Uncompileable with clang 14

[KOLANICH]

In file included from ../argh_tests.cpp:4:
../doctest.h:4403:33: error: variable length array declaration not allowed at file scope
        static char             altStackMem[SIGSTKSZ];
                                ^           ~~~~~~~~
In file included from ../argh_tests.cpp:4:
../doctest.h:4453:36: error: variable length array declaration not allowed at file scope
    char    FatalConditionHandler::altStackMem[SIGSTKSZ] = {};
                                   ^           ~~~~~~~~

[adishavit]

Pinging @onqtam.
This seems to be related to doctest.

[onqtam]

I just tried using clang trunk (couldn't find 14) on godbolt and it compiles a simple example without problem:
https://godbolt.org/z/dve19fb3d

What's your OS? What compiler options are you using?

[KOLANICH]

Ubuntu 21.10
To get clang 14 you can follow the instructions on https://apt.llvm.org/

[onqtam]

any clue why it doesn't happen with clang trunk and why there's no clang 14 in godbolt?

[adishavit]

@mattgodbolt?

[FabioLolix]

Hello, I'm on Arch Linux and I'm making the pkgbuilds for this software for both stable release and latest git commit, it currently fail with any combination of compiler and source I've tested

v1.3.1 with GCC 11.2.0

[ 50%] Building CXX object CMakeFiles/argh_example.dir/example.cpp.o
In file included from /usr/include/signal.h:328,
                 from /usr/include/c++/11.2.0/csignal:42,
                 from /home/fabio/Dev/Github/PKGBUILD-AUR_fix/a/argh/src/argh-1.3.1/doctest.h:3241,
                 from /home/fabio/Dev/Github/PKGBUILD-AUR_fix/a/argh/src/argh-1.3.1/argh_tests.cpp:4:
/home/fabio/Dev/Github/PKGBUILD-AUR_fix/a/argh/src/argh-1.3.1/doctest.h:4403:45: error: size of array ‘altStackMem’ is not an integral constant-expression
 4403 |         static char             altStackMem[SIGSTKSZ];
      |                                             ^~~~~~~~
/home/fabio/Dev/Github/PKGBUILD-AUR_fix/a/argh/src/argh-1.3.1/doctest.h:4453:48: error: size of array ‘altStackMem’ is not an integral constant-expression
 4453 |     char    FatalConditionHandler::altStackMem[SIGSTKSZ] = {};
      |                                                ^~~~~~~~
/home/fabio/Dev/Github/PKGBUILD-AUR_fix/a/argh/src/argh-1.3.1/argh_tests.cpp: In function ‘void _DOCTEST_ANON_FUNC_28()’:

v1.3.1 with Clang 13

 50%] Building CXX object CMakeFiles/argh_tests.dir/argh_tests.cpp.o
In file included from /home/fabio/Dev/Github/PKGBUILD-AUR_fix/a/argh/src/argh-1.3.1/argh_tests.cpp:4:
/home/fabio/Dev/Github/PKGBUILD-AUR_fix/a/argh/src/argh-1.3.1/doctest.h:4403:45: warning: variable length arrays are a C99 feature [-Wvla-extension]
        static char             altStackMem[SIGSTKSZ];
                                            ^~~~~~~~
/usr/include/bits/sigstksz.h:28:19: note: expanded from macro 'SIGSTKSZ'
# define SIGSTKSZ sysconf (_SC_SIGSTKSZ)
                  ^~~~~~~~~~~~~~~~~~~~~~
/home/fabio/Dev/Github/PKGBUILD-AUR_fix/a/argh/src/argh-1.3.1/doctest.h:4403:45: note: non-constexpr function 'sysconf' cannot be used in a constant expression
/usr/include/bits/sigstksz.h:28:19: note: expanded from macro 'SIGSTKSZ'
# define SIGSTKSZ sysconf (_SC_SIGSTKSZ)
                  ^
/usr/include/unistd.h:640:17: note: declared here
extern long int sysconf (int __name) __THROW;
                ^
In file included from /home/fabio/Dev/Github/PKGBUILD-AUR_fix/a/argh/src/argh-1.3.1/argh_tests.cpp:4:
/home/fabio/Dev/Github/PKGBUILD-AUR_fix/a/argh/src/argh-1.3.1/doctest.h:4403:33: error: variable length array declaration not allowed at file scope
        static char             altStackMem[SIGSTKSZ];
                                ^           ~~~~~~~~
/home/fabio/Dev/Github/PKGBUILD-AUR_fix/a/argh/src/argh-1.3.1/doctest.h:4453:48: warning: variable length arrays are a C99 feature [-Wvla-extension]
    char    FatalConditionHandler::altStackMem[SIGSTKSZ] = {};
                                               ^~~~~~~~
/usr/include/bits/sigstksz.h:28:19: note: expanded from macro 'SIGSTKSZ'
# define SIGSTKSZ sysconf (_SC_SIGSTKSZ)
                  ^~~~~~~~~~~~~~~~~~~~~~
/home/fabio/Dev/Github/PKGBUILD-AUR_fix/a/argh/src/argh-1.3.1/doctest.h:4453:48: note: non-constexpr function 'sysconf' cannot be used in a constant expression
/usr/include/bits/sigstksz.h:28:19: note: expanded from macro 'SIGSTKSZ'
# define SIGSTKSZ sysconf (_SC_SIGSTKSZ)
                  ^
/usr/include/unistd.h:640:17: note: declared here
extern long int sysconf (int __name) __THROW;
                ^
In file included from /home/fabio/Dev/Github/PKGBUILD-AUR_fix/a/argh/src/argh-1.3.1/argh_tests.cpp:4:
/home/fabio/Dev/Github/PKGBUILD-AUR_fix/a/argh/src/argh-1.3.1/doctest.h:4453:36: error: variable length array declaration not allowed at file scope
    char    FatalConditionHandler::altStackMem[SIGSTKSZ] = {};
                                   ^           ~~~~~~~~
/home/fabio/Dev/Github/PKGBUILD-AUR_fix/a/argh/src/argh-1.3.1/argh_tests.cpp:415:24: warning: ISO C++11 does not allow conversion from string literal to 'char *' [-Wwritable-strings]
      char* argv[] = { "0", "-a", "1", "-b", "2", "3", "4" };

v1.3.1 with GCC 10.3.0

[ 50%] Building CXX object CMakeFiles/argh_tests.dir/argh_tests.cpp.o
In file included from /home/fabio/Dev/Github/PKGBUILD-AUR_fix/a/argh/src/argh-1.3.1/argh_tests.cpp:4:
/home/fabio/Dev/Github/PKGBUILD-AUR_fix/a/argh/src/argh-1.3.1/doctest.h:4403:53: error: array bound is not an integer constant before ‘]’ token
 4403 |         static char             altStackMem[SIGSTKSZ];
      |                                                     ^
/home/fabio/Dev/Github/PKGBUILD-AUR_fix/a/argh/src/argh-1.3.1/doctest.h: In constructor ‘doctest::detail::FatalConditionHandler::FatalConditionHandler()’:
/home/fabio/Dev/Github/PKGBUILD-AUR_fix/a/argh/src/argh-1.3.1/doctest.h:4422:33: error: ‘altStackMem’ was not declared in this scope
 4422 |             sigStack.ss_sp    = altStackMem;
      |                                 ^~~~~~~~~~~
/home/fabio/Dev/Github/PKGBUILD-AUR_fix/a/argh/src/argh-1.3.1/doctest.h: At global scope:
/home/fabio/Dev/Github/PKGBUILD-AUR_fix/a/argh/src/argh-1.3.1/doctest.h:4453:56: error: array bound is not an integer constant before ‘]’ token
 4453 |     char    FatalConditionHandler::altStackMem[SIGSTKSZ] = {};
      |                                                        ^
/home/fabio/Dev/Github/PKGBUILD-AUR_fix/a/argh/src/argh-1.3.1/argh_tests.cpp: In function ‘void _DOCTEST_ANON_FUNC_28()’:
/home/fabio/Dev/Github/PKGBUILD-AUR_fix/a/argh/src/argh-1.3.1/argh_tests.cpp:415:24: warning: ISO C++ forbids converting a string constant to ‘char*’ [-Wwrite-strings]
  415 |       char* argv[] = { "0", "-a", "1", "-b", "2", "3", "4" };
      |                        ^~~

v1.3.1.r17.g01b6a4a with GCC 11.2.0

[ 50%] Building CXX object CMakeFiles/argh_tests.dir/argh_tests.cpp.o
[ 50%] Building CXX object CMakeFiles/argh_example.dir/example.cpp.o
In file included from /usr/include/signal.h:328,
                 from /usr/include/c++/11.2.0/csignal:42,
                 from /home/fabio/Dev/Github/PKGBUILD-AUR_fix/a/argh-git/src/argh/doctest.h:3241,
                 from /home/fabio/Dev/Github/PKGBUILD-AUR_fix/a/argh-git/src/argh/argh_tests.cpp:4:
/home/fabio/Dev/Github/PKGBUILD-AUR_fix/a/argh-git/src/argh/doctest.h:4403:45: error: size of array ‘altStackMem’ is not an integral constant-expression
 4403 |         static char             altStackMem[SIGSTKSZ];
      |                                             ^~~~~~~~
/home/fabio/Dev/Github/PKGBUILD-AUR_fix/a/argh-git/src/argh/doctest.h:4453:48: error: size of array ‘altStackMem’ is not an integral constant-expression
 4453 |     char    FatalConditionHandler::altStackMem[SIGSTKSZ] = {};
      |                                                ^~~~~~~~
/home/fabio/Dev/Github/PKGBUILD-AUR_fix/a/argh-git/src/argh/argh_tests.cpp: In lambda function:
/home/fabio/Dev/Github/PKGBUILD-AUR_fix/a/argh-git/src/argh/argh_tests.cpp:730:27: warning: declaration of ‘cmdl’ shadows a previous local [-Wshadow]
  730 |    [](argh::parser const& cmdl)
      |       ~~~~~~~~~~~~~~~~~~~~^~~~
/home/fabio/Dev/Github/PKGBUILD-AUR_fix/a/argh-git/src/argh/argh_tests.cpp:720:17: note: shadowed declaration is here
  720 |    const parser cmdl(argv);
      |                 ^~~~
[ 75%] Linking CXX executable argh_example
[ 75%] Built target argh_example
make[2]: *** [CMakeFiles/argh_tests.dir/build.make:76: CMakeFiles/argh_tests.dir/argh_tests.cpp.o] Errore 1

[onqtam]

oh, it just clicked for me - argh is using a very old version of doctest where indeed SIGSTKSZ is a problem. It's been fixed long ago - I'd suggest updating to version 2.4.6 from 1 year ago within the argh repository: https://github.com/doctest/doctest/blob/2.4.6/doctest/doctest.h

I don't recommend the newer versions (2.4.7/2.4.8/dev) because of this problem: #72 (it will be fixed eventually too).

[adishavit]

Thanks @onqtam. I pushed version 2.4.6.
@KOLANICH LMK if the problem is fixed.

[FabioLolix]

For me has been fixed

[KOLANICH]

Yeah, it has solved the problem. Thank you.