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workingjubileeworkingjubilee
authoredSep 27, 2024
Rollup merge of #130911 - notriddle:notriddle/suggest-wrap-parens-fn-pointer, r=compiler-errors
diagnostics: wrap fn cast suggestions in parens when needed Fixes #121632
·
1.86.01.83.0
2 parents 081b946 + c48b0d4 commit 6b0c897

12 files changed

+115
-11
lines changed
 

‎compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs

+25-4
Original file line numberDiff line numberDiff line change
@@ -33,7 +33,8 @@ use tracing::{debug, instrument};
3333
use super::on_unimplemented::{AppendConstMessage, OnUnimplementedNote};
3434
use super::suggestions::get_explanation_based_on_obligation;
3535
use super::{
36-
ArgKind, CandidateSimilarity, GetSafeTransmuteErrorAndReason, ImplCandidate, UnsatisfiedConst,
36+
ArgKind, CandidateSimilarity, FindExprBySpan, GetSafeTransmuteErrorAndReason, ImplCandidate,
37+
UnsatisfiedConst,
3738
};
3839
use crate::error_reporting::TypeErrCtxt;
3940
use crate::error_reporting::infer::TyCategory;
@@ -378,14 +379,34 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
378379
if let (ty::FnPtr(..), ty::FnDef(..)) =
379380
(cand.self_ty().kind(), main_trait_ref.self_ty().skip_binder().kind())
380381
{
381-
err.span_suggestion(
382-
span.shrink_to_hi(),
382+
// Wrap method receivers and `&`-references in parens
383+
let suggestion = if self.tcx.sess.source_map().span_look_ahead(span, ".", Some(50)).is_some() {
384+
vec![
385+
(span.shrink_to_lo(), format!("(")),
386+
(span.shrink_to_hi(), format!(" as {})", cand.self_ty())),
387+
]
388+
} else if let Some(body) = self.tcx.hir().maybe_body_owned_by(obligation.cause.body_id) {
389+
let mut expr_finder = FindExprBySpan::new(span, self.tcx);
390+
expr_finder.visit_expr(body.value);
391+
if let Some(expr) = expr_finder.result &&
392+
let hir::ExprKind::AddrOf(_, _, expr) = expr.kind {
393+
vec![
394+
(expr.span.shrink_to_lo(), format!("(")),
395+
(expr.span.shrink_to_hi(), format!(" as {})", cand.self_ty())),
396+
]
397+
} else {
398+
vec![(span.shrink_to_hi(), format!(" as {}", cand.self_ty()))]
399+
}
400+
} else {
401+
vec![(span.shrink_to_hi(), format!(" as {}", cand.self_ty()))]
402+
};
403+
err.multipart_suggestion(
383404
format!(
384405
"the trait `{}` is implemented for fn pointer `{}`, try casting using `as`",
385406
cand.print_trait_sugared(),
386407
cand.self_ty(),
387408
),
388-
format!(" as {}", cand.self_ty()),
409+
suggestion,
389410
Applicability::MaybeIncorrect,
390411
);
391412
true

‎src/tools/tidy/src/issues.txt

-1
Original file line numberDiff line numberDiff line change
@@ -4076,7 +4076,6 @@ ui/traits/issue-96664.rs
40764076
ui/traits/issue-96665.rs
40774077
ui/traits/issue-97576.rs
40784078
ui/traits/issue-97695-double-trivial-bound.rs
4079-
ui/traits/issue-99875.rs
40804079
ui/traits/next-solver/coherence/issue-102048.rs
40814080
ui/traits/next-solver/issue-118950-root-region.rs
40824081
ui/traits/object/issue-33140-traitobject-crate.rs

‎tests/ui/traits/issue-99875.stderr ‎tests/ui/traits/fn-pointer/bare-fn-no-impl-fn-ptr-99875.stderr

+6-6
Original file line numberDiff line numberDiff line change
@@ -1,13 +1,13 @@
11
error[E0277]: the trait bound `fn(Argument) -> Return {function}: Trait` is not satisfied
2-
--> $DIR/issue-99875.rs:12:11
2+
--> $DIR/bare-fn-no-impl-fn-ptr-99875.rs:12:11
33
|
44
LL | takes(function);
55
| ----- ^^^^^^^^ the trait `Trait` is not implemented for fn item `fn(Argument) -> Return {function}`
66
| |
77
| required by a bound introduced by this call
88
|
99
note: required by a bound in `takes`
10-
--> $DIR/issue-99875.rs:9:18
10+
--> $DIR/bare-fn-no-impl-fn-ptr-99875.rs:9:18
1111
|
1212
LL | fn takes(_: impl Trait) {}
1313
| ^^^^^ required by this bound in `takes`
@@ -16,17 +16,17 @@ help: the trait `Trait` is implemented for fn pointer `fn(Argument) -> Return`,
1616
LL | takes(function as fn(Argument) -> Return);
1717
| +++++++++++++++++++++++++
1818

19-
error[E0277]: the trait bound `{closure@$DIR/issue-99875.rs:14:11: 14:34}: Trait` is not satisfied
20-
--> $DIR/issue-99875.rs:14:11
19+
error[E0277]: the trait bound `{closure@$DIR/bare-fn-no-impl-fn-ptr-99875.rs:14:11: 14:34}: Trait` is not satisfied
20+
--> $DIR/bare-fn-no-impl-fn-ptr-99875.rs:14:11
2121
|
2222
LL | takes(|_: Argument| -> Return { todo!() });
23-
| ----- ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Trait` is not implemented for closure `{closure@$DIR/issue-99875.rs:14:11: 14:34}`
23+
| ----- ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Trait` is not implemented for closure `{closure@$DIR/bare-fn-no-impl-fn-ptr-99875.rs:14:11: 14:34}`
2424
| |
2525
| required by a bound introduced by this call
2626
|
2727
= help: the trait `Trait` is implemented for fn pointer `fn(Argument) -> Return`
2828
note: required by a bound in `takes`
29-
--> $DIR/issue-99875.rs:9:18
29+
--> $DIR/bare-fn-no-impl-fn-ptr-99875.rs:9:18
3030
|
3131
LL | fn takes(_: impl Trait) {}
3232
| ^^^^^ required by this bound in `takes`

‎tests/ui/traits/fn-pointer/suggest-wrap-parens-method.fixed

+15
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,15 @@
1+
//@ run-rustfix
2+
3+
trait Foo {}
4+
5+
impl Foo for fn() {}
6+
7+
trait Bar {
8+
fn do_stuff(&self) where Self: Foo {}
9+
}
10+
impl<T> Bar for T {}
11+
12+
fn main() {
13+
(main as fn()).do_stuff();
14+
//~^ ERROR the trait bound
15+
}

‎tests/ui/traits/fn-pointer/suggest-wrap-parens-method.rs

+15
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,15 @@
1+
//@ run-rustfix
2+
3+
trait Foo {}
4+
5+
impl Foo for fn() {}
6+
7+
trait Bar {
8+
fn do_stuff(&self) where Self: Foo {}
9+
}
10+
impl<T> Bar for T {}
11+
12+
fn main() {
13+
main.do_stuff();
14+
//~^ ERROR the trait bound
15+
}

‎tests/ui/traits/fn-pointer/suggest-wrap-parens-method.stderr

+19
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,19 @@
1+
error[E0277]: the trait bound `fn() {main}: Foo` is not satisfied
2+
--> $DIR/suggest-wrap-parens-method.rs:13:10
3+
|
4+
LL | main.do_stuff();
5+
| ^^^^^^^^ the trait `Foo` is not implemented for fn item `fn() {main}`
6+
|
7+
note: required by a bound in `Bar::do_stuff`
8+
--> $DIR/suggest-wrap-parens-method.rs:8:36
9+
|
10+
LL | fn do_stuff(&self) where Self: Foo {}
11+
| ^^^ required by this bound in `Bar::do_stuff`
12+
help: the trait `Foo` is implemented for fn pointer `fn()`, try casting using `as`
13+
|
14+
LL | (main as fn()).do_stuff();
15+
| + ++++++++
16+
17+
error: aborting due to 1 previous error
18+
19+
For more information about this error, try `rustc --explain E0277`.

‎tests/ui/traits/fn-pointer/suggest-wrap-parens.fixed

+10
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,10 @@
1+
//@ run-rustfix
2+
3+
trait Foo {}
4+
5+
impl Foo for fn() {}
6+
7+
fn main() {
8+
let _x: &dyn Foo = &(main as fn());
9+
//~^ ERROR the trait bound
10+
}

‎tests/ui/traits/fn-pointer/suggest-wrap-parens.rs

+10
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,10 @@
1+
//@ run-rustfix
2+
3+
trait Foo {}
4+
5+
impl Foo for fn() {}
6+
7+
fn main() {
8+
let _x: &dyn Foo = &main;
9+
//~^ ERROR the trait bound
10+
}

‎tests/ui/traits/fn-pointer/suggest-wrap-parens.stderr

+15
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,15 @@
1+
error[E0277]: the trait bound `fn() {main}: Foo` is not satisfied
2+
--> $DIR/suggest-wrap-parens.rs:8:24
3+
|
4+
LL | let _x: &dyn Foo = &main;
5+
| ^^^^^ the trait `Foo` is not implemented for fn item `fn() {main}`
6+
|
7+
= note: required for the cast from `&fn() {main}` to `&dyn Foo`
8+
help: the trait `Foo` is implemented for fn pointer `fn()`, try casting using `as`
9+
|
10+
LL | let _x: &dyn Foo = &(main as fn());
11+
| + ++++++++
12+
13+
error: aborting due to 1 previous error
14+
15+
For more information about this error, try `rustc --explain E0277`.

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