From 32dc02a6ec1f677226039d22645f6890778b9ed3 Mon Sep 17 00:00:00 2001 From: Lzu Tao Date: Tue, 16 Jul 2024 12:54:20 +0000 Subject: [PATCH 1/3] Add regression test for issue 13073 --- tests/ui/eta.fixed | 17 +++++++++ tests/ui/eta.rs | 17 +++++++++ tests/ui/eta.stderr | 86 +++++++++++++++++++++++++++------------------ 3 files changed, 86 insertions(+), 34 deletions(-) diff --git a/tests/ui/eta.fixed b/tests/ui/eta.fixed index 7126f279945..5323425de47 100644 --- a/tests/ui/eta.fixed +++ b/tests/ui/eta.fixed @@ -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 = 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(); + } +} diff --git a/tests/ui/eta.rs b/tests/ui/eta.rs index 0787abf5f3e..c0db91c03ef 100644 --- a/tests/ui/eta.rs +++ b/tests/ui/eta.rs @@ -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: &F) { x(); } } + +mod issue_13073 { + fn get_default() -> Option<&'static str> { + Some("foo") + } + + pub fn foo() { + // shouldn't lint + let bind: Option = 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(); + } +} diff --git a/tests/ui/eta.stderr b/tests/ui/eta.stderr index c757601042f..d35c37af37c 100644 --- a/tests/ui/eta.stderr +++ b/tests/ui/eta.stderr @@ -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> = 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 +41,184 @@ 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 = 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: `::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:495:46 + | +LL | let _field = bind.as_deref().or_else(|| get_default()).unwrap(); + | ^^^^^^^^^^^^^^^^ help: replace the closure with the function itself: `get_default` + +error: redundant closure + --> tests/ui/eta.rs:497:46 + | +LL | let _field = bind.as_deref().or_else(|| get_default()).unwrap(); + | ^^^^^^^^^^^^^^^^ help: replace the closure with the function itself: `get_default` + +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 36 previous errors From e53182a2b492613ce3988c1c893330d53e9caed1 Mon Sep 17 00:00:00 2001 From: Lzu Tao Date: Tue, 16 Jul 2024 19:48:42 +0700 Subject: [PATCH 2/3] Factor out check_closure function Also get the receiver T in `T.method(|| f())`. --- clippy_lints/src/eta_reduction.rs | 314 +++++++++++++++--------------- 1 file changed, 162 insertions(+), 152 deletions(-) diff --git a/clippy_lints/src/eta_reduction.rs b/clippy_lints/src/eta_reduction.rs index 0ed7859418b..d03ae101823 100644 --- a/clippy_lints/src/eta_reduction.rs +++ b/clippy_lints/src/eta_reduction.rs @@ -9,8 +9,8 @@ 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, RegionKind, Ty, TypeVisitableExt, + TypeckResults, }; use rustc_session::declare_lint_pass; use rustc_span::symbol::sym; @@ -74,159 +74,173 @@ 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<'_>) { - 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(_)) - && !expr.span.from_expansion() - { - cx.tcx.hir().body(c.body) - } else { - return; - }; - - if body.value.span.from_expansion() { - if body.params.is_empty() { - if let Some(VecArgs::Vec(&[])) = VecArgs::hir(cx, body.value) { - // 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, - ); - } + 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); } - // skip `foo(|| macro!())` - 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; + if let ExprKind::Call(func, args) = expr.kind { + check_clousure(cx, None, func); + for arg in args { + check_clousure(cx, None, arg); + } } + } +} - match body.value.kind { - ExprKind::Call(callee, args) - if matches!( - callee.kind, - ExprKind::Path(QPath::Resolved(..) | QPath::TypeRelative(..)) - ) => +#[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(_)) + && !expr.span.from_expansion() + { + cx.tcx.hir().body(c.body) + } else { + return; + }; + + if body.value.span.from_expansion() { + if body.params.is_empty() { + if let Some(VecArgs::Vec(&[])) = VecArgs::hir(cx, body.value) { + // 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 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; + }; + let closure_sig = cx.tcx.signature_unclosure(closure.sig(), Safety::Safe).skip_binder(); + match body.value.kind { + ExprKind::Call(callee, args) + if matches!( + callee.kind, + ExprKind::Path(QPath::Resolved(..) | QPath::TypeRelative(..)) + ) => + { + let callee_ty_raw = typeck.expr_ty(callee); + let callee_ty = callee_ty_raw.peel_refs(); + if matches!(type_diagnostic_name(cx, callee_ty), Some(sym::Arc | sym::Rc)) + || !check_inputs(typeck, body.params, None, args) { - let callee_ty_raw = typeck.expr_ty(callee); - let callee_ty = callee_ty_raw.peel_refs(); - if matches!(type_diagnostic_name(cx, callee_ty), Some(sym::Arc | sym::Rc)) - || !check_inputs(typeck, body.params, None, args) - { - return; - } - let callee_ty_adjusted = typeck - .expr_adjustments(callee) - .last() - .map_or(callee_ty, |a| a.target.peel_refs()); + return; + } + let callee_ty_adjusted = typeck + .expr_adjustments(callee) + .last() + .map_or(callee_ty, |a| a.target.peel_refs()); - let sig = match callee_ty_adjusted.kind() { - ty::FnDef(def, _) => { - // Rewriting `x(|| f())` to `x(f)` where f is marked `#[track_caller]` moves the `Location` - if cx.tcx.has_attr(*def, sym::track_caller) { - return; - } + let sig = match callee_ty_adjusted.kind() { + ty::FnDef(def, _) => { + // Rewriting `x(|| f())` to `x(f)` where f is marked `#[track_caller]` moves the `Location` + if cx.tcx.has_attr(*def, sym::track_caller) { + return; + } - cx.tcx.fn_sig(def).skip_binder().skip_binder() - }, - ty::FnPtr(sig) => sig.skip_binder(), - ty::Closure(_, subs) => cx - .tcx - .signature_unclosure(subs.as_closure().sig(), Safety::Safe) - .skip_binder(), - _ => { - if typeck.type_dependent_def_id(body.value.hir_id).is_some() - && let subs = typeck.node_args(body.value.hir_id) - && let output = typeck.expr_ty(body.value) - && let ty::Tuple(tys) = *subs.type_at(1).kind() - { - cx.tcx.mk_fn_sig(tys, output, false, Safety::Safe, Abi::Rust) - } else { - return; - } - }, - }; - if check_sig(cx, closure, 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 - // in a type which is `'static`. - // For now ignore all callee types which reference a type parameter. - && !generic_args.types().any(|t| matches!(t.kind(), ty::Param(_))) - { - span_lint_and_then(cx, REDUNDANT_CLOSURE, expr.span, "redundant closure", |diag| { - if let Some(mut snippet) = snippet_opt(cx, callee.span) { - if path_to_local(callee).map_or(false, |l| { - // FIXME: Do we really need this `local_used_in` check? - // Isn't it checking something like... `callee(callee)`? - // If somehow this check is needed, add some test for it, - // 'cuz currently nothing changes after deleting this check. - local_used_in(cx, l, args) || local_used_after_expr(cx, l, expr) - }) { - match cx.tcx.infer_ctxt().build().err_ctxt().type_implements_fn_trait( - cx.param_env, - Binder::bind_with_vars(callee_ty_adjusted, List::empty()), - ty::PredicatePolarity::Positive, - ) { - // Mutable closure is used after current expr; we cannot consume it. - Ok((ClosureKind::FnMut, _)) => snippet = format!("&mut {snippet}"), - Ok((ClosureKind::Fn, _)) if !callee_ty_raw.is_ref() => { - snippet = format!("&{snippet}"); - }, - _ => (), - } + cx.tcx.fn_sig(def).skip_binder().skip_binder() + }, + ty::FnPtr(sig) => sig.skip_binder(), + ty::Closure(_, subs) => cx + .tcx + .signature_unclosure(subs.as_closure().sig(), Safety::Safe) + .skip_binder(), + _ => { + if typeck.type_dependent_def_id(body.value.hir_id).is_some() + && let subs = typeck.node_args(body.value.hir_id) + && let output = typeck.expr_ty(body.value) + && let ty::Tuple(tys) = *subs.type_at(1).kind() + { + cx.tcx.mk_fn_sig(tys, output, false, Safety::Safe, Abi::Rust) + } else { + 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 + // in a type which is `'static`. + // For now ignore all callee types which reference a type parameter. + && !generic_args.types().any(|t| matches!(t.kind(), ty::Param(_))) + { + span_lint_and_then(cx, REDUNDANT_CLOSURE, expr.span, "redundant closure", |diag| { + if let Some(mut snippet) = snippet_opt(cx, callee.span) { + if path_to_local(callee).map_or(false, |l| { + // FIXME: Do we really need this `local_used_in` check? + // Isn't it checking something like... `callee(callee)`? + // If somehow this check is needed, add some test for it, + // 'cuz currently nothing changes after deleting this check. + local_used_in(cx, l, args) || local_used_after_expr(cx, l, expr) + }) { + match cx.tcx.infer_ctxt().build().err_ctxt().type_implements_fn_trait( + cx.param_env, + Binder::bind_with_vars(callee_ty_adjusted, List::empty()), + ty::PredicatePolarity::Positive, + ) { + // Mutable closure is used after current expr; we cannot consume it. + Ok((ClosureKind::FnMut, _)) => snippet = format!("&mut {snippet}"), + Ok((ClosureKind::Fn, _)) if !callee_ty_raw.is_ref() => { + snippet = format!("&{snippet}"); + }, + _ => (), } - diag.span_suggestion( - expr.span, - "replace the closure with the function itself", - snippet, - Applicability::MachineApplicable, - ); } - }); - } - }, - 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()) - { - span_lint_and_then( - cx, - REDUNDANT_CLOSURE_FOR_METHOD_CALLS, - expr.span, - "redundant closure", - |diag| { - let args = typeck.node_args(body.value.hir_id); - let caller = self_.hir_id.owner.def_id; - let type_name = get_path_from_caller_to_method_type(cx.tcx, caller, method_def_id, args); - diag.span_suggestion( - expr.span, - "replace the closure with the method itself", - format!("{}::{}", type_name, path.ident.name), - Applicability::MachineApplicable, - ); - }, - ); - } - }, - _ => (), - } + diag.span_suggestion( + expr.span, + "replace the closure with the function itself", + snippet, + Applicability::MachineApplicable, + ); + } + }); + } + }, + 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(closure_sig, cx.tcx.fn_sig(method_def_id).skip_binder().skip_binder()) + { + span_lint_and_then( + cx, + REDUNDANT_CLOSURE_FOR_METHOD_CALLS, + expr.span, + "redundant closure", + |diag| { + let args = typeck.node_args(body.value.hir_id); + let caller = self_.hir_id.owner.def_id; + let type_name = get_path_from_caller_to_method_type(cx.tcx, caller, method_def_id, args); + diag.span_suggestion( + expr.span, + "replace the closure with the method itself", + format!("{}::{}", type_name, path.ident.name), + Applicability::MachineApplicable, + ); + }, + ); + } + }, + _ => (), } } @@ -251,12 +265,8 @@ fn check_inputs( }) } -fn check_sig<'tcx>(cx: &LateContext<'tcx>, closure: ClosureArgs>, 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 From 0bc9f003a3fdf2d860647a22768297aaa07611e4 Mon Sep 17 00:00:00 2001 From: Lzu Tao Date: Wed, 17 Jul 2024 11:30:29 +0700 Subject: [PATCH 3/3] Check for 'static lifetime in return type --- clippy_lints/src/eta_reduction.rs | 21 ++++++++++++++++++--- tests/ui/eta.fixed | 4 ++-- tests/ui/eta.stderr | 14 +------------- 3 files changed, 21 insertions(+), 18 deletions(-) diff --git a/clippy_lints/src/eta_reduction.rs b/clippy_lints/src/eta_reduction.rs index d03ae101823..5a7226d590c 100644 --- a/clippy_lints/src/eta_reduction.rs +++ b/clippy_lints/src/eta_reduction.rs @@ -9,8 +9,7 @@ use rustc_infer::infer::TyCtxtInferExt; use rustc_lint::{LateContext, LateLintPass}; use rustc_middle::ty::{ - self, Binder, ClosureKind, FnSig, GenericArg, GenericArgKind, List, Region, RegionKind, Ty, TypeVisitableExt, - TypeckResults, + self, Binder, ClosureKind, FnSig, GenericArg, GenericArgKind, List, Region, Ty, TypeVisitableExt, TypeckResults, }; use rustc_session::declare_lint_pass; use rustc_span::symbol::sym; @@ -176,6 +175,17 @@ fn check_clousure<'tcx>(cx: &LateContext<'tcx>, outer_receiver: Option<&Expr<'tc } }, }; + 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::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 @@ -275,7 +285,7 @@ fn check_sig<'tcx>(closure_sig: FnSig<'tcx>, call_sig: FnSig<'tcx>) -> bool { /// 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 { @@ -328,3 +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())) +} diff --git a/tests/ui/eta.fixed b/tests/ui/eta.fixed index 5323425de47..ca422ee29c1 100644 --- a/tests/ui/eta.fixed +++ b/tests/ui/eta.fixed @@ -492,9 +492,9 @@ mod issue_13073 { pub fn foo() { // shouldn't lint let bind: Option = None; - let _field = bind.as_deref().or_else(get_default).unwrap(); + 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(); + let _field = bind.as_deref().or_else(|| get_default()).unwrap(); // should lint let _field = bind.or_else(get_default).unwrap(); } diff --git a/tests/ui/eta.stderr b/tests/ui/eta.stderr index d35c37af37c..5540261fc57 100644 --- a/tests/ui/eta.stderr +++ b/tests/ui/eta.stderr @@ -202,23 +202,11 @@ error: redundant closure 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:495:46 - | -LL | let _field = bind.as_deref().or_else(|| get_default()).unwrap(); - | ^^^^^^^^^^^^^^^^ help: replace the closure with the function itself: `get_default` - -error: redundant closure - --> tests/ui/eta.rs:497:46 - | -LL | let _field = bind.as_deref().or_else(|| get_default()).unwrap(); - | ^^^^^^^^^^^^^^^^ help: replace the closure with the function itself: `get_default` - 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 36 previous errors +error: aborting due to 34 previous errors