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This commit is contained in:
Esteban Küber 2020-01-16 11:32:50 -08:00
parent 00e2626895
commit 029a9c6253
2 changed files with 24 additions and 27 deletions
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49
src/librustc/traits/error_reporting/suggestions.rs
View File

@ -605,34 +605,31 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
let tables = self.in_progress_tables.map(|t| t.borrow()).unwrap();
let mut all_returns_conform_to_trait = true;
let mut all_returns_have_same_type = true;
let mut last_ty = None;
if let Some(ty_ret_ty) = tables.node_type_opt(ret_ty.hir_id) {
let cause = ObligationCause::misc(ret_ty.span, ret_ty.hir_id);
let param_env = ty::ParamEnv::empty();
if let ty::Dynamic(predicates, _) = &ty_ret_ty.kind {
for expr in &visitor.0 {
if let Some(returned_ty) = tables.node_type_opt(expr.hir_id) {
all_returns_have_same_type &=
Some(returned_ty) == last_ty || last_ty.is_none();
last_ty = Some(returned_ty);
for predicate in predicates.iter() {
let pred = predicate.with_self_ty(self.tcx, returned_ty);
let obl = Obligation::new(cause.clone(), param_env, pred);
all_returns_conform_to_trait &= self.predicate_may_hold(&obl);
}
let mut ret_types = visitor.0.iter().filter_map(|expr| tables.node_type_opt(expr.hir_id));
let (last_ty, all_returns_have_same_type) =
ret_types.clone().fold((None, true), |(last_ty, mut same), returned_ty| {
same &= last_ty.map_or(true, |ty| ty == returned_ty);
(Some(returned_ty), same)
});
let all_returns_conform_to_trait =
if let Some(ty_ret_ty) = tables.node_type_opt(ret_ty.hir_id) {
match ty_ret_ty.kind {
ty::Dynamic(predicates, _) => {
let cause = ObligationCause::misc(ret_ty.span, ret_ty.hir_id);
let param_env = ty::ParamEnv::empty();
ret_types.all(|returned_ty| {
predicates.iter().all(|predicate| {
let pred = predicate.with_self_ty(self.tcx, returned_ty);
let obl = Obligation::new(cause.clone(), param_env, pred);
self.predicate_may_hold(&obl)
})
})
}
_ => true,
}
}
} else {
// We still want to verify whether all the return types conform to each other.
for expr in &visitor.0 {
let returned_ty = tables.node_type_opt(expr.hir_id);
all_returns_have_same_type &= last_ty == returned_ty || last_ty.is_none();
last_ty = returned_ty;
}
}
} else {
true
};
let (snippet, last_ty) =
if let (true, hir::TyKind::TraitObject(..), Ok(snippet), true, Some(last_ty)) = (

2
src/librustc_error_codes/error_codes/E0746.md
View File

@ -13,7 +13,7 @@ impl T for S {
}
// Having the trait `T` as return type is invalid because
// bare trait objects do not have a statically known size:
// unboxed trait objects do not have a statically known size:
fn foo() -> dyn T {
S(42)
}