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Fix various redundant_closure bugs #7661

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merged 2 commits into from
Sep 13, 2021
Merged

Fix various redundant_closure bugs #7661

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5782dc0
Fix redundant closure bugs
camsteffen Sep 9, 2021
ae2a95f
Eat dogfood
camsteffen Sep 9, 2021
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2 changes: 1 addition & 1 deletion clippy_lints/src/disallowed_type.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -48,7 +48,7 @@ impl DisallowedType {
Self {
disallowed: disallowed
.iter()
.map(|s| s.split("::").map(|seg| Symbol::intern(seg)).collect::<Vec<_>>())
.map(|s| s.split("::").map(Symbol::intern).collect::<Vec<_>>())
.collect(),
def_ids: FxHashSet::default(),
prim_tys: FxHashSet::default(),
Expand Down
240 changes: 92 additions & 148 deletions clippy_lints/src/eta_reduction.rs
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Original file line number Diff line number Diff line change
@@ -1,16 +1,16 @@
use clippy_utils::diagnostics::{span_lint_and_sugg, span_lint_and_then};
use clippy_utils::higher::VecArgs;
use clippy_utils::source::snippet_opt;
use clippy_utils::ty::{implements_trait, type_is_unsafe_function};
use clippy_utils::usage::UsedAfterExprVisitor;
use clippy_utils::{get_enclosing_loop_or_closure, higher};
use clippy_utils::{is_adjusted, iter_input_pats};
use clippy_utils::{get_enclosing_loop_or_closure, higher, path_to_local_id};
use if_chain::if_chain;
use rustc_errors::Applicability;
use rustc_hir::{def_id, Expr, ExprKind, Param, PatKind, QPath};
use rustc_lint::{LateContext, LateLintPass, LintContext};
use rustc_middle::lint::in_external_macro;
use rustc_middle::ty::{self, ClosureKind, Ty};
use rustc_hir::def_id::DefId;
use rustc_hir::{Expr, ExprKind, Param, PatKind, Unsafety};
use rustc_lint::{LateContext, LateLintPass};
use rustc_middle::ty::adjustment::{Adjust, Adjustment, AutoBorrow};
use rustc_middle::ty::subst::Subst;
use rustc_middle::ty::{self, ClosureKind, Ty, TypeFoldable};
use rustc_session::{declare_lint_pass, declare_tool_lint};

declare_clippy_lint! {
Expand Down Expand Up @@ -52,12 +52,6 @@ declare_clippy_lint! {
/// ### Why is this bad?
/// It's unnecessary to create the closure.
///
/// ### Known problems
/// [#3071](https://github.com/rust-lang/rust-clippy/issues/3071),
/// [#3942](https://github.com/rust-lang/rust-clippy/issues/3942),
/// [#4002](https://github.com/rust-lang/rust-clippy/issues/4002)
///
///
/// ### Example
/// ```rust,ignore
/// Some('a').map(|s| s.to_uppercase());
Expand All @@ -75,32 +69,16 @@ declare_lint_pass!(EtaReduction => [REDUNDANT_CLOSURE, REDUNDANT_CLOSURE_FOR_MET

impl<'tcx> LateLintPass<'tcx> for EtaReduction {
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
if in_external_macro(cx.sess(), expr.span) {
if expr.span.from_expansion() {
return;
}

match expr.kind {
ExprKind::Call(_, args) | ExprKind::MethodCall(_, _, args, _) => {
for arg in args {
// skip `foo(macro!())`
if arg.span.ctxt() == expr.span.ctxt() {
check_closure(cx, arg);
}
}
},
_ => (),
}
}
}

fn check_closure<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
if let ExprKind::Closure(_, decl, eid, _, _) = expr.kind {
let body = cx.tcx.hir().body(eid);
let ex = &body.value;

if ex.span.ctxt() != expr.span.ctxt() {
if decl.inputs.is_empty() {
if let Some(VecArgs::Vec(&[])) = higher::VecArgs::hir(cx, ex) {
let body = match expr.kind {
ExprKind::Closure(_, _, id, _, _) => cx.tcx.hir().body(id),
_ => return,
};
if body.value.span.from_expansion() {
if body.params.is_empty() {
if let Some(VecArgs::Vec(&[])) = higher::VecArgs::hir(cx, &body.value) {
// replace `|| vec![]` with `Vec::new`
span_lint_and_sugg(
cx,
Expand All @@ -117,33 +95,30 @@ fn check_closure<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
return;
}

if_chain!(
if let ExprKind::Call(caller, args) = ex.kind;

if let ExprKind::Path(_) = caller.kind;

// Not the same number of arguments, there is no way the closure is the same as the function return;
if args.len() == decl.inputs.len();

// Are the expression or the arguments type-adjusted? Then we need the closure
if !(is_adjusted(cx, ex) || args.iter().any(|arg| is_adjusted(cx, arg)));

let fn_ty = cx.typeck_results().expr_ty(caller);

if matches!(fn_ty.kind(), ty::FnDef(_, _) | ty::FnPtr(_) | ty::Closure(_, _));

if !type_is_unsafe_function(cx, fn_ty);

if compare_inputs(&mut iter_input_pats(decl, body), &mut args.iter());
let closure_ty = cx.typeck_results().expr_ty(expr);

if_chain!(
if let ExprKind::Call(callee, args) = body.value.kind;
if let ExprKind::Path(_) = callee.kind;
if check_inputs(cx, body.params, args);
let callee_ty = cx.typeck_results().expr_ty_adjusted(callee);
let call_ty = cx.typeck_results().type_dependent_def_id(body.value.hir_id)
.map_or(callee_ty, |id| cx.tcx.type_of(id));
if check_sig(cx, closure_ty, call_ty);
let substs = cx.typeck_results().node_substs(callee.hir_id);
// This fixes some false positives that I don't entirely understand
if substs.is_empty() || !cx.typeck_results().expr_ty(expr).has_late_bound_regions();
// A type param function ref like `T::f` is not 'static, however
// it is if cast like `T::f as fn()`. This seems like a rustc bug.
if !substs.types().any(|t| matches!(t.kind(), ty::Param(_)));
then {
span_lint_and_then(cx, REDUNDANT_CLOSURE, expr.span, "redundant closure", |diag| {
if let Some(mut snippet) = snippet_opt(cx, caller.span) {
if let Some(mut snippet) = snippet_opt(cx, callee.span) {
if_chain! {
if let ty::Closure(_, substs) = fn_ty.kind();
if let ty::Closure(_, substs) = callee_ty.peel_refs().kind();
if let ClosureKind::FnMut = substs.as_closure().kind();
if UsedAfterExprVisitor::is_found(cx, caller)
|| get_enclosing_loop_or_closure(cx.tcx, expr).is_some();
if get_enclosing_loop_or_closure(cx.tcx, expr).is_some()
|| UsedAfterExprVisitor::is_found(cx, callee);

then {
// Mutable closure is used after current expr; we cannot consume it.
Expand All @@ -162,110 +137,79 @@ fn check_closure<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
);

if_chain!(
if let ExprKind::MethodCall(path, _, args, _) = ex.kind;

// Not the same number of arguments, there is no way the closure is the same as the function return;
if args.len() == decl.inputs.len();

// Are the expression or the arguments type-adjusted? Then we need the closure
if !(is_adjusted(cx, ex) || args.iter().skip(1).any(|arg| is_adjusted(cx, arg)));

let method_def_id = cx.typeck_results().type_dependent_def_id(ex.hir_id).unwrap();
if !type_is_unsafe_function(cx, cx.tcx.type_of(method_def_id));

if compare_inputs(&mut iter_input_pats(decl, body), &mut args.iter());

if let Some(name) = get_ufcs_type_name(cx, method_def_id, &args[0]);

if let ExprKind::MethodCall(path, _, args, _) = body.value.kind;
if check_inputs(cx, body.params, args);
let method_def_id = cx.typeck_results().type_dependent_def_id(body.value.hir_id).unwrap();
let substs = cx.typeck_results().node_substs(body.value.hir_id);
let call_ty = cx.tcx.type_of(method_def_id).subst(cx.tcx, substs);
if check_sig(cx, closure_ty, call_ty);
then {
span_lint_and_sugg(
cx,
REDUNDANT_CLOSURE_FOR_METHOD_CALLS,
expr.span,
"redundant closure",
"replace the closure with the method itself",
format!("{}::{}", name, path.ident.name),
Applicability::MachineApplicable,
);
span_lint_and_then(cx, REDUNDANT_CLOSURE_FOR_METHOD_CALLS, expr.span, "redundant closure", |diag| {
let name = get_ufcs_type_name(cx, method_def_id);
diag.span_suggestion(
expr.span,
"replace the closure with the method itself",
format!("{}::{}", name, path.ident.name),
Applicability::MachineApplicable,
);
})
}
);
}
}

/// Tries to determine the type for universal function call to be used instead of the closure
fn get_ufcs_type_name(cx: &LateContext<'_>, method_def_id: def_id::DefId, self_arg: &Expr<'_>) -> Option<String> {
let expected_type_of_self = &cx.tcx.fn_sig(method_def_id).inputs_and_output().skip_binder()[0];
let actual_type_of_self = &cx.typeck_results().node_type(self_arg.hir_id);

if let Some(trait_id) = cx.tcx.trait_of_item(method_def_id) {
if match_borrow_depth(expected_type_of_self, actual_type_of_self)
&& implements_trait(cx, actual_type_of_self, trait_id, &[])
{
return Some(cx.tcx.def_path_str(trait_id));
}
fn check_inputs(cx: &LateContext<'_>, params: &[Param<'_>], call_args: &[Expr<'_>]) -> bool {
if params.len() != call_args.len() {
return false;
}

cx.tcx.impl_of_method(method_def_id).and_then(|_| {
//a type may implicitly implement other type's methods (e.g. Deref)
if match_types(expected_type_of_self, actual_type_of_self) {
Some(get_type_name(cx, actual_type_of_self))
} else {
None
std::iter::zip(params, call_args).all(|(param, arg)| {
match param.pat.kind {
PatKind::Binding(_, id, ..) if path_to_local_id(arg, id) => {},
_ => return false,
}
match *cx.typeck_results().expr_adjustments(arg) {
[] => true,
[Adjustment {
kind: Adjust::Deref(None),
..
}, Adjustment {
kind: Adjust::Borrow(AutoBorrow::Ref(_, mu2)),
..
}] => {
// re-borrow with the same mutability is allowed
let ty = cx.typeck_results().expr_ty(arg);
matches!(*ty.kind(), ty::Ref(.., mu1) if mu1 == mu2.into())
},
_ => false,
}
})
}

fn match_borrow_depth(lhs: Ty<'_>, rhs: Ty<'_>) -> bool {
match (&lhs.kind(), &rhs.kind()) {
(ty::Ref(_, t1, mut1), ty::Ref(_, t2, mut2)) => mut1 == mut2 && match_borrow_depth(t1, t2),
(l, r) => !matches!((l, r), (ty::Ref(_, _, _), _) | (_, ty::Ref(_, _, _))),
}
}

fn match_types(lhs: Ty<'_>, rhs: Ty<'_>) -> bool {
match (&lhs.kind(), &rhs.kind()) {
(ty::Bool, ty::Bool)
| (ty::Char, ty::Char)
| (ty::Int(_), ty::Int(_))
| (ty::Uint(_), ty::Uint(_))
| (ty::Str, ty::Str) => true,
(ty::Ref(_, t1, mut1), ty::Ref(_, t2, mut2)) => mut1 == mut2 && match_types(t1, t2),
(ty::Array(t1, _), ty::Array(t2, _)) | (ty::Slice(t1), ty::Slice(t2)) => match_types(t1, t2),
(ty::Adt(def1, _), ty::Adt(def2, _)) => def1 == def2,
(_, _) => false,
fn check_sig<'tcx>(cx: &LateContext<'tcx>, closure_ty: Ty<'tcx>, call_ty: Ty<'tcx>) -> bool {
let call_sig = call_ty.fn_sig(cx.tcx);
if call_sig.unsafety() == Unsafety::Unsafe {
return false;
}
}

fn get_type_name(cx: &LateContext<'_>, ty: Ty<'_>) -> String {
match ty.kind() {
ty::Adt(t, _) => cx.tcx.def_path_str(t.did),
ty::Ref(_, r, _) => get_type_name(cx, r),
_ => ty.to_string(),
if !closure_ty.has_late_bound_regions() {
return true;
}
let substs = match closure_ty.kind() {
ty::Closure(_, substs) => substs,
_ => return false,
};
let closure_sig = cx.tcx.signature_unclosure(substs.as_closure().sig(), Unsafety::Normal);
cx.tcx.erase_late_bound_regions(closure_sig) == cx.tcx.erase_late_bound_regions(call_sig)
}

fn compare_inputs(
closure_inputs: &mut dyn Iterator<Item = &Param<'_>>,
call_args: &mut dyn Iterator<Item = &Expr<'_>>,
) -> bool {
for (closure_input, function_arg) in closure_inputs.zip(call_args) {
if let PatKind::Binding(_, _, ident, _) = closure_input.pat.kind {
// XXXManishearth Should I be checking the binding mode here?
if let ExprKind::Path(QPath::Resolved(None, p)) = function_arg.kind {
if p.segments.len() != 1 {
// If it's a proper path, it can't be a local variable
return false;
}
if p.segments[0].ident.name != ident.name {
// The two idents should be the same
return false;
}
} else {
return false;
fn get_ufcs_type_name(cx: &LateContext<'_>, method_def_id: DefId) -> String {
match cx.tcx.associated_item(method_def_id).container {
ty::TraitContainer(def_id) => cx.tcx.def_path_str(def_id),
ty::ImplContainer(def_id) => {
let ty = cx.tcx.type_of(def_id);
match ty.kind() {
ty::Adt(adt, _) => cx.tcx.def_path_str(adt.did),
_ => ty.to_string(),
}
} else {
return false;
}
},
}
true
}
4 changes: 2 additions & 2 deletions clippy_lints/src/format.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -69,8 +69,8 @@ impl<'tcx> LateLintPass<'tcx> for UselessFormat {
ty::Str => true,
_ => false,
};
if format_args.args.iter().all(|e| is_display_arg(e));
if format_args.fmt_expr.map_or(true, |e| check_unformatted(e));
if format_args.args.iter().all(is_display_arg);
if format_args.fmt_expr.map_or(true, check_unformatted);
then {
let is_new_string = match value.kind {
ExprKind::Binary(..) => true,
Expand Down
2 changes: 1 addition & 1 deletion clippy_lints/src/loops/while_let_loop.rs
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Expand Up @@ -65,7 +65,7 @@ fn extract_first_expr<'tcx>(block: &Block<'tcx>) -> Option<&'tcx Expr<'tcx>> {
fn is_simple_break_expr(expr: &Expr<'_>) -> bool {
match expr.kind {
ExprKind::Break(dest, ref passed_expr) if dest.label.is_none() && passed_expr.is_none() => true,
ExprKind::Block(b, _) => extract_first_expr(b).map_or(false, |subexpr| is_simple_break_expr(subexpr)),
ExprKind::Block(b, _) => extract_first_expr(b).map_or(false, is_simple_break_expr),
_ => false,
}
}
Expand Down
2 changes: 1 addition & 1 deletion clippy_lints/src/ptr.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -372,7 +372,7 @@ fn check_fn(cx: &LateContext<'_>, decl: &FnDecl<'_>, fn_id: HirId, opt_body_id:
for (_, ref mutbl, ref argspan) in decl
.inputs
.iter()
.filter_map(|ty| get_rptr_lm(ty))
.filter_map(get_rptr_lm)
.filter(|&(lt, _, _)| lt.name == out.name)
{
if *mutbl == Mutability::Mut {
Expand Down
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