On Sun, 2025-08-10 at 23:38 +0530, Rajeev Bansal via Gcc-help wrote: > Hello, > > I am working on a large C/C++ project compiled with GCC and am looking for > ways to identify unnecessary header files. I'm wondering if there's a tool > similar to `include-what-you-use` (IWYU) that can help with this > information in gcc. > > Any advice or recommendations would be greatly appreciated. Observe that C code (and C++) use a preprocessor, and some preprocessor parameters are passed in the compilation command (but not in C or C++ files), perhaps using GNUmake. Look also into GNU autoconf. Observe that some C or C++ files can be generated, e.g. by https://carburetta.com/ On Linux, you could use https://man7.org/linux/man-pages/man3/dlopen.3.html and generate dynamically C++ plugins, see https://arxiv.org/abs/1109.0779 You can also generate machine code at runtime with https://asmjit.com/ or https://www.gnu.org/software/lightning/ (this can improve runtime performance). The preprocessor is inside GCC open source, so you are allowed to improve it (under GPL license). C++20 has modules, and you could use that feature. A possibility could be to develop or extend your (open source) GCC plugin. The old (unmaintained and obsolete) Bismon project could be relevant. https://github.com/bstarynk/bismon Look also into old HorizonEurope https://www.decoder-project.eu/ I tend to think that for a large C++ project (the size of https://gcc.gnu.org/ or https://libreoffice.org/ ....) your goal is practically impossible. Without knowing how large your C++ project (e.g. what is the output of Wheeler's sloccount utility on it, see https://dwheeler.com/sloccount/ ...) we cannot help you. It would be nice to understand what kind of project it is. Most large projects follow domain specific coding rules (e.g. https://en.wikipedia.org/wiki/MISRA_C ...) and many do define and document their own coding rules. In that case, developing your GCC plugin to check some of them might be useful. Regards. -- Basile STARYNKEVITCH <basile@xxxxxxxxxxxxxxxxx> 8 rue de la Faïencerie http://starynkevitch.net/Basile/ 92340 Bourg-la-Reine https://github.com/bstarynk France https://github.com/RefPerSys/RefPerSys
