1 files changed, 14 insertions, 0 deletions
diff --git a/src/test/ui/type-alias-impl-trait/issue-77179.rs b/src/test/ui/type-alias-impl-trait/issue-77179.rs
new file mode 100644
index 000000000..8d818d4a3
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-77179.rs
@@ -0,0 +1,14 @@
+// Regression test for #77179.
+
+#![feature(type_alias_impl_trait)]
+
+type Pointer<T> = impl std::ops::Deref<Target=T>;
+
+fn test() -> Pointer<_> {
+    //~^ ERROR: the placeholder `_` is not allowed within types
+    Box::new(1)
+}
+
+fn main() {
+    test();
+}