bjoernager/rust
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suggest both immutable and mutable trait implementations

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This commit is contained in:
Takayuki Maeda 2021-09-26 16:16:04 +09:00
parent 4da89a180f
commit 0661c2de24
3 changed files with 70 additions and 32 deletions
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66
compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
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@ -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
@ -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,
"consider borrowing here",
[format!("&{}", snippet), format!("&mut {}", snippet)].into_iter(),
Applicability::MaybeIncorrect,
);
} else {
err.span_suggestion(
span,
&format!(
"consider{} borrowing here",
if mut_result { " mutably" } else { "" }
),
format!("&{}{}", if mut_result { "mut " } else { "" }, snippet),
Applicability::MaybeIncorrect,
);
}
}
return true;
}
@ -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
}