Rollup merge of #27202 - apasel422:issue-21174, r=alexcrichton

Author: steveklabnik

src/test/compile-fail/issue-21174.rs

@@ -15,7 +15,7 @@ trait Trait<'a> {
 
 fn foo<'a, T: Trait<'a>>(value: T::A) {
     let new: T::B = unsafe { std::mem::transmute(value) };
-//~^ ERROR: cannot transmute to or from a type that contains type parameters in its interior [E0139]
+//~^ ERROR: cannot transmute to or from a type that contains unsubstituted type parameters [E0139]
 }
 
 fn main() { }