bjoernager/rust
bjoernager/rust
1
Fork 0
Code Issues Pull requests Activity

Fix handling of substitutions and binders when deciding whether to suggest references

Browse source 
When suggesting references, substitutions were being forgotten and some types were misused. This led to at
least one ICE and other incorrectly emitted diagnostics. This has been fixed; in some cases this leads to
diagnostics changing, and tests have been adjusted.
This commit is contained in:
Jakob Degen 2021-11-11 18:28:19 -05:00
parent d71ba74f0d
commit d58d52a397
5 changed files with 55 additions and 50 deletions
Download patch file Download diff file Expand all files Collapse all files

59
compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
View file

@ -706,36 +706,29 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
}
let param_env = obligation.param_env;
let trait_ref = poly_trait_ref.skip_binder();
let found_ty = trait_ref.self_ty();
let found_ty_str = found_ty.to_string();
let imm_borrowed_found_ty = self.tcx.mk_imm_ref(self.tcx.lifetimes.re_static, found_ty);
let imm_substs = self.tcx.mk_substs_trait(imm_borrowed_found_ty, &[]);
let mut_borrowed_found_ty = self.tcx.mk_mut_ref(self.tcx.lifetimes.re_static, found_ty);
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_imm_trait_ref: ty::Binder<'tcx, ty::TraitRef<'tcx>>,
new_mut_trait_ref: ty::Binder<'tcx, ty::TraitRef<'tcx>>,
expected_trait_ref: ty::Binder<'tcx, ty::TraitRef<'tcx>>,
let mut try_borrowing = |old_ref: ty::Binder<'tcx, ty::TraitRef<'tcx>>,
blacklist: &[DefId]|
-> bool {
if blacklist.contains(&expected_trait_ref.def_id()) {
if blacklist.contains(&old_ref.def_id()) {
return false;
}
let imm_result = self.predicate_must_hold_modulo_regions(&Obligation::new(
ObligationCause::dummy(),
param_env,
new_imm_trait_ref.without_const().to_predicate(self.tcx),
));
let mut_result = self.predicate_must_hold_modulo_regions(&Obligation::new(
ObligationCause::dummy(),
param_env,
new_mut_trait_ref.without_const().to_predicate(self.tcx),
));
let orig_ty = old_ref.self_ty().skip_binder();
let mk_result = |new_ty| {
let new_ref = old_ref.rebind(ty::TraitRef::new(
old_ref.def_id(),
self.tcx.mk_substs_trait(new_ty, &old_ref.skip_binder().substs[1..]),
));
self.predicate_must_hold_modulo_regions(&Obligation::new(
ObligationCause::dummy(),
param_env,
new_ref.without_const().to_predicate(self.tcx),
))
};
let imm_result = mk_result(self.tcx.mk_imm_ref(self.tcx.lifetimes.re_static, orig_ty));
let mut_result = mk_result(self.tcx.mk_mut_ref(self.tcx.lifetimes.re_static, orig_ty));
if imm_result || mut_result {
if let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(span) {
@ -747,8 +740,8 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
let msg = format!(
"the trait bound `{}: {}` is not satisfied",
found_ty_str,
expected_trait_ref.print_only_trait_path(),
orig_ty.to_string(),
old_ref.print_only_trait_path(),
);
if has_custom_message {
err.note(&msg);
@ -764,7 +757,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
span,
&format!(
"expected an implementor of trait `{}`",
expected_trait_ref.print_only_trait_path(),
old_ref.print_only_trait_path(),
),
);
@ -807,21 +800,11 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
};
if let ObligationCauseCode::ImplDerivedObligation(obligation) = &*code {
let expected_trait_ref = obligation.parent_trait_ref;
let new_imm_trait_ref = poly_trait_ref
.rebind(ty::TraitRef::new(obligation.parent_trait_ref.def_id(), imm_substs));
let new_mut_trait_ref = poly_trait_ref
.rebind(ty::TraitRef::new(obligation.parent_trait_ref.def_id(), mut_substs));
return try_borrowing(new_imm_trait_ref, new_mut_trait_ref, expected_trait_ref, &[]);
try_borrowing(obligation.parent_trait_ref, &[])
} else if let ObligationCauseCode::BindingObligation(_, _)
| ObligationCauseCode::ItemObligation(_) = &*code
{
return try_borrowing(
poly_trait_ref.rebind(ty::TraitRef::new(trait_ref.def_id, imm_substs)),
poly_trait_ref.rebind(ty::TraitRef::new(trait_ref.def_id, mut_substs)),
*poly_trait_ref,
&never_suggest_borrow[..],
);
try_borrowing(*poly_trait_ref, &never_suggest_borrow[..])
} else {
false
}