Better group RFC ui tests together

tests/ui/rfcs/rfc-2632-const-trait-impl/specializing-constness.rs

@@ -0,0 +1,31 @@
+#![feature(const_trait_impl, min_specialization, rustc_attrs)]
+
+#[rustc_specialization_trait]
+#[const_trait]
+pub trait Sup {}
+
+impl const Sup for () {}
+
+#[const_trait]
+pub trait A {
+    fn a() -> u32;
+}
+
+#[const_trait]
+pub trait Spec {}
+
+impl<T: ~const Spec> const A for T {
+    default fn a() -> u32 {
+        2
+    }
+}
+
+impl<T: Spec + Sup> A for T {
+//~^ ERROR: cannot specialize
+//~| ERROR: missing `~const` qualifier
+    fn a() -> u32 {
+        3
+    }
+}
+
+fn main() {}