error[E0080]: reading memory at ALLOC0[0x0..0x8], but memory is uninitialized at [0x4..0x8], and this operation requires initialized memory
  --> $DIR/union-const-eval-field.rs:30:37
   |
LL |     const FIELD3: Field3 = unsafe { UNION.field3 };
   |                                     ^^^^^^^^^^^^ evaluation of `read_field3::FIELD3` failed here
   |
   = note: the raw bytes of the constant (size: $SIZE, align: $ALIGN) {
               HEX_DUMP
           }

note: erroneous constant encountered
  --> $DIR/union-const-eval-field.rs:32:5
   |
LL |     FIELD3
   |     ^^^^^^

note: erroneous constant encountered
  --> $DIR/union-const-eval-field.rs:32:5
   |
LL |     FIELD3
   |     ^^^^^^
   |
   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0080`.