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E0220: only suggests associated types if there's only one candidate

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Lieselotte 2023-09-08 08:44:23 +02:00
parent 96c96645c7
commit a0e0a3261e
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7 changed files with 27 additions and 49 deletions
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44
compiler/rustc_hir_analysis/src/astconv/errors.rs
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@ -201,34 +201,28 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
}
}
// If we still couldn't find any associated type, just list them all.
// If we still couldn't find any associated type, and only one associated type exists,
// suggests using it.
if all_candidate_names.is_empty() {
err.help(format!(
"`{ty_param_name}` has no associated type, try removing `{assoc_name}`"
));
return err.emit();
if all_candidate_names.len() == 1 {
// this should still compile, except on `#![feature(associated_type_defaults)]`
// where it could suggests `type A = Self::A`, thus recursing infinitely
let applicability = if self.tcx().features().associated_type_defaults {
Applicability::Unspecified
} else {
Applicability::MaybeIncorrect
};
err.span_suggestion(
assoc_name.span,
format!("`{ty_param_name}` has the following associated type"),
all_candidate_names.first().unwrap().to_string(),
applicability,
);
} else {
err.span_label(assoc_name.span, format!("associated type `{assoc_name}` not found"));
}
let msg = if all_candidate_names.len() > 1 {
format!("`{ty_param_name}` has the following associated types")
} else {
format!("`{ty_param_name}` has the following associated type")
};
let applicability = if self.tcx().features().associated_type_defaults {
Applicability::Unspecified // `type A = Self::B` would suggest `type A = Self::A`
} else {
Applicability::MaybeIncorrect
};
err.span_suggestions(
assoc_name.span,
msg,
all_candidate_names.iter().map(|symbol| symbol.to_string()),
applicability,
);
err.emit()
}