Variable length hexadecimal escape always fails in basic_regex_parser

[wbond <will@…>]

Using a variable length hexadecimal escape \x{41} causes the error Hexadecimal escape sequence was invalid.

This appears to be caused by the int cast at ​https://github.com/boostorg/regex/blob/aa6495ae486522456bb0d507cd93f8023c3c4c0c/include/boost/regex/v4/basic_regex_parser.hpp#L1759.

[wbond <will@…>]

Specifically, this occurs with the type boost::basic_regex<uint32_t>, which explains why (std::numeric_limits<charT>::max)() it overflows int.

[John Maddock]

I believe this is now fixed in:

​https://github.com/boostorg/regex/commit/955d077d2b69d7c1014e36d86c737f7eb4b057b7

plus test cases:

​https://github.com/boostorg/regex/commit/36b2fab2271bc97f8fae86029f587747f9fc1ff4 ​https://github.com/boostorg/regex/commit/e217808156e482dc1af6b97799e39a2fdfabe3fd

Note that strictly speaking this is still only a partial fix as basic_regex<uintmax_t> could still only parse values up until the largest value of intmax_t. It should fix this for char32_t etc though.