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Account for generics when suggesting bound

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Fix #81175.
This commit is contained in:
Esteban Küber 2021-01-19 12:44:49 -08:00
parent 1d0d76f8dd
commit 088c89d9ff
4 changed files with 156 additions and 15 deletions
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35
compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
View file

@ -286,21 +286,32 @@ fn suggest_restriction(
);
} else {
// Trivial case: `T` needs an extra bound: `T: Bound`.
let (sp, suggestion) = match super_traits {
None => predicate_constraint(
let (sp, suggestion) = match (
generics
.params
.iter()
.filter(
|p| !matches!(p.kind, hir::GenericParamKind::Type { synthetic: Some(_), ..}),
)
.next(),
super_traits,
) {
(_, None) => predicate_constraint(
generics,
trait_ref.without_const().to_predicate(tcx).to_string(),
),
Some((ident, bounds)) => match bounds {
[.., bound] => (
bound.span().shrink_to_hi(),
format!(" + {}", trait_ref.print_only_trait_path().to_string()),
),
[] => (
ident.span.shrink_to_hi(),
format!(": {}", trait_ref.print_only_trait_path().to_string()),
),
},
(None, Some((ident, []))) => (
ident.span.shrink_to_hi(),
format!(": {}", trait_ref.print_only_trait_path().to_string()),
),
(_, Some((_, [.., bounds]))) => (
bounds.span().shrink_to_hi(),
format!(" + {}", trait_ref.print_only_trait_path().to_string()),
),
(Some(_), Some((_, []))) => (
generics.span.shrink_to_hi(),
format!(": {}", trait_ref.print_only_trait_path().to_string()),
),
};
err.span_suggestion_verbose(