Update test error compilation message for E0512

Author: GuillaumeGomez

src/test/compile-fail/transmute-fat-pointers.rs

@@ -15,11 +15,11 @@
 use std::mem::transmute;
 
 fn a<T, U: ?Sized>(x: &[T]) -> &U {
-    unsafe { transmute(x) } //~ ERROR transmute called on types with potentially different sizes
+    unsafe { transmute(x) } //~ ERROR transmute called with differently sized types
 }
 
 fn b<T: ?Sized, U: ?Sized>(x: &T) -> &U {
-    unsafe { transmute(x) } //~ ERROR transmute called on types with potentially different sizes
+    unsafe { transmute(x) } //~ ERROR transmute called with differently sized types
 }
 
 fn c<T, U>(x: &T) -> &U {
@@ -31,11 +31,11 @@ fn d<T, U>(x: &[T]) -> &[U] {
 }
 
 fn e<T: ?Sized, U>(x: &T) -> &U {
-    unsafe { transmute(x) } //~ ERROR transmute called on types with potentially different sizes
+    unsafe { transmute(x) } //~ ERROR transmute called with differently sized types
 }
 
 fn f<T, U: ?Sized>(x: &T) -> &U {
-    unsafe { transmute(x) } //~ ERROR transmute called on types with potentially different sizes
+    unsafe { transmute(x) } //~ ERROR transmute called with differently sized types
 }
 
 fn main() { }

src/test/compile-fail/transmute-impl.rs

@@ -26,7 +26,7 @@ impl<T: ?Sized> Foo<T> {
 
     fn n(x: &T) -> &isize {
         // Not OK here, because T : Sized is not in scope.
-        unsafe { transmute(x) } //~ ERROR transmute called on types with potentially different sizes
+        unsafe { transmute(x) } //~ ERROR transmute called with differently sized types
     }
 }