Change byte align message wording rust-lang#58617

Author: pmccarter

src/librustc_mir/interpret/validity.rs

@@ -359,7 +359,7 @@ impl<'rt, 'a, 'mir, 'tcx, M: Machine<'a, 'mir, 'tcx>>
                                 return validation_failure!("NULL reference", self.path),
                             EvalErrorKind::AlignmentCheckFailed { required, has } =>
                                 return validation_failure!(format!("unaligned reference \
-                                    (required {} alignment but found {})",
+                                    (required {} byte alignment but found {})",
                                     required.bytes(), has.bytes()), self.path),
                             _ =>
                                 return validation_failure!(

src/test/ui/consts/const-eval/ub-ref.rs

@@ -5,7 +5,7 @@ use std::mem;
 
 const UNALIGNED: &u16 = unsafe { mem::transmute(&[0u8; 4]) };
 //~^ ERROR it is undefined behavior to use this value
-//~^^ type validation failed: encountered unaligned reference (required 2 alignment but found 1)
+//~^^ type validation failed: encountered unaligned reference (required 2 byte alignment but found 1)
 
 const NULL: &u16 = unsafe { mem::transmute(0usize) };
 //~^ ERROR it is undefined behavior to use this value

src/test/ui/consts/const-eval/ub-ref.stderr

@@ -2,7 +2,7 @@ error[E0080]: it is undefined behavior to use this value
   --> $DIR/ub-ref.rs:6:1
    |
 LL | const UNALIGNED: &u16 = unsafe { mem::transmute(&[0u8; 4]) };
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered unaligned reference (required 2 alignment but found 1)
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered unaligned reference (required 2 byte alignment but found 1)
    |
    = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rust compiler repository if you believe it should not be considered undefined behavior