error: this constant cannot be used
  --> $DIR/union-ice.rs:23:1
   |
LL | const FIELD3: Field3 = unsafe { UNION.field3 }; //~ ERROR this constant cannot be used
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ attempted to read undefined bytes
   |
   = note: #[deny(const_err)] on by default

error[E0080]: this constant likely exhibits undefined behavior
  --> $DIR/union-ice.rs:25:1
   |
LL | / const FIELD_PATH: Struct = Struct { //~ ERROR this constant likely exhibits undefined behavior
LL | |     a: 42,
LL | |     b: unsafe { UNION.field3 },
LL | | };
   | |__^ type validation failed: encountered uninitialized bytes at .b, but expected initialized plain bits
   |
   = 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

error[E0080]: this constant likely exhibits undefined behavior
  --> $DIR/union-ice.rs:35:1
   |
LL | / const FIELD_PATH2: Struct2 = Struct2 { //~ ERROR this constant likely exhibits undefined behavior
LL | |     b: [
LL | |         21,
LL | |         unsafe { UNION.field3 },
...  |
LL | |     a: 42,
LL | | };
   | |__^ type validation failed: encountered undefined bytes at .b[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

error: aborting due to 3 previous errors

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