Re: [PATCH v7 05/11] osdep: build with non-working system() function

From: Peter Maydell <peter.maydell@linaro.org>
To: Joelle van Dyne <j@getutm.app>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
	QEMU Developers <qemu-devel@nongnu.org>
Subject: Re: [PATCH v7 05/11] osdep: build with non-working system() function
Date: Sat, 23 Jan 2021 13:45:12 +0000	[thread overview]
Message-ID: <CAFEAcA8KZqxjDd0H7faF=YtkyY-XFB2WoP31qv_2ecFij_rLqQ@mail.gmail.com> (raw)
In-Reply-To: <CA+E+eSAhNNBxY06a5iQj9ANpgmYZk0Kf6LYQPduCLwNmr1UQvA@mail.gmail.com>

On Sat, 23 Jan 2021 at 03:18, Joelle van Dyne <j@getutm.app> wrote:
On Fri, Jan 22, 2021 at 3:17 PM Peter Maydell <peter.maydell@linaro.org> wrote:
>> Can we do the "does system() exist?" check in meson.build ?

>> config_host_data.set('HAVE_SYSTEM_FUNCTION', cc.has_function('system'))

> Unfortunately, this doesn't work for iOS, which defines system() but
> throws a compile time error if you try to call it.

That's odd -- as far as I can tell the meson implementation
of has_function() does what I expected it to do, ie
"try to compile and link a little program that uses the
function, and see if it successfully links":
https://github.com/mesonbuild/meson/blob/39ede12aa5b27376341df85bc9ec254913f044bd/mesonbuild/compilers/mixins/clike.py#L791
There's some initial cleverness there too, so I guess some
part of that must be what's tripping us up.

In any case, I think we should be doing new checks in
meson.build, not configure.  Paolo, what's the right
way to do a meson "really compile this program and
check it built" test?

thanks
-- PMM