diff options
| -rw-r--r-- | clippy_lints/src/eta_reduction.rs | 310 |
1 files changed, 160 insertions, 150 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_hir::{BindingMode, Expr, ExprKind, FnRetTy, Param, PatKind, QPath, Saf 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_clippy_lint! { 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); + } + } + if let ExprKind::Call(func, args) = expr.kind { + check_clousure(cx, None, func); + for arg in args { + check_clousure(cx, None, 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; - }; +#[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 is_adjusted(cx, body.value) { - 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; + } - match body.value.kind { - ExprKind::Call(callee, args) - if matches!( - callee.kind, - ExprKind::Path(QPath::Resolved(..) | QPath::TypeRelative(..)) - ) => + 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<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 |