For me, the point of writing something in C is portability. There were C compilers 30 years ago, there are C compilers now, and there will almost certainly be C compilers 30 years from now. If I want to write a good, portable library that's going to be useful for a long time, I'll do it in C. This is, at least, the standard in many gamedev circles (see: libsdl, libfreetype, the stb_* libraries). Under that expectation, I write to a standard, not a compiler.
For the cases in linked doc, does adding -std=gnu17 to packages not suffice?
I would consider the union initializer change (require adding -fzero-init-padding-bits=unions for old behavior) much more hidden and dangerous, which is not directly related to ISO C23 standard.
It's true that it does, yes. However that would still require changes to the build system. In any case for the vast majority of the packages we decided to fix (if you think this is a fix!) the code.
> Note that the bool type is not the same as int at ABI level,
Huh. Wonder what the benefits of that are. Bools being ints never struck me as a serious problem. I wonder if this catches people who accidentally assign rather than compare tho....
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.
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).
If I touch C it has to have control over allocations, memory layout, and wrapping low level code into functions I can call from other languages.
I'd target the latest C standard and won't even care to know how many old, niche compilers I'm leaving out. These are vastly different uses for C and obviously your gaols drastically change your standard or compiler targeted.
