mirror of
https://github.com/rust-lang/rust-clippy
synced 2024-11-10 15:14:29 +00:00
Auto merge of #4966 - bradsherman:iter-nth-zero, r=flip1995
New Lint: Iter nth zero Check for the use of `iter.nth(0)` and encourage `iter.next()` instead as it is more readable changelog: add new lint when `iter.nth(0)` is used Fixes #4957
This commit is contained in:
commit
d9d20138ec
9 changed files with 154 additions and 8 deletions
|
@ -1141,6 +1141,7 @@ Released 2018-09-13
|
|||
[`iter_cloned_collect`]: https://rust-lang.github.io/rust-clippy/master/index.html#iter_cloned_collect
|
||||
[`iter_next_loop`]: https://rust-lang.github.io/rust-clippy/master/index.html#iter_next_loop
|
||||
[`iter_nth`]: https://rust-lang.github.io/rust-clippy/master/index.html#iter_nth
|
||||
[`iter_nth_zero`]: https://rust-lang.github.io/rust-clippy/master/index.html#iter_nth_zero
|
||||
[`iter_skip_next`]: https://rust-lang.github.io/rust-clippy/master/index.html#iter_skip_next
|
||||
[`iterator_step_by_zero`]: https://rust-lang.github.io/rust-clippy/master/index.html#iterator_step_by_zero
|
||||
[`just_underscores_and_digits`]: https://rust-lang.github.io/rust-clippy/master/index.html#just_underscores_and_digits
|
||||
|
|
|
@ -6,7 +6,7 @@
|
|||
|
||||
A collection of lints to catch common mistakes and improve your [Rust](https://github.com/rust-lang/rust) code.
|
||||
|
||||
[There are 343 lints included in this crate!](https://rust-lang.github.io/rust-clippy/master/index.html)
|
||||
[There are 344 lints included in this crate!](https://rust-lang.github.io/rust-clippy/master/index.html)
|
||||
|
||||
We have a bunch of lint categories to allow you to choose how much Clippy is supposed to ~~annoy~~ help you:
|
||||
|
||||
|
|
|
@ -61,7 +61,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MultipleInherentImpl {
|
|||
}
|
||||
|
||||
fn check_crate_post(&mut self, cx: &LateContext<'a, 'tcx>, krate: &'tcx Crate<'_>) {
|
||||
if let Some(item) = krate.items.values().nth(0) {
|
||||
if let Some(item) = krate.items.values().next() {
|
||||
// Retrieve all inherent implementations from the crate, grouped by type
|
||||
for impls in cx
|
||||
.tcx
|
||||
|
@ -71,7 +71,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MultipleInherentImpl {
|
|||
{
|
||||
// Filter out implementations that have generic params (type or lifetime)
|
||||
let mut impl_spans = impls.iter().filter_map(|impl_def| self.impls.get(impl_def));
|
||||
if let Some(initial_span) = impl_spans.nth(0) {
|
||||
if let Some(initial_span) = impl_spans.next() {
|
||||
impl_spans.for_each(|additional_span| {
|
||||
span_lint_and_then(
|
||||
cx,
|
||||
|
|
|
@ -618,6 +618,7 @@ pub fn register_plugins(store: &mut lint::LintStore, sess: &Session, conf: &Conf
|
|||
&methods::ITERATOR_STEP_BY_ZERO,
|
||||
&methods::ITER_CLONED_COLLECT,
|
||||
&methods::ITER_NTH,
|
||||
&methods::ITER_NTH_ZERO,
|
||||
&methods::ITER_SKIP_NEXT,
|
||||
&methods::MANUAL_SATURATING_ARITHMETIC,
|
||||
&methods::MAP_FLATTEN,
|
||||
|
@ -1197,6 +1198,7 @@ pub fn register_plugins(store: &mut lint::LintStore, sess: &Session, conf: &Conf
|
|||
LintId::of(&methods::ITERATOR_STEP_BY_ZERO),
|
||||
LintId::of(&methods::ITER_CLONED_COLLECT),
|
||||
LintId::of(&methods::ITER_NTH),
|
||||
LintId::of(&methods::ITER_NTH_ZERO),
|
||||
LintId::of(&methods::ITER_SKIP_NEXT),
|
||||
LintId::of(&methods::MANUAL_SATURATING_ARITHMETIC),
|
||||
LintId::of(&methods::NEW_RET_NO_SELF),
|
||||
|
@ -1375,6 +1377,7 @@ pub fn register_plugins(store: &mut lint::LintStore, sess: &Session, conf: &Conf
|
|||
LintId::of(&methods::CHARS_LAST_CMP),
|
||||
LintId::of(&methods::INTO_ITER_ON_REF),
|
||||
LintId::of(&methods::ITER_CLONED_COLLECT),
|
||||
LintId::of(&methods::ITER_NTH_ZERO),
|
||||
LintId::of(&methods::ITER_SKIP_NEXT),
|
||||
LintId::of(&methods::MANUAL_SATURATING_ARITHMETIC),
|
||||
LintId::of(&methods::NEW_RET_NO_SELF),
|
||||
|
|
|
@ -20,6 +20,7 @@ use rustc_span::source_map::Span;
|
|||
use rustc_span::symbol::{sym, Symbol, SymbolStr};
|
||||
use syntax::ast;
|
||||
|
||||
use crate::consts::{constant, Constant};
|
||||
use crate::utils::usage::mutated_variables;
|
||||
use crate::utils::{
|
||||
get_arg_name, get_parent_expr, get_trait_def_id, has_iter_method, implements_trait, in_macro, is_copy,
|
||||
|
@ -756,6 +757,33 @@ declare_clippy_lint! {
|
|||
"using `Iterator::step_by(0)`, which will panic at runtime"
|
||||
}
|
||||
|
||||
declare_clippy_lint! {
|
||||
/// **What it does:** Checks for the use of `iter.nth(0)`.
|
||||
///
|
||||
/// **Why is this bad?** `iter.nth(0)` is unnecessary, and `iter.next()`
|
||||
/// is more readable.
|
||||
///
|
||||
/// **Known problems:** None.
|
||||
///
|
||||
/// **Example:**
|
||||
///
|
||||
/// ```rust
|
||||
/// # use std::collections::HashSet;
|
||||
/// // Bad
|
||||
/// # let mut s = HashSet::new();
|
||||
/// # s.insert(1);
|
||||
/// let x = s.iter().nth(0);
|
||||
///
|
||||
/// // Good
|
||||
/// # let mut s = HashSet::new();
|
||||
/// # s.insert(1);
|
||||
/// let x = s.iter().next();
|
||||
/// ```
|
||||
pub ITER_NTH_ZERO,
|
||||
style,
|
||||
"replace `iter.nth(0)` with `iter.next()`"
|
||||
}
|
||||
|
||||
declare_clippy_lint! {
|
||||
/// **What it does:** Checks for use of `.iter().nth()` (and the related
|
||||
/// `.iter_mut().nth()`) on standard library types with O(1) element access.
|
||||
|
@ -1136,6 +1164,7 @@ declare_lint_pass!(Methods => [
|
|||
MAP_FLATTEN,
|
||||
ITERATOR_STEP_BY_ZERO,
|
||||
ITER_NTH,
|
||||
ITER_NTH_ZERO,
|
||||
ITER_SKIP_NEXT,
|
||||
GET_UNWRAP,
|
||||
STRING_EXTEND_CHARS,
|
||||
|
@ -1191,8 +1220,9 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Methods {
|
|||
["as_ptr", "unwrap"] | ["as_ptr", "expect"] => {
|
||||
lint_cstring_as_ptr(cx, expr, &arg_lists[1][0], &arg_lists[0][0])
|
||||
},
|
||||
["nth", "iter"] => lint_iter_nth(cx, expr, arg_lists[1], false),
|
||||
["nth", "iter_mut"] => lint_iter_nth(cx, expr, arg_lists[1], true),
|
||||
["nth", "iter"] => lint_iter_nth(cx, expr, &arg_lists, false),
|
||||
["nth", "iter_mut"] => lint_iter_nth(cx, expr, &arg_lists, true),
|
||||
["nth", ..] => lint_iter_nth_zero(cx, expr, arg_lists[0]),
|
||||
["step_by", ..] => lint_step_by(cx, expr, arg_lists[0]),
|
||||
["next", "skip"] => lint_iter_skip_next(cx, expr),
|
||||
["collect", "cloned"] => lint_iter_cloned_collect(cx, expr, arg_lists[1]),
|
||||
|
@ -1983,7 +2013,6 @@ fn lint_unnecessary_fold(cx: &LateContext<'_, '_>, expr: &hir::Expr<'_>, fold_ar
|
|||
|
||||
fn lint_step_by<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &hir::Expr<'_>, args: &'tcx [hir::Expr<'_>]) {
|
||||
if match_trait_method(cx, expr, &paths::ITERATOR) {
|
||||
use crate::consts::{constant, Constant};
|
||||
if let Some((Constant::Int(0), _)) = constant(cx, cx.tables, &args[1]) {
|
||||
span_lint(
|
||||
cx,
|
||||
|
@ -1998,9 +2027,10 @@ fn lint_step_by<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &hir::Expr<'_>, args
|
|||
fn lint_iter_nth<'a, 'tcx>(
|
||||
cx: &LateContext<'a, 'tcx>,
|
||||
expr: &hir::Expr<'_>,
|
||||
iter_args: &'tcx [hir::Expr<'_>],
|
||||
nth_and_iter_args: &[&'tcx [hir::Expr<'tcx>]],
|
||||
is_mut: bool,
|
||||
) {
|
||||
let iter_args = nth_and_iter_args[1];
|
||||
let mut_str = if is_mut { "_mut" } else { "" };
|
||||
let caller_type = if derefs_to_slice(cx, &iter_args[0], cx.tables.expr_ty(&iter_args[0])).is_some() {
|
||||
"slice"
|
||||
|
@ -2009,6 +2039,8 @@ fn lint_iter_nth<'a, 'tcx>(
|
|||
} else if match_type(cx, cx.tables.expr_ty(&iter_args[0]), &paths::VEC_DEQUE) {
|
||||
"VecDeque"
|
||||
} else {
|
||||
let nth_args = nth_and_iter_args[0];
|
||||
lint_iter_nth_zero(cx, expr, &nth_args);
|
||||
return; // caller is not a type that we want to lint
|
||||
};
|
||||
|
||||
|
@ -2023,6 +2055,25 @@ fn lint_iter_nth<'a, 'tcx>(
|
|||
);
|
||||
}
|
||||
|
||||
fn lint_iter_nth_zero<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &hir::Expr<'_>, nth_args: &'tcx [hir::Expr<'_>]) {
|
||||
if_chain! {
|
||||
if match_trait_method(cx, expr, &paths::ITERATOR);
|
||||
if let Some((Constant::Int(0), _)) = constant(cx, cx.tables, &nth_args[1]);
|
||||
then {
|
||||
let mut applicability = Applicability::MachineApplicable;
|
||||
span_lint_and_sugg(
|
||||
cx,
|
||||
ITER_NTH_ZERO,
|
||||
expr.span,
|
||||
"called `.nth(0)` on a `std::iter::Iterator`",
|
||||
"try calling",
|
||||
format!("{}.next()", snippet_with_applicability(cx, nth_args[0].span, "..", &mut applicability)),
|
||||
applicability,
|
||||
);
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
fn lint_get_unwrap<'a, 'tcx>(
|
||||
cx: &LateContext<'a, 'tcx>,
|
||||
expr: &hir::Expr<'_>,
|
||||
|
|
|
@ -6,7 +6,7 @@ pub use lint::Lint;
|
|||
pub use lint::LINT_LEVELS;
|
||||
|
||||
// begin lint list, do not remove this comment, it’s used in `update_lints`
|
||||
pub const ALL_LINTS: [Lint; 343] = [
|
||||
pub const ALL_LINTS: [Lint; 344] = [
|
||||
Lint {
|
||||
name: "absurd_extreme_comparisons",
|
||||
group: "correctness",
|
||||
|
@ -875,6 +875,13 @@ pub const ALL_LINTS: [Lint; 343] = [
|
|||
deprecation: None,
|
||||
module: "methods",
|
||||
},
|
||||
Lint {
|
||||
name: "iter_nth_zero",
|
||||
group: "style",
|
||||
desc: "replace `iter.nth(0)` with `iter.next()`",
|
||||
deprecation: None,
|
||||
module: "methods",
|
||||
},
|
||||
Lint {
|
||||
name: "iter_skip_next",
|
||||
group: "style",
|
||||
|
|
31
tests/ui/iter_nth_zero.fixed
Normal file
31
tests/ui/iter_nth_zero.fixed
Normal file
|
@ -0,0 +1,31 @@
|
|||
// run-rustfix
|
||||
|
||||
#![warn(clippy::iter_nth_zero)]
|
||||
use std::collections::HashSet;
|
||||
|
||||
struct Foo {}
|
||||
|
||||
impl Foo {
|
||||
fn nth(&self, index: usize) -> usize {
|
||||
index + 1
|
||||
}
|
||||
}
|
||||
|
||||
fn main() {
|
||||
let f = Foo {};
|
||||
f.nth(0); // lint does not apply here
|
||||
|
||||
let mut s = HashSet::new();
|
||||
s.insert(1);
|
||||
let _x = s.iter().next();
|
||||
|
||||
let mut s2 = HashSet::new();
|
||||
s2.insert(2);
|
||||
let mut iter = s2.iter();
|
||||
let _y = iter.next();
|
||||
|
||||
let mut s3 = HashSet::new();
|
||||
s3.insert(3);
|
||||
let mut iter2 = s3.iter();
|
||||
let _unwrapped = iter2.next().unwrap();
|
||||
}
|
31
tests/ui/iter_nth_zero.rs
Normal file
31
tests/ui/iter_nth_zero.rs
Normal file
|
@ -0,0 +1,31 @@
|
|||
// run-rustfix
|
||||
|
||||
#![warn(clippy::iter_nth_zero)]
|
||||
use std::collections::HashSet;
|
||||
|
||||
struct Foo {}
|
||||
|
||||
impl Foo {
|
||||
fn nth(&self, index: usize) -> usize {
|
||||
index + 1
|
||||
}
|
||||
}
|
||||
|
||||
fn main() {
|
||||
let f = Foo {};
|
||||
f.nth(0); // lint does not apply here
|
||||
|
||||
let mut s = HashSet::new();
|
||||
s.insert(1);
|
||||
let _x = s.iter().nth(0);
|
||||
|
||||
let mut s2 = HashSet::new();
|
||||
s2.insert(2);
|
||||
let mut iter = s2.iter();
|
||||
let _y = iter.nth(0);
|
||||
|
||||
let mut s3 = HashSet::new();
|
||||
s3.insert(3);
|
||||
let mut iter2 = s3.iter();
|
||||
let _unwrapped = iter2.nth(0).unwrap();
|
||||
}
|
22
tests/ui/iter_nth_zero.stderr
Normal file
22
tests/ui/iter_nth_zero.stderr
Normal file
|
@ -0,0 +1,22 @@
|
|||
error: called `.nth(0)` on a `std::iter::Iterator`
|
||||
--> $DIR/iter_nth_zero.rs:20:14
|
||||
|
|
||||
LL | let _x = s.iter().nth(0);
|
||||
| ^^^^^^^^^^^^^^^ help: try calling: `s.iter().next()`
|
||||
|
|
||||
= note: `-D clippy::iter-nth-zero` implied by `-D warnings`
|
||||
|
||||
error: called `.nth(0)` on a `std::iter::Iterator`
|
||||
--> $DIR/iter_nth_zero.rs:25:14
|
||||
|
|
||||
LL | let _y = iter.nth(0);
|
||||
| ^^^^^^^^^^^ help: try calling: `iter.next()`
|
||||
|
||||
error: called `.nth(0)` on a `std::iter::Iterator`
|
||||
--> $DIR/iter_nth_zero.rs:30:22
|
||||
|
|
||||
LL | let _unwrapped = iter2.nth(0).unwrap();
|
||||
| ^^^^^^^^^^^^ help: try calling: `iter2.next()`
|
||||
|
||||
error: aborting due to 3 previous errors
|
||||
|
Loading…
Reference in a new issue