rustc: fix ICE when trait alias has bare Self

Author: seanmonstar

src/librustc/hir/map/mod.rs

@@ -541,15 +541,17 @@ impl<'hir> Map<'hir> {
 
     pub fn ty_param_owner(&self, id: HirId) -> HirId {
         match self.get_by_hir_id(id) {
-            Node::Item(&Item { node: ItemKind::Trait(..), .. }) => id,
+            Node::Item(&Item { node: ItemKind::Trait(..), .. }) |
+            Node::Item(&Item { node: ItemKind::TraitAlias(..), .. }) => id,
             Node::GenericParam(_) => self.get_parent_node_by_hir_id(id),
             _ => bug!("ty_param_owner: {} not a type parameter", self.hir_to_string(id))
         }
     }
 
     pub fn ty_param_name(&self, id: HirId) -> Name {
         match self.get_by_hir_id(id) {
-            Node::Item(&Item { node: ItemKind::Trait(..), .. }) => keywords::SelfUpper.name(),
+            Node::Item(&Item { node: ItemKind::Trait(..), .. }) |
+            Node::Item(&Item { node: ItemKind::TraitAlias(..), .. }) => keywords::SelfUpper.name(),
             Node::GenericParam(param) => param.name.ident().name,
             _ => bug!("ty_param_name: {} not a type parameter", self.hir_to_string(id)),
         }

src/test/ui/issues/issue-59029-1.rs

@@ -0,0 +1,8 @@
+#![feature(trait_alias)]
+
+trait Svc<Req> { type Res; }
+
+trait MkSvc<Target, Req> = Svc<Target> where Self::Res: Svc<Req>;
+//~^ ERROR associated type `Res` not found for `Self`
+
+fn main() {}

src/test/ui/issues/issue-59029-1.stderr

@@ -0,0 +1,9 @@
+error[E0220]: associated type `Res` not found for `Self`
+  --> $DIR/issue-59029-1.rs:5:46
+   |
+LL | trait MkSvc<Target, Req> = Svc<Target> where Self::Res: Svc<Req>;
+   |                                              ^^^^^^^^^ associated type `Res` not found
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0220`.

src/test/ui/issues/issue-59029-2.rs

@@ -0,0 +1,8 @@
+// run-pass
+#![feature(trait_alias)]
+
+trait Svc<Req> { type Res; }
+
+trait MkSvc<Target, Req> = Svc<Target> where <Self as Svc<Target>>::Res: Svc<Req>;
+
+fn main() {}