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diff --git a/tests/ui/rfcs/rfc-2632-const-trait-impl/mbe-const-trait-bound-theoretical-regression.rs b/tests/ui/rfcs/rfc-2632-const-trait-impl/mbe-const-trait-bound-theoretical-regression.rs
new file mode 100644
index 00000000000..9105cb6b043
--- /dev/null
+++ b/tests/ui/rfcs/rfc-2632-const-trait-impl/mbe-const-trait-bound-theoretical-regression.rs
@@ -0,0 +1,20 @@
+// Demonstrates and records a theoretical regressions / breaking changes caused by the
+// introduction of const trait bounds.
+
+// Setting the edition to 2018 since we don't regress `demo! { dyn const }` in Rust <2018.
+// edition:2018
+
+macro_rules! demo {
+    ($ty:ty) => { compile_error!("ty"); };
+    (impl $c:ident) => {};
+    (dyn $c:ident) => {};
+}
+
+demo! { impl const }
+//~^ ERROR expected identifier, found `<eof>`
+
+demo! { dyn const }
+//~^ ERROR const trait impls are experimental
+//~| ERROR expected identifier, found `<eof>`
+
+fn main() {}