On Wed, 16 Sep 2015, Jeffrey Walton wrote:
I'm trying to test for some C++ features via preprocessor macros. Some macros (like __GXX_VERSION__) are only triggered by including a C++ standard library file. According to Issue 67195, "cpp and g++ does not define __GLIBCXX__", I should only need to include c++config.h. The following is failing to pickup GCC's standard C++ configuration file: g++ -include c++config.h -dM -E - < /dev/.null | sort
Don't use this - < /dev/null, it only works halfway. Create a true empty file empty.cc instead.
The command (and variations like "-include c\+\+config.h" and "-include bits/c++config.h") produces:
bits/c++config.h is the right one.
I guess a related question is, why is G++ using cc1, and not cc1plus?
Add -x c++ (gcc guesses based on the file name). Yes, it would make sense for c++ to be the default with g++...
-- Marc Glisse
