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Rollup merge of #116553 - gurry:116464-assoc-type-invalid-suggestion, r=compiler-errors

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Do not suggest 'Trait<Assoc=arg>' when in trait impl

Fixes #116464

We now skip the suggestion if we're in an impl of the trait.
This commit is contained in:
Matthias Krüger 2023-10-25 23:37:09 +02:00 • committed by GitHub
commit 824dbb53fb
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3 changed files with 209 additions and 13 deletions
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70
compiler/rustc_hir_analysis/src/structured_errors/wrong_number_of_generic_args.rs
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@ -129,6 +129,44 @@ impl<'a, 'tcx> WrongNumberOfGenericArgs<'a, 'tcx> {
if self.missing_lifetimes() { "lifetime" } else { "generic" }
}
/// Returns true if the generic type is a trait
/// and is being referred to from one of its trait impls
fn is_in_trait_impl(&self) -> bool {
if self.tcx.is_trait(self.def_id) {
// Here we check if the reference to the generic type
// is from the 'of_trait' field of the enclosing impl
let parent = self.tcx.hir().get_parent(self.path_segment.hir_id);
let parent_item = self
.tcx
.hir()
.get_by_def_id(self.tcx.hir().get_parent_item(self.path_segment.hir_id).def_id);
// Get the HIR id of the trait ref
let hir::Node::TraitRef(hir::TraitRef { hir_ref_id: trait_ref_id, .. }) = parent else {
return false;
};
// Get the HIR id of the 'of_trait' field of the impl
let hir::Node::Item(hir::Item {
kind:
hir::ItemKind::Impl(hir::Impl {
of_trait: Some(hir::TraitRef { hir_ref_id: id_in_of_trait, .. }),
..
}),
..
}) = parent_item
else {
return false;
};
// Check that trait is referred to from the of_trait field of impl
trait_ref_id == id_in_of_trait
} else {
false
}
}
fn num_provided_args(&self) -> usize {
if self.missing_lifetimes() {
self.num_provided_lifetime_args()
@ -955,20 +993,26 @@ impl<'a, 'tcx> WrongNumberOfGenericArgs<'a, 'tcx> {
// If there is a single unbound associated type and a single excess generic param
// suggest replacing the generic param with the associated type bound
if provided_args_matches_unbound_traits && !unbound_types.is_empty() {
let unused_generics = &self.gen_args.args[self.num_expected_type_or_const_args()..];
let suggestions = iter::zip(unused_generics, &unbound_types)
.map(|(potential, name)| (potential.span().shrink_to_lo(), format!("{name} = ")))
.collect::<Vec<_>>();
// Don't suggest if we're in a trait impl as
// that would result in invalid syntax (fixes #116464)
if !self.is_in_trait_impl() {
let unused_generics = &self.gen_args.args[self.num_expected_type_or_const_args()..];
let suggestions = iter::zip(unused_generics, &unbound_types)
.map(|(potential, name)| {
(potential.span().shrink_to_lo(), format!("{name} = "))
})
.collect::<Vec<_>>();
if !suggestions.is_empty() {
err.multipart_suggestion_verbose(
format!(
"replace the generic bound{s} with the associated type{s}",
s = pluralize!(unbound_types.len())
),
suggestions,
Applicability::MaybeIncorrect,
);
if !suggestions.is_empty() {
err.multipart_suggestion_verbose(
format!(
"replace the generic bound{s} with the associated type{s}",
s = pluralize!(unbound_types.len())
),
suggestions,
Applicability::MaybeIncorrect,
);
}
}
} else if remove_entire_generics {
let span = self