Rollup merge of #57502 - nikomatsakis:fix-trait-alias-1b, r=nikomatsakis

make trait-aliases work across crates

This is rebase of a small part of @alexreg's PR #55994. It focuses just on the changes that integrate trait aliases properly into crate metadata, excluding the stylistic edits and the trait objects.

The stylistic edits I also rebased and can open a separate PR.

The trait object stuff I found challenging and decided it basically needed to be reimplemented. For now I've excluded it.

Since this is really @alexreg's work (I really just rebased) I am going to make it r=me once it is working.

Fixes #56488.
Fixes #57023.

1 files changed, 3 insertions, 0 deletions

diff --git a/src/librustc_resolve/build_reduced_graph.rs b/src/librustc_resolve/build_reduced_graph.rs
index a452bbf0c9d..28b80fe3aaf 100644
--- a/src/librustc_resolve/build_reduced_graph.rs
+++ b/src/librustc_resolve/build_reduced_graph.rs
@@ -673,6 +673,9 @@ impl<'a> Resolver<'a> {
                 }
                 module.populated.set(true);
             }
+            Def::TraitAlias(..) => {
+                self.define(parent, ident, TypeNS, (def, vis, DUMMY_SP, expansion));
+            }
             Def::Struct(..) | Def::Union(..) => {
                 self.define(parent, ident, TypeNS, (def, vis, DUMMY_SP, expansion));