https://github.com/vkmark/vkmark/blob/master/src/meson.build#L9

On Tue, Nov 30, 2021 at 10:53 AM Alexander Kanavin <alex.kanavin@gmail.com>
wrote:

> I do not quite understand the use case. What is being done with the full
> path to the header?
>
> Alex
>
> On Tue, 30 Nov 2021 at 19:26, Joel Winarske <joel.winarske@gmail.com>
> wrote:
>
>> This pattern works to get the absolute path of the header:
>>
>> Yocto
>>
>>     EXTRA_OEMESON += "--prefix ${STAGING_DIR_TARGET}/usr"
>>
>> Meson
>>
>>     vulkan_dep = dependency('vulkan')
>>     vulkan_hpp = join_paths([
>>         vulkan_dep.get_pkgconfig_variable('includedir', define_variable:
>> ['prefix', get_option('prefix')]),
>>         'vulkan',
>>         'vulkan.hpp'
>>         ])
>>
>> Implementation in build/meson-log.txt
>>
>> Called
>> `/b/github-ci/_work/meta-flutter/rpi4-drm-honister-latest/rpi4/tmp/work/cortexa72-poky-linux/vkmark/git-r0/recipe-sysroot-native/usr/bin/pkg-config
>> --define-variable=prefix=/b/github-ci/_work/meta-flutter/rpi4-drm-honister-latest/rpi4/tmp/work/cortexa72-poky-linux/vkmark/git-r0/recipe-sysroot/usr
>> --variable=includedir vulkan` -> 0
>>
>>
>> One would expect the following meson to work if STAGING_DIR_TARGET were
>> set, as that's how pkg-config works:
>>
>>     vulkan_dep = dependency('vulkan')
>>     vulkan_hpp = join_paths([
>>         vulkan_dep.get_pkgconfig_variable('includedir'),
>>         'vulkan',
>>         'vulkan.hpp'
>>         ])
>>
>> This will always return /usr/include/vulkan/vulkan.hpp regardless of
>> PKG_CONFIG_SYSROOT_DIR value.  With PKG_CONFIG_SYSROOT_DIR set, it should
>> be /usr/include/vulkan/vulkan.hpp with prepend of PKG_CONFIG_SYSROOT_DIR
>> value.
>>
>>
>> Sandbox testing of pkg-config
>>
>>     $ export
>> STAGING_DIR_TARGET=/b/github-ci/_work/meta-flutter/rpi4-drm-honister-latest/raspberrypi4-64/tmp/work/cortexa72-poky-linux/vkmark/git-r0/recipe-sysroot
>>     $ PKG_CONFIG_SYSROOT_DIR=$STAGING_DIR_TARGET pkg-config
>> --define-variable=prefix=/opt --variable=includedir vulkan
>>
>> /b/github-ci/_work/meta-flutter/rpi4-drm-honister-latest/raspberrypi4-64/tmp/work/cortexa72-poky-linux/vkmark/git-r0/recipe-sysroot/opt/include
>>
>>
>> meson.cross
>>
>> Setting sys_root in the properties section of meson.cross (patching
>> meson.bbclass) indirectly sets PKG_CONFIG_SYSROOT_DIR.  The setting of
>> sys_root is present in nativesdk_meson*.bb, not meson*.bb.
>>
>> The issue for meson is that they are not passing the
>> PKG_CONFIG_SYSROOT_DIR variable to the shell that launches pkg-config.
>>
>> My proposed work around (this email thread) would fix the behavior.  I
>> believe the proper fix is for meson to address upstream.  Still waiting on
>> a response from them: https://github.com/mesonbuild/meson/issues/9674
>>
>>
>> Joel
>>
>> On Tue, Nov 30, 2021 at 9:49 AM Alexander Kanavin <alex.kanavin@gmail.com>
>> wrote:
>>
>>> On Tue, 30 Nov 2021 at 18:20, Joel Winarske <joel.winarske@gmail.com>
>>> wrote:
>>>
>>>> Meson does not expose PKG_CONFIG_SYSROOT_DIR to the pkg-config process.
>>>>
>>>> Currently meson.cross as generated in meson.bbclass points directly to
>>>> the pkg-config executable (no wrapper script).
>>>>
>>>> PKG_CONFIG_SYSROOT_DIR behaves like a simple string prepend to all
>>>> package config variable queries.  So if you want to determine the absolute
>>>> path of a variable in .pc you set PKG_CONFIG_SYSROOT_DIR and make your
>>>> query.  Currently this is not possible with Yocto+Meson.
>>>>
>>>> I think a simple wrapper script would resolve this.  This is from
>>>> https://autotools.io/pkgconfig/cross-compiling.html:
>>>>
>>>> #!/bin/sh
>>>>
>>>> SYSROOT=/build/root
>>>>
>>>> export PKG_CONFIG_PATH=
>>>> export PKG_CONFIG_LIBDIR=${SYSROOT}/usr/lib/pkgconfig:${SYSROOT}/usr/share/pkgconfig
>>>> export PKG_CONFIG_SYSROOT_DIR=${SYSROOT}
>>>>
>>>> exec pkg-config "$@"
>>>>
>>>>
>>>> The wrapper script would be generated per recipe via meson.bbclass,
>>>> meson.cross would then reference this wrapper instead of the pkg-config
>>>> executable.
>>>>
>>>> Thoughts?
>>>>
>>>
>>> I don't think this is correct. Meson's way of doing things is that you
>>> are not supposed to get the include/library paths directly from pkg-config,
>>> but rather use
>>> https://mesonbuild.com/Reference-manual_functions.html#dependency and
>>> meson will take care of any needed prefixes to the paths.
>>>
>>> For the custom variables defined in .pc that happen to contain paths,
>>> PKG_CONFIG_SYSROOT_DIR has no effect at all, so you need to manually
>>> prepend it anyway everywhere where they're used. pkg-config does not know
>>> what variable is a path and what isn't.
>>>
>>> Alex
>>>
>>