Re: Target-dependent include path, why?

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

On 9/12/22 16:02, Richard Henderson wrote:
> On 12/9/22 02:51, Markus Armbruster wrote:
>> Richard Henderson <richard.henderson@linaro.org> writes:
>>
>>> On 12/8/22 23:12, Markus Armbruster wrote:
>>>> I stumbled over this:
>>>>       ../include/ui/qemu-pixman.h:12:10: fatal error: pixman.h: No 
>>>> such file or directory
>>>>          12 | #include <pixman.h>
>>>>             |          ^~~~~~~~~~
>>>> Works when included into target-dependent code.
>>>> Running make -V=1 shows we're passing a number of -I only when 
>>>> compiling
>>>> target-dependent code, i.e. together with -DNEED_CPU_H:
>>>>       -I/usr/include/pixman-1 -I/usr/include/capstone 
>>>> -I/usr/include/spice-server -I/usr/include/spice-1
>>>>       -I/usr/include/cacard -I/usr/include/nss3 -I/usr/include/nspr4 
>>>> -I/usr/include/PCSC
>>>>       -isystem../linux-headers -isystemlinux-headers
>>>> Why?
>>>
>>> Because of where [pixman] is added as a dependency in meson.build.
>>
>> Is it added where it is for a reason, or is it accidental?
> 
> I don't know for sure, but I doubt it's accidental.
> I'm sure it is where it is based on existing usage.

I hit a similar problem while converting units to be target-independent,
moving them out of specific_ss[] I got:

  In file included from ../monitor/misc.c:38:
  In file included from include/ui/console.h:4:
  include/ui/qemu-pixman.h:12:10: fatal error: 'pixman.h' file not found
  #include <pixman.h>
           ^~~~~~~~~~

The monitor/ dependency is odd because there is no pixman use in the
sources, only pulled by the headers:

   $ git grep pixman monitor/
   monitor/meson.build:9:specific_ss.add(when: 'CONFIG_SOFTMMU', 
if_true: [files('misc.c'), spice, pixman])

We require pixman for system emulation. The dependency is added in 
ui/meson.build:

   softmmu_ss.add(pixman)
   specific_ss.add(when: ['CONFIG_SOFTMMU'], if_true: pixman)   # for 
the include path

Due to the second line, I was expecting all files in specific_ss[] to 
have pixman path in their CPPFLAGS. The monitor/meson.build has:

   specific_ss.add(when: 'CONFIG_SOFTMMU', if_true: [files('misc.c'), 
spice])

Paolo, is it due to the [] that monitor/misc.c doesn't get the pixman
pkg-config flags?