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Factor out check_closure function

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Also get the receiver T in `T.method(|| f())`.
This commit is contained in:
Lzu Tao 2024-07-16 19:48:42 +07:00
parent 32dc02a6ec
commit e53182a2b4
1 changed files with 162 additions and 152 deletions
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314
clippy_lints/src/eta_reduction.rs
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@ -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);
}
// 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<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