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Auto merge of #89263 - TaKO8Ki:suggest-both-immutable-and-mutable-tra…
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…it-implementations, r=estebank

Suggest both of immutable and mutable trait implementations

closes #85865
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@bors
bors committed Sep 27, 2021
2 parents 583437a + 3bab363 commit 3e8f32e
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Showing 12 changed files with 211 additions and 92 deletions.
66 changes: 34 additions & 32 deletions compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -714,22 +714,28 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
let mut_substs = self.tcx.mk_substs_trait(mut_borrowed_found_ty, &[]);

// Try to apply the original trait binding obligation by borrowing.
let mut try_borrowing = |new_trait_ref: ty::TraitRef<'tcx>,
let mut try_borrowing = |new_imm_trait_ref: ty::TraitRef<'tcx>,
new_mut_trait_ref: ty::TraitRef<'tcx>,
expected_trait_ref: ty::TraitRef<'tcx>,
mtbl: bool,
blacklist: &[DefId]|
-> bool {
if blacklist.contains(&expected_trait_ref.def_id) {
return false;
}

let new_obligation = Obligation::new(
let imm_result = self.predicate_must_hold_modulo_regions(&Obligation::new(
ObligationCause::dummy(),
param_env,
ty::Binder::dummy(new_trait_ref).without_const().to_predicate(self.tcx),
);
ty::Binder::dummy(new_imm_trait_ref).without_const().to_predicate(self.tcx),
));

if self.predicate_must_hold_modulo_regions(&new_obligation) {
let mut_result = self.predicate_must_hold_modulo_regions(&Obligation::new(
ObligationCause::dummy(),
param_env,
ty::Binder::dummy(new_mut_trait_ref).without_const().to_predicate(self.tcx),
));

if imm_result || mut_result {
if let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(span) {
// We have a very specific type of error, where just borrowing this argument
// might solve the problem. In cases like this, the important part is the
Expand Down Expand Up @@ -773,15 +779,24 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
// }
// ```

err.span_suggestion(
span,
&format!(
"consider{} borrowing here",
if mtbl { " mutably" } else { "" }
),
format!("&{}{}", if mtbl { "mut " } else { "" }, snippet),
Applicability::MaybeIncorrect,
);
if imm_result && mut_result {
err.span_suggestions(
span.shrink_to_lo(),
"consider borrowing here",
["&".to_string(), "&mut ".to_string()].into_iter(),
Applicability::MaybeIncorrect,
);
} else {
err.span_suggestion_verbose(
span.shrink_to_lo(),
&format!(
"consider{} borrowing here",
if mut_result { " mutably" } else { "" }
),
format!("&{}", if mut_result { "mut " } else { "" }),
Applicability::MaybeIncorrect,
);
}
}
return true;
}
Expand All @@ -795,29 +810,16 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
ty::TraitRef::new(obligation.parent_trait_ref.def_id(), imm_substs);
let new_mut_trait_ref =
ty::TraitRef::new(obligation.parent_trait_ref.def_id(), mut_substs);
if try_borrowing(new_imm_trait_ref, expected_trait_ref, false, &[]) {
return true;
} else {
return try_borrowing(new_mut_trait_ref, expected_trait_ref, true, &[]);
}
return try_borrowing(new_imm_trait_ref, new_mut_trait_ref, expected_trait_ref, &[]);
} else if let ObligationCauseCode::BindingObligation(_, _)
| ObligationCauseCode::ItemObligation(_) = &*code
{
if try_borrowing(
return try_borrowing(
ty::TraitRef::new(trait_ref.def_id, imm_substs),
ty::TraitRef::new(trait_ref.def_id, mut_substs),
trait_ref,
false,
&never_suggest_borrow[..],
) {
return true;
} else {
return try_borrowing(
ty::TraitRef::new(trait_ref.def_id, mut_substs),
trait_ref,
true,
&never_suggest_borrow[..],
);
}
);
} else {
false
}
Expand Down
30 changes: 18 additions & 12 deletions src/test/ui/derives/deriving-copyclone.stderr
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2,10 +2,8 @@ error[E0277]: the trait bound `C: Copy` is not satisfied
--> $DIR/deriving-copyclone.rs:31:13
|
LL | is_copy(B { a: 1, b: C });
| ------- ^^^^^^^^^^^^^^^^
| | |
| | expected an implementor of trait `Copy`
| | help: consider borrowing here: `&B { a: 1, b: C }`
| ------- ^^^^^^^^^^^^^^^^ expected an implementor of trait `Copy`
| |
| required by a bound introduced by this call
|
note: required because of the requirements on the impl of `Copy` for `B<C>`
Expand All @@ -19,15 +17,17 @@ note: required by a bound in `is_copy`
LL | fn is_copy<T: Copy>(_: T) {}
| ^^^^ required by this bound in `is_copy`
= note: this error originates in the derive macro `Copy` (in Nightly builds, run with -Z macro-backtrace for more info)
help: consider borrowing here
|
LL | is_copy(&B { a: 1, b: C });
| +

error[E0277]: the trait bound `C: Clone` is not satisfied
--> $DIR/deriving-copyclone.rs:32:14
|
LL | is_clone(B { a: 1, b: C });
| -------- ^^^^^^^^^^^^^^^^
| | |
| | expected an implementor of trait `Clone`
| | help: consider borrowing here: `&B { a: 1, b: C }`
| -------- ^^^^^^^^^^^^^^^^ expected an implementor of trait `Clone`
| |
| required by a bound introduced by this call
|
note: required because of the requirements on the impl of `Clone` for `B<C>`
Expand All @@ -41,15 +41,17 @@ note: required by a bound in `is_clone`
LL | fn is_clone<T: Clone>(_: T) {}
| ^^^^^ required by this bound in `is_clone`
= note: this error originates in the derive macro `Clone` (in Nightly builds, run with -Z macro-backtrace for more info)
help: consider borrowing here
|
LL | is_clone(&B { a: 1, b: C });
| +

error[E0277]: the trait bound `D: Copy` is not satisfied
--> $DIR/deriving-copyclone.rs:35:13
|
LL | is_copy(B { a: 1, b: D });
| ------- ^^^^^^^^^^^^^^^^
| | |
| | expected an implementor of trait `Copy`
| | help: consider borrowing here: `&B { a: 1, b: D }`
| ------- ^^^^^^^^^^^^^^^^ expected an implementor of trait `Copy`
| |
| required by a bound introduced by this call
|
note: required because of the requirements on the impl of `Copy` for `B<D>`
Expand All @@ -63,6 +65,10 @@ note: required by a bound in `is_copy`
LL | fn is_copy<T: Copy>(_: T) {}
| ^^^^ required by this bound in `is_copy`
= note: this error originates in the derive macro `Copy` (in Nightly builds, run with -Z macro-backtrace for more info)
help: consider borrowing here
|
LL | is_copy(&B { a: 1, b: D });
| +

error: aborting due to 3 previous errors

Expand Down
9 changes: 5 additions & 4 deletions src/test/ui/issues/issue-20605.stderr
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2,10 +2,7 @@ error[E0277]: the size for values of type `dyn Iterator<Item = &'a mut u8>` cann
--> $DIR/issue-20605.rs:2:17
|
LL | for item in *things { *item = 0 }
| ^^^^^^^
| |
| expected an implementor of trait `IntoIterator`
| help: consider mutably borrowing here: `&mut *things`
| ^^^^^^^ expected an implementor of trait `IntoIterator`
|
= note: the trait bound `dyn Iterator<Item = &'a mut u8>: IntoIterator` is not satisfied
= note: required because of the requirements on the impl of `IntoIterator` for `dyn Iterator<Item = &'a mut u8>`
Expand All @@ -14,6 +11,10 @@ note: required by `into_iter`
|
LL | fn into_iter(self) -> Self::IntoIter;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
help: consider mutably borrowing here
|
LL | for item in &mut *things { *item = 0 }
| ++++

error: aborting due to previous error

Expand Down
10 changes: 6 additions & 4 deletions src/test/ui/suggestions/imm-ref-trait-object-literal.stderr
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Original file line number Diff line number Diff line change
Expand Up @@ -22,17 +22,19 @@ error[E0277]: the trait bound `S: Trait` is not satisfied
--> $DIR/imm-ref-trait-object-literal.rs:13:7
|
LL | foo(s);
| --- ^
| | |
| | expected an implementor of trait `Trait`
| | help: consider mutably borrowing here: `&mut s`
| --- ^ expected an implementor of trait `Trait`
| |
| required by a bound introduced by this call
|
note: required by a bound in `foo`
--> $DIR/imm-ref-trait-object-literal.rs:7:11
|
LL | fn foo<X: Trait>(_: X) {}
| ^^^^^ required by this bound in `foo`
help: consider mutably borrowing here
|
LL | foo(&mut s);
| ++++

error: aborting due to 2 previous errors

Expand Down
10 changes: 6 additions & 4 deletions src/test/ui/suggestions/issue-62843.stderr
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Original file line number Diff line number Diff line change
Expand Up @@ -2,14 +2,16 @@ error[E0277]: expected a `FnMut<(char,)>` closure, found `String`
--> $DIR/issue-62843.rs:4:32
|
LL | println!("{:?}", line.find(pattern));
| ---- ^^^^^^^
| | |
| | expected an implementor of trait `Pattern<'_>`
| | help: consider borrowing here: `&pattern`
| ---- ^^^^^^^ expected an implementor of trait `Pattern<'_>`
| |
| required by a bound introduced by this call
|
= note: the trait bound `String: Pattern<'_>` is not satisfied
= note: required because of the requirements on the impl of `Pattern<'_>` for `String`
help: consider borrowing here
|
LL | println!("{:?}", line.find(&pattern));
| +

error: aborting due to previous error

Expand Down
10 changes: 6 additions & 4 deletions src/test/ui/suggestions/issue-84973-2.stderr
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Original file line number Diff line number Diff line change
Expand Up @@ -2,17 +2,19 @@ error[E0277]: the trait bound `i32: Tr` is not satisfied
--> $DIR/issue-84973-2.rs:11:9
|
LL | foo(a);
| --- ^
| | |
| | expected an implementor of trait `Tr`
| | help: consider mutably borrowing here: `&mut a`
| --- ^ expected an implementor of trait `Tr`
| |
| required by a bound introduced by this call
|
note: required by a bound in `foo`
--> $DIR/issue-84973-2.rs:7:11
|
LL | fn foo<T: Tr>(i: T) {}
| ^^ required by this bound in `foo`
help: consider mutably borrowing here
|
LL | foo(&mut a);
| ++++

error: aborting due to previous error

Expand Down
10 changes: 6 additions & 4 deletions src/test/ui/suggestions/issue-84973-negative.stderr
View file
Original file line number Diff line number Diff line change
Expand Up @@ -16,17 +16,19 @@ error[E0277]: the trait bound `f32: Tr` is not satisfied
--> $DIR/issue-84973-negative.rs:11:9
|
LL | bar(b);
| --- ^
| | |
| | expected an implementor of trait `Tr`
| | help: consider borrowing here: `&b`
| --- ^ expected an implementor of trait `Tr`
| |
| required by a bound introduced by this call
|
note: required by a bound in `bar`
--> $DIR/issue-84973-negative.rs:5:11
|
LL | fn bar<T: Tr>(t: T) {}
| ^^ required by this bound in `bar`
help: consider borrowing here
|
LL | bar(&b);
| +

error: aborting due to 2 previous errors

Expand Down
10 changes: 6 additions & 4 deletions src/test/ui/suggestions/issue-84973.stderr
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2,17 +2,19 @@ error[E0277]: the trait bound `Fancy: SomeTrait` is not satisfied
--> $DIR/issue-84973.rs:6:24
|
LL | let o = Other::new(f);
| ---------- ^
| | |
| | expected an implementor of trait `SomeTrait`
| | help: consider borrowing here: `&f`
| ---------- ^ expected an implementor of trait `SomeTrait`
| |
| required by a bound introduced by this call
|
note: required by `Other::<'a, G>::new`
--> $DIR/issue-84973.rs:27:5
|
LL | pub fn new(g: G) -> Self {
| ^^^^^^^^^^^^^^^^^^^^^^^^
help: consider borrowing here
|
LL | let o = Other::new(&f);
| +

error: aborting due to previous error

Expand Down
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