1 files changed, 33 insertions, 0 deletions
diff --git a/tests/ui/traits/trait-upcasting/alias-where-clause-isnt-supertrait.rs b/tests/ui/traits/trait-upcasting/alias-where-clause-isnt-supertrait.rs
new file mode 100644
index 000000000..4a5e445d1
--- /dev/null
+++ b/tests/ui/traits/trait-upcasting/alias-where-clause-isnt-supertrait.rs
@@ -0,0 +1,33 @@
+#![feature(trait_upcasting)]
+#![feature(trait_alias)]
+
+// Although we *elaborate* `T: Alias` to `i32: B`, we should
+// not consider `B` to be a supertrait of the type.
+trait Alias = A where i32: B;
+
+trait A {}
+
+trait B {
+    fn test(&self);
+}
+
+trait C: Alias {}
+
+impl A for () {}
+
+impl C for () {}
+
+impl B for i32 {
+    fn test(&self) {
+        println!("hi {self}");
+    }
+}
+
+fn test(x: &dyn C) -> &dyn B {
+    x
+    //~^ ERROR mismatched types
+}
+
+fn main() {
+    let x: &dyn C = &();
+}