[cxx feature check] what satisfies GNU_POSIX_REGEX | POSIX_REGEX?

LLVM Project
#1

trying to compile llvm 11 from source with cmake 3.19 and a llvm 11 toolchain on a X86 debian userland based node

llvm source is pulling in Google’s benchmarking https://github.com/google/benchmark/blob/master/CMakeLists.txt#L263 which tests for

  • GNU_POSIX_REGEX
  • POSIX_REGEX

and the test fails

-- Performing Test HAVE_GNU_POSIX_REGEX
 -- Performing Test HAVE_GNU_POSIX_REGEX
 -- Performing Test HAVE_GNU_POSIX_REGEX -- failed to compile
 -- Performing Test HAVE_POSIX_REGEX
 -- Performing Test HAVE_POSIX_REGEX
 -- Performing Test HAVE_POSIX_REGEX -- failed to compile
 CMake Warning at utils/benchmark/CMakeLists.txt:244 (message):
   Using std::regex with exceptions disabled is not fully supported

indicating that neither is available on the node.

since the node is based on the Debian package feed I was trying to find a package that satisfies either one but came up empty.

What package/code would satisfy GNU_POSIX_REGEX or POSIX_REGEX?

#2

installed libghc-regex-posix-prof package but that did not help

#3

ibpcre2-dev & libpcre2-posix2 are also installed, which according to https://pcre.org:

provides its own native API, as well as a set of wrapper functions that correspond to the POSIX regular expression API.

#4

I think GNU_POSIX_REGEX should be satisfied with gnulib(https://github.com/coreutils/gnulib/blob/master/lib/regex.h) and POSIX_REGEX with libstd++(https://github.com/gcc-mirror/gcc/blob/master/libstdc%2B%2B-v3/include/bits/regex.h).

On my system but there is no gnuregex.h (https://github.com/llvm/llvm-project/blob/master/llvm/utils/benchmark/cmake/gnu_posix_regex.cpp#L1) available. So output is:-

– Performing Test HAVE_GNU_POSIX_REGEX – failed to compile
– Performing Test HAVE_POSIX_REGEX
– Performing Test HAVE_POSIX_REGEX
– Performing Test HAVE_POSIX_REGEX – success

If you don’t get a solution here you should either post on llvm-dev mailing list or open an issue on https://bugs.llvm.org/.

#5

Thank you for the input/feedback

dpkg -L libstdc++-10-dev | grep regex.h
/usr/include/c++/10/bits/regex.h

With that the benchmark test fails, as cited in the initial post. Will check about the gnulib, currently though taking it up with the benchmark source developers.

#6

It is not, it provides regex.h whilst, as you pointed out, CMake’s gnu_posix_regex.cpp is testing for gnuregex.h though. That seems rather for backward compatibility since gnuregex.h appears somehwat outdated and replaced by regex.h.