Rollup merge of #72556 - matthew-mcallister:trait-alias-inherent-impl, r=estebank

Fix trait alias inherent impl resolution

Fixes #60021 and fixes #72415.

Obviously, the fix was very easy, but getting started with the testing and debugging rust compiler was an interesting experience. Now I can cross it off my bucket list!

src/test/ui/traits/trait-alias/issue-60021-assoc-method-resolve.rs

@@ -0,0 +1,19 @@
+// check-pass
+
+#![feature(trait_alias)]
+
+trait SomeTrait {
+    fn map(&self) {}
+}
+
+impl<T> SomeTrait for Option<T> {}
+
+trait SomeAlias = SomeTrait;
+
+fn main() {
+    let x = Some(123);
+    // This should resolve to the trait impl for Option
+    Option::map(x, |z| z);
+    // This should resolve to the trait impl for SomeTrait
+    SomeTrait::map(&x);
+}

src/test/ui/traits/trait-alias/issue-72415-assoc-const-resolve.rs

@@ -0,0 +1,14 @@
+// check-pass
+
+#![feature(trait_alias)]
+
+trait Bounded { const MAX: Self; }
+
+impl Bounded for u32 {
+    // This should correctly resolve to the associated const in the inherent impl of u32.
+    const MAX: Self = u32::MAX;
+}
+
+trait Num = Bounded + Copy;
+
+fn main() {}