Merge #687

687: Fix byte char and byte string lexing code r=philberty a=tschwinge

There were two warnings in lexer parse_byte_char and parse_byte_string
code for arches with signed chars:

```
rust-lex.cc: In member function
             ‘Rust::TokenPtr Rust::Lexer::parse_byte_char(Location)’:
rust-lex.cc:1564:21: warning: comparison is always false due to limited
                     range of data type [-Wtype-limits]
 1564 |       if (byte_char > 127)
      |           ~~~~~~~~~~^~~~~
rust-lex.cc: In member function
             ‘Rust::TokenPtr Rust::Lexer::parse_byte_string(Location)’:
rust-lex.cc:1639:27: warning: comparison is always false due to limited
                     range of data type [-Wtype-limits]
 1639 |           if (output_char > 127)
      |               ~~~~~~~~~~~~^~~~~
```

The fix would be to cast to an unsigned char before the comparison.
But that is actually wrong, and would produce the following errors
parsing a byte char or byte string:

```
bytecharstring.rs:3:14: error: ‘byte char’ ‘�’ out of range
    3 |   let _bc = b'\x80';
      |              ^
bytecharstring.rs:4:14: error: character ‘�’ in byte string out of range
    4 |   let _bs = b"foo\x80bar";
      |              ^
```

Both byte chars and byte strings may contain up to \xFF (255)
characters. It is utf-8 chars or strings that can only

Remove the faulty check and add a new testcase bytecharstring.rs
that checks byte chars and strings do accept > 127 hex char
escapes, but utf-8 chars and strings reject such hex char escapes.

---

<http://mid.mail-archive.com/20210921225430.166550-1-mark@klomp.org>

---

Addresses: #336 
Fixes: #343, #344


Co-authored-by: Mark Wielaard <mark@klomp.org>

0 files changed, 0 insertions, 0 deletions