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Factored out part of conv_object_ty_poly_trait_ref method.

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This commit is contained in:
Alexander Regueiro 2019-03-28 01:29:31 +00:00
parent 16692f7b1a
commit 5f6c2127d7
1 changed files with 25 additions and 15 deletions
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40
src/librustc_typeck/astconv.rs
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@ -965,6 +965,30 @@ impl<'o, 'gcx: 'tcx, 'tcx> dyn AstConv<'gcx, 'tcx> + 'o {
ty::ExistentialTraitRef::erase_self_ty(self.tcx(), trait_ref)
}
fn expand_trait_refs(&self,
trait_refs: impl IntoIterator<Item = (ty::PolyTraitRef<'tcx>, Span)>
) -> Vec<DefId> {
let tcx = self.tcx();
// Expand trait aliases recursively and check that only one regular (non-auto) trait
// is used.
let expanded_traits = traits::expand_trait_refs(tcx, trait_refs);
let (auto_traits, regular_traits): (Vec<_>, Vec<_>) =
expanded_traits.partition(|i| tcx.trait_is_auto(i.trait_ref.def_id()));
if regular_traits.len() > 1 {
let extra_trait = &regular_traits[1];
let mut err = struct_span_err!(tcx.sess, extra_trait.top_level_span, E0225,
"only auto traits can be used as additional traits in a trait object");
err.span_label(extra_trait.span, "non-auto additional trait");
if extra_trait.span != extra_trait.top_level_span {
err.span_label(extra_trait.top_level_span, "expanded from this trait alias");
}
err.emit();
}
auto_traits.into_iter().map(|i| i.trait_ref.def_id()).collect()
}
fn conv_object_ty_poly_trait_ref(&self,
span: Span,
trait_bounds: &[hir::PolyTraitRef],
@ -1000,19 +1024,7 @@ impl<'o, 'gcx: 'tcx, 'tcx> dyn AstConv<'gcx, 'tcx> + 'o {
}
bound_trait_refs.push((principal, trait_bounds[0].span));
let expanded_traits = traits::expand_trait_refs(tcx, bound_trait_refs);
let (auto_traits, regular_traits): (Vec<_>, Vec<_>) =
expanded_traits.partition(|i| tcx.trait_is_auto(i.trait_ref.def_id()));
if regular_traits.len() > 1 {
let extra_trait = &regular_traits[1];
let mut err = struct_span_err!(tcx.sess, extra_trait.top_level_span, E0225,
"only auto traits can be used as additional traits in a trait object");
err.span_label(extra_trait.span, "non-auto additional trait");
if extra_trait.span != extra_trait.top_level_span {
err.span_label(extra_trait.top_level_span, "expanded from this trait alias");
}
err.emit();
}
let mut auto_traits = self.expand_trait_refs(bound_trait_refs);
// Check that there are no gross object safety violations;
// most importantly, that the supertraits don't contain `Self`,
@ -1156,8 +1168,6 @@ impl<'o, 'gcx: 'tcx, 'tcx> dyn AstConv<'gcx, 'tcx> + 'o {
// De-duplicate auto traits so that, e.g., `dyn Trait + Send + Send` is the same as
// `dyn Trait + Send`.
let mut auto_traits: Vec<_> =
auto_traits.into_iter().map(|i| i.trait_ref.def_id()).collect();
auto_traits.sort();
auto_traits.dedup();
debug!("auto_traits: {:?}", auto_traits);