind, Generics, ImplItem,
ImplItemKind, Item, ItemKind, Lifetime, LifetimeName, ParamName, PolyTraitRef, TraitBoundModifier, TraitFn,
TraitItem, TraitItemKind, Ty, TyKind, WhereClause, WherePredicate,
ImplItemKind, Item, ItemKind, LangItem, Lifetime, LifetimeName, ParamName, PolyTraitRef, TraitBoundModifier,
TraitFn, TraitItem, TraitItemKind, Ty, TyKind, WhereClause, WherePredicate,
};
use rustc_lint::{LateContext, LateLintPass};
use rustc_middle::hir::map::Map;
@ -300,7 +299,7 @@ fn unique_lifetimes(lts: &[RefLt]) -> usize {
lts.iter().collect::<FxHashSet<_>>().len()
}
const CLOSURE_TRAIT_BOUNDS: [&[&str]; 3] = [&paths::FN, &paths::FN_MUT, &paths::FN_ONCE];
const CLOSURE_TRAIT_BOUNDS: [LangItem; 3] = [LangItem::Fn, LangItem::FnMut, LangItem::FnOnce];
/// A visitor usable for `rustc_front::visit::walk_ty()`.
struct RefVisitor<'a, 'tcx> {
@ -359,10 +358,13 @@ impl<'a, 'tcx> Visitor<'tcx> for RefVisitor<'a, 'tcx> {
fn visit_poly_trait_ref(&mut self, poly_tref: &'tcx PolyTraitRef<'tcx>, tbm: TraitBoundModifier) {
let trait_ref = &poly_tref.trait_ref;
if CLOSURE_TRAIT_BOUNDS
.iter()
.any(|trait_path| trait_ref.trait_def_id() == get_trait_def_id(self.cx, trait_path))
{
if CLOSURE_TRAIT_BOUNDS.iter().any(|&item| {
self.cx
.tcx
.lang_items()
.require(item)
.map_or(false, |id| Some(id) == trait_ref.trait_def_id())
}) {
let mut sub_visitor = RefVisitor::new(self.cx);
sub_visitor.visit_trait_ref(trait_ref);
self.nested_elision_site_lts.append(&mut sub_visitor.all_lts());

3182
clippy_lints/src/loops.rs
View file

File diff suppressed because it is too large Load diff

17
clippy_lints/src/loops/empty_loop.rs Normal file
View file

@ -0,0 +1,17 @@
use super::EMPTY_LOOP;
use crate::utils::{is_in_panic_handler, is_no_std_crate, span_lint_and_help};
use rustc_hir::{Block, Expr};
use rustc_lint::LateContext;
pub(super) fn check(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, loop_block: &'tcx Block<'_>) {
if loop_block.stmts.is_empty() && loop_block.expr.is_none() && !is_in_panic_handler(cx, expr) {
let msg = "empty `loop {}` wastes CPU cycles";
let help = if is_no_std_crate(cx) {
"you should either use `panic!()` or add a call pausing or sleeping the thread to the loop body"
} else {
"you should either use `panic!()` or add `std::thread::sleep(..);` to the loop body"
};
span_lint_and_help(cx, EMPTY_LOOP, expr.span, msg, None, help);
}
}

58
clippy_lints/src/loops/explicit_counter_loop.rs Normal file
View file

@ -0,0 +1,58 @@
use super::{
get_span_of_entire_for_loop, make_iterator_snippet, IncrementVisitor, InitializeVisitor, EXPLICIT_COUNTER_LOOP,
};
use crate::utils::{get_enclosing_block, is_integer_const, snippet_with_applicability, span_lint_and_sugg};
use if_chain::if_chain;
use rustc_errors::Applicability;
use rustc_hir::intravisit::{walk_block, walk_expr};
use rustc_hir::{Expr, Pat};
use rustc_lint::LateContext;
// To trigger the EXPLICIT_COUNTER_LOOP lint, a variable must be
// incremented exactly once in the loop body, and initialized to zero
// at the start of the loop.
pub(super) fn check<'tcx>(
cx: &LateContext<'tcx>,
pat: &'tcx Pat<'_>,
arg: &'tcx Expr<'_>,
body: &'tcx Expr<'_>,
expr: &'tcx Expr<'_>,
) {
// Look for variables that are incremented once per loop iteration.
let mut increment_visitor = IncrementVisitor::new(cx);
walk_expr(&mut increment_visitor, body);
// For each candidate, check the parent block to see if
// it's initialized to zero at the start of the loop.
if let Some(block) = get_enclosing_block(&cx, expr.hir_id) {
for id in increment_visitor.into_results() {
let mut initialize_visitor = InitializeVisitor::new(cx, expr, id);
walk_block(&mut initialize_visitor, block);
if_chain! {
if let Some((name, initializer)) = initialize_visitor.get_result();
if is_integer_const(cx, initializer, 0);
then {
let mut applicability = Applicability::MachineApplicable;
let for_span = get_span_of_entire_for_loop(expr);
span_lint_and_sugg(
cx,
EXPLICIT_COUNTER_LOOP,
for_span.with_hi(arg.span.hi()),
&format!("the variable `{}` is used as a loop counter", name),
"consider using",
format!(
"for ({}, {}) in {}.enumerate()",
name,
snippet_with_applicability(cx, pat.span, "item", &mut applicability),
make_iterator_snippet(cx, arg, &mut applicability),
),
applicability,
);
}
}
}
}
}

27
clippy_lints/src/loops/explicit_into_iter_loop.rs Normal file
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use super::EXPLICIT_INTO_ITER_LOOP;
use crate::utils::{snippet_with_applicability, span_lint_and_sugg};
use rustc_errors::Applicability;
use rustc_hir::Expr;
use rustc_lint::LateContext;
use rustc_middle::ty::TyS;
pub(super) fn check(cx: &LateContext<'_>, args: &'hir [Expr<'hir>], arg: &Expr<'_>) {
let receiver_ty = cx.typeck_results().expr_ty(&args[0]);
let receiver_ty_adjusted = cx.typeck_results().expr_ty_adjusted(&args[0]);
if !TyS::same_type(receiver_ty, receiver_ty_adjusted) {
return;
}
let mut applicability = Applicability::MachineApplicable;
let object = snippet_with_applicability(cx, args[0].span, "_", &mut applicability);
span_lint_and_sugg(
cx,
EXPLICIT_INTO_ITER_LOOP,
arg.span,
"it is more concise to loop over containers instead of using explicit \
iteration methods",
"to write this more concisely, try",
object.to_string(),
applicability,
);
}

74
clippy_lints/src/loops/explicit_iter_loop.rs Normal file
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use super::EXPLICIT_ITER_LOOP;
use crate::utils::{match_trait_method, snippet_with_applicability, span_lint_and_sugg};
use rustc_errors::Applicability;
use rustc_hir::{Expr, Mutability};
use rustc_lint::LateContext;
use rustc_middle::ty::{self, Ty, TyS};
use rustc_span::symbol::sym;
use crate::utils::{is_type_diagnostic_item, match_type, paths};
pub(super) fn check(cx: &LateContext<'_>, args: &[Expr<'_>], arg: &Expr<'_>, method_name: &str) {
let should_lint = match method_name {
"iter" | "iter_mut" => is_ref_iterable_type(cx, &args[0]),
"into_iter" if match_trait_method(cx, arg, &paths::INTO_ITERATOR) => {
let receiver_ty = cx.typeck_results().expr_ty(&args[0]);
let receiver_ty_adjusted = cx.typeck_results().expr_ty_adjusted(&args[0]);
let ref_receiver_ty = cx.tcx.mk_ref(
cx.tcx.lifetimes.re_erased,
ty::TypeAndMut {
ty: receiver_ty,
mutbl: Mutability::Not,
},
);
TyS::same_type(receiver_ty_adjusted, ref_receiver_ty)
},
_ => false,
};
if !should_lint {
return;
}
let mut applicability = Applicability::MachineApplicable;
let object = snippet_with_applicability(cx, args[0].span, "_", &mut applicability);
let muta = if method_name == "iter_mut" { "mut " } else { "" };
span_lint_and_sugg(
cx,
EXPLICIT_ITER_LOOP,
arg.span,
"it is more concise to loop over references to containers instead of using explicit \
iteration methods",
"to write this more concisely, try",
format!("&{}{}", muta, object),
applicability,
)
}
/// Returns `true` if the type of expr is one that provides `IntoIterator` impls
/// for `&T` and `&mut T`, such as `Vec`.
#[rustfmt::skip]
fn is_ref_iterable_type(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
// no walk_ptrs_ty: calling iter() on a reference can make sense because it
// will allow further borrows afterwards
let ty = cx.typeck_results().expr_ty(e);
is_iterable_array(ty, cx) ||
is_type_diagnostic_item(cx, ty, sym::vec_type) ||
match_type(cx, ty, &paths::LINKED_LIST) ||
is_type_diagnostic_item(cx, ty, sym!(hashmap_type)) ||
is_type_diagnostic_item(cx, ty, sym!(hashset_type)) ||
is_type_diagnostic_item(cx, ty, sym!(vecdeque_type)) ||
match_type(cx, ty, &paths::BINARY_HEAP) ||
match_type(cx, ty, &paths::BTREEMAP) ||
match_type(cx, ty, &paths::BTREESET)
}
fn is_iterable_array<'tcx>(ty: Ty<'tcx>, cx: &LateContext<'tcx>) -> bool {
// IntoIterator is currently only implemented for array sizes <= 32 in rustc
match ty.kind() {
ty::Array(_, n) => n
.try_eval_usize(cx.tcx, cx.param_env)
.map_or(false, |val| (0..=32).contains(&val)),
_ => false,
}
}

70
clippy_lints/src/loops/for_kv_map.rs Normal file
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use super::FOR_KV_MAP;
use crate::utils::visitors::LocalUsedVisitor;
use crate::utils::{is_type_diagnostic_item, match_type, multispan_sugg, paths, snippet, span_lint_and_then, sugg};
use rustc_hir::{BorrowKind, Expr, ExprKind, Mutability, Pat, PatKind};
use rustc_lint::LateContext;
use rustc_middle::ty;
/// Checks for the `FOR_KV_MAP` lint.
pub(super) fn check<'tcx>(
cx: &LateContext<'tcx>,
pat: &'tcx Pat<'_>,
arg: &'tcx Expr<'_>,
body: &'tcx Expr<'_>,
expr: &'tcx Expr<'_>,
) {
let pat_span = pat.span;
if let PatKind::Tuple(ref pat, _) = pat.kind {
if pat.len() == 2 {
let arg_span = arg.span;
let (new_pat_span, kind, ty, mutbl) = match *cx.typeck_results().expr_ty(arg).kind() {
ty::Ref(_, ty, mutbl) => match (&pat[0].kind, &pat[1].kind) {
(key, _) if pat_is_wild(cx, key, body) => (pat[1].span, "value", ty, mutbl),
(_, value) if pat_is_wild(cx, value, body) => (pat[0].span, "key", ty, Mutability::Not),
_ => return,
},
_ => return,
};
let mutbl = match mutbl {
Mutability::Not => "",
Mutability::Mut => "_mut",
};
let arg = match arg.kind {
ExprKind::AddrOf(BorrowKind::Ref, _, ref expr) => &**expr,
_ => arg,
};
if is_type_diagnostic_item(cx, ty, sym!(hashmap_type)) || match_type(cx, ty, &paths::BTREEMAP) {
span_lint_and_then(
cx,
FOR_KV_MAP,
expr.span,
&format!("you seem to want to iterate on a map's {}s", kind),
|diag| {
let map = sugg::Sugg::hir(cx, arg, "map");
multispan_sugg(
diag,
"use the corresponding method",
vec![
(pat_span, snippet(cx, new_pat_span, kind).into_owned()),
(arg_span, format!("{}.{}s{}()", map.maybe_par(), kind, mutbl)),
],
);
},
);
}
}
}
}
/// Returns `true` if the pattern is a `PatWild` or an ident prefixed with `_`.
fn pat_is_wild<'tcx>(cx: &LateContext<'tcx>, pat: &'tcx PatKind<'_>, body: &'tcx Expr<'_>) -> bool {
match *pat {
PatKind::Wild => true,
PatKind::Binding(_, id, ident, None) if ident.as_str().starts_with('_') => {
!LocalUsedVisitor::new(cx, id).check_expr(body)
},
_ => false,
}
}

45
clippy_lints/src/loops/for_loops_over_fallibles.rs Normal file
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@ -0,0 +1,45 @@
use super::FOR_LOOPS_OVER_FALLIBLES;
use crate::utils::{is_type_diagnostic_item, snippet, span_lint_and_help};
use rustc_hir::{Expr, Pat};
use rustc_lint::LateContext;
use rustc_span::symbol::sym;
/// Checks for `for` loops over `Option`s and `Result`s.
pub(super) fn check(cx: &LateContext<'_>, pat: &Pat<'_>, arg: &Expr<'_>) {
let ty = cx.typeck_results().expr_ty(arg);
if is_type_diagnostic_item(cx, ty, sym::option_type) {
span_lint_and_help(
cx,
FOR_LOOPS_OVER_FALLIBLES,
arg.span,
&format!(
"for loop over `{0}`, which is an `Option`. This is more readably written as an \
`if let` statement",
snippet(cx, arg.span, "_")
),
None,
&format!(
"consider replacing `for {0} in {1}` with `if let Some({0}) = {1}`",
snippet(cx, pat.span, "_"),
snippet(cx, arg.span, "_")
),
);
} else if is_type_diagnostic_item(cx, ty, sym::result_type) {
span_lint_and_help(
cx,
FOR_LOOPS_OVER_FALLIBLES,
arg.span,
&format!(
"for loop over `{0}`, which is a `Result`. This is more readably written as an \
`if let` statement",
snippet(cx, arg.span, "_")
),
None,
&format!(
"consider replacing `for {0} in {1}` with `if let Ok({0}) = {1}`",
snippet(cx, pat.span, "_"),
snippet(cx, arg.span, "_")
),
);
}
}

19
clippy_lints/src/loops/iter_next_loop.rs Normal file
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@ -0,0 +1,19 @@
use super::ITER_NEXT_LOOP;
use crate::utils::{match_trait_method, paths, span_lint};
use rustc_hir::Expr;
use rustc_lint::LateContext;
pub(super) fn check(cx: &LateContext<'_>, arg: &Expr<'_>, expr: &Expr<'_>) -> bool {
if match_trait_method(cx, arg, &paths::ITERATOR) {
span_lint(
cx,
ITER_NEXT_LOOP,
expr.span,
"you are iterating over `Iterator::next()` which is an Option; this will compile but is \
probably not what you want",
);
true
} else {
false
}
}

79
clippy_lints/src/loops/manual_flatten.rs Normal file
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use super::utils::make_iterator_snippet;
use super::MANUAL_FLATTEN;
use crate::utils::{is_ok_ctor, is_some_ctor, path_to_local_id, span_lint_and_then};
use if_chain::if_chain;
use rustc_errors::Applicability;
use rustc_hir::{Expr, ExprKind, MatchSource, Pat, PatKind, QPath, StmtKind};
use rustc_lint::LateContext;
use rustc_span::source_map::Span;
/// Check for unnecessary `if let` usage in a for loop where only the `Some` or `Ok` variant of the
/// iterator element is used.
pub(super) fn check<'tcx>(
cx: &LateContext<'tcx>,
pat: &'tcx Pat<'_>,
arg: &'tcx Expr<'_>,
body: &'tcx Expr<'_>,
span: Span,
) {
if let ExprKind::Block(ref block, _) = body.kind {
// Ensure the `if let` statement is the only expression or statement in the for-loop
let inner_expr = if block.stmts.len() == 1 && block.expr.is_none() {
let match_stmt = &block.stmts[0];
if let StmtKind::Semi(inner_expr) = match_stmt.kind {
Some(inner_expr)
} else {
None
}
} else if block.stmts.is_empty() {
block.expr
} else {
None
};
if_chain! {
if let Some(inner_expr) = inner_expr;
if let ExprKind::Match(
ref match_expr, ref match_arms, MatchSource::IfLetDesugar{ contains_else_clause: false }
) = inner_expr.kind;
// Ensure match_expr in `if let` statement is the same as the pat from the for-loop
if let PatKind::Binding(_, pat_hir_id, _, _) = pat.kind;
if path_to_local_id(match_expr, pat_hir_id);
// Ensure the `if let` statement is for the `Some` variant of `Option` or the `Ok` variant of `Result`
if let PatKind::TupleStruct(QPath::Resolved(None, path), _, _) = match_arms[0].pat.kind;
let some_ctor = is_some_ctor(cx, path.res);
let ok_ctor = is_ok_ctor(cx, path.res);
if some_ctor || ok_ctor;
let if_let_type = if some_ctor { "Some" } else { "Ok" };
then {
// Prepare the error message
let msg = format!("unnecessary `if let` since only the `{}` variant of the iterator element is used", if_let_type);
// Prepare the help message
let mut applicability = Applicability::MaybeIncorrect;
let arg_snippet = make_iterator_snippet(cx, arg, &mut applicability);
span_lint_and_then(
cx,
MANUAL_FLATTEN,
span,
&msg,
|diag| {
let sugg = format!("{}.flatten()", arg_snippet);
diag.span_suggestion(
arg.span,
"try",
sugg,
Applicability::MaybeIncorrect,
);
diag.span_help(
inner_expr.span,
"...and remove the `if let` statement in the for loop",
);
}
);
}
}
}
}

451
clippy_lints/src/loops/manual_memcpy.rs Normal file
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use super::{get_span_of_entire_for_loop, IncrementVisitor, InitializeVisitor, MANUAL_MEMCPY};
use crate::utils::sugg::Sugg;
use crate::utils::{
get_enclosing_block, higher, is_type_diagnostic_item, path_to_local, snippet, span_lint_and_sugg, sugg,
};
use if_chain::if_chain;
use rustc_ast::ast;
use rustc_errors::Applicability;
use rustc_hir::intravisit::walk_block;
use rustc_hir::{BinOpKind, Block, Expr, ExprKind, HirId, Pat, PatKind, StmtKind};
use rustc_lint::LateContext;
use rustc_middle::ty::{self, Ty};
use rustc_span::symbol::sym;
use std::iter::Iterator;
/// Checks for for loops that sequentially copy items from one slice-like
/// object to another.
pub(super) fn check<'tcx>(
cx: &LateContext<'tcx>,
pat: &'tcx Pat<'_>,
arg: &'tcx Expr<'_>,
body: &'tcx Expr<'_>,
expr: &'tcx Expr<'_>,
) -> bool {
if let Some(higher::Range {
start: Some(start),
end: Some(end),
limits,
}) = higher::range(arg)
{
// the var must be a single name
if let PatKind::Binding(_, canonical_id, _, _) = pat.kind {
let mut starts = vec![Start {
id: canonical_id,
kind: StartKind::Range,
}];
// This is one of few ways to return different iterators
// derived from: https://stackoverflow.com/questions/29760668/conditionally-iterate-over-one-of-several-possible-iterators/52064434#52064434
let mut iter_a = None;
let mut iter_b = None;
if let ExprKind::Block(block, _) = body.kind {
if let Some(loop_counters) = get_loop_counters(cx, block, expr) {
starts.extend(loop_counters);
}
iter_a = Some(get_assignments(block, &starts));
} else {
iter_b = Some(get_assignment(body));
}
let assignments = iter_a.into_iter().flatten().chain(iter_b.into_iter());
let big_sugg = assignments
// The only statements in the for loops can be indexed assignments from
// indexed retrievals (except increments of loop counters).
.map(|o| {
o.and_then(|(lhs, rhs)| {
let rhs = fetch_cloned_expr(rhs);
if_chain! {
if let ExprKind::Index(base_left, idx_left) = lhs.kind;
if let ExprKind::Index(base_right, idx_right) = rhs.kind;
if is_slice_like(cx, cx.typeck_results().expr_ty(base_left))
&& is_slice_like(cx, cx.typeck_results().expr_ty(base_right));
if let Some((start_left, offset_left)) = get_details_from_idx(cx, &idx_left, &starts);
if let Some((start_right, offset_right)) = get_details_from_idx(cx, &idx_right, &starts);
// Source and destination must be different
if path_to_local(base_left) != path_to_local(base_right);
then {
Some((IndexExpr { base: base_left, idx: start_left, idx_offset: offset_left },
IndexExpr { base: base_right, idx: start_right, idx_offset: offset_right }))
} else {
None
}
}
})
})
.map(|o| o.map(|(dst, src)| build_manual_memcpy_suggestion(cx, start, end, limits, &dst, &src)))
.collect::<Option<Vec<_>>>()
.filter(|v| !v.is_empty())
.map(|v| v.join("\n "));
if let Some(big_sugg) = big_sugg {
span_lint_and_sugg(
cx,
MANUAL_MEMCPY,
get_span_of_entire_for_loop(expr),
"it looks like you're manually copying between slices",
"try replacing the loop by",
big_sugg,
Applicability::Unspecified,
);
return true;
}
}
}
false
}
fn build_manual_memcpy_suggestion<'tcx>(
cx: &LateContext<'tcx>,
start: &Expr<'_>,
end: &Expr<'_>,
limits: ast::RangeLimits,
dst: &IndexExpr<'_>,
src: &IndexExpr<'_>,
) -> String {
fn print_offset(offset: MinifyingSugg<'static>) -> MinifyingSugg<'static> {
if offset.as_str() == "0" {
sugg::EMPTY.into()
} else {
offset
}
}
let print_limit = |end: &Expr<'_>, end_str: &str, base: &Expr<'_>, sugg: MinifyingSugg<'static>| {
if_chain! {
if let ExprKind::MethodCall(method, _, len_args, _) = end.kind;
if method.ident.name == sym!(len);
if len_args.len() == 1;
if let Some(arg) = len_args.get(0);
if path_to_local(arg) == path_to_local(base);
then {
if sugg.as_str() == end_str {
sugg::EMPTY.into()
} else {
sugg
}
} else {
match limits {
ast::RangeLimits::Closed => {
sugg + &sugg::ONE.into()
},
ast::RangeLimits::HalfOpen => sugg,
}
}
}
};
let start_str = Sugg::hir(cx, start, "").into();
let end_str: MinifyingSugg<'_> = Sugg::hir(cx, end, "").into();
let print_offset_and_limit = |idx_expr: &IndexExpr<'_>| match idx_expr.idx {
StartKind::Range => (
print_offset(apply_offset(&start_str, &idx_expr.idx_offset)).into_sugg(),
print_limit(
end,
end_str.as_str(),
idx_expr.base,
apply_offset(&end_str, &idx_expr.idx_offset),
)
.into_sugg(),
),
StartKind::Counter { initializer } => {
let counter_start = Sugg::hir(cx, initializer, "").into();
(
print_offset(apply_offset(&counter_start, &idx_expr.idx_offset)).into_sugg(),
print_limit(
end,
end_str.as_str(),
idx_expr.base,
apply_offset(&end_str, &idx_expr.idx_offset) + &counter_start - &start_str,
)
.into_sugg(),
)
},
};
let (dst_offset, dst_limit) = print_offset_and_limit(&dst);
let (src_offset, src_limit) = print_offset_and_limit(&src);
let dst_base_str = snippet(cx, dst.base.span, "???");
let src_base_str = snippet(cx, src.base.span, "???");
let dst = if dst_offset == sugg::EMPTY && dst_limit == sugg::EMPTY {
dst_base_str
} else {
format!(
"{}[{}..{}]",
dst_base_str,
dst_offset.maybe_par(),
dst_limit.maybe_par()
)
.into()
};
format!(
"{}.clone_from_slice(&{}[{}..{}]);",
dst,
src_base_str,
src_offset.maybe_par(),
src_limit.maybe_par()
)
}
/// a wrapper of `Sugg`. Besides what `Sugg` do, this removes unnecessary `0`;
/// and also, it avoids subtracting a variable from the same one by replacing it with `0`.
/// it exists for the convenience of the overloaded operators while normal functions can do the
/// same.
#[derive(Clone)]
struct MinifyingSugg<'a>(Sugg<'a>);
impl<'a> MinifyingSugg<'a> {
fn as_str(&self) -> &str {
let (Sugg::NonParen(s) | Sugg::MaybeParen(s) | Sugg::BinOp(_, s)) = &self.0;
s.as_ref()
}
fn into_sugg(self) -> Sugg<'a> {
self.0
}
}
impl<'a> From<Sugg<'a>> for MinifyingSugg<'a> {
fn from(sugg: Sugg<'a>) -> Self {
Self(sugg)
}
}
impl std::ops::Add for &MinifyingSugg<'static> {
type Output = MinifyingSugg<'static>;
fn add(self, rhs: &MinifyingSugg<'static>) -> MinifyingSugg<'static> {
match (self.as_str(), rhs.as_str()) {
("0", _) => rhs.clone(),
(_, "0") => self.clone(),
(_, _) => (&self.0 + &rhs.0).into(),
}
}
}
impl std::ops::Sub for &MinifyingSugg<'static> {
type Output = MinifyingSugg<'static>;
fn sub(self, rhs: &MinifyingSugg<'static>) -> MinifyingSugg<'static> {
match (self.as_str(), rhs.as_str()) {
(_, "0") => self.clone(),
("0", _) => (-rhs.0.clone()).into(),
(x, y) if x == y => sugg::ZERO.into(),
(_, _) => (&self.0 - &rhs.0).into(),
}
}
}
impl std::ops::Add<&MinifyingSugg<'static>> for MinifyingSugg<'static> {
type Output = MinifyingSugg<'static>;
fn add(self, rhs: &MinifyingSugg<'static>) -> MinifyingSugg<'static> {
match (self.as_str(), rhs.as_str()) {
("0", _) => rhs.clone(),
(_, "0") => self,
(_, _) => (self.0 + &rhs.0).into(),
}
}
}
impl std::ops::Sub<&MinifyingSugg<'static>> for MinifyingSugg<'static> {
type Output = MinifyingSugg<'static>;
fn sub(self, rhs: &MinifyingSugg<'static>) -> MinifyingSugg<'static> {
match (self.as_str(), rhs.as_str()) {
(_, "0") => self,
("0", _) => (-rhs.0.clone()).into(),
(x, y) if x == y => sugg::ZERO.into(),
(_, _) => (self.0 - &rhs.0).into(),
}
}
}
/// a wrapper around `MinifyingSugg`, which carries a operator like currying
/// so that the suggested code become more efficient (e.g. `foo + -bar` `foo - bar`).
struct Offset {
value: MinifyingSugg<'static>,
sign: OffsetSign,
}
#[derive(Clone, Copy)]
enum OffsetSign {
Positive,
Negative,
}
impl Offset {
fn negative(value: Sugg<'static>) -> Self {
Self {
value: value.into(),
sign: OffsetSign::Negative,
}
}
fn positive(value: Sugg<'static>) -> Self {
Self {
value: value.into(),
sign: OffsetSign::Positive,
}
}
fn empty() -> Self {
Self::positive(sugg::ZERO)
}
}
fn apply_offset(lhs: &MinifyingSugg<'static>, rhs: &Offset) -> MinifyingSugg<'static> {
match rhs.sign {
OffsetSign::Positive => lhs + &rhs.value,
OffsetSign::Negative => lhs - &rhs.value,
}
}
#[derive(Debug, Clone, Copy)]
enum StartKind<'hir> {
Range,
Counter { initializer: &'hir Expr<'hir> },
}
struct IndexExpr<'hir> {
base: &'hir Expr<'hir>,
idx: StartKind<'hir>,
idx_offset: Offset,
}
struct Start<'hir> {
id: HirId,
kind: StartKind<'hir>,
}
fn is_slice_like<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'_>) -> bool {
let is_slice = match ty.kind() {
ty::Ref(_, subty, _) => is_slice_like(cx, subty),
ty::Slice(..) | ty::Array(..) => true,
_ => false,
};
is_slice || is_type_diagnostic_item(cx, ty, sym::vec_type) || is_type_diagnostic_item(cx, ty, sym!(vecdeque_type))
}
fn fetch_cloned_expr<'tcx>(expr: &'tcx Expr<'tcx>) -> &'tcx Expr<'tcx> {
if_chain! {
if let ExprKind::MethodCall(method, _, args, _) = expr.kind;
if method.ident.name == sym::clone;
if args.len() == 1;
if let Some(arg) = args.get(0);
then { arg } else { expr }
}
}
fn get_details_from_idx<'tcx>(
cx: &LateContext<'tcx>,
idx: &Expr<'_>,
starts: &[Start<'tcx>],
) -> Option<(StartKind<'tcx>, Offset)> {
fn get_start<'tcx>(e: &Expr<'_>, starts: &[Start<'tcx>]) -> Option<StartKind<'tcx>> {
let id = path_to_local(e)?;
starts.iter().find(|start| start.id == id).map(|start| start.kind)
}
fn get_offset<'tcx>(cx: &LateContext<'tcx>, e: &Expr<'_>, starts: &[Start<'tcx>]) -> Option<Sugg<'static>> {
match &e.kind {
ExprKind::Lit(l) => match l.node {
ast::LitKind::Int(x, _ty) => Some(Sugg::NonParen(x.to_string().into())),
_ => None,
},
ExprKind::Path(..) if get_start(e, starts).is_none() => Some(Sugg::hir(cx, e, "???")),
_ => None,
}
}
match idx.kind {
ExprKind::Binary(op, lhs, rhs) => match op.node {
BinOpKind::Add => {
let offset_opt = get_start(lhs, starts)
.and_then(|s| get_offset(cx, rhs, starts).map(|o| (s, o)))
.or_else(|| get_start(rhs, starts).and_then(|s| get_offset(cx, lhs, starts).map(|o| (s, o))));
offset_opt.map(|(s, o)| (s, Offset::positive(o)))
},
BinOpKind::Sub => {
get_start(lhs, starts).and_then(|s| get_offset(cx, rhs, starts).map(|o| (s, Offset::negative(o))))
},
_ => None,
},
ExprKind::Path(..) => get_start(idx, starts).map(|s| (s, Offset::empty())),
_ => None,
}
}
fn get_assignment<'tcx>(e: &'tcx Expr<'tcx>) -> Option<(&'tcx Expr<'tcx>, &'tcx Expr<'tcx>)> {
if let ExprKind::Assign(lhs, rhs, _) = e.kind {
Some((lhs, rhs))
} else {
None
}
}
/// Get assignments from the given block.
/// The returned iterator yields `None` if no assignment expressions are there,
/// filtering out the increments of the given whitelisted loop counters;
/// because its job is to make sure there's nothing other than assignments and the increments.
fn get_assignments<'a, 'tcx>(
Block { stmts, expr, .. }: &'tcx Block<'tcx>,
loop_counters: &'a [Start<'tcx>],
) -> impl Iterator<Item = Option<(&'tcx Expr<'tcx>, &'tcx Expr<'tcx>)>> + 'a {
// As the `filter` and `map` below do different things, I think putting together
// just increases complexity. (cc #3188 and #4193)
stmts
.iter()
.filter_map(move |stmt| match stmt.kind {
StmtKind::Local(..) | StmtKind::Item(..) => None,
StmtKind::Expr(e) | StmtKind::Semi(e) => Some(e),
})
.chain((*expr).into_iter())
.filter(move |e| {
if let ExprKind::AssignOp(_, place, _) = e.kind {
path_to_local(place).map_or(false, |id| {
!loop_counters
.iter()
// skip the first item which should be `StartKind::Range`
// this makes it possible to use the slice with `StartKind::Range` in the same iterator loop.
.skip(1)
.any(|counter| counter.id == id)
})
} else {
true
}
})
.map(get_assignment)
}
fn get_loop_counters<'a, 'tcx>(
cx: &'a LateContext<'tcx>,
body: &'tcx Block<'tcx>,
expr: &'tcx Expr<'_>,
) -> Option<impl Iterator<Item = Start<'tcx>> + 'a> {
// Look for variables that are incremented once per loop iteration.
let mut increment_visitor = IncrementVisitor::new(cx);
walk_block(&mut increment_visitor, body);
// For each candidate, check the parent block to see if
// it's initialized to zero at the start of the loop.
get_enclosing_block(&cx, expr.hir_id).and_then(|block| {
increment_visitor
.into_results()
.filter_map(move |var_id| {
let mut initialize_visitor = InitializeVisitor::new(cx, expr, var_id);
walk_block(&mut initialize_visitor, block);
initialize_visitor.get_result().map(|(_, initializer)| Start {
id: var_id,
kind: StartKind::Counter { initializer },
})
})
.into()
})
}

627
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@ -0,0 +1,627 @@
mod empty_loop;
mod explicit_counter_loop;
mod explicit_into_iter_loop;
mod explicit_iter_loop;
mod for_kv_map;
mod for_loops_over_fallibles;
mod iter_next_loop;
mod manual_flatten;
mod manual_memcpy;
mod mut_range_bound;
mod needless_collect;
mod needless_range_loop;
mod never_loop;
mod same_item_push;
mod single_element_loop;
mod utils;
mod while_immutable_condition;
mod while_let_loop;
mod while_let_on_iterator;
use crate::utils::higher;
use rustc_hir::{Expr, ExprKind, LoopSource, Pat};
use rustc_lint::{LateContext, LateLintPass};
use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_span::source_map::Span;
use utils::{get_span_of_entire_for_loop, make_iterator_snippet, IncrementVisitor, InitializeVisitor};
declare_clippy_lint! {
/// **What it does:** Checks for for-loops that manually copy items between
/// slices that could be optimized by having a memcpy.
///
/// **Why is this bad?** It is not as fast as a memcpy.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// # let src = vec![1];
/// # let mut dst = vec![0; 65];
/// for i in 0..src.len() {
/// dst[i + 64] = src[i];
/// }
/// ```
/// Could be written as:
/// ```rust
/// # let src = vec![1];
/// # let mut dst = vec![0; 65];
/// dst[64..(src.len() + 64)].clone_from_slice(&src[..]);
/// ```
pub MANUAL_MEMCPY,
perf,
"manually copying items between slices"
}
declare_clippy_lint! {
/// **What it does:** Checks for looping over the range of `0..len` of some
/// collection just to get the values by index.
///
/// **Why is this bad?** Just iterating the collection itself makes the intent
/// more clear and is probably faster.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// let vec = vec!['a', 'b', 'c'];
/// for i in 0..vec.len() {
/// println!("{}", vec[i]);
/// }
/// ```
/// Could be written as:
/// ```rust
/// let vec = vec!['a', 'b', 'c'];
/// for i in vec {
/// println!("{}", i);
/// }
/// ```
pub NEEDLESS_RANGE_LOOP,
style,
"for-looping over a range of indices where an iterator over items would do"
}
declare_clippy_lint! {
/// **What it does:** Checks for loops on `x.iter()` where `&x` will do, and
/// suggests the latter.
///
/// **Why is this bad?** Readability.
///
/// **Known problems:** False negatives. We currently only warn on some known
/// types.
///
/// **Example:**
/// ```rust
/// // with `y` a `Vec` or slice:
/// # let y = vec![1];
/// for x in y.iter() {
/// // ..
/// }
/// ```
/// can be rewritten to
/// ```rust
/// # let y = vec![1];
/// for x in &y {
/// // ..
/// }
/// ```
pub EXPLICIT_ITER_LOOP,
pedantic,
"for-looping over `_.iter()` or `_.iter_mut()` when `&_` or `&mut _` would do"
}
declare_clippy_lint! {
/// **What it does:** Checks for loops on `y.into_iter()` where `y` will do, and
/// suggests the latter.
///
/// **Why is this bad?** Readability.
///
/// **Known problems:** None
///
/// **Example:**
/// ```rust
/// # let y = vec![1];
/// // with `y` a `Vec` or slice:
/// for x in y.into_iter() {
/// // ..
/// }
/// ```
/// can be rewritten to
/// ```rust
/// # let y = vec![1];
/// for x in y {
/// // ..
/// }
/// ```
pub EXPLICIT_INTO_ITER_LOOP,
pedantic,
"for-looping over `_.into_iter()` when `_` would do"
}
declare_clippy_lint! {
/// **What it does:** Checks for loops on `x.next()`.
///
/// **Why is this bad?** `next()` returns either `Some(value)` if there was a
/// value, or `None` otherwise. The insidious thing is that `Option<_>`
/// implements `IntoIterator`, so that possibly one value will be iterated,
/// leading to some hard to find bugs. No one will want to write such code
/// [except to win an Underhanded Rust
/// Contest](https://www.reddit.com/r/rust/comments/3hb0wm/underhanded_rust_contest/cu5yuhr).
///
/// **Known problems:** None.
///
/// **Example:**
/// ```ignore
/// for x in y.next() {
/// ..
/// }
/// ```
pub ITER_NEXT_LOOP,
correctness,
"for-looping over `_.next()` which is probably not intended"
}
declare_clippy_lint! {
/// **What it does:** Checks for `for` loops over `Option` or `Result` values.
///
/// **Why is this bad?** Readability. This is more clearly expressed as an `if
/// let`.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// # let opt = Some(1);
///
/// // Bad
/// for x in opt {
/// // ..
/// }
///
/// // Good
/// if let Some(x) = opt {
/// // ..
/// }
/// ```
///
/// // or
///
/// ```rust
/// # let res: Result<i32, std::io::Error> = Ok(1);
///
/// // Bad
/// for x in &res {
/// // ..
/// }
///
/// // Good
/// if let Ok(x) = res {
/// // ..
/// }
/// ```
pub FOR_LOOPS_OVER_FALLIBLES,
correctness,
"for-looping over an `Option` or a `Result`, which is more clearly expressed as an `if let`"
}
declare_clippy_lint! {
/// **What it does:** Detects `loop + match` combinations that are easier
/// written as a `while let` loop.
///
/// **Why is this bad?** The `while let` loop is usually shorter and more
/// readable.
///
/// **Known problems:** Sometimes the wrong binding is displayed ([#383](https://github.com/rust-lang/rust-clippy/issues/383)).
///
/// **Example:**
/// ```rust,no_run
/// # let y = Some(1);
/// loop {
/// let x = match y {
/// Some(x) => x,
/// None => break,
/// };
/// // .. do something with x
/// }
/// // is easier written as
/// while let Some(x) = y {
/// // .. do something with x
/// };
/// ```
pub WHILE_LET_LOOP,
complexity,
"`loop { if let { ... } else break }`, which can be written as a `while let` loop"
}
declare_clippy_lint! {
/// **What it does:** Checks for functions collecting an iterator when collect
/// is not needed.
///
/// **Why is this bad?** `collect` causes the allocation of a new data structure,
/// when this allocation may not be needed.
///
/// **Known problems:**
/// None
///
/// **Example:**
/// ```rust
/// # let iterator = vec![1].into_iter();
/// let len = iterator.clone().collect::<Vec<_>>().len();
/// // should be
/// let len = iterator.count();
/// ```
pub NEEDLESS_COLLECT,
perf,
"collecting an iterator when collect is not needed"
}
declare_clippy_lint! {
/// **What it does:** Checks `for` loops over slices with an explicit counter
/// and suggests the use of `.enumerate()`.
///
/// **Why is it bad?** Using `.enumerate()` makes the intent more clear,
/// declutters the code and may be faster in some instances.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// # let v = vec![1];
/// # fn bar(bar: usize, baz: usize) {}
/// let mut i = 0;
/// for item in &v {
/// bar(i, *item);
/// i += 1;
/// }
/// ```
/// Could be written as
/// ```rust
/// # let v = vec![1];
/// # fn bar(bar: usize, baz: usize) {}
/// for (i, item) in v.iter().enumerate() { bar(i, *item); }
/// ```
pub EXPLICIT_COUNTER_LOOP,
complexity,
"for-looping with an explicit counter when `_.enumerate()` would do"
}
declare_clippy_lint! {
/// **What it does:** Checks for empty `loop` expressions.
///
/// **Why is this bad?** These busy loops burn CPU cycles without doing
/// anything. It is _almost always_ a better idea to `panic!` than to have
/// a busy loop.
///
/// If panicking isn't possible, think of the environment and either:
/// - block on something
/// - sleep the thread for some microseconds
/// - yield or pause the thread
///
/// For `std` targets, this can be done with
/// [`std::thread::sleep`](https://doc.rust-lang.org/std/thread/fn.sleep.html)
/// or [`std::thread::yield_now`](https://doc.rust-lang.org/std/thread/fn.yield_now.html).
///
/// For `no_std` targets, doing this is more complicated, especially because
/// `#[panic_handler]`s can't panic. To stop/pause the thread, you will
/// probably need to invoke some target-specific intrinsic. Examples include:
/// - [`x86_64::instructions::hlt`](https://docs.rs/x86_64/0.12.2/x86_64/instructions/fn.hlt.html)
/// - [`cortex_m::asm::wfi`](https://docs.rs/cortex-m/0.6.3/cortex_m/asm/fn.wfi.html)
///
/// **Known problems:** None.
///
/// **Example:**
/// ```no_run
/// loop {}
/// ```
pub EMPTY_LOOP,
style,
"empty `loop {}`, which should block or sleep"
}
declare_clippy_lint! {
/// **What it does:** Checks for `while let` expressions on iterators.
///
/// **Why is this bad?** Readability. A simple `for` loop is shorter and conveys
/// the intent better.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```ignore
/// while let Some(val) = iter() {
/// ..
/// }
/// ```
pub WHILE_LET_ON_ITERATOR,
style,
"using a `while let` loop instead of a for loop on an iterator"
}
declare_clippy_lint! {
/// **What it does:** Checks for iterating a map (`HashMap` or `BTreeMap`) and
/// ignoring either the keys or values.
///
/// **Why is this bad?** Readability. There are `keys` and `values` methods that
/// can be used to express that don't need the values or keys.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```ignore
/// for (k, _) in &map {
/// ..
/// }
/// ```
///
/// could be replaced by
///
/// ```ignore
/// for k in map.keys() {
/// ..
/// }
/// ```
pub FOR_KV_MAP,
style,
"looping on a map using `iter` when `keys` or `values` would do"
}
declare_clippy_lint! {
/// **What it does:** Checks for loops that will always `break`, `return` or
/// `continue` an outer loop.
///
/// **Why is this bad?** This loop never loops, all it does is obfuscating the
/// code.
///
/// **Known problems:** None
///
/// **Example:**
/// ```rust
/// loop {
/// ..;
/// break;
/// }
/// ```
pub NEVER_LOOP,
correctness,
"any loop that will always `break` or `return`"
}
declare_clippy_lint! {
/// **What it does:** Checks for loops which have a range bound that is a mutable variable
///
/// **Why is this bad?** One might think that modifying the mutable variable changes the loop bounds
///
/// **Known problems:** None
///
/// **Example:**
/// ```rust
/// let mut foo = 42;
/// for i in 0..foo {
/// foo -= 1;
/// println!("{}", i); // prints numbers from 0 to 42, not 0 to 21
/// }
/// ```
pub MUT_RANGE_BOUND,
complexity,
"for loop over a range where one of the bounds is a mutable variable"
}
declare_clippy_lint! {
/// **What it does:** Checks whether variables used within while loop condition
/// can be (and are) mutated in the body.
///
/// **Why is this bad?** If the condition is unchanged, entering the body of the loop
/// will lead to an infinite loop.
///
/// **Known problems:** If the `while`-loop is in a closure, the check for mutation of the
/// condition variables in the body can cause false negatives. For example when only `Upvar` `a` is
/// in the condition and only `Upvar` `b` gets mutated in the body, the lint will not trigger.
///
/// **Example:**
/// ```rust
/// let i = 0;
/// while i > 10 {
/// println!("let me loop forever!");
/// }
/// ```
pub WHILE_IMMUTABLE_CONDITION,
correctness,
"variables used within while expression are not mutated in the body"
}
declare_clippy_lint! {
/// **What it does:** Checks whether a for loop is being used to push a constant
/// value into a Vec.
///
/// **Why is this bad?** This kind of operation can be expressed more succinctly with
/// `vec![item;SIZE]` or `vec.resize(NEW_SIZE, item)` and using these alternatives may also
/// have better performance.
/// **Known problems:** None
///
/// **Example:**
/// ```rust
/// let item1 = 2;
/// let item2 = 3;
/// let mut vec: Vec<u8> = Vec::new();
/// for _ in 0..20 {
/// vec.push(item1);
/// }
/// for _ in 0..30 {
/// vec.push(item2);
/// }
/// ```
/// could be written as
/// ```rust
/// let item1 = 2;
/// let item2 = 3;
/// let mut vec: Vec<u8> = vec![item1; 20];
/// vec.resize(20 + 30, item2);
/// ```
pub SAME_ITEM_PUSH,
style,
"the same item is pushed inside of a for loop"
}
declare_clippy_lint! {
/// **What it does:** Checks whether a for loop has a single element.
///
/// **Why is this bad?** There is no reason to have a loop of a
/// single element.
/// **Known problems:** None
///
/// **Example:**
/// ```rust
/// let item1 = 2;
/// for item in &[item1] {
/// println!("{}", item);
/// }
/// ```
/// could be written as
/// ```rust
/// let item1 = 2;
/// let item = &item1;
/// println!("{}", item);
/// ```
pub SINGLE_ELEMENT_LOOP,
complexity,
"there is no reason to have a single element loop"
}
declare_clippy_lint! {
/// **What it does:** Check for unnecessary `if let` usage in a for loop
/// where only the `Some` or `Ok` variant of the iterator element is used.
///
/// **Why is this bad?** It is verbose and can be simplified
/// by first calling the `flatten` method on the `Iterator`.
///
/// **Known problems:** None.
///
/// **Example:**
///
/// ```rust
/// let x = vec![Some(1), Some(2), Some(3)];
/// for n in x {
/// if let Some(n) = n {
/// println!("{}", n);
/// }
/// }
/// ```
/// Use instead:
/// ```rust
/// let x = vec![Some(1), Some(2), Some(3)];
/// for n in x.into_iter().flatten() {
/// println!("{}", n);
/// }
/// ```
pub MANUAL_FLATTEN,
complexity,
"for loops over `Option`s or `Result`s with a single expression can be simplified"
}
declare_lint_pass!(Loops => [
MANUAL_MEMCPY,
MANUAL_FLATTEN,
NEEDLESS_RANGE_LOOP,
EXPLICIT_ITER_LOOP,
EXPLICIT_INTO_ITER_LOOP,
ITER_NEXT_LOOP,
FOR_LOOPS_OVER_FALLIBLES,
WHILE_LET_LOOP,
NEEDLESS_COLLECT,
EXPLICIT_COUNTER_LOOP,
EMPTY_LOOP,
WHILE_LET_ON_ITERATOR,
FOR_KV_MAP,
NEVER_LOOP,
MUT_RANGE_BOUND,
WHILE_IMMUTABLE_CONDITION,
SAME_ITEM_PUSH,
SINGLE_ELEMENT_LOOP,
]);
impl<'tcx> LateLintPass<'tcx> for Loops {
#[allow(clippy::too_many_lines)]
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
if let Some((pat, arg, body, span)) = higher::for_loop(expr) {
// we don't want to check expanded macros
// this check is not at the top of the function
// since higher::for_loop expressions are marked as expansions
if body.span.from_expansion() {
return;
}
check_for_loop(cx, pat, arg, body, expr, span);
}
// we don't want to check expanded macros
if expr.span.from_expansion() {
return;
}
// check for never_loop
never_loop::check(cx, expr);
// check for `loop { if let {} else break }` that could be `while let`
// (also matches an explicit "match" instead of "if let")
// (even if the "match" or "if let" is used for declaration)
if let ExprKind::Loop(ref block, _, LoopSource::Loop, _) = expr.kind {
// also check for empty `loop {}` statements, skipping those in #[panic_handler]
empty_loop::check(cx, expr, block);
while_let_loop::check(cx, expr, block);
}
while_let_on_iterator::check(cx, expr);
if let Some((cond, body)) = higher::while_loop(&expr) {
while_immutable_condition::check(cx, cond, body);
}
needless_collect::check(expr, cx);
}
}
fn check_for_loop<'tcx>(
cx: &LateContext<'tcx>,
pat: &'tcx Pat<'_>,
arg: &'tcx Expr<'_>,
body: &'tcx Expr<'_>,
expr: &'tcx Expr<'_>,
span: Span,
) {
let is_manual_memcpy_triggered = manual_memcpy::check(cx, pat, arg, body, expr);
if !is_manual_memcpy_triggered {
needless_range_loop::check(cx, pat, arg, body, expr);
explicit_counter_loop::check(cx, pat, arg, body, expr);
}
check_for_loop_arg(cx, pat, arg, expr);
for_kv_map::check(cx, pat, arg, body, expr);
mut_range_bound::check(cx, arg, body);
single_element_loop::check(cx, pat, arg, body, expr);
same_item_push::check(cx, pat, arg, body, expr);
manual_flatten::check(cx, pat, arg, body, span);
}
fn check_for_loop_arg(cx: &LateContext<'_>, pat: &Pat<'_>, arg: &Expr<'_>, expr: &Expr<'_>) {
let mut next_loop_linted = false; // whether or not ITER_NEXT_LOOP lint was used
if let ExprKind::MethodCall(ref method, _, ref args, _) = arg.kind {
// just the receiver, no arguments
if args.len() == 1 {
let method_name = &*method.ident.as_str();
// check for looping over x.iter() or x.iter_mut(), could use &x or &mut x
match method_name {
"iter" | "iter_mut" => explicit_iter_loop::check(cx, args, arg, method_name),
"into_iter" => {
explicit_iter_loop::check(cx, args, arg, method_name);
explicit_into_iter_loop::check(cx, args, arg);
},
"next" => {
next_loop_linted = iter_next_loop::check(cx, arg, expr);
},
_ => {},
}
}
}
if !next_loop_linted {
for_loops_over_fallibles::check(cx, pat, arg);
}
}

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use super::MUT_RANGE_BOUND;
use crate::utils::{higher, path_to_local, span_lint};
use if_chain::if_chain;
use rustc_hir::{BindingAnnotation, Expr, HirId, Node, PatKind};
use rustc_infer::infer::TyCtxtInferExt;
use rustc_lint::LateContext;
use rustc_middle::ty;
use rustc_span::source_map::Span;
use rustc_typeck::expr_use_visitor::{ConsumeMode, Delegate, ExprUseVisitor, PlaceBase, PlaceWithHirId};
pub(super) fn check(cx: &LateContext<'_>, arg: &Expr<'_>, body: &Expr<'_>) {
if let Some(higher::Range {
start: Some(start),
end: Some(end),
..
}) = higher::range(arg)
{
let mut_ids = vec![check_for_mutability(cx, start), check_for_mutability(cx, end)];
if mut_ids[0].is_some() || mut_ids[1].is_some() {
let (span_low, span_high) = check_for_mutation(cx, body, &mut_ids);
mut_warn_with_span(cx, span_low);
mut_warn_with_span(cx, span_high);
}
}
}
fn mut_warn_with_span(cx: &LateContext<'_>, span: Option<Span>) {
if let Some(sp) = span {
span_lint(
cx,
MUT_RANGE_BOUND,
sp,
"attempt to mutate range bound within loop; note that the range of the loop is unchanged",
);
}
}
fn check_for_mutability(cx: &LateContext<'_>, bound: &Expr<'_>) -> Option<HirId> {
if_chain! {
if let Some(hir_id) = path_to_local(bound);
if let Node::Binding(pat) = cx.tcx.hir().get(hir_id);
if let PatKind::Binding(BindingAnnotation::Mutable, ..) = pat.kind;
then {
return Some(hir_id);
}
}
None
}
fn check_for_mutation<'tcx>(
cx: &LateContext<'tcx>,
body: &Expr<'_>,
bound_ids: &[Option<HirId>],
) -> (Option<Span>, Option<Span>) {
let mut delegate = MutatePairDelegate {
cx,
hir_id_low: bound_ids[0],
hir_id_high: bound_ids[1],
span_low: None,
span_high: None,
};
cx.tcx.infer_ctxt().enter(|infcx| {
ExprUseVisitor::new(
&mut delegate,
&infcx,
body.hir_id.owner,
cx.param_env,
cx.typeck_results(),
)
.walk_expr(body);
});
delegate.mutation_span()
}
struct MutatePairDelegate<'a, 'tcx> {
cx: &'a LateContext<'tcx>,
hir_id_low: Option<HirId>,
hir_id_high: Option<HirId>,
span_low: Option<Span>,
span_high: Option<Span>,
}
impl<'tcx> Delegate<'tcx> for MutatePairDelegate<'_, 'tcx> {
fn consume(&mut self, _: &PlaceWithHirId<'tcx>, _: HirId, _: ConsumeMode) {}
fn borrow(&mut self, cmt: &PlaceWithHirId<'tcx>, diag_expr_id: HirId, bk: ty::BorrowKind) {
if let ty::BorrowKind::MutBorrow = bk {
if let PlaceBase::Local(id) = cmt.place.base {
if Some(id) == self.hir_id_low {
self.span_low = Some(self.cx.tcx.hir().span(diag_expr_id))
}
if Some(id) == self.hir_id_high {
self.span_high = Some(self.cx.tcx.hir().span(diag_expr_id))
}
}
}
}
fn mutate(&mut self, cmt: &PlaceWithHirId<'tcx>, diag_expr_id: HirId) {
if let PlaceBase::Local(id) = cmt.place.base {
if Some(id) == self.hir_id_low {
self.span_low = Some(self.cx.tcx.hir().span(diag_expr_id))
}
if Some(id) == self.hir_id_high {
self.span_high = Some(self.cx.tcx.hir().span(diag_expr_id))
}
}
}
}
impl MutatePairDelegate<'_, '_> {
fn mutation_span(&self) -> (Option<Span>, Option<Span>) {
(self.span_low, self.span_high)
}
}

283
clippy_lints/src/loops/needless_collect.rs Normal file
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use super::NEEDLESS_COLLECT;
use crate::utils::sugg::Sugg;
use crate::utils::{
is_type_diagnostic_item, match_trait_method, match_type, path_to_local_id, paths, snippet, span_lint_and_sugg,
span_lint_and_then,
};
use if_chain::if_chain;
use rustc_errors::Applicability;
use rustc_hir::intravisit::{walk_block, walk_expr, NestedVisitorMap, Visitor};
use rustc_hir::{Block, Expr, ExprKind, GenericArg, HirId, Local, Pat, PatKind, QPath, StmtKind};
use rustc_lint::LateContext;
use rustc_middle::hir::map::Map;
use rustc_span::source_map::Span;
use rustc_span::symbol::{sym, Ident};
const NEEDLESS_COLLECT_MSG: &str = "avoid using `collect()` when not needed";
pub(super) fn check<'tcx>(expr: &'tcx Expr<'_>, cx: &LateContext<'tcx>) {
check_needless_collect_direct_usage(expr, cx);
check_needless_collect_indirect_usage(expr, cx);
}
fn check_needless_collect_direct_usage<'tcx>(expr: &'tcx Expr<'_>, cx: &LateContext<'tcx>) {
if_chain! {
if let ExprKind::MethodCall(ref method, _, ref args, _) = expr.kind;
if let ExprKind::MethodCall(ref chain_method, _, _, _) = args[0].kind;
if chain_method.ident.name == sym!(collect) && match_trait_method(cx, &args[0], &paths::ITERATOR);
if let Some(ref generic_args) = chain_method.args;
if let Some(GenericArg::Type(ref ty)) = generic_args.args.get(0);
then {
let ty = cx.typeck_results().node_type(ty.hir_id);
if is_type_diagnostic_item(cx, ty, sym::vec_type) ||
is_type_diagnostic_item(cx, ty, sym!(vecdeque_type)) ||
match_type(cx, ty, &paths::BTREEMAP) ||
is_type_diagnostic_item(cx, ty, sym!(hashmap_type)) {
if method.ident.name == sym!(len) {
let span = shorten_needless_collect_span(expr);
span_lint_and_sugg(
cx,
NEEDLESS_COLLECT,
span,
NEEDLESS_COLLECT_MSG,
"replace with",
"count()".to_string(),
Applicability::MachineApplicable,
);
}
if method.ident.name == sym!(is_empty) {
let span = shorten_needless_collect_span(expr);
span_lint_and_sugg(
cx,
NEEDLESS_COLLECT,
span,
NEEDLESS_COLLECT_MSG,
"replace with",
"next().is_none()".to_string(),
Applicability::MachineApplicable,
);
}
if method.ident.name == sym!(contains) {
let contains_arg = snippet(cx, args[1].span, "??");
let span = shorten_needless_collect_span(expr);
span_lint_and_then(
cx,
NEEDLESS_COLLECT,
span,
NEEDLESS_COLLECT_MSG,
|diag| {
let (arg, pred) = contains_arg
.strip_prefix('&')
.map_or(("&x", &*contains_arg), |s| ("x", s));
diag.span_suggestion(
span,
"replace with",
format!(
"any(|{}| x == {})",
arg, pred
),
Applicability::MachineApplicable,
);
}
);
}
}
}
}
}
fn check_needless_collect_indirect_usage<'tcx>(expr: &'tcx Expr<'_>, cx: &LateContext<'tcx>) {
if let ExprKind::Block(ref block, _) = expr.kind {
for ref stmt in block.stmts {
if_chain! {
if let StmtKind::Local(
Local { pat: Pat { hir_id: pat_id, kind: PatKind::Binding(_, _, ident, .. ), .. },
init: Some(ref init_expr), .. }
) = stmt.kind;
if let ExprKind::MethodCall(ref method_name, _, &[ref iter_source], ..) = init_expr.kind;
if method_name.ident.name == sym!(collect) && match_trait_method(cx, &init_expr, &paths::ITERATOR);
if let Some(ref generic_args) = method_name.args;
if let Some(GenericArg::Type(ref ty)) = generic_args.args.get(0);
if let ty = cx.typeck_results().node_type(ty.hir_id);
if is_type_diagnostic_item(cx, ty, sym::vec_type) ||
is_type_diagnostic_item(cx, ty, sym!(vecdeque_type)) ||
match_type(cx, ty, &paths::LINKED_LIST);
if let Some(iter_calls) = detect_iter_and_into_iters(block, *ident);
if iter_calls.len() == 1;
then {
let mut used_count_visitor = UsedCountVisitor {
cx,
id: *pat_id,
count: 0,
};
walk_block(&mut used_count_visitor, block);
if used_count_visitor.count > 1 {
return;
}
// Suggest replacing iter_call with iter_replacement, and removing stmt
let iter_call = &iter_calls[0];
span_lint_and_then(
cx,
super::NEEDLESS_COLLECT,
stmt.span.until(iter_call.span),
NEEDLESS_COLLECT_MSG,
|diag| {
let iter_replacement = format!("{}{}", Sugg::hir(cx, iter_source, ".."), iter_call.get_iter_method(cx));
diag.multipart_suggestion(
iter_call.get_suggestion_text(),
vec![
(stmt.span, String::new()),
(iter_call.span, iter_replacement)
],
Applicability::MachineApplicable,// MaybeIncorrect,
).emit();
},
);
}
}
}
}
}
struct IterFunction {
func: IterFunctionKind,
span: Span,
}
impl IterFunction {
fn get_iter_method(&self, cx: &LateContext<'_>) -> String {
match &self.func {
IterFunctionKind::IntoIter => String::new(),
IterFunctionKind::Len => String::from(".count()"),
IterFunctionKind::IsEmpty => String::from(".next().is_none()"),
IterFunctionKind::Contains(span) => {
let s = snippet(cx, *span, "..");
if let Some(stripped) = s.strip_prefix('&') {
format!(".any(|x| x == {})", stripped)
} else {
format!(".any(|x| x == *{})", s)
}
},
}
}
fn get_suggestion_text(&self) -> &'static str {
match &self.func {
IterFunctionKind::IntoIter => {
"use the original Iterator instead of collecting it and then producing a new one"
},
IterFunctionKind::Len => {
"take the original Iterator's count instead of collecting it and finding the length"
},
IterFunctionKind::IsEmpty => {
"check if the original Iterator has anything instead of collecting it and seeing if it's empty"
},
IterFunctionKind::Contains(_) => {
"check if the original Iterator contains an element instead of collecting then checking"
},
}
}
}
enum IterFunctionKind {
IntoIter,
Len,
IsEmpty,
Contains(Span),
}
struct IterFunctionVisitor {
uses: Vec<IterFunction>,
seen_other: bool,
target: Ident,
}
impl<'tcx> Visitor<'tcx> for IterFunctionVisitor {
fn visit_expr(&mut self, expr: &'tcx Expr<'tcx>) {
// Check function calls on our collection
if_chain! {
if let ExprKind::MethodCall(method_name, _, ref args, _) = &expr.kind;
if let Some(Expr { kind: ExprKind::Path(QPath::Resolved(_, ref path)), .. }) = args.get(0);
if let &[name] = &path.segments;
if name.ident == self.target;
then {
let len = sym!(len);
let is_empty = sym!(is_empty);
let contains = sym!(contains);
match method_name.ident.name {
sym::into_iter => self.uses.push(
IterFunction { func: IterFunctionKind::IntoIter, span: expr.span }
),
name if name == len => self.uses.push(
IterFunction { func: IterFunctionKind::Len, span: expr.span }
),
name if name == is_empty => self.uses.push(
IterFunction { func: IterFunctionKind::IsEmpty, span: expr.span }
),
name if name == contains => self.uses.push(
IterFunction { func: IterFunctionKind::Contains(args[1].span), span: expr.span }
),
_ => self.seen_other = true,
}
return
}
}
// Check if the collection is used for anything else
if_chain! {
if let Expr { kind: ExprKind::Path(QPath::Resolved(_, ref path)), .. } = expr;
if let &[name] = &path.segments;
if name.ident == self.target;
then {
self.seen_other = true;
} else {
walk_expr(self, expr);
}
}
}
type Map = Map<'tcx>;
fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
NestedVisitorMap::None
}
}
struct UsedCountVisitor<'a, 'tcx> {
cx: &'a LateContext<'tcx>,
id: HirId,
count: usize,
}
impl<'a, 'tcx> Visitor<'tcx> for UsedCountVisitor<'a, 'tcx> {
type Map = Map<'tcx>;
fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
if path_to_local_id(expr, self.id) {
self.count += 1;
} else {
walk_expr(self, expr);
}
}
fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
NestedVisitorMap::OnlyBodies(self.cx.tcx.hir())
}
}
/// Detect the occurrences of calls to `iter` or `into_iter` for the
/// given identifier
fn detect_iter_and_into_iters<'tcx>(block: &'tcx Block<'tcx>, identifier: Ident) -> Option<Vec<IterFunction>> {
let mut visitor = IterFunctionVisitor {
uses: Vec::new(),
target: identifier,
seen_other: false,
};
visitor.visit_block(block);
if visitor.seen_other { None } else { Some(visitor.uses) }
}
fn shorten_needless_collect_span(expr: &Expr<'_>) -> Span {
if_chain! {
if let ExprKind::MethodCall(.., args, _) = &expr.kind;
if let ExprKind::MethodCall(_, span, ..) = &args[0].kind;
then {
return expr.span.with_lo(span.lo());
}
}
unreachable!();
}

391
clippy_lints/src/loops/needless_range_loop.rs Normal file
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@ -0,0 +1,391 @@
use super::NEEDLESS_RANGE_LOOP;
use crate::utils::visitors::LocalUsedVisitor;
use crate::utils::{
contains_name, has_iter_method, higher, is_integer_const, match_trait_method, multispan_sugg, path_to_local_id,
paths, snippet, span_lint_and_then, sugg, SpanlessEq,
};
use if_chain::if_chain;
use rustc_ast::ast;
use rustc_data_structures::fx::{FxHashMap, FxHashSet};
use rustc_hir::def::{DefKind, Res};
use rustc_hir::intravisit::{walk_expr, NestedVisitorMap, Visitor};
use rustc_hir::{BinOpKind, BorrowKind, Expr, ExprKind, HirId, Mutability, Pat, PatKind, QPath};
use rustc_lint::LateContext;
use rustc_middle::hir::map::Map;
use rustc_middle::middle::region;
use rustc_middle::ty::{self, Ty};
use rustc_span::symbol::{sym, Symbol};
use std::iter::Iterator;
use std::mem;
/// Checks for looping over a range and then indexing a sequence with it.
/// The iteratee must be a range literal.
#[allow(clippy::too_many_lines)]
pub(super) fn check<'tcx>(
cx: &LateContext<'tcx>,
pat: &'tcx Pat<'_>,
arg: &'tcx Expr<'_>,
body: &'tcx Expr<'_>,
expr: &'tcx Expr<'_>,
) {
if let Some(higher::Range {
start: Some(start),
ref end,
limits,
}) = higher::range(arg)
{
// the var must be a single name
if let PatKind::Binding(_, canonical_id, ident, _) = pat.kind {
let mut visitor = VarVisitor {
cx,
var: canonical_id,
indexed_mut: FxHashSet::default(),
indexed_indirectly: FxHashMap::default(),
indexed_directly: FxHashMap::default(),
referenced: FxHashSet::default(),
nonindex: false,
prefer_mutable: false,
};
walk_expr(&mut visitor, body);
// linting condition: we only indexed one variable, and indexed it directly
if visitor.indexed_indirectly.is_empty() && visitor.indexed_directly.len() == 1 {
let (indexed, (indexed_extent, indexed_ty)) = visitor
.indexed_directly
.into_iter()
.next()
.expect("already checked that we have exactly 1 element");
// ensure that the indexed variable was declared before the loop, see #601
if let Some(indexed_extent) = indexed_extent {
let parent_id = cx.tcx.hir().get_parent_item(expr.hir_id);
let parent_def_id = cx.tcx.hir().local_def_id(parent_id);
let region_scope_tree = cx.tcx.region_scope_tree(parent_def_id);
let pat_extent = region_scope_tree.var_scope(pat.hir_id.local_id);
if region_scope_tree.is_subscope_of(indexed_extent, pat_extent) {
return;
}
}
// don't lint if the container that is indexed does not have .iter() method
let has_iter = has_iter_method(cx, indexed_ty);
if has_iter.is_none() {
return;
}
// don't lint if the container that is indexed into is also used without
// indexing
if visitor.referenced.contains(&indexed) {
return;
}
let starts_at_zero = is_integer_const(cx, start, 0);
let skip = if starts_at_zero {
String::new()
} else if visitor.indexed_mut.contains(&indexed) && contains_name(indexed, start) {
return;
} else {
format!(".skip({})", snippet(cx, start.span, ".."))
};
let mut end_is_start_plus_val = false;
let take = if let Some(end) = *end {
let mut take_expr = end;
if let ExprKind::Binary(ref op, ref left, ref right) = end.kind {
if let BinOpKind::Add = op.node {
let start_equal_left = SpanlessEq::new(cx).eq_expr(start, left);
let start_equal_right = SpanlessEq::new(cx).eq_expr(start, right);
if start_equal_left {
take_expr = right;
} else if start_equal_right {
take_expr = left;
}
end_is_start_plus_val = start_equal_left | start_equal_right;
}
}
if is_len_call(end, indexed) || is_end_eq_array_len(cx, end, limits, indexed_ty) {
String::new()
} else if visitor.indexed_mut.contains(&indexed) && contains_name(indexed, take_expr) {
return;
} else {
match limits {
ast::RangeLimits::Closed => {
let take_expr = sugg::Sugg::hir(cx, take_expr, "<count>");
format!(".take({})", take_expr + sugg::ONE)
},
ast::RangeLimits::HalfOpen => format!(".take({})", snippet(cx, take_expr.span, "..")),
}
}
} else {
String::new()
};
let (ref_mut, method) = if visitor.indexed_mut.contains(&indexed) {
("mut ", "iter_mut")
} else {
("", "iter")
};
let take_is_empty = take.is_empty();
let mut method_1 = take;
let mut method_2 = skip;
if end_is_start_plus_val {
mem::swap(&mut method_1, &mut method_2);
}
if visitor.nonindex {
span_lint_and_then(
cx,
NEEDLESS_RANGE_LOOP,
expr.span,
&format!("the loop variable `{}` is used to index `{}`", ident.name, indexed),
|diag| {
multispan_sugg(
diag,
"consider using an iterator",
vec![
(pat.span, format!("({}, <item>)", ident.name)),
(
arg.span,
format!("{}.{}().enumerate(){}{}", indexed, method, method_1, method_2),
),
],
);
},
);
} else {
let repl = if starts_at_zero && take_is_empty {
format!("&{}{}", ref_mut, indexed)
} else {
format!("{}.{}(){}{}", indexed, method, method_1, method_2)
};
span_lint_and_then(
cx,
NEEDLESS_RANGE_LOOP,
expr.span,
&format!("the loop variable `{}` is only used to index `{}`", ident.name, indexed),
|diag| {
multispan_sugg(
diag,
"consider using an iterator",
vec![(pat.span, "<item>".to_string()), (arg.span, repl)],
);
},
);
}
}
}
}
}
fn is_len_call(expr: &Expr<'_>, var: Symbol) -> bool {
if_chain! {
if let ExprKind::MethodCall(ref method, _, ref len_args, _) = expr.kind;
if len_args.len() == 1;
if method.ident.name == sym!(len);
if let ExprKind::Path(QPath::Resolved(_, ref path)) = len_args[0].kind;
if path.segments.len() == 1;
if path.segments[0].ident.name == var;
then {
return true;
}
}
false
}
fn is_end_eq_array_len<'tcx>(
cx: &LateContext<'tcx>,
end: &Expr<'_>,
limits: ast::RangeLimits,
indexed_ty: Ty<'tcx>,
) -> bool {
if_chain! {
if let ExprKind::Lit(ref lit) = end.kind;
if let ast::LitKind::Int(end_int, _) = lit.node;
if let ty::Array(_, arr_len_const) = indexed_ty.kind();
if let Some(arr_len) = arr_len_const.try_eval_usize(cx.tcx, cx.param_env);
then {
return match limits {
ast::RangeLimits::Closed => end_int + 1 >= arr_len.into(),
ast::RangeLimits::HalfOpen => end_int >= arr_len.into(),
};
}
}
false
}
struct VarVisitor<'a, 'tcx> {
/// context reference
cx: &'a LateContext<'tcx>,
/// var name to look for as index
var: HirId,
/// indexed variables that are used mutably
indexed_mut: FxHashSet<Symbol>,
/// indirectly indexed variables (`v[(i + 4) % N]`), the extend is `None` for global
indexed_indirectly: FxHashMap<Symbol, Option<region::Scope>>,
/// subset of `indexed` of vars that are indexed directly: `v[i]`
/// this will not contain cases like `v[calc_index(i)]` or `v[(i + 4) % N]`
indexed_directly: FxHashMap<Symbol, (Option<region::Scope>, Ty<'tcx>)>,
/// Any names that are used outside an index operation.
/// Used to detect things like `&mut vec` used together with `vec[i]`
referenced: FxHashSet<Symbol>,
/// has the loop variable been used in expressions other than the index of
/// an index op?
nonindex: bool,
/// Whether we are inside the `$` in `&mut $` or `$ = foo` or `$.bar`, where bar
/// takes `&mut self`
prefer_mutable: bool,
}
impl<'a, 'tcx> VarVisitor<'a, 'tcx> {
fn check(&mut self, idx: &'tcx Expr<'_>, seqexpr: &'tcx Expr<'_>, expr: &'tcx Expr<'_>) -> bool {
if_chain! {
// the indexed container is referenced by a name
if let ExprKind::Path(ref seqpath) = seqexpr.kind;
if let QPath::Resolved(None, ref seqvar) = *seqpath;
if seqvar.segments.len() == 1;
then {
let index_used_directly = path_to_local_id(idx, self.var);
let indexed_indirectly = {
let mut used_visitor = LocalUsedVisitor::new(self.cx, self.var);
walk_expr(&mut used_visitor, idx);
used_visitor.used
};
if indexed_indirectly || index_used_directly {
if self.prefer_mutable {
self.indexed_mut.insert(seqvar.segments[0].ident.name);
}
let res = self.cx.qpath_res(seqpath, seqexpr.hir_id);
match res {
Res::Local(hir_id) => {
let parent_id = self.cx.tcx.hir().get_parent_item(expr.hir_id);
let parent_def_id = self.cx.tcx.hir().local_def_id(parent_id);
let extent = self.cx.tcx.region_scope_tree(parent_def_id).var_scope(hir_id.local_id);
if indexed_indirectly {
self.indexed_indirectly.insert(seqvar.segments[0].ident.name, Some(extent));
}
if index_used_directly {
self.indexed_directly.insert(
seqvar.segments[0].ident.name,
(Some(extent), self.cx.typeck_results().node_type(seqexpr.hir_id)),
);
}
return false; // no need to walk further *on the variable*
}
Res::Def(DefKind::Static | DefKind::Const, ..) => {
if indexed_indirectly {
self.indexed_indirectly.insert(seqvar.segments[0].ident.name, None);
}
if index_used_directly {
self.indexed_directly.insert(
seqvar.segments[0].ident.name,
(None, self.cx.typeck_results().node_type(seqexpr.hir_id)),
);
}
return false; // no need to walk further *on the variable*
}
_ => (),
}
}
}
}
true
}
}
impl<'a, 'tcx> Visitor<'tcx> for VarVisitor<'a, 'tcx> {
type Map = Map<'tcx>;
fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
if_chain! {
// a range index op
if let ExprKind::MethodCall(ref meth, _, ref args, _) = expr.kind;
if (meth.ident.name == sym::index && match_trait_method(self.cx, expr, &paths::INDEX))
|| (meth.ident.name == sym::index_mut && match_trait_method(self.cx, expr, &paths::INDEX_MUT));
if !self.check(&args[1], &args[0], expr);
then { return }
}
if_chain! {
// an index op
if let ExprKind::Index(ref seqexpr, ref idx) = expr.kind;
if !self.check(idx, seqexpr, expr);
then { return }
}
if_chain! {
// directly using a variable
if let ExprKind::Path(QPath::Resolved(None, path)) = expr.kind;
if let Res::Local(local_id) = path.res;
then {
if local_id == self.var {
self.nonindex = true;
} else {
// not the correct variable, but still a variable
self.referenced.insert(path.segments[0].ident.name);
}
}
}
let old = self.prefer_mutable;
match expr.kind {
ExprKind::AssignOp(_, ref lhs, ref rhs) | ExprKind::Assign(ref lhs, ref rhs, _) => {
self.prefer_mutable = true;
self.visit_expr(lhs);
self.prefer_mutable = false;
self.visit_expr(rhs);
},
ExprKind::AddrOf(BorrowKind::Ref, mutbl, ref expr) => {
if mutbl == Mutability::Mut {
self.prefer_mutable = true;
}
self.visit_expr(expr);
},
ExprKind::Call(ref f, args) => {
self.visit_expr(f);
for expr in args {
let ty = self.cx.typeck_results().expr_ty_adjusted(expr);
self.prefer_mutable = false;
if let ty::Ref(_, _, mutbl) = *ty.kind() {
if mutbl == Mutability::Mut {
self.prefer_mutable = true;
}
}
self.visit_expr(expr);
}
},
ExprKind::MethodCall(_, _, args, _) => {
let def_id = self.cx.typeck_results().type_dependent_def_id(expr.hir_id).unwrap();
for (ty, expr) in self.cx.tcx.fn_sig(def_id).inputs().skip_binder().iter().zip(args) {
self.prefer_mutable = false;
if let ty::Ref(_, _, mutbl) = *ty.kind() {
if mutbl == Mutability::Mut {
self.prefer_mutable = true;
}
}
self.visit_expr(expr);
}
},
ExprKind::Closure(_, _, body_id, ..) => {
let body = self.cx.tcx.hir().body(body_id);
self.visit_expr(&body.value);
},
_ => walk_expr(self, expr),
}
self.prefer_mutable = old;
}
fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
NestedVisitorMap::None
}
}

172
clippy_lints/src/loops/never_loop.rs Normal file
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use super::NEVER_LOOP;
use crate::utils::span_lint;
use rustc_hir::{Block, Expr, ExprKind, HirId, InlineAsmOperand, Stmt, StmtKind};
use rustc_lint::LateContext;
use std::iter::{once, Iterator};
pub(super) fn check(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
if let ExprKind::Loop(ref block, _, _, _) = expr.kind {
match never_loop_block(block, expr.hir_id) {
NeverLoopResult::AlwaysBreak => span_lint(cx, NEVER_LOOP, expr.span, "this loop never actually loops"),
NeverLoopResult::MayContinueMainLoop | NeverLoopResult::Otherwise => (),
}
}
}
enum NeverLoopResult {
// A break/return always get triggered but not necessarily for the main loop.
AlwaysBreak,
// A continue may occur for the main loop.
MayContinueMainLoop,
Otherwise,
}
#[must_use]
fn absorb_break(arg: &NeverLoopResult) -> NeverLoopResult {
match *arg {
NeverLoopResult::AlwaysBreak | NeverLoopResult::Otherwise => NeverLoopResult::Otherwise,
NeverLoopResult::MayContinueMainLoop => NeverLoopResult::MayContinueMainLoop,
}
}
// Combine two results for parts that are called in order.
#[must_use]
fn combine_seq(first: NeverLoopResult, second: NeverLoopResult) -> NeverLoopResult {
match first {
NeverLoopResult::AlwaysBreak | NeverLoopResult::MayContinueMainLoop => first,
NeverLoopResult::Otherwise => second,
}
}
// Combine two results where both parts are called but not necessarily in order.
#[must_use]
fn combine_both(left: NeverLoopResult, right: NeverLoopResult) -> NeverLoopResult {
match (left, right) {
(NeverLoopResult::MayContinueMainLoop, _) | (_, NeverLoopResult::MayContinueMainLoop) => {
NeverLoopResult::MayContinueMainLoop
},
(NeverLoopResult::AlwaysBreak, _) | (_, NeverLoopResult::AlwaysBreak) => NeverLoopResult::AlwaysBreak,
(NeverLoopResult::Otherwise, NeverLoopResult::Otherwise) => NeverLoopResult::Otherwise,
}
}
// Combine two results where only one of the part may have been executed.
#[must_use]
fn combine_branches(b1: NeverLoopResult, b2: NeverLoopResult) -> NeverLoopResult {
match (b1, b2) {
(NeverLoopResult::AlwaysBreak, NeverLoopResult::AlwaysBreak) => NeverLoopResult::AlwaysBreak,
(NeverLoopResult::MayContinueMainLoop, _) | (_, NeverLoopResult::MayContinueMainLoop) => {
NeverLoopResult::MayContinueMainLoop
},
(NeverLoopResult::Otherwise, _) | (_, NeverLoopResult::Otherwise) => NeverLoopResult::Otherwise,
}
}
fn never_loop_block(block: &Block<'_>, main_loop_id: HirId) -> NeverLoopResult {
let stmts = block.stmts.iter().map(stmt_to_expr);
let expr = once(block.expr.as_deref());
let mut iter = stmts.chain(expr).flatten();
never_loop_expr_seq(&mut iter, main_loop_id)
}
fn never_loop_expr_seq<'a, T: Iterator<Item = &'a Expr<'a>>>(es: &mut T, main_loop_id: HirId) -> NeverLoopResult {
es.map(|e| never_loop_expr(e, main_loop_id))
.fold(NeverLoopResult::Otherwise, combine_seq)
}
fn stmt_to_expr<'tcx>(stmt: &Stmt<'tcx>) -> Option<&'tcx Expr<'tcx>> {
match stmt.kind {
StmtKind::Semi(ref e, ..) | StmtKind::Expr(ref e, ..) => Some(e),
StmtKind::Local(ref local) => local.init.as_deref(),
_ => None,
}
}
fn never_loop_expr(expr: &Expr<'_>, main_loop_id: HirId) -> NeverLoopResult {
match expr.kind {
ExprKind::Box(ref e)
| ExprKind::Unary(_, ref e)
| ExprKind::Cast(ref e, _)
| ExprKind::Type(ref e, _)
| ExprKind::Field(ref e, _)
| ExprKind::AddrOf(_, _, ref e)
| ExprKind::Struct(_, _, Some(ref e))
| ExprKind::Repeat(ref e, _)
| ExprKind::DropTemps(ref e) => never_loop_expr(e, main_loop_id),
ExprKind::Array(ref es) | ExprKind::MethodCall(_, _, ref es, _) | ExprKind::Tup(ref es) => {
never_loop_expr_all(&mut es.iter(), main_loop_id)
},
ExprKind::Call(ref e, ref es) => never_loop_expr_all(&mut once(&**e).chain(es.iter()), main_loop_id),
ExprKind::Binary(_, ref e1, ref e2)
| ExprKind::Assign(ref e1, ref e2, _)
| ExprKind::AssignOp(_, ref e1, ref e2)
| ExprKind::Index(ref e1, ref e2) => never_loop_expr_all(&mut [&**e1, &**e2].iter().cloned(), main_loop_id),
ExprKind::Loop(ref b, _, _, _) => {
// Break can come from the inner loop so remove them.
absorb_break(&never_loop_block(b, main_loop_id))
},
ExprKind::If(ref e, ref e2, ref e3) => {
let e1 = never_loop_expr(e, main_loop_id);
let e2 = never_loop_expr(e2, main_loop_id);
let e3 = e3
.as_ref()
.map_or(NeverLoopResult::Otherwise, |e| never_loop_expr(e, main_loop_id));
combine_seq(e1, combine_branches(e2, e3))
},
ExprKind::Match(ref e, ref arms, _) => {
let e = never_loop_expr(e, main_loop_id);
if arms.is_empty() {
e
} else {
let arms = never_loop_expr_branch(&mut arms.iter().map(|a| &*a.body), main_loop_id);
combine_seq(e, arms)
}
},
ExprKind::Block(ref b, _) => never_loop_block(b, main_loop_id),
ExprKind::Continue(d) => {
let id = d
.target_id
.expect("target ID can only be missing in the presence of compilation errors");
if id == main_loop_id {
NeverLoopResult::MayContinueMainLoop
} else {
NeverLoopResult::AlwaysBreak
}
},
ExprKind::Break(_, ref e) | ExprKind::Ret(ref e) => e.as_ref().map_or(NeverLoopResult::AlwaysBreak, |e| {
combine_seq(never_loop_expr(e, main_loop_id), NeverLoopResult::AlwaysBreak)
}),
ExprKind::InlineAsm(ref asm) => asm
.operands
.iter()
.map(|(o, _)| match o {
InlineAsmOperand::In { expr, .. }
| InlineAsmOperand::InOut { expr, .. }
| InlineAsmOperand::Const { expr }
| InlineAsmOperand::Sym { expr } => never_loop_expr(expr, main_loop_id),
InlineAsmOperand::Out { expr, .. } => never_loop_expr_all(&mut expr.iter(), main_loop_id),
InlineAsmOperand::SplitInOut { in_expr, out_expr, .. } => {
never_loop_expr_all(&mut once(in_expr).chain(out_expr.iter()), main_loop_id)
},
})
.fold(NeverLoopResult::Otherwise, combine_both),
ExprKind::Struct(_, _, None)
| ExprKind::Yield(_, _)
| ExprKind::Closure(_, _, _, _, _)
| ExprKind::LlvmInlineAsm(_)
| ExprKind::Path(_)
| ExprKind::ConstBlock(_)
| ExprKind::Lit(_)
| ExprKind::Err => NeverLoopResult::Otherwise,
}
}
fn never_loop_expr_all<'a, T: Iterator<Item = &'a Expr<'a>>>(es: &mut T, main_loop_id: HirId) -> NeverLoopResult {
es.map(|e| never_loop_expr(e, main_loop_id))
.fold(NeverLoopResult::Otherwise, combine_both)
}
fn never_loop_expr_branch<'a, T: Iterator<Item = &'a Expr<'a>>>(e: &mut T, main_loop_id: HirId) -> NeverLoopResult {
e.map(|e| never_loop_expr(e, main_loop_id))
.fold(NeverLoopResult::AlwaysBreak, combine_branches)
}

169
clippy_lints/src/loops/same_item_push.rs Normal file
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use super::SAME_ITEM_PUSH;
use crate::utils::{implements_trait, is_type_diagnostic_item, snippet_with_macro_callsite, span_lint_and_help};
use if_chain::if_chain;
use rustc_hir::def::{DefKind, Res};
use rustc_hir::intravisit::{walk_expr, NestedVisitorMap, Visitor};
use rustc_hir::{BindingAnnotation, Block, Expr, ExprKind, Node, Pat, PatKind, Stmt, StmtKind};
use rustc_lint::LateContext;
use rustc_middle::hir::map::Map;
use rustc_span::symbol::sym;
use std::iter::Iterator;
/// Detects for loop pushing the same item into a Vec
pub(super) fn check<'tcx>(
cx: &LateContext<'tcx>,
pat: &'tcx Pat<'_>,
_: &'tcx Expr<'_>,
body: &'tcx Expr<'_>,
_: &'tcx Expr<'_>,
) {
fn emit_lint(cx: &LateContext<'_>, vec: &Expr<'_>, pushed_item: &Expr<'_>) {
let vec_str = snippet_with_macro_callsite(cx, vec.span, "");
let item_str = snippet_with_macro_callsite(cx, pushed_item.span, "");
span_lint_and_help(
cx,
SAME_ITEM_PUSH,
vec.span,
"it looks like the same item is being pushed into this Vec",
None,
&format!(
"try using vec![{};SIZE] or {}.resize(NEW_SIZE, {})",
item_str, vec_str, item_str
),
)
}
if !matches!(pat.kind, PatKind::Wild) {
return;
}
// Determine whether it is safe to lint the body
let mut same_item_push_visitor = SameItemPushVisitor {
should_lint: true,
vec_push: None,
cx,
};
walk_expr(&mut same_item_push_visitor, body);
if same_item_push_visitor.should_lint {
if let Some((vec, pushed_item)) = same_item_push_visitor.vec_push {
let vec_ty = cx.typeck_results().expr_ty(vec);
let ty = vec_ty.walk().nth(1).unwrap().expect_ty();
if cx
.tcx
.lang_items()
.clone_trait()
.map_or(false, |id| implements_trait(cx, ty, id, &[]))
{
// Make sure that the push does not involve possibly mutating values
match pushed_item.kind {
ExprKind::Path(ref qpath) => {
match cx.qpath_res(qpath, pushed_item.hir_id) {
// immutable bindings that are initialized with literal or constant
Res::Local(hir_id) => {
if_chain! {
let node = cx.tcx.hir().get(hir_id);
if let Node::Binding(pat) = node;
if let PatKind::Binding(bind_ann, ..) = pat.kind;
if !matches!(bind_ann, BindingAnnotation::RefMut | BindingAnnotation::Mutable);
let parent_node = cx.tcx.hir().get_parent_node(hir_id);
if let Some(Node::Local(parent_let_expr)) = cx.tcx.hir().find(parent_node);
if let Some(init) = parent_let_expr.init;
then {
match init.kind {
// immutable bindings that are initialized with literal
ExprKind::Lit(..) => emit_lint(cx, vec, pushed_item),
// immutable bindings that are initialized with constant
ExprKind::Path(ref path) => {
if let Res::Def(DefKind::Const, ..) = cx.qpath_res(path, init.hir_id) {
emit_lint(cx, vec, pushed_item);
}
}
_ => {},
}
}
}
},
// constant
Res::Def(DefKind::Const, ..) => emit_lint(cx, vec, pushed_item),
_ => {},
}
},
ExprKind::Lit(..) => emit_lint(cx, vec, pushed_item),
_ => {},
}
}
}
}
}
// Scans the body of the for loop and determines whether lint should be given
struct SameItemPushVisitor<'a, 'tcx> {
should_lint: bool,
// this field holds the last vec push operation visited, which should be the only push seen
vec_push: Option<(&'tcx Expr<'tcx>, &'tcx Expr<'tcx>)>,
cx: &'a LateContext<'tcx>,
}
impl<'a, 'tcx> Visitor<'tcx> for SameItemPushVisitor<'a, 'tcx> {
type Map = Map<'tcx>;
fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
match &expr.kind {
// Non-determinism may occur ... don't give a lint
ExprKind::Loop(..) | ExprKind::Match(..) => self.should_lint = false,
ExprKind::Block(block, _) => self.visit_block(block),
_ => {},
}
}
fn visit_block(&mut self, b: &'tcx Block<'_>) {
for stmt in b.stmts.iter() {
self.visit_stmt(stmt);
}
}
fn visit_stmt(&mut self, s: &'tcx Stmt<'_>) {
let vec_push_option = get_vec_push(self.cx, s);
if vec_push_option.is_none() {
// Current statement is not a push so visit inside
match &s.kind {
StmtKind::Expr(expr) | StmtKind::Semi(expr) => self.visit_expr(&expr),
_ => {},
}
} else {
// Current statement is a push ...check whether another
// push had been previously done
if self.vec_push.is_none() {
self.vec_push = vec_push_option;
} else {
// There are multiple pushes ... don't lint
self.should_lint = false;
}
}
}
fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
NestedVisitorMap::None
}
}
// Given some statement, determine if that statement is a push on a Vec. If it is, return
// the Vec being pushed into and the item being pushed
fn get_vec_push<'tcx>(cx: &LateContext<'tcx>, stmt: &'tcx Stmt<'_>) -> Option<(&'tcx Expr<'tcx>, &'tcx Expr<'tcx>)> {
if_chain! {
// Extract method being called
if let StmtKind::Semi(semi_stmt) = &stmt.kind;
if let ExprKind::MethodCall(path, _, args, _) = &semi_stmt.kind;
// Figure out the parameters for the method call
if let Some(self_expr) = args.get(0);
if let Some(pushed_item) = args.get(1);
// Check that the method being called is push() on a Vec
if is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(self_expr), sym::vec_type);
if path.ident.name.as_str() == "push";
then {
return Some((self_expr, pushed_item))
}
}
None
}

42
clippy_lints/src/loops/single_element_loop.rs Normal file
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@ -0,0 +1,42 @@
use super::{get_span_of_entire_for_loop, SINGLE_ELEMENT_LOOP};
use crate::utils::{indent_of, single_segment_path, snippet, span_lint_and_sugg};
use if_chain::if_chain;
use rustc_errors::Applicability;
use rustc_hir::{BorrowKind, Expr, ExprKind, Pat, PatKind};
use rustc_lint::LateContext;
pub(super) fn check<'tcx>(
cx: &LateContext<'tcx>,
pat: &'tcx Pat<'_>,
arg: &'tcx Expr<'_>,
body: &'tcx Expr<'_>,
expr: &'tcx Expr<'_>,
) {
if_chain! {
if let ExprKind::AddrOf(BorrowKind::Ref, _, ref arg_expr) = arg.kind;
if let PatKind::Binding(.., target, _) = pat.kind;
if let ExprKind::Array([arg_expression]) = arg_expr.kind;
if let ExprKind::Path(ref list_item) = arg_expression.kind;
if let Some(list_item_name) = single_segment_path(list_item).map(|ps| ps.ident.name);
if let ExprKind::Block(ref block, _) = body.kind;
if !block.stmts.is_empty();
then {
let for_span = get_span_of_entire_for_loop(expr);
let mut block_str = snippet(cx, block.span, "..").into_owned();
block_str.remove(0);
block_str.pop();
span_lint_and_sugg(
cx,
SINGLE_ELEMENT_LOOP,
for_span,
"for loop over a single element",
"try",
format!("{{\n{}let {} = &{};{}}}", " ".repeat(indent_of(cx, block.stmts[0].span).unwrap_or(0)), target.name, list_item_name, block_str),
Applicability::MachineApplicable
)
}
}
}

350
clippy_lints/src/loops/utils.rs Normal file
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@ -0,0 +1,350 @@
use crate::utils::{
get_parent_expr, get_trait_def_id, has_iter_method, implements_trait, is_integer_const, path_to_local,
path_to_local_id, paths, sugg,
};
use if_chain::if_chain;
use rustc_data_structures::fx::FxHashMap;
use rustc_errors::Applicability;
use rustc_hir::intravisit::{walk_expr, walk_pat, walk_stmt, NestedVisitorMap, Visitor};
use rustc_hir::{BinOpKind, BorrowKind, Expr, ExprKind, HirId, Mutability, Pat, PatKind, Stmt, StmtKind};
use rustc_lint::LateContext;
use rustc_middle::hir::map::Map;
use rustc_span::source_map::Span;
use rustc_span::symbol::Symbol;
use std::iter::Iterator;
#[derive(Debug, PartialEq)]
enum IncrementVisitorVarState {
Initial, // Not examined yet
IncrOnce, // Incremented exactly once, may be a loop counter
DontWarn,
}
/// Scan a for loop for variables that are incremented exactly once and not used after that.
pub(super) struct IncrementVisitor<'a, 'tcx> {
cx: &'a LateContext<'tcx>, // context reference
states: FxHashMap<HirId, IncrementVisitorVarState>, // incremented variables
depth: u32, // depth of conditional expressions
done: bool,
}
impl<'a, 'tcx> IncrementVisitor<'a, 'tcx> {
pub(super) fn new(cx: &'a LateContext<'tcx>) -> Self {
Self {
cx,
states: FxHashMap::default(),
depth: 0,
done: false,
}
}
pub(super) fn into_results(self) -> impl Iterator<Item = HirId> {
self.states.into_iter().filter_map(|(id, state)| {
if state == IncrementVisitorVarState::IncrOnce {
Some(id)
} else {
None
}
})
}
}
impl<'a, 'tcx> Visitor<'tcx> for IncrementVisitor<'a, 'tcx> {
type Map = Map<'tcx>;
fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
if self.done {
return;
}
// If node is a variable
if let Some(def_id) = path_to_local(expr) {
if let Some(parent) = get_parent_expr(self.cx, expr) {
let state = self.states.entry(def_id).or_insert(IncrementVisitorVarState::Initial);
if *state == IncrementVisitorVarState::IncrOnce {
*state = IncrementVisitorVarState::DontWarn;
return;
}
match parent.kind {
ExprKind::AssignOp(op, ref lhs, ref rhs) => {
if lhs.hir_id == expr.hir_id {
*state = if op.node == BinOpKind::Add
&& is_integer_const(self.cx, rhs, 1)
&& *state == IncrementVisitorVarState::Initial
&& self.depth == 0
{
IncrementVisitorVarState::IncrOnce
} else {
// Assigned some other value or assigned multiple times
IncrementVisitorVarState::DontWarn
};
}
},
ExprKind::Assign(ref lhs, _, _) if lhs.hir_id == expr.hir_id => {
*state = IncrementVisitorVarState::DontWarn
},
ExprKind::AddrOf(BorrowKind::Ref, mutability, _) if mutability == Mutability::Mut => {
*state = IncrementVisitorVarState::DontWarn
},
_ => (),
}
}
walk_expr(self, expr);
} else if is_loop(expr) || is_conditional(expr) {
self.depth += 1;
walk_expr(self, expr);
self.depth -= 1;
} else if let ExprKind::Continue(_) = expr.kind {
self.done = true;
} else {
walk_expr(self, expr);
}
}
fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
NestedVisitorMap::None
}
}
enum InitializeVisitorState<'hir> {
Initial, // Not examined yet
Declared(Symbol), // Declared but not (yet) initialized
Initialized {
name: Symbol,
initializer: &'hir Expr<'hir>,
},
DontWarn,
}
/// Checks whether a variable is initialized at the start of a loop and not modified
/// and used after the loop.
pub(super) struct InitializeVisitor<'a, 'tcx> {
cx: &'a LateContext<'tcx>, // context reference
end_expr: &'tcx Expr<'tcx>, // the for loop. Stop scanning here.
var_id: HirId,
state: InitializeVisitorState<'tcx>,
depth: u32, // depth of conditional expressions
past_loop: bool,
}
impl<'a, 'tcx> InitializeVisitor<'a, 'tcx> {
pub(super) fn new(cx: &'a LateContext<'tcx>, end_expr: &'tcx Expr<'tcx>, var_id: HirId) -> Self {
Self {
cx,
end_expr,
var_id,
state: InitializeVisitorState::Initial,
depth: 0,
past_loop: false,
}
}
pub(super) fn get_result(&self) -> Option<(Symbol, &'tcx Expr<'tcx>)> {
if let InitializeVisitorState::Initialized { name, initializer } = self.state {
Some((name, initializer))
} else {
None
}
}
}
impl<'a, 'tcx> Visitor<'tcx> for InitializeVisitor<'a, 'tcx> {
type Map = Map<'tcx>;
fn visit_stmt(&mut self, stmt: &'tcx Stmt<'_>) {
// Look for declarations of the variable
if_chain! {
if let StmtKind::Local(ref local) = stmt.kind;
if local.pat.hir_id == self.var_id;
if let PatKind::Binding(.., ident, _) = local.pat.kind;
then {
self.state = local.init.map_or(InitializeVisitorState::Declared(ident.name), |init| {
InitializeVisitorState::Initialized {
initializer: init,
name: ident.name,
}
})
}
}
walk_stmt(self, stmt);
}
fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
if matches!(self.state, InitializeVisitorState::DontWarn) {
return;
}
if expr.hir_id == self.end_expr.hir_id {
self.past_loop = true;
return;
}
// No need to visit expressions before the variable is
// declared
if matches!(self.state, InitializeVisitorState::Initial) {
return;
}
// If node is the desired variable, see how it's used
if path_to_local_id(expr, self.var_id) {
if self.past_loop {
self.state = InitializeVisitorState::DontWarn;
return;
}
if let Some(parent) = get_parent_expr(self.cx, expr) {
match parent.kind {
ExprKind::AssignOp(_, ref lhs, _) if lhs.hir_id == expr.hir_id => {
self.state = InitializeVisitorState::DontWarn;
},
ExprKind::Assign(ref lhs, ref rhs, _) if lhs.hir_id == expr.hir_id => {
self.state = if_chain! {
if self.depth == 0;
if let InitializeVisitorState::Declared(name)
| InitializeVisitorState::Initialized { name, ..} = self.state;
then {
InitializeVisitorState::Initialized { initializer: rhs, name }
} else {
InitializeVisitorState::DontWarn
}
}
},
ExprKind::AddrOf(BorrowKind::Ref, mutability, _) if mutability == Mutability::Mut => {
self.state = InitializeVisitorState::DontWarn
},
_ => (),
}
}
walk_expr(self, expr);
} else if !self.past_loop && is_loop(expr) {
self.state = InitializeVisitorState::DontWarn;
} else if is_conditional(expr) {
self.depth += 1;
walk_expr(self, expr);
self.depth -= 1;
} else {
walk_expr(self, expr);
}
}
fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
NestedVisitorMap::OnlyBodies(self.cx.tcx.hir())
}
}
fn is_loop(expr: &Expr<'_>) -> bool {
matches!(expr.kind, ExprKind::Loop(..))
}
fn is_conditional(expr: &Expr<'_>) -> bool {
matches!(expr.kind, ExprKind::If(..) | ExprKind::Match(..))
}
#[derive(PartialEq, Eq)]
pub(super) enum Nesting {
Unknown, // no nesting detected yet
RuledOut, // the iterator is initialized or assigned within scope
LookFurther, // no nesting detected, no further walk required
}
use self::Nesting::{LookFurther, RuledOut, Unknown};
pub(super) struct LoopNestVisitor {
pub(super) hir_id: HirId,
pub(super) iterator: HirId,
pub(super) nesting: Nesting,
}
impl<'tcx> Visitor<'tcx> for LoopNestVisitor {
type Map = Map<'tcx>;
fn visit_stmt(&mut self, stmt: &'tcx Stmt<'_>) {
if stmt.hir_id == self.hir_id {
self.nesting = LookFurther;
} else if self.nesting == Unknown {
walk_stmt(self, stmt);
}
}
fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
if self.nesting != Unknown {
return;
}
if expr.hir_id == self.hir_id {
self.nesting = LookFurther;
return;
}
match expr.kind {
ExprKind::Assign(ref path, _, _) | ExprKind::AssignOp(_, ref path, _) => {
if path_to_local_id(path, self.iterator) {
self.nesting = RuledOut;
}
},
_ => walk_expr(self, expr),
}
}
fn visit_pat(&mut self, pat: &'tcx Pat<'_>) {
if self.nesting != Unknown {
return;
}
if let PatKind::Binding(_, id, ..) = pat.kind {
if id == self.iterator {
self.nesting = RuledOut;
return;
}
}
walk_pat(self, pat)
}
fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
NestedVisitorMap::None
}
}
// this function assumes the given expression is a `for` loop.
pub(super) fn get_span_of_entire_for_loop(expr: &Expr<'_>) -> Span {
// for some reason this is the only way to get the `Span`
// of the entire `for` loop
if let ExprKind::Match(_, arms, _) = &expr.kind {
arms[0].body.span
} else {
unreachable!()
}
}
/// If `arg` was the argument to a `for` loop, return the "cleanest" way of writing the
/// actual `Iterator` that the loop uses.
pub(super) fn make_iterator_snippet(cx: &LateContext<'_>, arg: &Expr<'_>, applic_ref: &mut Applicability) -> String {
let impls_iterator = get_trait_def_id(cx, &paths::ITERATOR).map_or(false, |id| {
implements_trait(cx, cx.typeck_results().expr_ty(arg), id, &[])
});
if impls_iterator {
format!(
"{}",
sugg::Sugg::hir_with_applicability(cx, arg, "_", applic_ref).maybe_par()
)
} else {
// (&x).into_iter() ==> x.iter()
// (&mut x).into_iter() ==> x.iter_mut()
match &arg.kind {
ExprKind::AddrOf(BorrowKind::Ref, mutability, arg_inner)
if has_iter_method(cx, cx.typeck_results().expr_ty(&arg_inner)).is_some() =>
{
let meth_name = match mutability {
Mutability::Mut => "iter_mut",
Mutability::Not => "iter",
};
format!(
"{}.{}()",
sugg::Sugg::hir_with_applicability(cx, &arg_inner, "_", applic_ref).maybe_par(),
meth_name,
)
}
_ => format!(
"{}.into_iter()",
sugg::Sugg::hir_with_applicability(cx, arg, "_", applic_ref).maybe_par()
),
}
}
}

139
clippy_lints/src/loops/while_immutable_condition.rs Normal file
View file

@ -0,0 +1,139 @@
use super::WHILE_IMMUTABLE_CONDITION;
use crate::consts::constant;
use crate::utils::span_lint_and_then;
use crate::utils::usage::mutated_variables;
use if_chain::if_chain;
use rustc_data_structures::fx::{FxHashMap, FxHashSet};
use rustc_hir::def::{DefKind, Res};
use rustc_hir::intravisit::{walk_expr, NestedVisitorMap, Visitor};
use rustc_hir::{def_id, Expr, ExprKind, HirId, QPath};
use rustc_lint::LateContext;
use rustc_middle::hir::map::Map;
use std::iter::Iterator;
pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, cond: &'tcx Expr<'_>, expr: &'tcx Expr<'_>) {
if constant(cx, cx.typeck_results(), cond).is_some() {
// A pure constant condition (e.g., `while false`) is not linted.
return;
}
let mut var_visitor = VarCollectorVisitor {
cx,
ids: FxHashSet::default(),
def_ids: FxHashMap::default(),
skip: false,
};
var_visitor.visit_expr(cond);
if var_visitor.skip {
return;
}
let used_in_condition = &var_visitor.ids;
let no_cond_variable_mutated = if let Some(used_mutably) = mutated_variables(expr, cx) {
used_in_condition.is_disjoint(&used_mutably)
} else {
return;
};
let mutable_static_in_cond = var_visitor.def_ids.iter().any(|(_, v)| *v);
let mut has_break_or_return_visitor = HasBreakOrReturnVisitor {
has_break_or_return: false,
};
has_break_or_return_visitor.visit_expr(expr);
let has_break_or_return = has_break_or_return_visitor.has_break_or_return;
if no_cond_variable_mutated && !mutable_static_in_cond {
span_lint_and_then(
cx,
WHILE_IMMUTABLE_CONDITION,
cond.span,
"variables in the condition are not mutated in the loop body",
|diag| {
diag.note("this may lead to an infinite or to a never running loop");
if has_break_or_return {
diag.note("this loop contains `return`s or `break`s");
diag.help("rewrite it as `if cond { loop { } }`");
}
},
);
}
}
struct HasBreakOrReturnVisitor {
has_break_or_return: bool,
}
impl<'tcx> Visitor<'tcx> for HasBreakOrReturnVisitor {
type Map = Map<'tcx>;
fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
if self.has_break_or_return {
return;
}
match expr.kind {
ExprKind::Ret(_) | ExprKind::Break(_, _) => {
self.has_break_or_return = true;
return;
},
_ => {},
}
walk_expr(self, expr);
}
fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
NestedVisitorMap::None
}
}
/// Collects the set of variables in an expression
/// Stops analysis if a function call is found
/// Note: In some cases such as `self`, there are no mutable annotation,
/// All variables definition IDs are collected
struct VarCollectorVisitor<'a, 'tcx> {
cx: &'a LateContext<'tcx>,
ids: FxHashSet<HirId>,
def_ids: FxHashMap<def_id::DefId, bool>,
skip: bool,
}
impl<'a, 'tcx> VarCollectorVisitor<'a, 'tcx> {
fn insert_def_id(&mut self, ex: &'tcx Expr<'_>) {
if_chain! {
if let ExprKind::Path(ref qpath) = ex.kind;
if let QPath::Resolved(None, _) = *qpath;
let res = self.cx.qpath_res(qpath, ex.hir_id);
then {
match res {
Res::Local(hir_id) => {
self.ids.insert(hir_id);
},
Res::Def(DefKind::Static, def_id) => {
let mutable = self.cx.tcx.is_mutable_static(def_id);
self.def_ids.insert(def_id, mutable);
},
_ => {},
}
}
}
}
}
impl<'a, 'tcx> Visitor<'tcx> for VarCollectorVisitor<'a, 'tcx> {
type Map = Map<'tcx>;
fn visit_expr(&mut self, ex: &'tcx Expr<'_>) {
match ex.kind {
ExprKind::Path(_) => self.insert_def_id(ex),
// If there is any function/method call… we just stop analysis
ExprKind::Call(..) | ExprKind::MethodCall(..) => self.skip = true,
_ => walk_expr(self, ex),
}
}
fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
NestedVisitorMap::None
}
}

87
clippy_lints/src/loops/while_let_loop.rs Normal file
View file

@ -0,0 +1,87 @@
use super::WHILE_LET_LOOP;
use crate::utils::{snippet_with_applicability, span_lint_and_sugg};
use rustc_errors::Applicability;
use rustc_hir::{Block, Expr, ExprKind, MatchSource, StmtKind};
use rustc_lint::{LateContext, LintContext};
use rustc_middle::lint::in_external_macro;
pub(super) fn check(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, loop_block: &'tcx Block<'_>) {
// extract the expression from the first statement (if any) in a block
let inner_stmt_expr = extract_expr_from_first_stmt(loop_block);
// or extract the first expression (if any) from the block
if let Some(inner) = inner_stmt_expr.or_else(|| extract_first_expr(loop_block)) {
if let ExprKind::Match(ref matchexpr, ref arms, ref source) = inner.kind {
// ensure "if let" compatible match structure
match *source {
MatchSource::Normal | MatchSource::IfLetDesugar { .. } => {
if arms.len() == 2
&& arms[0].guard.is_none()
&& arms[1].guard.is_none()
&& is_simple_break_expr(&arms[1].body)
{
if in_external_macro(cx.sess(), expr.span) {
return;
}
// NOTE: we used to build a body here instead of using
// ellipsis, this was removed because:
// 1) it was ugly with big bodies;
// 2) it was not indented properly;
// 3) it wasn’t very smart (see #675).
let mut applicability = Applicability::HasPlaceholders;
span_lint_and_sugg(
cx,
WHILE_LET_LOOP,
expr.span,
"this loop could be written as a `while let` loop",
"try",
format!(
"while let {} = {} {{ .. }}",
snippet_with_applicability(cx, arms[0].pat.span, "..", &mut applicability),
snippet_with_applicability(cx, matchexpr.span, "..", &mut applicability),
),
applicability,
);
}
},
_ => (),
}
}
}
}
/// If a block begins with a statement (possibly a `let` binding) and has an
/// expression, return it.
fn extract_expr_from_first_stmt<'tcx>(block: &Block<'tcx>) -> Option<&'tcx Expr<'tcx>> {
if block.stmts.is_empty() {
return None;
}
if let StmtKind::Local(ref local) = block.stmts[0].kind {
local.init //.map(|expr| expr)
} else {
None
}
}
/// If a block begins with an expression (with or without semicolon), return it.
fn extract_first_expr<'tcx>(block: &Block<'tcx>) -> Option<&'tcx Expr<'tcx>> {
match block.expr {
Some(ref expr) if block.stmts.is_empty() => Some(expr),
None if !block.stmts.is_empty() => match block.stmts[0].kind {
StmtKind::Expr(ref expr) | StmtKind::Semi(ref expr) => Some(expr),
StmtKind::Local(..) | StmtKind::Item(..) => None,
},
_ => None,
}
}
/// Returns `true` if expr contains a single break expr without destination label
/// and
/// passed expression. The expression may be within a block.
fn is_simple_break_expr(expr: &Expr<'_>) -> bool {
match expr.kind {
ExprKind::Break(dest, ref passed_expr) if dest.label.is_none() && passed_expr.is_none() => true,
ExprKind::Block(ref b, _) => extract_first_expr(b).map_or(false, |subexpr| is_simple_break_expr(subexpr)),
_ => false,
}
}

171
clippy_lints/src/loops/while_let_on_iterator.rs Normal file
View file

@ -0,0 +1,171 @@
use super::utils::{LoopNestVisitor, Nesting};
use super::WHILE_LET_ON_ITERATOR;
use crate::utils::usage::mutated_variables;
use crate::utils::{
get_enclosing_block, get_trait_def_id, implements_trait, is_refutable, last_path_segment, match_trait_method,
path_to_local, path_to_local_id, paths, snippet_with_applicability, span_lint_and_sugg,
};
use if_chain::if_chain;
use rustc_errors::Applicability;
use rustc_hir::intravisit::{walk_block, walk_expr, NestedVisitorMap, Visitor};
use rustc_hir::{Expr, ExprKind, HirId, MatchSource, Node, PatKind};
use rustc_lint::LateContext;
use rustc_middle::hir::map::Map;
use rustc_span::symbol::sym;
pub(super) fn check(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
if let ExprKind::Match(ref match_expr, ref arms, MatchSource::WhileLetDesugar) = expr.kind {
let pat = &arms[0].pat.kind;
if let (
&PatKind::TupleStruct(ref qpath, ref pat_args, _),
&ExprKind::MethodCall(ref method_path, _, ref method_args, _),
) = (pat, &match_expr.kind)
{
let iter_expr = &method_args[0];
// Don't lint when the iterator is recreated on every iteration
if_chain! {
if let ExprKind::MethodCall(..) | ExprKind::Call(..) = iter_expr.kind;
if let Some(iter_def_id) = get_trait_def_id(cx, &paths::ITERATOR);
if implements_trait(cx, cx.typeck_results().expr_ty(iter_expr), iter_def_id, &[]);
then {
return;
}
}
let lhs_constructor = last_path_segment(qpath);
if method_path.ident.name == sym::next
&& match_trait_method(cx, match_expr, &paths::ITERATOR)
&& lhs_constructor.ident.name == sym::Some
&& (pat_args.is_empty()
|| !is_refutable(cx, &pat_args[0])
&& !is_used_inside(cx, iter_expr, &arms[0].body)
&& !is_iterator_used_after_while_let(cx, iter_expr)
&& !is_nested(cx, expr, &method_args[0]))
{
let mut applicability = Applicability::MachineApplicable;
let iterator = snippet_with_applicability(cx, method_args[0].span, "_", &mut applicability);
let loop_var = if pat_args.is_empty() {
"_".to_string()
} else {
snippet_with_applicability(cx, pat_args[0].span, "_", &mut applicability).into_owned()
};
span_lint_and_sugg(
cx,
WHILE_LET_ON_ITERATOR,
expr.span.with_hi(match_expr.span.hi()),
"this loop could be written as a `for` loop",
"try",
format!("for {} in {}", loop_var, iterator),
applicability,
);
}
}
}
}
fn is_used_inside<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, container: &'tcx Expr<'_>) -> bool {
let def_id = match path_to_local(expr) {
Some(id) => id,
None => return false,
};
if let Some(used_mutably) = mutated_variables(container, cx) {
if used_mutably.contains(&def_id) {
return true;
}
}
false
}
fn is_iterator_used_after_while_let<'tcx>(cx: &LateContext<'tcx>, iter_expr: &'tcx Expr<'_>) -> bool {
let def_id = match path_to_local(iter_expr) {
Some(id) => id,
None => return false,
};
let mut visitor = VarUsedAfterLoopVisitor {
def_id,
iter_expr_id: iter_expr.hir_id,
past_while_let: false,
var_used_after_while_let: false,
};
if let Some(enclosing_block) = get_enclosing_block(cx, def_id) {
walk_block(&mut visitor, enclosing_block);
}
visitor.var_used_after_while_let
}
fn is_nested(cx: &LateContext<'_>, match_expr: &Expr<'_>, iter_expr: &Expr<'_>) -> bool {
if_chain! {
if let Some(loop_block) = get_enclosing_block(cx, match_expr.hir_id);
let parent_node = cx.tcx.hir().get_parent_node(loop_block.hir_id);
if let Some(Node::Expr(loop_expr)) = cx.tcx.hir().find(parent_node);
then {
return is_loop_nested(cx, loop_expr, iter_expr)
}
}
false
}
fn is_loop_nested(cx: &LateContext<'_>, loop_expr: &Expr<'_>, iter_expr: &Expr<'_>) -> bool {
let mut id = loop_expr.hir_id;
let iter_id = if let Some(id) = path_to_local(iter_expr) {
id
} else {
return true;
};
loop {
let parent = cx.tcx.hir().get_parent_node(id);
if parent == id {
return false;
}
match cx.tcx.hir().find(parent) {
Some(Node::Expr(expr)) => {
if let ExprKind::Loop(..) = expr.kind {
return true;
};
},
Some(Node::Block(block)) => {
let mut block_visitor = LoopNestVisitor {
hir_id: id,
iterator: iter_id,
nesting: Nesting::Unknown,
};
walk_block(&mut block_visitor, block);
if block_visitor.nesting == Nesting::RuledOut {
return false;
}
},
Some(Node::Stmt(_)) => (),
_ => {
return false;
},
}
id = parent;
}
}
struct VarUsedAfterLoopVisitor {
def_id: HirId,
iter_expr_id: HirId,
past_while_let: bool,
var_used_after_while_let: bool,
}
impl<'tcx> Visitor<'tcx> for VarUsedAfterLoopVisitor {
type Map = Map<'tcx>;
fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
if self.past_while_let {
if path_to_local_id(expr, self.def_id) {
self.var_used_after_while_let = true;
}
} else if self.iter_expr_id == expr.hir_id {
self.past_while_let = true;
}
walk_expr(self, expr);
}
fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
NestedVisitorMap::None
}
}

206
clippy_lints/src/manual_map.rs
View file

@ -2,17 +2,25 @@ use crate::{
map_unit_fn::OPTION_MAP_UNIT_FN,
matches::MATCH_AS_REF,
utils::{
is_allowed, is_type_diagnostic_item, match_def_path, match_var, paths, peel_hir_expr_refs,
peel_mid_ty_refs_is_mutable, snippet_with_applicability, span_lint_and_sugg,
can_partially_move_ty, is_allowed, is_type_diagnostic_item, match_def_path, match_var, paths,
peel_hir_expr_refs, peel_mid_ty_refs_is_mutable, snippet_with_applicability, snippet_with_context,
span_lint_and_sugg,
},
};
use rustc_ast::util::parser::PREC_POSTFIX;
use rustc_errors::Applicability;
use rustc_hir::{Arm, BindingAnnotation, Block, Expr, ExprKind, Mutability, Pat, PatKind, QPath};
use rustc_hir::{
def::Res,
intravisit::{walk_expr, ErasedMap, NestedVisitorMap, Visitor},
Arm, BindingAnnotation, Block, Expr, ExprKind, Mutability, Pat, PatKind, Path, QPath,
};
use rustc_lint::{LateContext, LateLintPass, LintContext};
use rustc_middle::lint::in_external_macro;
use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_span::symbol::{sym, Ident};
use rustc_span::{
symbol::{sym, Ident},
SyntaxContext,
};
declare_clippy_lint! {
/// **What it does:** Checks for usages of `match` which could be implemented using `map`
@ -52,43 +60,46 @@ impl LateLintPass<'_> for ManualMap {
{
let (scrutinee_ty, ty_ref_count, ty_mutability) =
peel_mid_ty_refs_is_mutable(cx.typeck_results().expr_ty(scrutinee));
if !is_type_diagnostic_item(cx, scrutinee_ty, sym::option_type)
|| !is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(expr), sym::option_type)
if !(is_type_diagnostic_item(cx, scrutinee_ty, sym::option_type)
&& is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(expr), sym::option_type))
{
return;
}
let (some_expr, some_pat, pat_ref_count, is_wild_none) =
match (try_parse_pattern(cx, arm1.pat), try_parse_pattern(cx, arm2.pat)) {
(Some(OptionPat::Wild), Some(OptionPat::Some { pattern, ref_count }))
if is_none_expr(cx, arm1.body) =>
{
(arm2.body, pattern, ref_count, true)
},
(Some(OptionPat::None), Some(OptionPat::Some { pattern, ref_count }))
if is_none_expr(cx, arm1.body) =>
{
(arm2.body, pattern, ref_count, false)
},
(Some(OptionPat::Some { pattern, ref_count }), Some(OptionPat::Wild))
if is_none_expr(cx, arm2.body) =>
{
(arm1.body, pattern, ref_count, true)
},
(Some(OptionPat::Some { pattern, ref_count }), Some(OptionPat::None))
if is_none_expr(cx, arm2.body) =>
{
(arm1.body, pattern, ref_count, false)
},
_ => return,
};
let expr_ctxt = expr.span.ctxt();
let (some_expr, some_pat, pat_ref_count, is_wild_none) = match (
try_parse_pattern(cx, arm1.pat, expr_ctxt),
try_parse_pattern(cx, arm2.pat, expr_ctxt),
) {
(Some(OptionPat::Wild), Some(OptionPat::Some { pattern, ref_count }))
if is_none_expr(cx, arm1.body) =>
{
(arm2.body, pattern, ref_count, true)
},
(Some(OptionPat::None), Some(OptionPat::Some { pattern, ref_count }))
if is_none_expr(cx, arm1.body) =>
{
(arm2.body, pattern, ref_count, false)
},
(Some(OptionPat::Some { pattern, ref_count }), Some(OptionPat::Wild))
if is_none_expr(cx, arm2.body) =>
{
(arm1.body, pattern, ref_count, true)
},
(Some(OptionPat::Some { pattern, ref_count }), Some(OptionPat::None))
if is_none_expr(cx, arm2.body) =>
{
(arm1.body, pattern, ref_count, false)
},
_ => return,
};
// Top level or patterns aren't allowed in closures.
if matches!(some_pat.kind, PatKind::Or(_)) {
return;
}
let some_expr = match get_some_expr(cx, some_expr) {
let some_expr = match get_some_expr(cx, some_expr, expr_ctxt) {
Some(expr) => expr,
None => return,
};
@ -99,6 +110,10 @@ impl LateLintPass<'_> for ManualMap {
return;
}
if !can_move_expr_to_closure(cx, some_expr) {
return;
}
// Determine which binding mode to use.
let explicit_ref = some_pat.contains_explicit_ref_binding();
let binding_ref = explicit_ref.or_else(|| (ty_ref_count != pat_ref_count).then(|| ty_mutability));
@ -111,47 +126,50 @@ impl LateLintPass<'_> for ManualMap {
let mut app = Applicability::MachineApplicable;
// Remove address-of expressions from the scrutinee. `as_ref` will be called,
// the type is copyable, or the option is being passed by value.
// Remove address-of expressions from the scrutinee. Either `as_ref` will be called, or
// it's being passed by value.
let scrutinee = peel_hir_expr_refs(scrutinee).0;
let scrutinee_str = snippet_with_applicability(cx, scrutinee.span, "_", &mut app);
let scrutinee_str = if expr.precedence().order() < PREC_POSTFIX {
// Parens are needed to chain method calls.
format!("({})", scrutinee_str)
} else {
scrutinee_str.into()
};
let scrutinee_str = snippet_with_context(cx, scrutinee.span, expr_ctxt, "..", &mut app);
let scrutinee_str =
if scrutinee.span.ctxt() == expr.span.ctxt() && scrutinee.precedence().order() < PREC_POSTFIX {
format!("({})", scrutinee_str)
} else {
scrutinee_str.into()
};
let body_str = if let PatKind::Binding(annotation, _, some_binding, None) = some_pat.kind {
if let Some(func) = can_pass_as_func(cx, some_binding, some_expr) {
snippet_with_applicability(cx, func.span, "..", &mut app).into_owned()
} else {
if match_var(some_expr, some_binding.name)
&& !is_allowed(cx, MATCH_AS_REF, expr.hir_id)
&& binding_ref.is_some()
{
return;
}
match can_pass_as_func(cx, some_binding, some_expr) {
Some(func) if func.span.ctxt() == some_expr.span.ctxt() => {
snippet_with_applicability(cx, func.span, "..", &mut app).into_owned()
},
_ => {
if match_var(some_expr, some_binding.name)
&& !is_allowed(cx, MATCH_AS_REF, expr.hir_id)
&& binding_ref.is_some()
{
return;
}
// `ref` and `ref mut` annotations were handled earlier.
let annotation = if matches!(annotation, BindingAnnotation::Mutable) {
"mut "
} else {
""
};
format!(
"|{}{}| {}",
annotation,
some_binding,
snippet_with_applicability(cx, some_expr.span, "..", &mut app)
)
// `ref` and `ref mut` annotations were handled earlier.
let annotation = if matches!(annotation, BindingAnnotation::Mutable) {
"mut "
} else {
""
};
format!(
"|{}{}| {}",
annotation,
some_binding,
snippet_with_context(cx, some_expr.span, expr_ctxt, "..", &mut app)
)
},
}
} else if !is_wild_none && explicit_ref.is_none() {
// TODO: handle explicit reference annotations.
format!(
"|{}| {}",
snippet_with_applicability(cx, some_pat.span, "..", &mut app),
snippet_with_applicability(cx, some_expr.span, "..", &mut app)
snippet_with_context(cx, some_pat.span, expr_ctxt, "..", &mut app),
snippet_with_context(cx, some_expr.span, expr_ctxt, "..", &mut app)
)
} else {
// Refutable bindings and mixed reference annotations can't be handled by `map`.
@ -171,6 +189,51 @@ impl LateLintPass<'_> for ManualMap {
}
}
// Checks if the expression can be moved into a closure as is.
fn can_move_expr_to_closure(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> bool {
struct V<'cx, 'tcx> {
cx: &'cx LateContext<'tcx>,
make_closure: bool,
}
impl Visitor<'tcx> for V<'_, 'tcx> {
type Map = ErasedMap<'tcx>;
fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
NestedVisitorMap::None
}
fn visit_expr(&mut self, e: &'tcx Expr<'_>) {
match e.kind {
ExprKind::Break(..)
| ExprKind::Continue(_)
| ExprKind::Ret(_)
| ExprKind::Yield(..)
| ExprKind::InlineAsm(_)
| ExprKind::LlvmInlineAsm(_) => {
self.make_closure = false;
},
// Accessing a field of a local value can only be done if the type isn't
// partially moved.
ExprKind::Field(base_expr, _)
if matches!(
base_expr.kind,
ExprKind::Path(QPath::Resolved(_, Path { res: Res::Local(_), .. }))
) && can_partially_move_ty(self.cx, self.cx.typeck_results().expr_ty(base_expr)) =>
{
// TODO: check if the local has been partially moved. Assume it has for now.
self.make_closure = false;
return;
}
_ => (),
};
walk_expr(self, e);
}
}
let mut v = V { cx, make_closure: true };
v.visit_expr(expr);
v.make_closure
}
// Checks whether the expression could be passed as a function, or whether a closure is needed.
// Returns the function to be passed to `map` if it exists.
fn can_pass_as_func(cx: &LateContext<'tcx>, binding: Ident, expr: &'tcx Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
@ -198,11 +261,11 @@ enum OptionPat<'a> {
// Try to parse into a recognized `Option` pattern.
// i.e. `_`, `None`, `Some(..)`, or a reference to any of those.
fn try_parse_pattern(cx: &LateContext<'tcx>, pat: &'tcx Pat<'_>) -> Option<OptionPat<'tcx>> {
fn f(cx: &LateContext<'tcx>, pat: &'tcx Pat<'_>, ref_count: usize) -> Option<OptionPat<'tcx>> {
fn try_parse_pattern(cx: &LateContext<'tcx>, pat: &'tcx Pat<'_>, ctxt: SyntaxContext) -> Option<OptionPat<'tcx>> {
fn f(cx: &LateContext<'tcx>, pat: &'tcx Pat<'_>, ref_count: usize, ctxt: SyntaxContext) -> Option<OptionPat<'tcx>> {
match pat.kind {
PatKind::Wild => Some(OptionPat::Wild),
PatKind::Ref(pat, _) => f(cx, pat, ref_count + 1),
PatKind::Ref(pat, _) => f(cx, pat, ref_count + 1, ctxt),
PatKind::Path(QPath::Resolved(None, path))
if path
.res
@ -215,18 +278,19 @@ fn try_parse_pattern(cx: &LateContext<'tcx>, pat: &'tcx Pat<'_>) -> Option<Optio
if path
.res
.opt_def_id()
.map_or(false, |id| match_def_path(cx, id, &paths::OPTION_SOME)) =>
.map_or(false, |id| match_def_path(cx, id, &paths::OPTION_SOME))
&& pat.span.ctxt() == ctxt =>
{
Some(OptionPat::Some { pattern, ref_count })
},
_ => None,
}
}
f(cx, pat, 0)
f(cx, pat, 0, ctxt)
}
// Checks for an expression wrapped by the `Some` constructor. Returns the contained expression.
fn get_some_expr(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
fn get_some_expr(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, ctxt: SyntaxContext) -> Option<&'tcx Expr<'tcx>> {
// TODO: Allow more complex expressions.
match expr.kind {
ExprKind::Call(
@ -235,7 +299,7 @@ fn get_some_expr(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<&'tcx E
..
},
[arg],
) => {
) if ctxt == expr.span.ctxt() => {
if match_def_path(cx, path.res.opt_def_id()?, &paths::OPTION_SOME) {
Some(arg)
} else {
@ -249,7 +313,7 @@ fn get_some_expr(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<&'tcx E
..
},
_,
) => get_some_expr(cx, expr),
) => get_some_expr(cx, expr, ctxt),
_ => None,
}
}

4
clippy_lints/src/map_clone.rs
View file

@ -79,7 +79,9 @@ impl<'tcx> LateLintPass<'tcx> for MapClone {
},
hir::ExprKind::MethodCall(ref method, _, [obj], _) => if_chain! {
if ident_eq(name, obj) && method.ident.name == sym::clone;
if match_trait_method(cx, closure_expr, &paths::CLONE_TRAIT);
if let Some(fn_id) = cx.typeck_results().type_dependent_def_id(closure_expr.hir_id);
if let Some(trait_id) = cx.tcx.trait_of_item(fn_id);
if cx.tcx.lang_items().clone_trait().map_or(false, |id| id == trait_id);
// no autoderefs
if !cx.typeck_results().expr_adjustments(obj).iter()
.any(|a| matches!(a.kind, Adjust::Deref(Some(..))));

4
clippy_lints/src/matches.rs
View file

@ -1173,9 +1173,9 @@ fn check_wild_in_or_pats(cx: &LateContext<'_>, arms: &[Arm<'_>]) {
cx,
WILDCARD_IN_OR_PATTERNS,
arm.pat.span,
"wildcard pattern covers any other pattern as it will match anyway.",
"wildcard pattern covers any other pattern as it will match anyway",
None,
"Consider handling `_` separately.",
"consider handling `_` separately",
);
}
}

32
clippy_lints/src/methods/implicit_clone.rs Normal file
View file

@ -0,0 +1,32 @@
use crate::utils::span_lint_and_sugg;
use if_chain::if_chain;
use rustc_errors::Applicability;
use rustc_hir as hir;
use rustc_hir::ExprKind;
use rustc_lint::LateContext;
use rustc_middle::ty::TyS;
use rustc_span::symbol::Symbol;
use super::IMPLICIT_CLONE;
use clippy_utils::is_diagnostic_assoc_item;
pub fn check(cx: &LateContext<'_>, expr: &hir::Expr<'_>, trait_diagnostic: Symbol) {
if_chain! {
if let ExprKind::MethodCall(method_path, _, [arg], _) = &expr.kind;
let return_type = cx.typeck_results().expr_ty(&expr);
let input_type = cx.typeck_results().expr_ty(arg).peel_refs();
if let Some(expr_def_id) = cx.typeck_results().type_dependent_def_id(expr.hir_id);
if let Some(ty_name) = input_type.ty_adt_def().map(|adt_def| cx.tcx.item_name(adt_def.did));
if TyS::same_type(return_type, input_type);
if is_diagnostic_assoc_item(cx, expr_def_id, trait_diagnostic);
then {
span_lint_and_sugg(
cx,IMPLICIT_CLONE,method_path.ident.span,
&format!("implicitly cloning a `{}` by calling `{}` on its dereferenced type", ty_name, method_path.ident.name),
"consider using",
"clone".to_string(),
Applicability::MachineApplicable
);
}
}
}

47
clippy_lints/src/methods/iter_count.rs Normal file
View file

@ -0,0 +1,47 @@
use crate::methods::derefs_to_slice;
use crate::utils::{is_type_diagnostic_item, match_type, paths, snippet_with_applicability, span_lint_and_sugg};
use rustc_errors::Applicability;
use rustc_hir::Expr;
use rustc_lint::LateContext;
use rustc_span::sym;
use super::ITER_COUNT;
pub(crate) fn lints<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'_>, iter_args: &'tcx [Expr<'tcx>], iter_method: &str) {
let ty = cx.typeck_results().expr_ty(&iter_args[0]);
let caller_type = if derefs_to_slice(cx, &iter_args[0], ty).is_some() {
"slice"
} else if is_type_diagnostic_item(cx, ty, sym::vec_type) {
"Vec"
} else if is_type_diagnostic_item(cx, ty, sym!(vecdeque_type)) {
"VecDeque"
} else if is_type_diagnostic_item(cx, ty, sym!(hashset_type)) {
"HashSet"
} else if is_type_diagnostic_item(cx, ty, sym!(hashmap_type)) {
"HashMap"
} else if match_type(cx, ty, &paths::BTREEMAP) {
"BTreeMap"
} else if match_type(cx, ty, &paths::BTREESET) {
"BTreeSet"
} else if match_type(cx, ty, &paths::LINKED_LIST) {
"LinkedList"
} else if match_type(cx, ty, &paths::BINARY_HEAP) {
"BinaryHeap"
} else {
return;
};
let mut applicability = Applicability::MachineApplicable;
span_lint_and_sugg(
cx,
ITER_COUNT,
expr.span,
&format!("called `.{}().count()` on a `{}`", iter_method, caller_type),
"try",
format!(
"{}.len()",
snippet_with_applicability(cx, iter_args[0].span, "..", &mut applicability),
),
applicability,
);
}

87
clippy_lints/src/methods/mod.rs
View file

@ -1,8 +1,10 @@
mod bind_instead_of_map;
mod bytes_nth;
mod filter_map_identity;
mod implicit_clone;
mod inefficient_to_string;
mod inspect_for_each;
mod iter_count;
mod manual_saturating_arithmetic;
mod option_map_unwrap_or;
mod unnecessary_filter_map;
@ -401,7 +403,7 @@ declare_clippy_lint! {
}
declare_clippy_lint! {
/// **What it does:** Checks for usage of `_.map(_).flatten(_)`,
/// **What it does:** Checks for usage of `_.map(_).flatten(_)` on `Iterator` and `Option`
///
/// **Why is this bad?** Readability, this can be written more concisely as
/// `_.flat_map(_)`
@ -1513,6 +1515,58 @@ declare_clippy_lint! {
"replace `.bytes().nth()` with `.as_bytes().get()`"
}
declare_clippy_lint! {
/// **What it does:** Checks for the usage of `_.to_owned()`, `vec.to_vec()`, or similar when calling `_.clone()` would be clearer.
///
/// **Why is this bad?** These methods do the same thing as `_.clone()` but may be confusing as
/// to why we are calling `to_vec` on something that is already a `Vec` or calling `to_owned` on something that is already owned.
///
/// **Known problems:** None.
///
/// **Example:**
///
/// ```rust
/// let a = vec![1, 2, 3];
/// let b = a.to_vec();
/// let c = a.to_owned();
/// ```
/// Use instead:
/// ```rust
/// let a = vec![1, 2, 3];
/// let b = a.clone();
/// let c = a.clone();
/// ```
pub IMPLICIT_CLONE,
pedantic,
"implicitly cloning a value by invoking a function on its dereferenced type"
}
declare_clippy_lint! {
/// **What it does:** Checks for the use of `.iter().count()`.
///
/// **Why is this bad?** `.len()` is more efficient and more
/// readable.
///
/// **Known problems:** None.
///
/// **Example:**
///
/// ```rust
/// // Bad
/// let some_vec = vec![0, 1, 2, 3];
/// let _ = some_vec.iter().count();
/// let _ = &some_vec[..].iter().count();
///
/// // Good
/// let some_vec = vec![0, 1, 2, 3];
/// let _ = some_vec.len();
/// let _ = &some_vec[..].len();
/// ```
pub ITER_COUNT,
complexity,
"replace `.iter().count()` with `.len()`"
}
pub struct Methods {
msrv: Option<RustcVersion>,
}
@ -1558,6 +1612,7 @@ impl_lint_pass!(Methods => [
MAP_FLATTEN,
ITERATOR_STEP_BY_ZERO,
ITER_NEXT_SLICE,
ITER_COUNT,
ITER_NTH,
ITER_NTH_ZERO,
BYTES_NTH,
@ -1579,6 +1634,7 @@ impl_lint_pass!(Methods => [
MAP_COLLECT_RESULT_UNIT,
FROM_ITER_INSTEAD_OF_COLLECT,
INSPECT_FOR_EACH,
IMPLICIT_CLONE
]);
impl<'tcx> LateLintPass<'tcx> for Methods {
@ -1636,6 +1692,9 @@ impl<'tcx> LateLintPass<'tcx> for Methods {
lint_search_is_some(cx, expr, "rposition", arg_lists[1], arg_lists[0], method_spans[1])
},
["extend", ..] => lint_extend(cx, expr, arg_lists[0]),
["count", "into_iter"] => iter_count::lints(cx, expr, &arg_lists[1], "into_iter"),
["count", "iter"] => iter_count::lints(cx, expr, &arg_lists[1], "iter"),
["count", "iter_mut"] => iter_count::lints(cx, expr, &arg_lists[1], "iter_mut"),
["nth", "iter"] => lint_iter_nth(cx, expr, &arg_lists, false),
["nth", "iter_mut"] => lint_iter_nth(cx, expr, &arg_lists, true),
["nth", "bytes"] => bytes_nth::lints(cx, expr, &arg_lists[1]),
@ -1670,6 +1729,10 @@ impl<'tcx> LateLintPass<'tcx> for Methods {
["ok_or_else", ..] => unnecessary_lazy_eval::lint(cx, expr, arg_lists[0], "ok_or"),
["collect", "map"] => lint_map_collect(cx, expr, arg_lists[1], arg_lists[0]),
["for_each", "inspect"] => inspect_for_each::lint(cx, expr, method_spans[1]),
["to_owned", ..] => implicit_clone::check(cx, expr, sym::ToOwned),
["to_os_string", ..] => implicit_clone::check(cx, expr, sym::OsStr),
["to_path_buf", ..] => implicit_clone::check(cx, expr, sym::Path),
["to_vec", ..] => implicit_clone::check(cx, expr, sym::slice),
_ => {},
}
@ -2003,12 +2066,26 @@ fn lint_or_fun_call<'tcx>(
if poss.contains(&name);
then {
let macro_expanded_snipped;
let sugg: Cow<'_, str> = {
let (snippet_span, use_lambda) = match (fn_has_arguments, fun_span) {
(false, Some(fun_span)) => (fun_span, false),
_ => (arg.span, true),
};
let snippet = snippet_with_macro_callsite(cx, snippet_span, "..");
let snippet = {
let not_macro_argument_snippet = snippet_with_macro_callsite(cx, snippet_span, "..");
if not_macro_argument_snippet == "vec![]" {
macro_expanded_snipped = snippet(cx, snippet_span, "..");
match macro_expanded_snipped.strip_prefix("$crate::vec::") {
Some(stripped) => Cow::from(stripped),
None => macro_expanded_snipped
}
}
else {
not_macro_argument_snippet
}
};
if use_lambda {
let l_arg = if fn_has_arguments { "_" } else { "" };
format!("|{}| {}", l_arg, snippet).into()
@ -2523,7 +2600,7 @@ fn lint_step_by<'tcx>(cx: &LateContext<'tcx>, expr: &hir::Expr<'_>, args: &'tcx
cx,
ITERATOR_STEP_BY_ZERO,
expr.span,
"Iterator::step_by(0) will panic at runtime",
"`Iterator::step_by(0)` will panic at runtime",
);
}
}
@ -3035,7 +3112,7 @@ fn lint_filter_next<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>, fil
// lint if caller of `.filter().next()` is an Iterator
if match_trait_method(cx, expr, &paths::ITERATOR) {
let msg = "called `filter(..).next()` on an `Iterator`. This is more succinctly expressed by calling \
`.find(..)` instead.";
`.find(..)` instead";
let filter_snippet = snippet(cx, filter_args[1].span, "..");
if filter_snippet.lines().count() <= 1 {
let iter_snippet = snippet(cx, filter_args[0].span, "..");
@ -3163,7 +3240,7 @@ fn lint_filter_map_next<'tcx>(
}
let msg = "called `filter_map(..).next()` on an `Iterator`. This is more succinctly expressed by calling \
`.find_map(..)` instead.";
`.find_map(..)` instead";
let filter_snippet = snippet(cx, filter_args[1].span, "..");
if filter_snippet.lines().count() <= 1 {
let iter_snippet = snippet(cx, filter_args[0].span, "..");

2
clippy_lints/src/methods/unnecessary_lazy_eval.rs
View file

@ -50,7 +50,7 @@ pub(super) fn lint<'tcx>(
UNNECESSARY_LAZY_EVALUATIONS,
expr.span,
msg,
&format!("Use `{}` instead", simplify_using),
&format!("use `{}` instead", simplify_using),
format!(
"{0}.{1}({2})",
snippet(cx, args[0].span, ".."),

24
clippy_lints/src/misc.rs
View file

@ -12,12 +12,13 @@ use rustc_middle::ty::{self, Ty};
use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_span::hygiene::DesugaringKind;
use rustc_span::source_map::{ExpnKind, Span};
use rustc_span::symbol::sym;
use crate::consts::{constant, Constant};
use crate::utils::sugg::Sugg;
use crate::utils::{
get_item_name, get_parent_expr, higher, implements_trait, in_constant, is_integer_const, iter_input_pats,
last_path_segment, match_qpath, match_trait_method, paths, snippet, snippet_opt, span_lint, span_lint_and_sugg,
get_item_name, get_parent_expr, higher, implements_trait, in_constant, is_diagnostic_assoc_item, is_integer_const,
iter_input_pats, last_path_segment, match_qpath, snippet, snippet_opt, span_lint, span_lint_and_sugg,
span_lint_and_then, span_lint_hir_and_then, unsext, SpanlessEq,
};
@ -292,7 +293,7 @@ impl<'tcx> LateLintPass<'tcx> for MiscLints {
TOPLEVEL_REF_ARG,
arg.pat.span,
"`ref` directly on a function argument is ignored. \
Consider using a reference type instead.",
Consider using a reference type instead",
);
}
}
@ -422,7 +423,7 @@ impl<'tcx> LateLintPass<'tcx> for MiscLints {
expr.span,
&format!(
"used binding `{}` which is prefixed with an underscore. A leading \
underscore signals that a binding will not be used.",
underscore signals that a binding will not be used",
binding
),
);
@ -554,11 +555,16 @@ fn check_to_owned(cx: &LateContext<'_>, expr: &Expr<'_>, other: &Expr<'_>, left:
let (arg_ty, snip) = match expr.kind {
ExprKind::MethodCall(.., ref args, _) if args.len() == 1 => {
if match_trait_method(cx, expr, &paths::TO_STRING) || match_trait_method(cx, expr, &paths::TO_OWNED) {
(cx.typeck_results().expr_ty(&args[0]), snippet(cx, args[0].span, ".."))
} else {
return;
}
if_chain!(
if let Some(expr_def_id) = cx.typeck_results().type_dependent_def_id(expr.hir_id);
if is_diagnostic_assoc_item(cx, expr_def_id, sym::ToString)
|| is_diagnostic_assoc_item(cx, expr_def_id, sym::ToOwned);
then {
(cx.typeck_results().expr_ty(&args[0]), snippet(cx, args[0].span, ".."))
} else {
return;
}
)
},
ExprKind::Call(ref path, ref v) if v.len() == 1 => {
if let ExprKind::Path(ref path) = path.kind {

8
clippy_lints/src/missing_inline.rs
View file

@ -69,21 +69,21 @@ fn check_missing_inline_attrs(cx: &LateContext<'_>, attrs: &[ast::Attribute], sp
}
}
fn is_executable(cx: &LateContext<'_>) -> bool {
fn is_executable_or_proc_macro(cx: &LateContext<'_>) -> bool {
use rustc_session::config::CrateType;
cx.tcx
.sess
.crate_types()
.iter()
.any(|t: &CrateType| matches!(t, CrateType::Executable))
.any(|t: &CrateType| matches!(t, CrateType::Executable | CrateType::ProcMacro))
}
declare_lint_pass!(MissingInline => [MISSING_INLINE_IN_PUBLIC_ITEMS]);
impl<'tcx> LateLintPass<'tcx> for MissingInline {
fn check_item(&mut self, cx: &LateContext<'tcx>, it: &'tcx hir::Item<'_>) {
if rustc_middle::lint::in_external_macro(cx.sess(), it.span) || is_executable(cx) {
if rustc_middle::lint::in_external_macro(cx.sess(), it.span) || is_executable_or_proc_macro(cx) {
return;
}
@ -135,7 +135,7 @@ impl<'tcx> LateLintPass<'tcx> for MissingInline {
fn check_impl_item(&mut self, cx: &LateContext<'tcx>, impl_item: &'tcx hir::ImplItem<'_>) {
use rustc_middle::ty::{ImplContainer, TraitContainer};
if rustc_middle::lint::in_external_macro(cx.sess(), impl_item.span) || is_executable(cx) {
if rustc_middle::lint::in_external_macro(cx.sess(), impl_item.span) || is_executable_or_proc_macro(cx) {
return;
}

10
clippy_lints/src/mutable_debug_assertion.rs
View file

@ -73,11 +73,7 @@ impl<'a, 'tcx> MutArgVisitor<'a, 'tcx> {
}
fn expr_span(&self) -> Option<Span> {
if self.found {
self.expr_span
} else {
None
}
if self.found { self.expr_span } else { None }
}
}
@ -90,10 +86,6 @@ impl<'a, 'tcx> Visitor<'tcx> for MutArgVisitor<'a, 'tcx> {
self.found = true;
return;
},
ExprKind::If(..) => {
self.found = true;
return;
},
ExprKind::Path(_) => {
if let Some(adj) = self.cx.typeck_results().adjustments().get(expr.hir_id) {
if adj

47
clippy_lints/src/needless_borrowed_ref.rs
View file

@ -1,7 +1,3 @@
//! Checks for useless borrowed references.
//!
//! This lint is **warn** by default
use crate::utils::{snippet_with_applicability, span_lint_and_then};
use if_chain::if_chain;
use rustc_errors::Applicability;
@ -10,44 +6,37 @@ use rustc_lint::{LateContext, LateLintPass};
use rustc_session::{declare_lint_pass, declare_tool_lint};
declare_clippy_lint! {
/// **What it does:** Checks for useless borrowed references.
/// **What it does:** Checks for bindings that destructure a reference and borrow the inner
/// value with `&ref`.
///
/// **Why is this bad?** It is mostly useless and make the code look more
/// complex than it
/// actually is.
/// **Why is this bad?** This pattern has no effect in almost all cases.
///
/// **Known problems:** It seems that the `&ref` pattern is sometimes useful.
/// For instance in the following snippet:
/// ```rust,ignore
/// enum Animal {
/// Cat(u64),
/// Dog(u64),
/// }
///
/// fn foo(a: &Animal, b: &Animal) {
/// **Known problems:** In some cases, `&ref` is needed to avoid a lifetime mismatch error.
/// Example:
/// ```rust
/// fn foo(a: &Option<String>, b: &Option<String>) {
/// match (a, b) {
/// (&Animal::Cat(v), k) | (k, &Animal::Cat(v)) => (), // lifetime mismatch error
/// (&Animal::Dog(ref c), &Animal::Dog(_)) => ()
/// }
/// (None, &ref c) | (&ref c, None) => (),
/// (&Some(ref c), _) => (),
/// };
/// }
/// ```
/// There is a lifetime mismatch error for `k` (indeed a and b have distinct
/// lifetime).
/// This can be fixed by using the `&ref` pattern.
/// However, the code can also be fixed by much cleaner ways
///
/// **Example:**
/// Bad:
/// ```rust
/// let mut v = Vec::<String>::new();
/// let _ = v.iter_mut().filter(|&ref a| a.is_empty());
/// ```
/// This closure takes a reference on something that has been matched as a
/// reference and
/// de-referenced.
/// As such, it could just be |a| a.is_empty()
///
/// Good:
/// ```rust
/// let mut v = Vec::<String>::new();
/// let _ = v.iter_mut().filter(|a| a.is_empty());
/// ```
pub NEEDLESS_BORROWED_REFERENCE,
complexity,
"taking a needless borrowed reference"
"destructuring a reference and borrowing the inner value"
}
declare_lint_pass!(NeedlessBorrowedRef => [NEEDLESS_BORROWED_REFERENCE]);

6
clippy_lints/src/needless_continue.rs
View file

@ -416,11 +416,7 @@ fn erode_from_back(s: &str) -> String {
break;
}
}
if ret.is_empty() {
s.to_string()
} else {
ret
}
if ret.is_empty() { s.to_string() } else { ret }
}
fn span_of_first_expr_in_block(block: &ast::Block) -> Option<Span> {

2
clippy_lints/src/needless_question_mark.rs
View file

@ -142,7 +142,7 @@ fn emit_lint(cx: &LateContext<'_>, expr: &SomeOkCall<'_>) {
cx,
NEEDLESS_QUESTION_MARK,
entire_expr.span,
"Question mark operator is useless here",
"question mark operator is useless here",
"try",
format!("{}", utils::snippet(cx, inner_expr.span, r#""...""#)),
Applicability::MachineApplicable,

3
clippy_lints/src/non_expressive_names.rs
View file

@ -1,7 +1,6 @@
use crate::utils::{span_lint, span_lint_and_then};
use rustc_ast::ast::{
Arm, AssocItem, AssocItemKind, Attribute, Block, FnDecl, FnKind, Item, ItemKind, Local, Pat,
PatKind,
Arm, AssocItem, AssocItemKind, Attribute, Block, FnDecl, FnKind, Item, ItemKind, Local, Pat, PatKind,
};
use rustc_ast::visit::{walk_block, walk_expr, walk_pat, Visitor};
use rustc_lint::{EarlyContext, EarlyLintPass};

12
clippy_lints/src/open_options.rs
View file

@ -69,15 +69,11 @@ fn get_open_options(cx: &LateContext<'_>, argument: &Expr<'_>, options: &mut Vec
..
} = *span
{
if lit {
Argument::True
} else {
Argument::False
}
if lit { Argument::True } else { Argument::False }
} else {
return; // The function is called with a literal
// which is not a boolean literal. This is theoretically
// possible, but not very likely.
// The function is called with a literal which is not a boolean literal.
// This is theoretically possible, but not very likely.
return;
}
},
_ => Argument::Unknown,

5
clippy_lints/src/path_buf_push_overwrite.rs
View file

@ -1,10 +1,11 @@
use crate::utils::{match_type, paths, span_lint_and_sugg};
use crate::utils::{is_type_diagnostic_item, span_lint_and_sugg};
use if_chain::if_chain;
use rustc_ast::ast::LitKind;
use rustc_errors::Applicability;
use rustc_hir::{Expr, ExprKind};
use rustc_lint::{LateContext, LateLintPass};
use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_span::symbol::sym;
use std::path::{Component, Path};
declare_clippy_lint! {
@ -46,7 +47,7 @@ impl<'tcx> LateLintPass<'tcx> for PathBufPushOverwrite {
if let ExprKind::MethodCall(ref path, _, ref args, _) = expr.kind;
if path.ident.name == sym!(push);
if args.len() == 2;
if match_type(cx, cx.typeck_results().expr_ty(&args[0]).peel_refs(), &paths::PATH_BUF);
if is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(&args[0]).peel_refs(), sym::PathBuf);
if let Some(get_index_arg) = args.get(1);
if let ExprKind::Lit(ref lit) = get_index_arg.kind;
if let LitKind::Str(ref path_lit, _) = lit.node;

10
clippy_lints/src/ptr.rs
View file

@ -188,7 +188,7 @@ fn check_fn(cx: &LateContext<'_>, decl: &FnDecl<'_>, fn_id: HirId, opt_body_id:
PTR_ARG,
arg.span,
"writing `&Vec<_>` instead of `&[_]` involves one more reference and cannot be used \
with non-Vec-based slices.",
with non-Vec-based slices",
|diag| {
if let Some(ref snippet) = get_only_generic_arg_snippet(cx, arg) {
diag.span_suggestion(
@ -217,7 +217,7 @@ fn check_fn(cx: &LateContext<'_>, decl: &FnDecl<'_>, fn_id: HirId, opt_body_id:
cx,
PTR_ARG,
arg.span,
"writing `&String` instead of `&str` involves a new object where a slice will do.",
"writing `&String` instead of `&str` involves a new object where a slice will do",
|diag| {
diag.span_suggestion(arg.span, "change this to", "&str".into(), Applicability::Unspecified);
for (clonespan, suggestion) in spans {
@ -233,13 +233,13 @@ fn check_fn(cx: &LateContext<'_>, decl: &FnDecl<'_>, fn_id: HirId, opt_body_id:
},
);
}
} else if match_type(cx, ty, &paths::PATH_BUF) {
} else if is_type_diagnostic_item(cx, ty, sym::PathBuf) {
if let Some(spans) = get_spans(cx, opt_body_id, idx, &[("clone", ".to_path_buf()"), ("as_path", "")]) {
span_lint_and_then(
cx,
PTR_ARG,
arg.span,
"writing `&PathBuf` instead of `&Path` involves a new object where a slice will do.",
"writing `&PathBuf` instead of `&Path` involves a new object where a slice will do",
|diag| {
diag.span_suggestion(
arg.span,
@ -278,7 +278,7 @@ fn check_fn(cx: &LateContext<'_>, decl: &FnDecl<'_>, fn_id: HirId, opt_body_id:
cx,
PTR_ARG,
arg.span,
"using a reference to `Cow` is not recommended.",
"using a reference to `Cow` is not recommended",
"change this to",
"&".to_owned() + &r,
Applicability::Unspecified,

12
clippy_lints/src/redundant_clone.rs
View file

@ -1,6 +1,6 @@
use crate::utils::{
fn_has_unsatisfiable_preds, has_drop, is_copy, is_type_diagnostic_item, match_def_path, match_type, paths,
snippet_opt, span_lint_hir, span_lint_hir_and_then, walk_ptrs_ty_depth,
fn_has_unsatisfiable_preds, has_drop, is_copy, is_type_diagnostic_item, match_def_path, paths, snippet_opt,
span_lint_hir, span_lint_hir_and_then, walk_ptrs_ty_depth,
};
use if_chain::if_chain;
use rustc_data_structures::{fx::FxHashMap, transitive_relation::TransitiveRelation};
@ -165,9 +165,9 @@ impl<'tcx> LateLintPass<'tcx> for RedundantClone {
if let Some((pred_fn_def_id, pred_arg, pred_arg_ty, res)) =
is_call_with_ref_arg(cx, mir, &pred_terminator.kind);
if res == cloned;
if match_def_path(cx, pred_fn_def_id, &paths::DEREF_TRAIT_METHOD);
if match_type(cx, pred_arg_ty, &paths::PATH_BUF)
|| match_type(cx, pred_arg_ty, &paths::OS_STRING);
if cx.tcx.is_diagnostic_item(sym::deref_method, pred_fn_def_id);
if is_type_diagnostic_item(cx, pred_arg_ty, sym::PathBuf)
|| is_type_diagnostic_item(cx, pred_arg_ty, sym::OsString);
then {
(pred_arg, res)
} else {
@ -587,7 +587,7 @@ fn rvalue_locals(rvalue: &mir::Rvalue<'_>, mut visit: impl FnMut(mir::Local)) {
BinaryOp(_, box (lhs, rhs)) | CheckedBinaryOp(_, box (lhs, rhs)) => {
visit_op(lhs);
visit_op(rhs);
}
},
_ => (),
}
}

4
clippy_lints/src/suspicious_operation_groupings.rs
View file

@ -261,8 +261,8 @@ fn emit_suggestion(cx: &EarlyContext<'_>, span: Span, sugg: String, applicabilit
cx,
SUSPICIOUS_OPERATION_GROUPINGS,
span,
"This sequence of operators looks suspiciously like a bug.",
"I think you meant",
"this sequence of operators looks suspiciously like a bug",
"did you mean",
sugg,
applicability,
)

6
clippy_lints/src/to_string_in_display.rs
View file

@ -1,8 +1,9 @@
use crate::utils::{match_def_path, match_trait_method, path_to_local_id, paths, span_lint};
use crate::utils::{is_diagnostic_assoc_item, match_def_path, path_to_local_id, paths, span_lint};
use if_chain::if_chain;
use rustc_hir::{Expr, ExprKind, HirId, Impl, ImplItem, ImplItemKind, Item, ItemKind};
use rustc_lint::{LateContext, LateLintPass};
use rustc_session::{declare_tool_lint, impl_lint_pass};
use rustc_span::symbol::sym;
declare_clippy_lint! {
/// **What it does:** Checks for uses of `to_string()` in `Display` traits.
@ -92,7 +93,8 @@ impl LateLintPass<'_> for ToStringInDisplay {
if let Some(self_hir_id) = self.self_hir_id;
if let ExprKind::MethodCall(ref path, _, args, _) = expr.kind;
if path.ident.name == sym!(to_string);
if match_trait_method(cx, expr, &paths::TO_STRING);
if let Some(expr_def_id) = cx.typeck_results().type_dependent_def_id(expr.hir_id);
if is_diagnostic_assoc_item(cx, expr_def_id, sym::ToString);
if path_to_local_id(&args[0], self_hir_id);
then {
span_lint(

763
clippy_lints/src/transmute.rs
View file

@ -1,763 +0,0 @@
use crate::utils::{
in_constant, is_normalizable, last_path_segment, match_def_path, paths, snippet, span_lint, span_lint_and_sugg,
span_lint_and_then, sugg,
};
use if_chain::if_chain;
use rustc_ast as ast;
use rustc_errors::Applicability;
use rustc_hir::{Expr, ExprKind, GenericArg, Mutability, QPath, TyKind, UnOp};
use rustc_lint::{LateContext, LateLintPass};
use rustc_middle::ty::{self, cast::CastKind, Ty};
use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_span::DUMMY_SP;
use rustc_typeck::check::{cast::CastCheck, FnCtxt, Inherited};
use std::borrow::Cow;
declare_clippy_lint! {
/// **What it does:** Checks for transmutes that can't ever be correct on any
/// architecture.
///
/// **Why is this bad?** It's basically guaranteed to be undefined behaviour.
///
/// **Known problems:** When accessing C, users might want to store pointer
/// sized objects in `extradata` arguments to save an allocation.
///
/// **Example:**
/// ```ignore
/// let ptr: *const T = core::intrinsics::transmute('x')
/// ```
pub WRONG_TRANSMUTE,
correctness,
"transmutes that are confusing at best, undefined behaviour at worst and always useless"
}
// FIXME: Move this to `complexity` again, after #5343 is fixed
declare_clippy_lint! {
/// **What it does:** Checks for transmutes to the original type of the object
/// and transmutes that could be a cast.
///
/// **Why is this bad?** Readability. The code tricks people into thinking that
/// something complex is going on.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust,ignore
/// core::intrinsics::transmute(t); // where the result type is the same as `t`'s
/// ```
pub USELESS_TRANSMUTE,
nursery,
"transmutes that have the same to and from types or could be a cast/coercion"
}
// FIXME: Merge this lint with USELESS_TRANSMUTE once that is out of the nursery.
declare_clippy_lint! {
/// **What it does:**Checks for transmutes that could be a pointer cast.
///
/// **Why is this bad?** Readability. The code tricks people into thinking that
/// something complex is going on.
///
/// **Known problems:** None.
///
/// **Example:**
///
/// ```rust
/// # let p: *const [i32] = &[];
/// unsafe { std::mem::transmute::<*const [i32], *const [u16]>(p) };
/// ```
/// Use instead:
/// ```rust
/// # let p: *const [i32] = &[];
/// p as *const [u16];
/// ```
pub TRANSMUTES_EXPRESSIBLE_AS_PTR_CASTS,
complexity,
"transmutes that could be a pointer cast"
}
declare_clippy_lint! {
/// **What it does:** Checks for transmutes between a type `T` and `*T`.
///
/// **Why is this bad?** It's easy to mistakenly transmute between a type and a
/// pointer to that type.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust,ignore
/// core::intrinsics::transmute(t) // where the result type is the same as
/// // `*t` or `&t`'s
/// ```
pub CROSSPOINTER_TRANSMUTE,
complexity,
"transmutes that have to or from types that are a pointer to the other"
}
declare_clippy_lint! {
/// **What it does:** Checks for transmutes from a pointer to a reference.
///
/// **Why is this bad?** This can always be rewritten with `&` and `*`.
///
/// **Known problems:**
/// - `mem::transmute` in statics and constants is stable from Rust 1.46.0,
/// while dereferencing raw pointer is not stable yet.
/// If you need to do this in those places,
/// you would have to use `transmute` instead.
///
/// **Example:**
/// ```rust,ignore
/// unsafe {
/// let _: &T = std::mem::transmute(p); // where p: *const T
/// }
///
/// // can be written:
/// let _: &T = &*p;
/// ```
pub TRANSMUTE_PTR_TO_REF,
complexity,
"transmutes from a pointer to a reference type"
}
declare_clippy_lint! {
/// **What it does:** Checks for transmutes from an integer to a `char`.
///
/// **Why is this bad?** Not every integer is a Unicode scalar value.
///
/// **Known problems:**
/// - [`from_u32`] which this lint suggests using is slower than `transmute`
/// as it needs to validate the input.
/// If you are certain that the input is always a valid Unicode scalar value,
/// use [`from_u32_unchecked`] which is as fast as `transmute`
/// but has a semantically meaningful name.
/// - You might want to handle `None` returned from [`from_u32`] instead of calling `unwrap`.
///
/// [`from_u32`]: https://doc.rust-lang.org/std/char/fn.from_u32.html
/// [`from_u32_unchecked`]: https://doc.rust-lang.org/std/char/fn.from_u32_unchecked.html
///
/// **Example:**
/// ```rust
/// let x = 1_u32;
/// unsafe {
/// let _: char = std::mem::transmute(x); // where x: u32
/// }
///
/// // should be:
/// let _ = std::char::from_u32(x).unwrap();
/// ```
pub TRANSMUTE_INT_TO_CHAR,
complexity,
"transmutes from an integer to a `char`"
}
declare_clippy_lint! {
/// **What it does:** Checks for transmutes from a `&[u8]` to a `&str`.
///
/// **Why is this bad?** Not every byte slice is a valid UTF-8 string.
///
/// **Known problems:**
/// - [`from_utf8`] which this lint suggests using is slower than `transmute`
/// as it needs to validate the input.
/// If you are certain that the input is always a valid UTF-8,
/// use [`from_utf8_unchecked`] which is as fast as `transmute`
/// but has a semantically meaningful name.
/// - You might want to handle errors returned from [`from_utf8`] instead of calling `unwrap`.
///
/// [`from_utf8`]: https://doc.rust-lang.org/std/str/fn.from_utf8.html
/// [`from_utf8_unchecked`]: https://doc.rust-lang.org/std/str/fn.from_utf8_unchecked.html
///
/// **Example:**
/// ```rust
/// let b: &[u8] = &[1_u8, 2_u8];
/// unsafe {
/// let _: &str = std::mem::transmute(b); // where b: &[u8]
/// }
///
/// // should be:
/// let _ = std::str::from_utf8(b).unwrap();
/// ```
pub TRANSMUTE_BYTES_TO_STR,
complexity,
"transmutes from a `&[u8]` to a `&str`"
}
declare_clippy_lint! {
/// **What it does:** Checks for transmutes from an integer to a `bool`.
///
/// **Why is this bad?** This might result in an invalid in-memory representation of a `bool`.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// let x = 1_u8;
/// unsafe {
/// let _: bool = std::mem::transmute(x); // where x: u8
/// }
///
/// // should be:
/// let _: bool = x != 0;
/// ```
pub TRANSMUTE_INT_TO_BOOL,
complexity,
"transmutes from an integer to a `bool`"
}
declare_clippy_lint! {
/// **What it does:** Checks for transmutes from an integer to a float.
///
/// **Why is this bad?** Transmutes are dangerous and error-prone, whereas `from_bits` is intuitive
/// and safe.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// unsafe {
/// let _: f32 = std::mem::transmute(1_u32); // where x: u32
/// }
///
/// // should be:
/// let _: f32 = f32::from_bits(1_u32);
/// ```
pub TRANSMUTE_INT_TO_FLOAT,
complexity,
"transmutes from an integer to a float"
}
declare_clippy_lint! {
/// **What it does:** Checks for transmutes from a float to an integer.
///
/// **Why is this bad?** Transmutes are dangerous and error-prone, whereas `to_bits` is intuitive
/// and safe.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// unsafe {
/// let _: u32 = std::mem::transmute(1f32);
/// }
///
/// // should be:
/// let _: u32 = 1f32.to_bits();
/// ```
pub TRANSMUTE_FLOAT_TO_INT,
complexity,
"transmutes from a float to an integer"
}
declare_clippy_lint! {
/// **What it does:** Checks for transmutes from a pointer to a pointer, or
/// from a reference to a reference.
///
/// **Why is this bad?** Transmutes are dangerous, and these can instead be
/// written as casts.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// let ptr = &1u32 as *const u32;
/// unsafe {
/// // pointer-to-pointer transmute
/// let _: *const f32 = std::mem::transmute(ptr);
/// // ref-ref transmute
/// let _: &f32 = std::mem::transmute(&1u32);
/// }
/// // These can be respectively written:
/// let _ = ptr as *const f32;
/// let _ = unsafe{ &*(&1u32 as *const u32 as *const f32) };
/// ```
pub TRANSMUTE_PTR_TO_PTR,
complexity,
"transmutes from a pointer to a pointer / a reference to a reference"
}
declare_clippy_lint! {
/// **What it does:** Checks for transmutes between collections whose
/// types have different ABI, size or alignment.
///
/// **Why is this bad?** This is undefined behavior.
///
/// **Known problems:** Currently, we cannot know whether a type is a
/// collection, so we just lint the ones that come with `std`.
///
/// **Example:**
/// ```rust
/// // different size, therefore likely out-of-bounds memory access
/// // You absolutely do not want this in your code!
/// unsafe {
/// std::mem::transmute::<_, Vec<u32>>(vec![2_u16])
/// };
/// ```
///
/// You must always iterate, map and collect the values:
///
/// ```rust
/// vec![2_u16].into_iter().map(u32::from).collect::<Vec<_>>();
/// ```
pub UNSOUND_COLLECTION_TRANSMUTE,
correctness,
"transmute between collections of layout-incompatible types"
}
declare_lint_pass!(Transmute => [
CROSSPOINTER_TRANSMUTE,
TRANSMUTE_PTR_TO_REF,
TRANSMUTE_PTR_TO_PTR,
USELESS_TRANSMUTE,
WRONG_TRANSMUTE,
TRANSMUTE_INT_TO_CHAR,
TRANSMUTE_BYTES_TO_STR,
TRANSMUTE_INT_TO_BOOL,
TRANSMUTE_INT_TO_FLOAT,
TRANSMUTE_FLOAT_TO_INT,
UNSOUND_COLLECTION_TRANSMUTE,
TRANSMUTES_EXPRESSIBLE_AS_PTR_CASTS,
]);
// used to check for UNSOUND_COLLECTION_TRANSMUTE
static COLLECTIONS: &[&[&str]] = &[
&paths::VEC,
&paths::VEC_DEQUE,
&paths::BINARY_HEAP,
&paths::BTREESET,
&paths::BTREEMAP,
&paths::HASHSET,
&paths::HASHMAP,
];
impl<'tcx> LateLintPass<'tcx> for Transmute {
#[allow(clippy::similar_names, clippy::too_many_lines)]
fn check_expr(&mut self, cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) {
if_chain! {
if let ExprKind::Call(ref path_expr, ref args) = e.kind;
if let ExprKind::Path(ref qpath) = path_expr.kind;
if let Some(def_id) = cx.qpath_res(qpath, path_expr.hir_id).opt_def_id();
if match_def_path(cx, def_id, &paths::TRANSMUTE);
then {
// Avoid suggesting from/to bits and dereferencing raw pointers in const contexts.
// See https://github.com/rust-lang/rust/issues/73736 for progress on making them `const fn`.
// And see https://github.com/rust-lang/rust/issues/51911 for dereferencing raw pointers.
let const_context = in_constant(cx, e.hir_id);
let from_ty = cx.typeck_results().expr_ty(&args[0]);
let to_ty = cx.typeck_results().expr_ty(e);
match (&from_ty.kind(), &to_ty.kind()) {
_ if from_ty == to_ty => span_lint(
cx,
USELESS_TRANSMUTE,
e.span,
&format!("transmute from a type (`{}`) to itself", from_ty),
),
(ty::Ref(_, rty, rty_mutbl), ty::RawPtr(ptr_ty)) => span_lint_and_then(
cx,
USELESS_TRANSMUTE,
e.span,
"transmute from a reference to a pointer",
|diag| {
if let Some(arg) = sugg::Sugg::hir_opt(cx, &args[0]) {
let rty_and_mut = ty::TypeAndMut {
ty: rty,
mutbl: *rty_mutbl,
};
let sugg = if *ptr_ty == rty_and_mut {
arg.as_ty(to_ty)
} else {
arg.as_ty(cx.tcx.mk_ptr(rty_and_mut)).as_ty(to_ty)
};
diag.span_suggestion(e.span, "try", sugg.to_string(), Applicability::Unspecified);
}
},
),
(ty::Int(_) | ty::Uint(_), ty::RawPtr(_)) => span_lint_and_then(
cx,
USELESS_TRANSMUTE,
e.span,
"transmute from an integer to a pointer",
|diag| {
if let Some(arg) = sugg::Sugg::hir_opt(cx, &args[0]) {
diag.span_suggestion(
e.span,
"try",
arg.as_ty(&to_ty.to_string()).to_string(),
Applicability::Unspecified,
);
}
},
),
(ty::Float(_) | ty::Char, ty::Ref(..) | ty::RawPtr(_)) => span_lint(
cx,
WRONG_TRANSMUTE,
e.span,
&format!("transmute from a `{}` to a pointer", from_ty),
),
(ty::RawPtr(from_ptr), _) if from_ptr.ty == to_ty => span_lint(
cx,
CROSSPOINTER_TRANSMUTE,
e.span,
&format!(
"transmute from a type (`{}`) to the type that it points to (`{}`)",
from_ty, to_ty
),
),
(_, ty::RawPtr(to_ptr)) if to_ptr.ty == from_ty => span_lint(
cx,
CROSSPOINTER_TRANSMUTE,
e.span,
&format!(
"transmute from a type (`{}`) to a pointer to that type (`{}`)",
from_ty, to_ty
),
),
(ty::RawPtr(from_pty), ty::Ref(_, to_ref_ty, mutbl)) => span_lint_and_then(
cx,
TRANSMUTE_PTR_TO_REF,
e.span,
&format!(
"transmute from a pointer type (`{}`) to a reference type \
(`{}`)",
from_ty, to_ty
),
|diag| {
let arg = sugg::Sugg::hir(cx, &args[0], "..");
let (deref, cast) = if *mutbl == Mutability::Mut {
("&mut *", "*mut")
} else {
("&*", "*const")
};
let arg = if from_pty.ty == *to_ref_ty {
arg
} else {
arg.as_ty(&format!("{} {}", cast, get_type_snippet(cx, qpath, to_ref_ty)))
};
diag.span_suggestion(
e.span,
"try",
sugg::make_unop(deref, arg).to_string(),
Applicability::Unspecified,
);
},
),
(ty::Int(ty::IntTy::I32) | ty::Uint(ty::UintTy::U32), &ty::Char) => {
span_lint_and_then(
cx,
TRANSMUTE_INT_TO_CHAR,
e.span,
&format!("transmute from a `{}` to a `char`", from_ty),
|diag| {
let arg = sugg::Sugg::hir(cx, &args[0], "..");
let arg = if let ty::Int(_) = from_ty.kind() {
arg.as_ty(ast::UintTy::U32.name_str())
} else {
arg
};
diag.span_suggestion(
e.span,
"consider using",
format!("std::char::from_u32({}).unwrap()", arg.to_string()),
Applicability::Unspecified,
);
},
)
},
(ty::Ref(_, ty_from, from_mutbl), ty::Ref(_, ty_to, to_mutbl)) => {
if_chain! {
if let (&ty::Slice(slice_ty), &ty::Str) = (&ty_from.kind(), &ty_to.kind());
if let ty::Uint(ty::UintTy::U8) = slice_ty.kind();
if from_mutbl == to_mutbl;
then {
let postfix = if *from_mutbl == Mutability::Mut {
"_mut"
} else {
""
};
span_lint_and_sugg(
cx,
TRANSMUTE_BYTES_TO_STR,
e.span,
&format!("transmute from a `{}` to a `{}`", from_ty, to_ty),
"consider using",
format!(
"std::str::from_utf8{}({}).unwrap()",
postfix,
snippet(cx, args[0].span, ".."),
),
Applicability::Unspecified,
);
} else {
if (cx.tcx.erase_regions(from_ty) != cx.tcx.erase_regions(to_ty))
&& !const_context {
span_lint_and_then(
cx,
TRANSMUTE_PTR_TO_PTR,
e.span,
"transmute from a reference to a reference",
|diag| if let Some(arg) = sugg::Sugg::hir_opt(cx, &args[0]) {
let ty_from_and_mut = ty::TypeAndMut {
ty: ty_from,
mutbl: *from_mutbl
};
let ty_to_and_mut = ty::TypeAndMut { ty: ty_to, mutbl: *to_mutbl };
let sugg_paren = arg
.as_ty(cx.tcx.mk_ptr(ty_from_and_mut))
.as_ty(cx.tcx.mk_ptr(ty_to_and_mut));
let sugg = if *to_mutbl == Mutability::Mut {
sugg_paren.mut_addr_deref()
} else {
sugg_paren.addr_deref()
};
diag.span_suggestion(
e.span,
"try",
sugg.to_string(),
Applicability::Unspecified,
);
},
)
}
}
}
},
(ty::RawPtr(_), ty::RawPtr(to_ty)) => span_lint_and_then(
cx,
TRANSMUTE_PTR_TO_PTR,
e.span,
"transmute from a pointer to a pointer",
|diag| {
if let Some(arg) = sugg::Sugg::hir_opt(cx, &args[0]) {
let sugg = arg.as_ty(cx.tcx.mk_ptr(*to_ty));
diag.span_suggestion(e.span, "try", sugg.to_string(), Applicability::Unspecified);
}
},
),
(ty::Int(ty::IntTy::I8) | ty::Uint(ty::UintTy::U8), ty::Bool) => {
span_lint_and_then(
cx,
TRANSMUTE_INT_TO_BOOL,
e.span,
&format!("transmute from a `{}` to a `bool`", from_ty),
|diag| {
let arg = sugg::Sugg::hir(cx, &args[0], "..");
let zero = sugg::Sugg::NonParen(Cow::from("0"));
diag.span_suggestion(
e.span,
"consider using",
sugg::make_binop(ast::BinOpKind::Ne, &arg, &zero).to_string(),
Applicability::Unspecified,
);
},
)
},
(ty::Int(_) | ty::Uint(_), ty::Float(_)) if !const_context => span_lint_and_then(
cx,
TRANSMUTE_INT_TO_FLOAT,
e.span,
&format!("transmute from a `{}` to a `{}`", from_ty, to_ty),
|diag| {
let arg = sugg::Sugg::hir(cx, &args[0], "..");
let arg = if let ty::Int(int_ty) = from_ty.kind() {
arg.as_ty(format!(
"u{}",
int_ty.bit_width().map_or_else(|| "size".to_string(), |v| v.to_string())
))
} else {
arg
};
diag.span_suggestion(
e.span,
"consider using",
format!("{}::from_bits({})", to_ty, arg.to_string()),
Applicability::Unspecified,
);
},
),
(ty::Float(float_ty), ty::Int(_) | ty::Uint(_)) if !const_context => span_lint_and_then(
cx,
TRANSMUTE_FLOAT_TO_INT,
e.span,
&format!("transmute from a `{}` to a `{}`", from_ty, to_ty),
|diag| {
let mut expr = &args[0];
let mut arg = sugg::Sugg::hir(cx, expr, "..");
if let ExprKind::Unary(UnOp::Neg, inner_expr) = &expr.kind {
expr = &inner_expr;
}
if_chain! {
// if the expression is a float literal and it is unsuffixed then
// add a suffix so the suggestion is valid and unambiguous
let op = format!("{}{}", arg, float_ty.name_str()).into();
if let ExprKind::Lit(lit) = &expr.kind;
if let ast::LitKind::Float(_, ast::LitFloatType::Unsuffixed) = lit.node;
then {
match arg {
sugg::Sugg::MaybeParen(_) => arg = sugg::Sugg::MaybeParen(op),
_ => arg = sugg::Sugg::NonParen(op)
}
}
}
arg = sugg::Sugg::NonParen(format!("{}.to_bits()", arg.maybe_par()).into());
// cast the result of `to_bits` if `to_ty` is signed
arg = if let ty::Int(int_ty) = to_ty.kind() {
arg.as_ty(int_ty.name_str().to_string())
} else {
arg
};
diag.span_suggestion(
e.span,
"consider using",
arg.to_string(),
Applicability::Unspecified,
);
},
),
(ty::Adt(from_adt, from_substs), ty::Adt(to_adt, to_substs)) => {
if from_adt.did != to_adt.did ||
!COLLECTIONS.iter().any(|path| match_def_path(cx, to_adt.did, path)) {
return;
}
if from_substs.types().zip(to_substs.types())
.any(|(from_ty, to_ty)| is_layout_incompatible(cx, from_ty, to_ty)) {
span_lint(
cx,
UNSOUND_COLLECTION_TRANSMUTE,
e.span,
&format!(
"transmute from `{}` to `{}` with mismatched layout is unsound",
from_ty,
to_ty
)
);
}
},
(_, _) if can_be_expressed_as_pointer_cast(cx, e, from_ty, to_ty) => span_lint_and_then(
cx,
TRANSMUTES_EXPRESSIBLE_AS_PTR_CASTS,
e.span,
&format!(
"transmute from `{}` to `{}` which could be expressed as a pointer cast instead",
from_ty,
to_ty
),
|diag| {
if let Some(arg) = sugg::Sugg::hir_opt(cx, &args[0]) {
let sugg = arg.as_ty(&to_ty.to_string()).to_string();
diag.span_suggestion(e.span, "try", sugg, Applicability::MachineApplicable);
}
}
),
_ => {
return;
},
}
}
}
}
}
/// Gets the snippet of `Bar` in `…::transmute<Foo, &Bar>`. If that snippet is
/// not available , use
/// the type's `ToString` implementation. In weird cases it could lead to types
/// with invalid `'_`
/// lifetime, but it should be rare.
fn get_type_snippet(cx: &LateContext<'_>, path: &QPath<'_>, to_ref_ty: Ty<'_>) -> String {
let seg = last_path_segment(path);
if_chain! {
if let Some(ref params) = seg.args;
if !params.parenthesized;
if let Some(to_ty) = params.args.iter().filter_map(|arg| match arg {
GenericArg::Type(ty) => Some(ty),
_ => None,
}).nth(1);
if let TyKind::Rptr(_, ref to_ty) = to_ty.kind;
then {
return snippet(cx, to_ty.ty.span, &to_ref_ty.to_string()).to_string();
}
}
to_ref_ty.to_string()
}
// check if the component types of the transmuted collection and the result have different ABI,
// size or alignment
fn is_layout_incompatible<'tcx>(cx: &LateContext<'tcx>, from: Ty<'tcx>, to: Ty<'tcx>) -> bool {
let empty_param_env = ty::ParamEnv::empty();
// check if `from` and `to` are normalizable to avoid ICE (#4968)
if !(is_normalizable(cx, empty_param_env, from) && is_normalizable(cx, empty_param_env, to)) {
return false;
}
let from_ty_layout = cx.tcx.layout_of(empty_param_env.and(from));
let to_ty_layout = cx.tcx.layout_of(empty_param_env.and(to));
if let (Ok(from_layout), Ok(to_layout)) = (from_ty_layout, to_ty_layout) {
from_layout.size != to_layout.size || from_layout.align != to_layout.align || from_layout.abi != to_layout.abi
} else {
// no idea about layout, so don't lint
false
}
}
/// Check if the type conversion can be expressed as a pointer cast, instead of
/// a transmute. In certain cases, including some invalid casts from array
/// references to pointers, this may cause additional errors to be emitted and/or
/// ICE error messages. This function will panic if that occurs.
fn can_be_expressed_as_pointer_cast<'tcx>(
cx: &LateContext<'tcx>,
e: &'tcx Expr<'_>,
from_ty: Ty<'tcx>,
to_ty: Ty<'tcx>,
) -> bool {
use CastKind::{AddrPtrCast, ArrayPtrCast, FnPtrAddrCast, FnPtrPtrCast, PtrAddrCast, PtrPtrCast};
matches!(
check_cast(cx, e, from_ty, to_ty),
Some(PtrPtrCast | PtrAddrCast | AddrPtrCast | ArrayPtrCast | FnPtrPtrCast | FnPtrAddrCast)
)
}
/// If a cast from `from_ty` to `to_ty` is valid, returns an Ok containing the kind of
/// the cast. In certain cases, including some invalid casts from array references
/// to pointers, this may cause additional errors to be emitted and/or ICE error
/// messages. This function will panic if that occurs.
fn check_cast<'tcx>(cx: &LateContext<'tcx>, e: &'tcx Expr<'_>, from_ty: Ty<'tcx>, to_ty: Ty<'tcx>) -> Option<CastKind> {
let hir_id = e.hir_id;
let local_def_id = hir_id.owner;
Inherited::build(cx.tcx, local_def_id).enter(|inherited| {
let fn_ctxt = FnCtxt::new(&inherited, cx.param_env, hir_id);
// If we already have errors, we can't be sure we can pointer cast.
assert!(
!fn_ctxt.errors_reported_since_creation(),
"Newly created FnCtxt contained errors"
);
if let Ok(check) = CastCheck::new(
&fn_ctxt, e, from_ty, to_ty,
// We won't show any error to the user, so we don't care what the span is here.
DUMMY_SP, DUMMY_SP,
) {
let res = check.do_check(&fn_ctxt);
// do_check's documentation says that it might return Ok and create
// errors in the fcx instead of returing Err in some cases. Those cases
// should be filtered out before getting here.
assert!(
!fn_ctxt.errors_reported_since_creation(),
"`fn_ctxt` contained errors after cast check!"
);
res.ok()
} else {
None
}
})
}

37
clippy_lints/src/transmute/crosspointer_transmute.rs Normal file
View file

@ -0,0 +1,37 @@
use super::CROSSPOINTER_TRANSMUTE;
use crate::utils::span_lint;
use rustc_hir::Expr;
use rustc_lint::LateContext;
use rustc_middle::ty::{self, Ty};
/// Checks for `crosspointer_transmute` lint.
/// Returns `true` if it's triggered, otherwise returns `false`.
pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, e: &'tcx Expr<'_>, from_ty: Ty<'tcx>, to_ty: Ty<'tcx>) -> bool {
match (&from_ty.kind(), &to_ty.kind()) {
(ty::RawPtr(from_ptr), _) if from_ptr.ty == to_ty => {
span_lint(
cx,
CROSSPOINTER_TRANSMUTE,
e.span,
&format!(
"transmute from a type (`{}`) to the type that it points to (`{}`)",
from_ty, to_ty
),
);
true
},
(_, ty::RawPtr(to_ptr)) if to_ptr.ty == from_ty => {
span_lint(
cx,
CROSSPOINTER_TRANSMUTE,
e.span,
&format!(
"transmute from a type (`{}`) to a pointer to that type (`{}`)",
from_ty, to_ty
),
);
true
},
_ => false,
}
}

363
clippy_lints/src/transmute/mod.rs Normal file
View file

@ -0,0 +1,363 @@
mod crosspointer_transmute;
mod transmute_float_to_int;
mod transmute_int_to_bool;
mod transmute_int_to_char;
mod transmute_int_to_float;
mod transmute_ptr_to_ptr;
mod transmute_ptr_to_ref;
mod transmute_ref_to_ref;
mod transmutes_expressible_as_ptr_casts;
mod unsound_collection_transmute;
mod useless_transmute;
mod utils;
mod wrong_transmute;
use crate::utils::{in_constant, match_def_path, paths};
use if_chain::if_chain;
use rustc_hir::{Expr, ExprKind};
use rustc_lint::{LateContext, LateLintPass};
use rustc_session::{declare_lint_pass, declare_tool_lint};
declare_clippy_lint! {
/// **What it does:** Checks for transmutes that can't ever be correct on any
/// architecture.
///
/// **Why is this bad?** It's basically guaranteed to be undefined behaviour.
///
/// **Known problems:** When accessing C, users might want to store pointer
/// sized objects in `extradata` arguments to save an allocation.
///
/// **Example:**
/// ```ignore
/// let ptr: *const T = core::intrinsics::transmute('x')
/// ```
pub WRONG_TRANSMUTE,
correctness,
"transmutes that are confusing at best, undefined behaviour at worst and always useless"
}
// FIXME: Move this to `complexity` again, after #5343 is fixed
declare_clippy_lint! {
/// **What it does:** Checks for transmutes to the original type of the object
/// and transmutes that could be a cast.
///
/// **Why is this bad?** Readability. The code tricks people into thinking that
/// something complex is going on.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust,ignore
/// core::intrinsics::transmute(t); // where the result type is the same as `t`'s
/// ```
pub USELESS_TRANSMUTE,
nursery,
"transmutes that have the same to and from types or could be a cast/coercion"
}
// FIXME: Merge this lint with USELESS_TRANSMUTE once that is out of the nursery.
declare_clippy_lint! {
/// **What it does:**Checks for transmutes that could be a pointer cast.
///
/// **Why is this bad?** Readability. The code tricks people into thinking that
/// something complex is going on.
///
/// **Known problems:** None.
///
/// **Example:**
///
/// ```rust
/// # let p: *const [i32] = &[];
/// unsafe { std::mem::transmute::<*const [i32], *const [u16]>(p) };
/// ```
/// Use instead:
/// ```rust
/// # let p: *const [i32] = &[];
/// p as *const [u16];
/// ```
pub TRANSMUTES_EXPRESSIBLE_AS_PTR_CASTS,
complexity,
"transmutes that could be a pointer cast"
}
declare_clippy_lint! {
/// **What it does:** Checks for transmutes between a type `T` and `*T`.
///
/// **Why is this bad?** It's easy to mistakenly transmute between a type and a
/// pointer to that type.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust,ignore
/// core::intrinsics::transmute(t) // where the result type is the same as
/// // `*t` or `&t`'s
/// ```
pub CROSSPOINTER_TRANSMUTE,
complexity,
"transmutes that have to or from types that are a pointer to the other"
}
declare_clippy_lint! {
/// **What it does:** Checks for transmutes from a pointer to a reference.
///
/// **Why is this bad?** This can always be rewritten with `&` and `*`.
///
/// **Known problems:**
/// - `mem::transmute` in statics and constants is stable from Rust 1.46.0,
/// while dereferencing raw pointer is not stable yet.
/// If you need to do this in those places,
/// you would have to use `transmute` instead.
///
/// **Example:**
/// ```rust,ignore
/// unsafe {
/// let _: &T = std::mem::transmute(p); // where p: *const T
/// }
///
/// // can be written:
/// let _: &T = &*p;
/// ```
pub TRANSMUTE_PTR_TO_REF,
complexity,
"transmutes from a pointer to a reference type"
}
declare_clippy_lint! {
/// **What it does:** Checks for transmutes from an integer to a `char`.
///
/// **Why is this bad?** Not every integer is a Unicode scalar value.
///
/// **Known problems:**
/// - [`from_u32`] which this lint suggests using is slower than `transmute`
/// as it needs to validate the input.
/// If you are certain that the input is always a valid Unicode scalar value,
/// use [`from_u32_unchecked`] which is as fast as `transmute`
/// but has a semantically meaningful name.
/// - You might want to handle `None` returned from [`from_u32`] instead of calling `unwrap`.
///
/// [`from_u32`]: https://doc.rust-lang.org/std/char/fn.from_u32.html
/// [`from_u32_unchecked`]: https://doc.rust-lang.org/std/char/fn.from_u32_unchecked.html
///
/// **Example:**
/// ```rust
/// let x = 1_u32;
/// unsafe {
/// let _: char = std::mem::transmute(x); // where x: u32
/// }
///
/// // should be:
/// let _ = std::char::from_u32(x).unwrap();
/// ```
pub TRANSMUTE_INT_TO_CHAR,
complexity,
"transmutes from an integer to a `char`"
}
declare_clippy_lint! {
/// **What it does:** Checks for transmutes from a `&[u8]` to a `&str`.
///
/// **Why is this bad?** Not every byte slice is a valid UTF-8 string.
///
/// **Known problems:**
/// - [`from_utf8`] which this lint suggests using is slower than `transmute`
/// as it needs to validate the input.
/// If you are certain that the input is always a valid UTF-8,
/// use [`from_utf8_unchecked`] which is as fast as `transmute`
/// but has a semantically meaningful name.
/// - You might want to handle errors returned from [`from_utf8`] instead of calling `unwrap`.
///
/// [`from_utf8`]: https://doc.rust-lang.org/std/str/fn.from_utf8.html
/// [`from_utf8_unchecked`]: https://doc.rust-lang.org/std/str/fn.from_utf8_unchecked.html
///
/// **Example:**
/// ```rust
/// let b: &[u8] = &[1_u8, 2_u8];
/// unsafe {
/// let _: &str = std::mem::transmute(b); // where b: &[u8]
/// }
///
/// // should be:
/// let _ = std::str::from_utf8(b).unwrap();
/// ```
pub TRANSMUTE_BYTES_TO_STR,
complexity,
"transmutes from a `&[u8]` to a `&str`"
}
declare_clippy_lint! {
/// **What it does:** Checks for transmutes from an integer to a `bool`.
///
/// **Why is this bad?** This might result in an invalid in-memory representation of a `bool`.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// let x = 1_u8;
/// unsafe {
/// let _: bool = std::mem::transmute(x); // where x: u8
/// }
///
/// // should be:
/// let _: bool = x != 0;
/// ```
pub TRANSMUTE_INT_TO_BOOL,
complexity,
"transmutes from an integer to a `bool`"
}
declare_clippy_lint! {
/// **What it does:** Checks for transmutes from an integer to a float.
///
/// **Why is this bad?** Transmutes are dangerous and error-prone, whereas `from_bits` is intuitive
/// and safe.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// unsafe {
/// let _: f32 = std::mem::transmute(1_u32); // where x: u32
/// }
///
/// // should be:
/// let _: f32 = f32::from_bits(1_u32);
/// ```
pub TRANSMUTE_INT_TO_FLOAT,
complexity,
"transmutes from an integer to a float"
}
declare_clippy_lint! {
/// **What it does:** Checks for transmutes from a float to an integer.
///
/// **Why is this bad?** Transmutes are dangerous and error-prone, whereas `to_bits` is intuitive
/// and safe.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// unsafe {
/// let _: u32 = std::mem::transmute(1f32);
/// }
///
/// // should be:
/// let _: u32 = 1f32.to_bits();
/// ```
pub TRANSMUTE_FLOAT_TO_INT,
complexity,
"transmutes from a float to an integer"
}
declare_clippy_lint! {
/// **What it does:** Checks for transmutes from a pointer to a pointer, or
/// from a reference to a reference.
///
/// **Why is this bad?** Transmutes are dangerous, and these can instead be
/// written as casts.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// let ptr = &1u32 as *const u32;
/// unsafe {
/// // pointer-to-pointer transmute
/// let _: *const f32 = std::mem::transmute(ptr);
/// // ref-ref transmute
/// let _: &f32 = std::mem::transmute(&1u32);
/// }
/// // These can be respectively written:
/// let _ = ptr as *const f32;
/// let _ = unsafe{ &*(&1u32 as *const u32 as *const f32) };
/// ```
pub TRANSMUTE_PTR_TO_PTR,
complexity,
"transmutes from a pointer to a pointer / a reference to a reference"
}
declare_clippy_lint! {
/// **What it does:** Checks for transmutes between collections whose
/// types have different ABI, size or alignment.
///
/// **Why is this bad?** This is undefined behavior.
///
/// **Known problems:** Currently, we cannot know whether a type is a
/// collection, so we just lint the ones that come with `std`.
///
/// **Example:**
/// ```rust
/// // different size, therefore likely out-of-bounds memory access
/// // You absolutely do not want this in your code!
/// unsafe {
/// std::mem::transmute::<_, Vec<u32>>(vec![2_u16])
/// };
/// ```
///
/// You must always iterate, map and collect the values:
///
/// ```rust
/// vec![2_u16].into_iter().map(u32::from).collect::<Vec<_>>();
/// ```
pub UNSOUND_COLLECTION_TRANSMUTE,
correctness,
"transmute between collections of layout-incompatible types"
}
declare_lint_pass!(Transmute => [
CROSSPOINTER_TRANSMUTE,
TRANSMUTE_PTR_TO_REF,
TRANSMUTE_PTR_TO_PTR,
USELESS_TRANSMUTE,
WRONG_TRANSMUTE,
TRANSMUTE_INT_TO_CHAR,
TRANSMUTE_BYTES_TO_STR,
TRANSMUTE_INT_TO_BOOL,
TRANSMUTE_INT_TO_FLOAT,
TRANSMUTE_FLOAT_TO_INT,
UNSOUND_COLLECTION_TRANSMUTE,
TRANSMUTES_EXPRESSIBLE_AS_PTR_CASTS,
]);
impl<'tcx> LateLintPass<'tcx> for Transmute {
#[allow(clippy::similar_names, clippy::too_many_lines)]
fn check_expr(&mut self, cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) {
if_chain! {
if let ExprKind::Call(ref path_expr, ref args) = e.kind;
if let ExprKind::Path(ref qpath) = path_expr.kind;
if let Some(def_id) = cx.qpath_res(qpath, path_expr.hir_id).opt_def_id();
if match_def_path(cx, def_id, &paths::TRANSMUTE);
then {
// Avoid suggesting from/to bits and dereferencing raw pointers in const contexts.
// See https://github.com/rust-lang/rust/issues/73736 for progress on making them `const fn`.
// And see https://github.com/rust-lang/rust/issues/51911 for dereferencing raw pointers.
let const_context = in_constant(cx, e.hir_id);
let from_ty = cx.typeck_results().expr_ty(&args[0]);
let to_ty = cx.typeck_results().expr_ty(e);
// If useless_transmute is triggered, the other lints can be skipped.
if useless_transmute::check(cx, e, from_ty, to_ty, args) {
return;
}
let mut linted = wrong_transmute::check(cx, e, from_ty, to_ty);
linted |= crosspointer_transmute::check(cx, e, from_ty, to_ty);
linted |= transmute_ptr_to_ref::check(cx, e, from_ty, to_ty, args, qpath);
linted |= transmute_int_to_char::check(cx, e, from_ty, to_ty, args);
linted |= transmute_ref_to_ref::check(cx, e, from_ty, to_ty, args, const_context);
linted |= transmute_ptr_to_ptr::check(cx, e, from_ty, to_ty, args);
linted |= transmute_int_to_bool::check(cx, e, from_ty, to_ty, args);
linted |= transmute_int_to_float::check(cx, e, from_ty, to_ty, args, const_context);
linted |= transmute_float_to_int::check(cx, e, from_ty, to_ty, args, const_context);
linted |= unsound_collection_transmute::check(cx, e, from_ty, to_ty);
if !linted {
transmutes_expressible_as_ptr_casts::check(cx, e, from_ty, to_ty, args);
}
}
}
}
}

65
clippy_lints/src/transmute/transmute_float_to_int.rs Normal file
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@ -0,0 +1,65 @@
use super::TRANSMUTE_FLOAT_TO_INT;
use crate::utils::{span_lint_and_then, sugg};
use if_chain::if_chain;
use rustc_ast as ast;
use rustc_errors::Applicability;
use rustc_hir::{Expr, ExprKind, UnOp};
use rustc_lint::LateContext;
use rustc_middle::ty::{self, Ty};
/// Checks for `transmute_float_to_int` lint.
/// Returns `true` if it's triggered, otherwise returns `false`.
pub(super) fn check<'tcx>(
cx: &LateContext<'tcx>,
e: &'tcx Expr<'_>,
from_ty: Ty<'tcx>,
to_ty: Ty<'tcx>,
args: &'tcx [Expr<'_>],
const_context: bool,
) -> bool {
match (&from_ty.kind(), &to_ty.kind()) {
(ty::Float(float_ty), ty::Int(_) | ty::Uint(_)) if !const_context => {
span_lint_and_then(
cx,
TRANSMUTE_FLOAT_TO_INT,
e.span,
&format!("transmute from a `{}` to a `{}`", from_ty, to_ty),
|diag| {
let mut expr = &args[0];
let mut arg = sugg::Sugg::hir(cx, expr, "..");
if let ExprKind::Unary(UnOp::Neg, inner_expr) = &expr.kind {
expr = &inner_expr;
}
if_chain! {
// if the expression is a float literal and it is unsuffixed then
// add a suffix so the suggestion is valid and unambiguous
let op = format!("{}{}", arg, float_ty.name_str()).into();
if let ExprKind::Lit(lit) = &expr.kind;
if let ast::LitKind::Float(_, ast::LitFloatType::Unsuffixed) = lit.node;
then {
match arg {
sugg::Sugg::MaybeParen(_) => arg = sugg::Sugg::MaybeParen(op),
_ => arg = sugg::Sugg::NonParen(op)
}
}
}
arg = sugg::Sugg::NonParen(format!("{}.to_bits()", arg.maybe_par()).into());
// cast the result of `to_bits` if `to_ty` is signed
arg = if let ty::Int(int_ty) = to_ty.kind() {
arg.as_ty(int_ty.name_str().to_string())
} else {
arg
};
diag.span_suggestion(e.span, "consider using", arg.to_string(), Applicability::Unspecified);
},
);
true
},
_ => false,
}
}

41
clippy_lints/src/transmute/transmute_int_to_bool.rs Normal file
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@ -0,0 +1,41 @@
use super::TRANSMUTE_INT_TO_BOOL;
use crate::utils::{span_lint_and_then, sugg};
use rustc_ast as ast;
use rustc_errors::Applicability;
use rustc_hir::Expr;
use rustc_lint::LateContext;
use rustc_middle::ty::{self, Ty};
use std::borrow::Cow;
/// Checks for `transmute_int_to_bool` lint.
/// Returns `true` if it's triggered, otherwise returns `false`.
pub(super) fn check<'tcx>(
cx: &LateContext<'tcx>,
e: &'tcx Expr<'_>,
from_ty: Ty<'tcx>,
to_ty: Ty<'tcx>,
args: &'tcx [Expr<'_>],
) -> bool {
match (&from_ty.kind(), &to_ty.kind()) {
(ty::Int(ty::IntTy::I8) | ty::Uint(ty::UintTy::U8), ty::Bool) => {
span_lint_and_then(
cx,
TRANSMUTE_INT_TO_BOOL,
e.span,
&format!("transmute from a `{}` to a `bool`", from_ty),
|diag| {
let arg = sugg::Sugg::hir(cx, &args[0], "..");
let zero = sugg::Sugg::NonParen(Cow::from("0"));
diag.span_suggestion(
e.span,
"consider using",
sugg::make_binop(ast::BinOpKind::Ne, &arg, &zero).to_string(),
Applicability::Unspecified,
);
},
);
true
},
_ => false,
}
}

44
clippy_lints/src/transmute/transmute_int_to_char.rs Normal file
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@ -0,0 +1,44 @@
use super::TRANSMUTE_INT_TO_CHAR;
use crate::utils::{span_lint_and_then, sugg};
use rustc_ast as ast;
use rustc_errors::Applicability;
use rustc_hir::Expr;
use rustc_lint::LateContext;
use rustc_middle::ty::{self, Ty};
/// Checks for `transmute_int_to_char` lint.
/// Returns `true` if it's triggered, otherwise returns `false`.
pub(super) fn check<'tcx>(
cx: &LateContext<'tcx>,
e: &'tcx Expr<'_>,
from_ty: Ty<'tcx>,
to_ty: Ty<'tcx>,
args: &'tcx [Expr<'_>],
) -> bool {
match (&from_ty.kind(), &to_ty.kind()) {
(ty::Int(ty::IntTy::I32) | ty::Uint(ty::UintTy::U32), &ty::Char) => {
span_lint_and_then(
cx,
TRANSMUTE_INT_TO_CHAR,
e.span,
&format!("transmute from a `{}` to a `char`", from_ty),
|diag| {
let arg = sugg::Sugg::hir(cx, &args[0], "..");
let arg = if let ty::Int(_) = from_ty.kind() {
arg.as_ty(ast::UintTy::U32.name_str())
} else {
arg
};
diag.span_suggestion(
e.span,
"consider using",
format!("std::char::from_u32({}).unwrap()", arg.to_string()),
Applicability::Unspecified,
);
},
);
true
},
_ => false,
}
}

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