The document say gcc 4.8 is supported but failed to run with gcc 4.9.2

[hcoona]

It's easy to understand so didn't follow the template.

GCC didn't support std::regex at least in v4.9.2, see https://gcc.gnu.org/onlinedocs/gcc-4.9.2/libstdc++/manual/manual/status.html 7.11.2.

[hcoona]

I found the option HAVE_WORKING_REGEX. It detects against gcc 4.8, so not working on gcc 4.9.2. I think it better to detect against libstdc++ instead of the compiler version.

[lalitb]

I think it better to detect against libstdc++ instead of the compiler version.

Yes, there are better ways to detect regex support than to check the compiler version.

[hcoona]

_GLIBCXX_RELEASE could do that but only provided after GCC v7.1. (https://gcc.gnu.org/onlinedocs/libstdc++/manual/using_macros.html)

__GLIBCXX__ is the release date. However, some minor updates could be later than next major release. For example:

• GCC 4.9.4: 2016-08-03
• GCC 7.1.0: 2016-04-27

Google cpplint mark that only versions <= 4.9 have such problem. (google/styleguide#432)

The GCC document shows that until GCC 11.2.0 std::regex_match is not supported, which is absolutely wrong. (https://gcc.gnu.org/onlinedocs/gcc-11.2.0/libstdc++/manual/manual/status.html). I found std::regex_match is only mentioned in TR1, I'll do a futher investigation.

[hcoona]

I'll just exclude gcc 4.9.x just like 4.8.x