error: unicode escape sequences cannot be used as a byte or in a byte string
  --> $DIR/issue-23620-invalid-escapes.rs:4:15
   |
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:7:15
   |
LL |     let _ = b'\u{a66e}';
   |               ^^^^^^^^

error: incorrect unicode escape sequence
  --> $DIR/issue-23620-invalid-escapes.rs:10:15
   |
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:13:15
   |
LL |     let _ = b'\x5';
   |               ^^^

error: invalid character in numeric character escape: x
  --> $DIR/issue-23620-invalid-escapes.rs:16:17
   |
LL |     let _ = b'\xxy';
   |                 ^

error: numeric character escape is too short
  --> $DIR/issue-23620-invalid-escapes.rs:19:14
   |
LL |     let _ = '\x5';
   |              ^^^

error: invalid character in numeric character escape: x
  --> $DIR/issue-23620-invalid-escapes.rs:22:16
   |
LL |     let _ = '\xxy';
   |                ^

error: unicode escape sequences cannot be used as a byte or in a byte string
  --> $DIR/issue-23620-invalid-escapes.rs:25:15
   |
LL |     let _ = b"\u{a4a4} \xf \u";
   |               ^^^^^^^^

error: invalid character in numeric character escape:  
  --> $DIR/issue-23620-invalid-escapes.rs:25:27
   |
LL |     let _ = b"\u{a4a4} \xf \u";
   |                           ^

error: incorrect unicode escape sequence
  --> $DIR/issue-23620-invalid-escapes.rs:25:28
   |
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:30:17
   |
LL |     let _ = "\xf \u";
   |                 ^

error: incorrect unicode escape sequence
  --> $DIR/issue-23620-invalid-escapes.rs:30:18
   |
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:34:14
   |
LL |     let _ = "\u8f";
   |              ^^--
   |                |
   |                help: format of unicode escape sequences uses braces: `\u{8f}`

error: aborting due to 13 previous errors