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Tweak output for bare dyn Trait in arguments

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Fix #35825.
This commit is contained in:
Esteban Küber 2022-12-14 18:51:55 -08:00
parent ba64ba8b0d
commit 124f19485d
10 changed files with 85 additions and 23 deletions
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28
compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
View file

@ -1618,7 +1618,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
let trait_obj = if has_dyn { &snippet[4..] } else { &snippet };
if only_never_return {
// No return paths, probably using `panic!()` or similar.
// Suggest `-> T`, `-> impl Trait`, and if `Trait` is object safe, `-> Box<dyn Trait>`.
// Suggest `-> impl Trait`, and if `Trait` is object safe, `-> Box<dyn Trait>`.
suggest_trait_object_return_type_alternatives(
err,
ret_ty.span,
@ -2540,6 +2540,25 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
}
ObligationCauseCode::SizedArgumentType(sp) => {
if let Some(span) = sp {
if let ty::PredicateKind::Clause(clause) = predicate.kind().skip_binder()
&& let ty::Clause::Trait(trait_pred) = clause
&& let ty::Dynamic(..) = trait_pred.self_ty().kind()
{
let span = if let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(span)
&& snippet.starts_with("dyn ")
{
let pos = snippet.len() - snippet[3..].trim_start().len();
span.with_hi(span.lo() + BytePos(pos as u32))
} else {
span.shrink_to_lo()
};
err.span_suggestion_verbose(
span,
"you can use `impl Trait` as the argument type",
"impl ".to_string(),
Applicability::MaybeIncorrect,
);
}
err.span_suggestion_verbose(
span.shrink_to_lo(),
"function arguments must have a statically known size, borrowed types \
@ -3580,13 +3599,6 @@ fn suggest_trait_object_return_type_alternatives(
trait_obj: &str,
is_object_safe: bool,
) {
err.span_suggestion(
ret_ty,
"use some type `T` that is `T: Sized` as the return type if all return paths have the \
same type",
"T",
Applicability::MaybeIncorrect,
);
err.span_suggestion(
ret_ty,
&format!(