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From:   Linus Torvalds <torvalds@linuxfoundation.org>
Date:   Mon, 6 Sep 2021 11:11:35 -0700
Message-ID: <CAHk-=wh0MBVfA89WLWnCiSnJ2a=hSAoSxfG-jyf7JJeBDPK3ew@mail.gmail.com>
Subject: Re: [GIT PULL v2] Kbuild updates for v5.15-rc1
To:     Segher Boessenkool <segher@kernel.crashing.org>
Cc:     Florian Weimer <fweimer@redhat.com>,
        Nathan Chancellor <nathan@kernel.org>,
        Masahiro Yamada <masahiroy@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        clang-built-linux <clang-built-linux@googlegroups.com>,
        llvm@lists.linux.dev, linux-toolchains@vger.kernel.org
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On Mon, Sep 6, 2021 at 10:30 AM Segher Boessenkool
<segher@kernel.crashing.org> wrote:
>
> But this whole thread is about removing uses of <stdarg.h>, and
> eventually removing the
>   -nostdinc -isystem $(shell $(CC) -print-file-name=include)

Yes.

But your argument against it was based on that past argument of it
being compiler-specific, in ways that are not true any more.

Happily, it clearly is the case that compilers have standardized their
internal implementation of this in ways that means that we actually
_could_ do this for <stdarg.h>.

Exactly the way we do it for pretty much every other header file.

IOW, <stdarg.h> is no longer the special thing it used to be.

We use the compiler intrinsics without the C library header files for
everything else, so doing so for <stdarg.h> seems to actually be a
clarification and improvement.

             Linus