--- /dev/null
+error[E0658]: const generics are unstable
+ --> $DIR/const-param-in-trait-ungated.rs:1:19
+ |
+LL | trait Trait<const T: ()> {}
+ | ^
+ |
+ = note: for more information, see https://github.com/rust-lang/rust/issues/44580
+ = help: add #![feature(const_generics)] to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
--- /dev/null
+warning: the feature `const_generics` is incomplete and may cause the compiler to crash
+ --> $DIR/const-param-in-trait.rs:3:12
+ |
+LL | #![feature(const_generics)]
+ | ^^^^^^^^^^^^^^
+