error: unicode escape sequences cannot be used as a byte or in a byte string
  --> $DIR/issue-23620-invalid-escapes.rs:2:15
   |
LL |     let _ = b"\u{a66e}";
   |               ^^^^^^^^

error: unicode escape sequences cannot be used as a byte or in a byte string
  --> $DIR/issue-23620-invalid-escapes.rs:5:15
   |
LL |     let _ = b'\u{a66e}';
   |               ^^^^^^^^

error: incorrect unicode escape sequence
  --> $DIR/issue-23620-invalid-escapes.rs:8:15
   |
LL |     let _ = b'\u';
   |               ^^ incorrect unicode escape sequence
   |
   = help: format of unicode escape sequences is `\u{...}`

error: numeric character escape is too short
  --> $DIR/issue-23620-invalid-escapes.rs:11:15
   |
LL |     let _ = b'\x5';
   |               ^^^

error: invalid character in numeric character escape: x
  --> $DIR/issue-23620-invalid-escapes.rs:14:17
   |
LL |     let _ = b'\xxy';
   |                 ^

error: numeric character escape is too short
  --> $DIR/issue-23620-invalid-escapes.rs:17:14
   |
LL |     let _ = '\x5';
   |              ^^^

error: invalid character in numeric character escape: x
  --> $DIR/issue-23620-invalid-escapes.rs:20:16
   |
LL |     let _ = '\xxy';
   |                ^

error: unicode escape sequences cannot be used as a byte or in a byte string
  --> $DIR/issue-23620-invalid-escapes.rs:23:15
   |
LL |     let _ = b"\u{a4a4} \xf \u";
   |               ^^^^^^^^

error: invalid character in numeric character escape:  
  --> $DIR/issue-23620-invalid-escapes.rs:23:27
   |
LL |     let _ = b"\u{a4a4} \xf \u";
   |                           ^

error: incorrect unicode escape sequence
  --> $DIR/issue-23620-invalid-escapes.rs:23:28
   |
LL |     let _ = b"\u{a4a4} \xf \u";
   |                            ^^ incorrect unicode escape sequence
   |
   = help: format of unicode escape sequences is `\u{...}`

error: invalid character in numeric character escape:  
  --> $DIR/issue-23620-invalid-escapes.rs:28:17
   |
LL |     let _ = "\xf \u";
   |                 ^

error: incorrect unicode escape sequence
  --> $DIR/issue-23620-invalid-escapes.rs:28:18
   |
LL |     let _ = "\xf \u";
   |                  ^^ incorrect unicode escape sequence
   |
   = help: format of unicode escape sequences is `\u{...}`

error: incorrect unicode escape sequence
  --> $DIR/issue-23620-invalid-escapes.rs:32:14
   |
LL |     let _ = "\u8f";
   |              ^^^-
   |              |
   |              help: format of unicode escape sequences uses braces: `\u{8f}`

error: aborting due to 13 previous errors