On 2023-08-29 11:26:19+0200, Willy Tarreau wrote: > On Tue, Aug 29, 2023 at 11:14:09AM +0200, Thomas Weißschuh wrote: > > Hi Willy! > > > > On 2023-08-29 08:28:27+0200, Willy Tarreau wrote: > > > On Sun, Aug 27, 2023 at 10:00:15AM +0200, Thomas Weißschuh wrote: > > > > This allows nolic to work with `-nostdinc` avoiding any reliance on > > > > system headers. > > > > > > > > The implementation has been lifted from musl libc 1.2.4. > > > > There is already an implementation of stdarg.h in include/linux/stdarg.h > > > > but that is GPL licensed and therefore not suitable for nolibc. > > > > > > I'm a bit confused because for me, stdarg was normally provided by the > > > compiler, but I could be mistaken. It's just that it reminds me not so > > > old memories. Therefore maybe we just need to include or define > > > "something" to use it. > > > > It is indeed provided by the compiler. > > OK. But then, doesn't it mean that if we don't provide our stdarg.h, > the compilers' will be used ? I'm asking because we're already using > va_list and va_args, for example in vfprintf() in stdio.h, which > precisely includes <stdarg.h> so it must indeed come from the compiler. It will be used *iff* -nostdinc is *not* passed. I think we need to clarify the definition of the word "provided". For me it means that the compiler ships an implementation of this header file in the compiler-specific include directory. If -nostdinc is passed this include directory is not actually usable. If a user wants to avoid the implicit usage of any system-provided headers they need to pass -nostdinc, as far as I know there is no flag to keep only the compiler-specific include directories. One usecase is in nolibc-test itself, where Zhangjin ran into weird and inconsistent behavior of system includes being pulled in. By using -nostdinc we avoid this. I can also see this being useful for normal users. > > I could not find anybody doing this differently. > > Using builtins seems to me to be the normal way to expose compiler > > implementation specifics. > > OK but it's already what the compiler does itself in its own stdarg that > is provided. That's why I don't understand what specific case we're trying > to cover here, I feel like we're providing an alternate stdarg in case the > compiler doesn't provide one except that I've not seen a compiler not > provide it (even tcc comes with it), it's like stddef. It's all about supporting -nostdinc. FYI stdint.h is also provided by nolibc, gcc and glibc.
