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Auto merge of #13108 - tesuji:fix_redundant_closure, r=xFrednet

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Fix `redundant_closure` false positive with closures has return type contains  `'static`

Fix #13073 .

Please enable "ignore white-space change" settings in github UI for easy reviewing.

HACK: The third commit contains a hack to check if a type `T: 'static` when `fn() -> U where U: 'static`.
I don't have a clean way to check for it.

changelog: [`redundant_closure`] Fix false positive with closures has return type contains  `'static`
This commit is contained in:
bors 2024-08-01 07:55:37 +00:00
commit 2fc74a3931
4 changed files with 252 additions and 187 deletions
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63
clippy_lints/src/eta_reduction.rs
View File

@ -9,8 +9,7 @@
use rustc_infer::infer::TyCtxtInferExt;
use rustc_lint::{LateContext, LateLintPass};
use rustc_middle::ty::{
self, Binder, ClosureArgs, ClosureKind, FnSig, GenericArg, GenericArgKind, List, Region, RegionKind, Ty, TyCtxt,
TypeVisitableExt, TypeckResults,
self, Binder, ClosureKind, FnSig, GenericArg, GenericArgKind, List, Region, Ty, TypeVisitableExt, TypeckResults,
};
use rustc_session::declare_lint_pass;
use rustc_span::symbol::sym;
@ -74,8 +73,23 @@
declare_lint_pass!(EtaReduction => [REDUNDANT_CLOSURE, REDUNDANT_CLOSURE_FOR_METHOD_CALLS]);
impl<'tcx> LateLintPass<'tcx> for EtaReduction {
#[allow(clippy::too_many_lines)]
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &Expr<'tcx>) {
if let ExprKind::MethodCall(_method, receiver, args, _) = expr.kind {
for arg in args {
check_clousure(cx, Some(receiver), arg);
}
}
if let ExprKind::Call(func, args) = expr.kind {
check_clousure(cx, None, func);
for arg in args {
check_clousure(cx, None, arg);
}
}
}
}
#[allow(clippy::too_many_lines)]
fn check_clousure<'tcx>(cx: &LateContext<'tcx>, outer_receiver: Option<&Expr<'tcx>>, expr: &Expr<'tcx>) {
let body = if let ExprKind::Closure(c) = expr.kind
&& c.fn_decl.inputs.iter().all(|ty| matches!(ty.kind, TyKind::Infer))
&& matches!(c.fn_decl.output, FnRetTy::DefaultReturn(_))
@ -105,17 +119,17 @@ fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
return;
}
if is_adjusted(cx, body.value) {
return;
}
let typeck = cx.typeck_results();
let closure = if let ty::Closure(_, closure_subs) = typeck.expr_ty(expr).kind() {
closure_subs.as_closure()
} else {
return;
};
if is_adjusted(cx, body.value) {
return;
}
let closure_sig = cx.tcx.signature_unclosure(closure.sig(), Safety::Safe).skip_binder();
match body.value.kind {
ExprKind::Call(callee, args)
if matches!(
@ -161,7 +175,18 @@ fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
}
},
};
if check_sig(cx, closure, sig)
if let Some(outer) = outer_receiver
&& ty_has_static(sig.output())
&& let generic_args = typeck.node_args(outer.hir_id)
// HACK: Given a closure in `T.method(|| f())`, where `fn f() -> U where U: 'static`, `T.method(f)`
// will succeed iff `T: 'static`. But the region of `T` is always erased by `typeck.expr_ty()` when
// T is a generic type. For example, return type of `Option<String>::as_deref()` is a generic.
// So we have a hack like this.
&& generic_args.len() > 0
{
return;
}
if check_sig(closure_sig, sig)
&& let generic_args = typeck.node_args(callee.hir_id)
// Given some trait fn `fn f() -> ()` and some type `T: Trait`, `T::f` is not
// `'static` unless `T: 'static`. The cast `T::f as fn()` will, however, result
@ -204,7 +229,7 @@ fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
ExprKind::MethodCall(path, self_, args, _) if check_inputs(typeck, body.params, Some(self_), args) => {
if let Some(method_def_id) = typeck.type_dependent_def_id(body.value.hir_id)
&& !cx.tcx.has_attr(method_def_id, sym::track_caller)
&& check_sig(cx, closure, cx.tcx.fn_sig(method_def_id).skip_binder().skip_binder())
&& check_sig(closure_sig, cx.tcx.fn_sig(method_def_id).skip_binder().skip_binder())
{
span_lint_and_then(
cx,
@ -227,7 +252,6 @@ fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
},
_ => (),
}
}
}
fn check_inputs(
@ -251,12 +275,8 @@ fn check_inputs(
})
}
fn check_sig<'tcx>(cx: &LateContext<'tcx>, closure: ClosureArgs<TyCtxt<'tcx>>, call_sig: FnSig<'_>) -> bool {
call_sig.safety == Safety::Safe
&& !has_late_bound_to_non_late_bound_regions(
cx.tcx.signature_unclosure(closure.sig(), Safety::Safe).skip_binder(),
call_sig,
)
fn check_sig<'tcx>(closure_sig: FnSig<'tcx>, call_sig: FnSig<'tcx>) -> bool {
call_sig.safety == Safety::Safe && !has_late_bound_to_non_late_bound_regions(closure_sig, call_sig)
}
/// This walks through both signatures and checks for any time a late-bound region is expected by an
@ -265,7 +285,7 @@ fn check_sig<'tcx>(cx: &LateContext<'tcx>, closure: ClosureArgs<TyCtxt<'tcx>>, c
/// This is needed because rustc is unable to late bind early-bound regions in a function signature.
fn has_late_bound_to_non_late_bound_regions(from_sig: FnSig<'_>, to_sig: FnSig<'_>) -> bool {
fn check_region(from_region: Region<'_>, to_region: Region<'_>) -> bool {
matches!(from_region.kind(), RegionKind::ReBound(..)) && !matches!(to_region.kind(), RegionKind::ReBound(..))
from_region.is_bound() && !to_region.is_bound()
}
fn check_subs(from_subs: &[GenericArg<'_>], to_subs: &[GenericArg<'_>]) -> bool {
@ -318,3 +338,8 @@ fn check_ty(from_ty: Ty<'_>, to_ty: Ty<'_>) -> bool {
.zip(to_sig.inputs_and_output)
.any(|(from_ty, to_ty)| check_ty(from_ty, to_ty))
}
fn ty_has_static(ty: Ty<'_>) -> bool {
ty.walk()
.any(|arg| matches!(arg.unpack(), GenericArgKind::Lifetime(re) if re.is_static()))
}

17
tests/ui/eta.fixed
View File

@ -2,6 +2,7 @@
#![allow(unused)]
#![allow(
clippy::needless_borrow,
clippy::needless_option_as_deref,
clippy::needless_pass_by_value,
clippy::no_effect,
clippy::option_map_unit_fn,
@ -482,3 +483,19 @@ mod issue_12853 {
x();
}
}
mod issue_13073 {
fn get_default() -> Option<&'static str> {
Some("foo")
}
pub fn foo() {
// shouldn't lint
let bind: Option<String> = None;
let _field = bind.as_deref().or_else(|| get_default()).unwrap();
let bind: Option<&'static str> = None;
let _field = bind.as_deref().or_else(|| get_default()).unwrap();
// should lint
let _field = bind.or_else(get_default).unwrap();
}
}

17
tests/ui/eta.rs
View File

@ -2,6 +2,7 @@
#![allow(unused)]
#![allow(
clippy::needless_borrow,
clippy::needless_option_as_deref,
clippy::needless_pass_by_value,
clippy::no_effect,
clippy::option_map_unit_fn,
@ -482,3 +483,19 @@ fn f_by_ref<F: Fn(u32)>(f: &F) {
x();
}
}
mod issue_13073 {
fn get_default() -> Option<&'static str> {
Some("foo")
}
pub fn foo() {
// shouldn't lint
let bind: Option<String> = None;
let _field = bind.as_deref().or_else(|| get_default()).unwrap();
let bind: Option<&'static str> = None;
let _field = bind.as_deref().or_else(|| get_default()).unwrap();
// should lint
let _field = bind.or_else(|| get_default()).unwrap();
}
}

74
tests/ui/eta.stderr
View File

@ -1,5 +1,5 @@
error: redundant closure
--> tests/ui/eta.rs:29:27
--> tests/ui/eta.rs:30:27
|
LL | let a = Some(1u8).map(|a| foo(a));
| ^^^^^^^^^^ help: replace the closure with the function itself: `foo`
@ -8,31 +8,31 @@ LL | let a = Some(1u8).map(|a| foo(a));
= help: to override `-D warnings` add `#[allow(clippy::redundant_closure)]`
error: redundant closure
--> tests/ui/eta.rs:33:40
--> tests/ui/eta.rs:34:40
|
LL | let _: Option<Vec<u8>> = true.then(|| vec![]); // special case vec!
| ^^^^^^^^^ help: replace the closure with `Vec::new`: `std::vec::Vec::new`
error: redundant closure
--> tests/ui/eta.rs:34:35
--> tests/ui/eta.rs:35:35
|
LL | let d = Some(1u8).map(|a| foo((|b| foo2(b))(a))); //is adjusted?
| ^^^^^^^^^^^^^ help: replace the closure with the function itself: `foo2`
error: redundant closure
--> tests/ui/eta.rs:35:26
--> tests/ui/eta.rs:36:26
|
LL | all(&[1, 2, 3], &&2, |x, y| below(x, y)); //is adjusted
| ^^^^^^^^^^^^^^^^^^ help: replace the closure with the function itself: `below`
error: redundant closure
--> tests/ui/eta.rs:42:27
--> tests/ui/eta.rs:43:27
|
LL | let e = Some(1u8).map(|a| generic(a));
| ^^^^^^^^^^^^^^ help: replace the closure with the function itself: `generic`
error: redundant closure
--> tests/ui/eta.rs:94:51
--> tests/ui/eta.rs:95:51
|
LL | let e = Some(TestStruct { some_ref: &i }).map(|a| a.foo());
| ^^^^^^^^^^^ help: replace the closure with the method itself: `TestStruct::foo`
@ -41,166 +41,172 @@ LL | let e = Some(TestStruct { some_ref: &i }).map(|a| a.foo());
= help: to override `-D warnings` add `#[allow(clippy::redundant_closure_for_method_calls)]`
error: redundant closure
--> tests/ui/eta.rs:95:51
--> tests/ui/eta.rs:96:51
|
LL | let e = Some(TestStruct { some_ref: &i }).map(|a| a.trait_foo());
| ^^^^^^^^^^^^^^^^^ help: replace the closure with the method itself: `TestTrait::trait_foo`
error: redundant closure
--> tests/ui/eta.rs:97:42
--> tests/ui/eta.rs:98:42
|
LL | let e = Some(&mut vec![1, 2, 3]).map(|v| v.clear());
| ^^^^^^^^^^^^^ help: replace the closure with the method itself: `std::vec::Vec::clear`
error: redundant closure
--> tests/ui/eta.rs:101:29
--> tests/ui/eta.rs:102:29
|
LL | let e = Some("str").map(|s| s.to_string());
| ^^^^^^^^^^^^^^^^^ help: replace the closure with the method itself: `std::string::ToString::to_string`
error: redundant closure
--> tests/ui/eta.rs:102:27
--> tests/ui/eta.rs:103:27
|
LL | let e = Some('a').map(|s| s.to_uppercase());
| ^^^^^^^^^^^^^^^^^^^^ help: replace the closure with the method itself: `char::to_uppercase`
error: redundant closure
--> tests/ui/eta.rs:104:65
--> tests/ui/eta.rs:105:65
|
LL | let e: std::vec::Vec<char> = vec!['a', 'b', 'c'].iter().map(|c| c.to_ascii_uppercase()).collect();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace the closure with the method itself: `char::to_ascii_uppercase`
error: redundant closure
--> tests/ui/eta.rs:167:22
--> tests/ui/eta.rs:168:22
|
LL | requires_fn_once(|| x());
| ^^^^^^ help: replace the closure with the function itself: `x`
error: redundant closure
--> tests/ui/eta.rs:174:27
--> tests/ui/eta.rs:175:27
|
LL | let a = Some(1u8).map(|a| foo_ptr(a));
| ^^^^^^^^^^^^^^ help: replace the closure with the function itself: `foo_ptr`
error: redundant closure
--> tests/ui/eta.rs:179:27
--> tests/ui/eta.rs:180:27
|
LL | let a = Some(1u8).map(|a| closure(a));
| ^^^^^^^^^^^^^^ help: replace the closure with the function itself: `closure`
error: redundant closure
--> tests/ui/eta.rs:211:28
--> tests/ui/eta.rs:212:28
|
LL | x.into_iter().for_each(|x| add_to_res(x));
| ^^^^^^^^^^^^^^^^^ help: replace the closure with the function itself: `&mut add_to_res`
error: redundant closure
--> tests/ui/eta.rs:212:28
--> tests/ui/eta.rs:213:28
|
LL | y.into_iter().for_each(|x| add_to_res(x));
| ^^^^^^^^^^^^^^^^^ help: replace the closure with the function itself: `&mut add_to_res`
error: redundant closure
--> tests/ui/eta.rs:213:28
--> tests/ui/eta.rs:214:28
|
LL | z.into_iter().for_each(|x| add_to_res(x));
| ^^^^^^^^^^^^^^^^^ help: replace the closure with the function itself: `add_to_res`
error: redundant closure
--> tests/ui/eta.rs:220:21
--> tests/ui/eta.rs:221:21
|
LL | Some(1).map(|n| closure(n));
| ^^^^^^^^^^^^^^ help: replace the closure with the function itself: `&mut closure`
error: redundant closure
--> tests/ui/eta.rs:224:21
--> tests/ui/eta.rs:225:21
|
LL | Some(1).map(|n| in_loop(n));
| ^^^^^^^^^^^^^^ help: replace the closure with the function itself: `in_loop`
error: redundant closure
--> tests/ui/eta.rs:317:18
--> tests/ui/eta.rs:318:18
|
LL | takes_fn_mut(|| f());
| ^^^^^^ help: replace the closure with the function itself: `&mut f`
error: redundant closure
--> tests/ui/eta.rs:320:19
--> tests/ui/eta.rs:321:19
|
LL | takes_fn_once(|| f());
| ^^^^^^ help: replace the closure with the function itself: `&mut f`
error: redundant closure
--> tests/ui/eta.rs:324:26
--> tests/ui/eta.rs:325:26
|
LL | move || takes_fn_mut(|| f_used_once())
| ^^^^^^^^^^^^^^^^ help: replace the closure with the function itself: `&mut f_used_once`
error: redundant closure
--> tests/ui/eta.rs:336:19
--> tests/ui/eta.rs:337:19
|
LL | array_opt.map(|a| a.as_slice());
| ^^^^^^^^^^^^^^^^ help: replace the closure with the method itself: `<[u8; 3]>::as_slice`
error: redundant closure
--> tests/ui/eta.rs:339:19
--> tests/ui/eta.rs:340:19
|
LL | slice_opt.map(|s| s.len());
| ^^^^^^^^^^^ help: replace the closure with the method itself: `<[u8]>::len`
error: redundant closure
--> tests/ui/eta.rs:342:17
--> tests/ui/eta.rs:343:17
|
LL | ptr_opt.map(|p| p.is_null());
| ^^^^^^^^^^^^^^^ help: replace the closure with the method itself: `<*const usize>::is_null`
error: redundant closure
--> tests/ui/eta.rs:346:17
--> tests/ui/eta.rs:347:17
|
LL | dyn_opt.map(|d| d.method_on_dyn());
| ^^^^^^^^^^^^^^^^^^^^^ help: replace the closure with the method itself: `<dyn TestTrait>::method_on_dyn`
error: redundant closure
--> tests/ui/eta.rs:406:19
--> tests/ui/eta.rs:407:19
|
LL | let _ = f(&0, |x, y| f2(x, y));
| ^^^^^^^^^^^^^^^ help: replace the closure with the function itself: `f2`
error: redundant closure
--> tests/ui/eta.rs:434:22
--> tests/ui/eta.rs:435:22
|
LL | test.map(|t| t.method())
| ^^^^^^^^^^^^^^ help: replace the closure with the method itself: `Test::method`
error: redundant closure
--> tests/ui/eta.rs:438:22
--> tests/ui/eta.rs:439:22
|
LL | test.map(|t| t.method())
| ^^^^^^^^^^^^^^ help: replace the closure with the method itself: `super::Outer::method`
error: redundant closure
--> tests/ui/eta.rs:451:18
--> tests/ui/eta.rs:452:18
|
LL | test.map(|t| t.method())
| ^^^^^^^^^^^^^^ help: replace the closure with the method itself: `test_mod::Test::method`
error: redundant closure
--> tests/ui/eta.rs:458:30
--> tests/ui/eta.rs:459:30
|
LL | test.map(|t| t.method())
| ^^^^^^^^^^^^^^ help: replace the closure with the method itself: `crate::issue_10854::d::Test::method`
error: redundant closure
--> tests/ui/eta.rs:477:38
--> tests/ui/eta.rs:478:38
|
LL | let x = Box::new(|| None.map(|x| f(x)));
| ^^^^^^^^ help: replace the closure with the function itself: `&f`
error: redundant closure
--> tests/ui/eta.rs:481:38
--> tests/ui/eta.rs:482:38
|
LL | let x = Box::new(|| None.map(|x| f(x)));
| ^^^^^^^^ help: replace the closure with the function itself: `f`
error: aborting due to 33 previous errors
error: redundant closure
--> tests/ui/eta.rs:499:35
|
LL | let _field = bind.or_else(|| get_default()).unwrap();
| ^^^^^^^^^^^^^^^^ help: replace the closure with the function itself: `get_default`
error: aborting due to 34 previous errors