Re: [PATCH] kbuild: make Clang build userprogs for target architecture

From: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
To: Masahiro Yamada <masahiroy@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>,
	Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Michal Marek <michal.lkml@markovi.net>,
	Sam Ravnborg <sam@ravnborg.org>,
	clang-built-linux <clang-built-linux@googlegroups.com>
Subject: Re: [PATCH] kbuild: make Clang build userprogs for target architecture
Date: Mon, 6 Jul 2020 06:48:58 +0200	[thread overview]
Message-ID: <CANiq72=LOgebNs7kwLGrkgsM2pr=dQG4F1VWskdndAh39jHWcw@mail.gmail.com> (raw)
In-Reply-To: <CAK7LNATRAuEXp+Wz7f_VUTSFS4jqmdTE4Xugi1MZozimsj6zuA@mail.gmail.com>

Hi Masahiro,

On Sun, Jul 5, 2020 at 5:30 PM Masahiro Yamada <masahiroy@kernel.org> wrote:
>
> Hmm, adding '#include <sys/types.h>' did not make any difference.

That should have worked, because POSIX defines it to be there. It
sounds like you need --sysroot to point it to the proper ones.

> If I add -std=c99, I get a different error.

Yeah, that is the expected behavior. C99 does not have the implicit
int rule anymore (unlike older C) so ssize_t (an unknown type given
that program) is not being interpreted as int anymore (which is what
triggers the warning later about the mismatch between size_t and int
in the format string).

> In contrast, 'size_t' has no problem.

That is expected too, because size_t is defined via stdio.h (size_t is
a C standard type, ssize_t is not -- it is a POSIX one).

Hope that helps,

Cheers,
Miguel