[flohofwoe]

For accessing any post-1970s operating system feature (e.g. async IO or virtual memory) you already cannot use standard C anymore (and POSIX is not the C stdlib).

The libraries you listed are all full of platform-specific code, and also have plenty of compiler-specific code behind ifdefs (for instance the stb headers have MSVC specific declspec declarations in them).

E.g. there is hardly any real-world C code out there that is 'pure standard C', if the code compiles on different compilers and for different target platforms then that's because the code specifically supports those compilers and target platforms.

[amjoshuamichael]

My argument is that using these non-standard extensions to do important things like memory management in a C library is malpractice—it effectively locks down the library to specific C compilers. I'm sure that's fine if you're writing to clang specifically, but at that point, you can just write C++. libfreetype & stb_* are used and continue to be used because they can be relied on to be portable, and using compiler-specific extensions (without ifdefs) defeats that. If I relied on a clang-specific `defer`, I'm preventing my library from possibly being compiled via a future C compiler, let alone the compilers that exist now. To me, that's the point of writing C instead of C++ for a library (unless you're just a fan of the simplicity, which is more of an ideological, opinion-based reason).