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

[Paolo Bonzini]

On 23/01/21 14:45, Peter Maydell wrote:
> 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?

One possibility is that you have to specify the #include in the "prefix" 
argument of cc.has_function for the test to behave as the QEMU code?

If cc.has_function doesn't work, there's cc.compiles() and cc.links().

Paolo