Implementation of the const_static_lifetime lint.

This commit is contained in:
Paul Florence 2017-10-20 09:51:35 -04:00
parent 9293188b65
commit 322effe415
4 changed files with 120 additions and 2 deletions

View file

@ -0,0 +1,82 @@
use syntax::ast::{Item, ItemKind, TyKind, Ty};
use rustc::lint::{LintPass, EarlyLintPass, LintArray, EarlyContext};
use utils::{span_help_and_lint, in_macro};
/// **What it does:** Checks for constants with an explicit `'static` lifetime.
///
/// **Why is this bad?** Adding `'static` to every reference can create very complicated types.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// const FOO: &'static [(&'static str, &'static str, fn(&Bar) -> bool)] = &[..]
/// ```
/// This code can be rewritten as
/// ```rust
/// const FOO: &[(&str, &str, fn(&Bar) -> bool)] = &[...]
/// ```
declare_lint! {
pub CONST_STATIC_LIFETIME,
Warn,
"Using explicit `'static` lifetime for constants when elision rules would allow omitting them."
}
pub struct StaticConst;
impl LintPass for StaticConst {
fn get_lints(&self) -> LintArray {
lint_array!(CONST_STATIC_LIFETIME)
}
}
impl StaticConst {
// Recursively visit types
fn visit_type(&mut self, ty: &Ty, cx: &EarlyContext) {
match ty.node {
// Be carefull of nested structures (arrays and tuples)
TyKind::Array(ref ty, _) => {
println!("array");
self.visit_type(&*ty, cx);
},
TyKind::Tup(ref tup) => {
for tup_ty in tup {
self.visit_type(&*tup_ty, cx);
}
},
// This is what we are looking for !
TyKind::Rptr(ref optional_lifetime, ref borrow_type) => {
// Match the 'static lifetime
if let Some(lifetime) = *optional_lifetime {
if let TyKind::Path(_, _) = borrow_type.ty.node {
// Verify that the path is a str
if lifetime.ident.name == "'static" {
span_help_and_lint(cx,
CONST_STATIC_LIFETIME,
lifetime.span,
"Constants have by default a `'static` lifetime",
"consider removing `'static`");
}
}
}
self.visit_type(&*borrow_type.ty, cx);
},
TyKind::Slice(ref ty) => {
self.visit_type(&ty, cx);
},
_ => {},
}
}
}
impl EarlyLintPass for StaticConst {
fn check_item(&mut self, cx: &EarlyContext, item: &Item) {
if !in_macro(item.span) {
// Match only constants...
if let ItemKind::Const(ref var_type, _) = item.node {
self.visit_type(var_type, cx);
}
}
}
}

View file

@ -76,6 +76,7 @@ pub mod block_in_if_condition;
pub mod booleans;
pub mod bytecount;
pub mod collapsible_if;
pub mod const_static_lifetime;
pub mod copies;
pub mod cyclomatic_complexity;
pub mod derive;
@ -339,6 +340,7 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry) {
reg.register_late_lint_pass(box invalid_ref::InvalidRef);
reg.register_late_lint_pass(box identity_conversion::IdentityConversion::default());
reg.register_late_lint_pass(box types::ImplicitHasher);
reg.register_early_lint_pass(box const_static_lifetime::StaticConst);
reg.register_lint_group("clippy_restrictions", vec![
arithmetic::FLOAT_ARITHMETIC,
@ -349,6 +351,7 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry) {
reg.register_lint_group("clippy_pedantic", vec![
booleans::NONMINIMAL_BOOL,
const_static_lifetime::CONST_STATIC_LIFETIME,
empty_enum::EMPTY_ENUM,
enum_glob_use::ENUM_GLOB_USE,
enum_variants::PUB_ENUM_VARIANT_NAMES,

View file

@ -0,0 +1,33 @@
#![feature(plugin)]
#[derive(Debug)]
struct Foo {}
const VAR_ONE: &'static str = "Test constant #1"; // ERROR Consider removing 'static.
const VAR_TWO: &str = "Test constant #2"; // This line should not raise a warning.
const VAR_THREE: &[&'static str] = &["one", "two"]; // ERROR Consider removing 'static
const VAR_FOUR: (&str, (&str, &'static str), &'static str) = ("on", ("th", "th"), "on"); // ERROR Consider removing 'static
const VAR_FIVE: &'static [&[&'static str]] = &[&["test"], &["other one"]]; // ERROR Consider removing 'static
const VAR_SIX: &'static u8 = &5;
const VAR_SEVEN: &[&(&str, &'static [&'static str])] = &[&("one", &["other one"])];
const VAR_HEIGHT: &'static Foo = &Foo {};
fn main() {
let false_positive: &'static str = "test";
println!("{}", VAR_ONE);
println!("{}", VAR_TWO);
println!("{:?}", VAR_THREE);
println!("{:?}", VAR_FOUR);
println!("{:?}", VAR_FIVE);
println!("{:?}", VAR_SIX);
println!("{:?}", VAR_SEVEN);
println!("{:?}", VAR_HEIGHT);
println!("{}", false_positive);
}

View file

@ -9,8 +9,8 @@ extern crate regex;
use regex::{Regex, RegexSet, RegexBuilder};
use regex::bytes::{Regex as BRegex, RegexSet as BRegexSet, RegexBuilder as BRegexBuilder};
const OPENING_PAREN : &'static str = "(";
const NOT_A_REAL_REGEX : &'static str = "foobar";
const OPENING_PAREN: &str = "(";
const NOT_A_REAL_REGEX: &str = "foobar";
fn syntax_error() {
let pipe_in_wrong_position = Regex::new("|");