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Rollup merge of #122174 - notriddle:master, r=TaKO8Ki

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diagnostics: suggest `Clone` bounds when noop `clone()`

Fixes #121524
This commit is contained in:
Matthias Krüger 2024-03-15 10:14:54 +01:00 • committed by GitHub
commit e66c7e479c
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3 changed files with 88 additions and 10 deletions
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60
compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
View file

@ -987,10 +987,6 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
else {
return false;
};
let arg_node = self.tcx.hir_node(*arg_hir_id);
let Node::Expr(Expr { kind: hir::ExprKind::Path(_), .. }) = arg_node else {
return false;
};
let clone_trait = self.tcx.require_lang_item(LangItem::Clone, None);
let has_clone = |ty| {
@ -998,6 +994,39 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
.must_apply_modulo_regions()
};
let existing_clone_call = match self.tcx.hir_node(*arg_hir_id) {
// It's just a variable. Propose cloning it.
Node::Expr(Expr { kind: hir::ExprKind::Path(_), .. }) => None,
// It's already a call to `clone()`. We might be able to suggest
// adding a `+ Clone` bound, though.
Node::Expr(Expr {
kind:
hir::ExprKind::MethodCall(
hir::PathSegment { ident, .. },
_receiver,
&[],
call_span,
),
hir_id,
..
}) if ident.name == sym::clone
&& !call_span.from_expansion()
&& !has_clone(*inner_ty) =>
{
// We only care about method calls corresponding to the real `Clone` trait.
let Some(typeck_results) = self.typeck_results.as_ref() else { return false };
let Some((DefKind::AssocFn, did)) = typeck_results.type_dependent_def(*hir_id)
else {
return false;
};
if self.tcx.trait_of_item(did) != Some(clone_trait) {
return false;
}
Some(ident.span)
}
_ => return false,
};
let new_obligation = self.mk_trait_obligation_with_new_self_ty(
obligation.param_env,
trait_pred.map_bound(|trait_pred| (trait_pred, *inner_ty)),
@ -1015,12 +1044,23 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
None,
);
}
err.span_suggestion_verbose(
obligation.cause.span.shrink_to_hi(),
"consider using clone here",
".clone()".to_string(),
Applicability::MaybeIncorrect,
);
if let Some(existing_clone_call) = existing_clone_call {
err.span_note(
existing_clone_call,
format!(
"this `clone()` copies the reference, \
which does not do anything, \
because `{inner_ty}` does not implement `Clone`"
),
);
} else {
err.span_suggestion_verbose(
obligation.cause.span.shrink_to_hi(),
"consider using clone here",
".clone()".to_string(),
Applicability::MaybeIncorrect,
);
}
return true;
}
false