1 files changed, 31 insertions, 0 deletions
diff --git a/tests/ui/consts/underscore_const_names.rs b/tests/ui/consts/underscore_const_names.rs
new file mode 100644
index 000000000..d0e625bf1
--- /dev/null
+++ b/tests/ui/consts/underscore_const_names.rs
@@ -0,0 +1,31 @@
+// build-pass (FIXME(62277): could be check-pass?)
+
+#![deny(unused)]
+
+trait Trt {}
+pub struct Str {}
+impl Trt for Str {}
+
+macro_rules! check_impl {
+    ($struct:ident,$trait:ident) => {
+        const _ : () = {
+            use std::marker::PhantomData;
+            struct ImplementsTrait<T: $trait>(PhantomData<T>);
+            let _ = ImplementsTrait::<$struct>(PhantomData);
+            ()
+        };
+    }
+}
+
+const _ : () = ();
+
+const _ : i32 = 42;
+const _ : Str = Str{};
+
+check_impl!(Str, Trt);
+check_impl!(Str, Trt);
+
+fn main() {
+  check_impl!(Str, Trt);
+  check_impl!(Str, Trt);
+}