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add lint

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This commit is contained in:
Mikhail Babenko 2020-01-27 17:34:30 +03:00 committed by Areredify
parent f69835bab7
commit d1f8621711
7 changed files with 108 additions and 19 deletions
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1
CHANGELOG.md
View file

@ -1153,6 +1153,7 @@ Released 2018-09-13
[`len_without_is_empty`]: https://rust-lang.github.io/rust-clippy/master/index.html#len_without_is_empty
[`len_zero`]: https://rust-lang.github.io/rust-clippy/master/index.html#len_zero
[`let_and_return`]: https://rust-lang.github.io/rust-clippy/master/index.html#let_and_return
[`let_underscore_lock`]: https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_lock
[`let_underscore_must_use`]: https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_must_use
[`let_unit_value`]: https://rust-lang.github.io/rust-clippy/master/index.html#let_unit_value
[`linkedlist`]: https://rust-lang.github.io/rust-clippy/master/index.html#linkedlist

79
clippy_lints/src/let_underscore.rs
View file

@ -4,7 +4,7 @@ use rustc_hir::*;
use rustc_lint::{LateContext, LateLintPass};
use rustc_session::{declare_lint_pass, declare_tool_lint};
use crate::utils::{is_must_use_func_call, is_must_use_ty, span_lint_and_help};
use crate::utils::{is_must_use_func_call, is_must_use_ty, match_def_path, paths, span_lint_and_help};
declare_clippy_lint! {
/// **What it does:** Checks for `let _ = <expr>`
@ -30,7 +30,35 @@ declare_clippy_lint! {
"non-binding let on a `#[must_use]` expression"
}
declare_lint_pass!(LetUnderscore => [LET_UNDERSCORE_MUST_USE]);
declare_clippy_lint! {
/// **What it does:** Checks for `let _ = sync_primitive.lock()`
///
/// **Why is this bad?** This statement locks the synchronization
/// primitive and immediately drops the lock, which is probably
/// not intended. To extend lock lifetime to the end of the scope,
/// use an underscore-prefixed name instead (i.e. _lock).
///
/// **Known problems:** None.
///
/// **Example:**
///
/// Bad:
/// ```rust,ignore
/// let _ = mutex.lock();
/// ```
///
/// Good:
/// ```rust,ignore
/// let _lock = mutex.lock();
/// ```
pub LET_UNDERSCORE_LOCK,
correctness,
"non-binding let on a synchronization lock"
}
declare_lint_pass!(LetUnderscore => [LET_UNDERSCORE_MUST_USE, LET_UNDERSCORE_LOCK]);
const LOCK_METHODS_PATHS: [&[&str]; 3] = [&paths::MUTEX_LOCK, &paths::RWLOCK_READ, &paths::RWLOCK_WRITE];
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for LetUnderscore {
fn check_stmt(&mut self, cx: &LateContext<'_, '_>, stmt: &Stmt<'_>) {
@ -43,22 +71,37 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for LetUnderscore {
if let PatKind::Wild = local.pat.kind;
if let Some(ref init) = local.init;
then {
if is_must_use_ty(cx, cx.tables.expr_ty(init)) {
span_lint_and_help(
cx,
LET_UNDERSCORE_MUST_USE,
stmt.span,
"non-binding let on an expression with `#[must_use]` type",
"consider explicitly using expression value"
)
} else if is_must_use_func_call(cx, init) {
span_lint_and_help(
cx,
LET_UNDERSCORE_MUST_USE,
stmt.span,
"non-binding let on a result of a `#[must_use]` function",
"consider explicitly using function result"
)
if_chain! {
if let ExprKind::MethodCall(_, _, _) = init.kind;
let method_did = cx.tables.type_dependent_def_id(init.hir_id).unwrap();
if LOCK_METHODS_PATHS.iter().any(|path| match_def_path(cx, method_did, path));
then {
span_lint_and_help(
cx,
LET_UNDERSCORE_LOCK,
stmt.span,
"non-binding let on an a synchronization lock",
"consider using an underscore-prefixed named binding"
)
} else {
if is_must_use_ty(cx, cx.tables.expr_ty(init)) {
span_lint_and_help(
cx,
LET_UNDERSCORE_MUST_USE,
stmt.span,
"non-binding let on an expression with `#[must_use]` type",
"consider explicitly using expression value"
)
} else if is_must_use_func_call(cx, init) {
span_lint_and_help(
cx,
LET_UNDERSCORE_MUST_USE,
stmt.span,
"non-binding let on a result of a `#[must_use]` function",
"consider explicitly using function result"
)
}
}
}
}
}

3
clippy_lints/src/lib.rs
View file

@ -566,6 +566,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
&len_zero::LEN_WITHOUT_IS_EMPTY,
&len_zero::LEN_ZERO,
&let_if_seq::USELESS_LET_IF_SEQ,
&let_underscore::LET_UNDERSCORE_LOCK,
&let_underscore::LET_UNDERSCORE_MUST_USE,
&lifetimes::EXTRA_UNUSED_LIFETIMES,
&lifetimes::NEEDLESS_LIFETIMES,
@ -1171,6 +1172,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
LintId::of(&len_zero::LEN_WITHOUT_IS_EMPTY),
LintId::of(&len_zero::LEN_ZERO),
LintId::of(&let_if_seq::USELESS_LET_IF_SEQ),
LintId::of(&let_underscore::LET_UNDERSCORE_LOCK),
LintId::of(&lifetimes::EXTRA_UNUSED_LIFETIMES),
LintId::of(&lifetimes::NEEDLESS_LIFETIMES),
LintId::of(&literal_representation::INCONSISTENT_DIGIT_GROUPING),
@ -1556,6 +1558,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
LintId::of(&infinite_iter::INFINITE_ITER),
LintId::of(&inherent_to_string::INHERENT_TO_STRING_SHADOW_DISPLAY),
LintId::of(&inline_fn_without_body::INLINE_FN_WITHOUT_BODY),
LintId::of(&let_underscore::LET_UNDERSCORE_LOCK),
LintId::of(&literal_representation::MISTYPED_LITERAL_SUFFIXES),
LintId::of(&loops::FOR_LOOP_OVER_OPTION),
LintId::of(&loops::FOR_LOOP_OVER_RESULT),

3
clippy_lints/src/utils/paths.rs
View file

@ -58,6 +58,7 @@ pub const MEM_REPLACE: [&str; 3] = ["core", "mem", "replace"];
pub const MEM_UNINITIALIZED: [&str; 3] = ["core", "mem", "uninitialized"];
pub const MEM_ZEROED: [&str; 3] = ["core", "mem", "zeroed"];
pub const MUTEX: [&str; 4] = ["std", "sync", "mutex", "Mutex"];
pub const MUTEX_LOCK: [&str; 5] = ["std", "sync", "mutex", "Mutex", "lock"];
pub const OPEN_OPTIONS: [&str; 3] = ["std", "fs", "OpenOptions"];
pub const OPS_MODULE: [&str; 2] = ["core", "ops"];
pub const OPTION: [&str; 3] = ["core", "option", "Option"];
@ -100,6 +101,8 @@ pub const REPEAT: [&str; 3] = ["core", "iter", "repeat"];
pub const RESULT: [&str; 3] = ["core", "result", "Result"];
pub const RESULT_ERR: [&str; 4] = ["core", "result", "Result", "Err"];
pub const RESULT_OK: [&str; 4] = ["core", "result", "Result", "Ok"];
pub const RWLOCK_READ: [&str; 5] = ["std", "sync", "rwlock", "RwLock", "read"];
pub const RWLOCK_WRITE: [&str; 5] = ["std", "sync", "rwlock", "RwLock", "write"];
pub const SERDE_DE_VISITOR: [&str; 3] = ["serde", "de", "Visitor"];
pub const SLICE_INTO_VEC: [&str; 4] = ["alloc", "slice", "<impl [T]>", "into_vec"];
pub const SLICE_ITER: [&str; 3] = ["core", "slice", "Iter"];

7
src/lintlist/mod.rs
View file

@ -959,6 +959,13 @@ pub const ALL_LINTS: [Lint; 350] = [
deprecation: None,
module: "returns",
},
Lint {
name: "let_underscore_lock",
group: "correctness",
desc: "non-binding let on a synchronization lock",
deprecation: None,
module: "let_underscore",
},
Lint {
name: "let_underscore_must_use",
group: "restriction",

7
tests/ui/let_underscore.rs
View file

@ -88,4 +88,11 @@ fn main() {
let _ = a.map(|_| ());
let _ = a;
let m = std::sync::Mutex::new(());
let rw = std::sync::RwLock::new(());
let _ = m.lock();
let _ = rw.read();
let _ = rw.write();
}

27
tests/ui/let_underscore.stderr
View file

@ -95,5 +95,30 @@ LL | let _ = a;
|
= help: consider explicitly using expression value
error: aborting due to 12 previous errors
error: non-binding let on an a synchronization lock
--> $DIR/let_underscore.rs:95:5
|
LL | let _ = m.lock();
| ^^^^^^^^^^^^^^^^^
|
= note: `#[deny(clippy::let_underscore_lock)]` on by default
= help: consider using an underscore-prefixed named binding
error: non-binding let on an a synchronization lock
--> $DIR/let_underscore.rs:96:5
|
LL | let _ = rw.read();
| ^^^^^^^^^^^^^^^^^^
|
= help: consider using an underscore-prefixed named binding
error: non-binding let on an a synchronization lock
--> $DIR/let_underscore.rs:97:5
|
LL | let _ = rw.write();
| ^^^^^^^^^^^^^^^^^^^
|
= help: consider using an underscore-prefixed named binding
error: aborting due to 15 previous errors