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Auto merge of #12104 - GuillaumeGomez:map-clone, r=llogiq
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Extend `map_clone` lint to also work on non-explicit closures

I found it weird that this case was not handled by the current line so I added it. The only thing is that I don't see an obvious way to infer the current type to determine if it's copyable or not, so for now I always suggest `cloned` and I added a FIXME.

r? `@llogiq`

changelog: Extend `map_clone` lint to also work on non-explicit closures
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@bors
bors committed Jan 6, 2024
2 parents 5d57ba8 + af35d37 commit 17b2418
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Showing 5 changed files with 97 additions and 36 deletions.
98 changes: 64 additions & 34 deletions clippy_lints/src/methods/map_clone.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,7 @@ use clippy_config::msrvs::{self, Msrv};
use clippy_utils::diagnostics::span_lint_and_sugg;
use clippy_utils::source::snippet_with_applicability;
use clippy_utils::ty::{is_copy, is_type_diagnostic_item};
use clippy_utils::{is_diag_trait_item, peel_blocks};
use clippy_utils::{is_diag_trait_item, match_def_path, paths, peel_blocks};
use rustc_errors::Applicability;
use rustc_hir as hir;
use rustc_lint::LateContext;
Expand All @@ -19,50 +19,63 @@ pub(super) fn check(cx: &LateContext<'_>, e: &hir::Expr<'_>, recv: &hir::Expr<'_
&& (cx.tcx.impl_of_method(method_id).map_or(false, |id| {
is_type_diagnostic_item(cx, cx.tcx.type_of(id).instantiate_identity(), sym::Option)
}) || is_diag_trait_item(cx, method_id, sym::Iterator))
&& let hir::ExprKind::Closure(&hir::Closure { body, .. }) = arg.kind
{
let closure_body = cx.tcx.hir().body(body);
let closure_expr = peel_blocks(closure_body.value);
match closure_body.params[0].pat.kind {
hir::PatKind::Ref(inner, hir::Mutability::Not) => {
if let hir::PatKind::Binding(hir::BindingAnnotation::NONE, .., name, None) = inner.kind {
if ident_eq(name, closure_expr) {
lint_explicit_closure(cx, e.span, recv.span, true, msrv);
}
}
},
hir::PatKind::Binding(hir::BindingAnnotation::NONE, .., name, None) => {
match closure_expr.kind {
hir::ExprKind::Unary(hir::UnOp::Deref, inner) => {
if ident_eq(name, inner) {
if let ty::Ref(.., Mutability::Not) = cx.typeck_results().expr_ty(inner).kind() {
match arg.kind {
hir::ExprKind::Closure(&hir::Closure { body, .. }) => {
let closure_body = cx.tcx.hir().body(body);
let closure_expr = peel_blocks(closure_body.value);
match closure_body.params[0].pat.kind {
hir::PatKind::Ref(inner, hir::Mutability::Not) => {
if let hir::PatKind::Binding(hir::BindingAnnotation::NONE, .., name, None) = inner.kind {
if ident_eq(name, closure_expr) {
lint_explicit_closure(cx, e.span, recv.span, true, msrv);
}
}
},
hir::ExprKind::MethodCall(method, obj, [], _) => {
if ident_eq(name, obj) && method.ident.name == sym::clone
&& let Some(fn_id) = cx.typeck_results().type_dependent_def_id(closure_expr.hir_id)
&& let Some(trait_id) = cx.tcx.trait_of_item(fn_id)
&& cx.tcx.lang_items().clone_trait().map_or(false, |id| id == trait_id)
// no autoderefs
&& !cx.typeck_results().expr_adjustments(obj).iter()
.any(|a| matches!(a.kind, Adjust::Deref(Some(..))))
{
let obj_ty = cx.typeck_results().expr_ty(obj);
if let ty::Ref(_, ty, mutability) = obj_ty.kind() {
if matches!(mutability, Mutability::Not) {
let copy = is_copy(cx, *ty);
lint_explicit_closure(cx, e.span, recv.span, copy, msrv);
hir::PatKind::Binding(hir::BindingAnnotation::NONE, .., name, None) => {
match closure_expr.kind {
hir::ExprKind::Unary(hir::UnOp::Deref, inner) => {
if ident_eq(name, inner) {
if let ty::Ref(.., Mutability::Not) = cx.typeck_results().expr_ty(inner).kind() {
lint_explicit_closure(cx, e.span, recv.span, true, msrv);
}
}
} else {
lint_needless_cloning(cx, e.span, recv.span);
}
},
hir::ExprKind::MethodCall(method, obj, [], _) => {
if ident_eq(name, obj) && method.ident.name == sym::clone
&& let Some(fn_id) = cx.typeck_results().type_dependent_def_id(closure_expr.hir_id)
&& let Some(trait_id) = cx.tcx.trait_of_item(fn_id)
&& cx.tcx.lang_items().clone_trait().map_or(false, |id| id == trait_id)
// no autoderefs
&& !cx.typeck_results().expr_adjustments(obj).iter()
.any(|a| matches!(a.kind, Adjust::Deref(Some(..))))
{
let obj_ty = cx.typeck_results().expr_ty(obj);
if let ty::Ref(_, ty, mutability) = obj_ty.kind() {
if matches!(mutability, Mutability::Not) {
let copy = is_copy(cx, *ty);
lint_explicit_closure(cx, e.span, recv.span, copy, msrv);
}
} else {
lint_needless_cloning(cx, e.span, recv.span);
}
}
},
_ => {},
}
},
_ => {},
}
},
hir::ExprKind::Path(qpath) => {
if let Some(path_def_id) = cx.qpath_res(&qpath, arg.hir_id).opt_def_id()
&& match_def_path(cx, path_def_id, &paths::CLONE_TRAIT_METHOD)
{
// FIXME: It would be better to infer the type to check if it's copyable or not
// to suggest to use `.copied()` instead of `.cloned()` where applicable.
lint_path(cx, e.span, recv.span);
}
},
_ => {},
}
}
Expand All @@ -88,6 +101,23 @@ fn lint_needless_cloning(cx: &LateContext<'_>, root: Span, receiver: Span) {
);
}

fn lint_path(cx: &LateContext<'_>, replace: Span, root: Span) {
let mut applicability = Applicability::MachineApplicable;

span_lint_and_sugg(
cx,
MAP_CLONE,
replace,
"you are explicitly cloning with `.map()`",
"consider calling the dedicated `cloned` method",
format!(
"{}.cloned()",
snippet_with_applicability(cx, root, "..", &mut applicability),
),
applicability,
);
}

fn lint_explicit_closure(cx: &LateContext<'_>, replace: Span, root: Span, is_copy: bool, msrv: &Msrv) {
let mut applicability = Applicability::MachineApplicable;

Expand Down
2 changes: 1 addition & 1 deletion clippy_utils/src/macros.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -420,7 +420,7 @@ pub fn find_format_args(cx: &LateContext<'_>, start: &Expr<'_>, expn_id: ExpnId)
ast_format_args
.get()?
.get(&format_args_expr.span.with_parent(None))
.map(Rc::clone)
.cloned()
})
}

Expand Down
8 changes: 8 additions & 0 deletions tests/ui/useless_asref.fixed
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Original file line number Diff line number Diff line change
Expand Up @@ -132,6 +132,14 @@ fn generic_ok<U: AsMut<T> + AsRef<T> + ?Sized, T: Debug + ?Sized>(mru: &mut U) {
foo_rt(mru.as_ref());
}

fn foo() {
let x = Some(String::new());
let y = x.as_ref().cloned();
//~^ ERROR: you are explicitly cloning with `.map()`
let y = x.as_ref().cloned();
//~^ ERROR: you are explicitly cloning with `.map()`
}

fn main() {
not_ok();
ok();
Expand Down
8 changes: 8 additions & 0 deletions tests/ui/useless_asref.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -132,6 +132,14 @@ fn generic_ok<U: AsMut<T> + AsRef<T> + ?Sized, T: Debug + ?Sized>(mru: &mut U) {
foo_rt(mru.as_ref());
}

fn foo() {
let x = Some(String::new());
let y = x.as_ref().map(Clone::clone);
//~^ ERROR: you are explicitly cloning with `.map()`
let y = x.as_ref().map(String::clone);
//~^ ERROR: you are explicitly cloning with `.map()`
}

fn main() {
not_ok();
ok();
Expand Down
17 changes: 16 additions & 1 deletion tests/ui/useless_asref.stderr
View file
Original file line number Diff line number Diff line change
Expand Up @@ -70,5 +70,20 @@ error: this call to `as_ref` does nothing
LL | foo_rt(mrt.as_ref());
| ^^^^^^^^^^^^ help: try: `mrt`

error: aborting due to 11 previous errors
error: you are explicitly cloning with `.map()`
--> $DIR/useless_asref.rs:137:13
|
LL | let y = x.as_ref().map(Clone::clone);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider calling the dedicated `cloned` method: `x.as_ref().cloned()`
|
= note: `-D clippy::map-clone` implied by `-D warnings`
= help: to override `-D warnings` add `#[allow(clippy::map_clone)]`

error: you are explicitly cloning with `.map()`
--> $DIR/useless_asref.rs:139:13
|
LL | let y = x.as_ref().map(String::clone);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider calling the dedicated `cloned` method: `x.as_ref().cloned()`

error: aborting due to 13 previous errors

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