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Sep 27, 2021
Merged

Suggest both of immutable and mutable trait implementations #89263

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0661c2d
suggest both immutable and mutable trait implementations
TaKO8Ki Sep 26, 2021
e2aad3f
fix the relevant tests
TaKO8Ki Sep 26, 2021
620f480
better suggestions
TaKO8Ki Sep 26, 2021
3e41397
fix test error
TaKO8Ki Sep 26, 2021
3bab363
test suggesting immutable or mutable trait implementations
TaKO8Ki Sep 26, 2021
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66 changes: 34 additions & 32 deletions compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
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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
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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
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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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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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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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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
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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
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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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