[Development] Coin, Boot2Qt, and OE_QMAKE_PATH_HOST_BINS variable

[Konstantin Tokarev]

Hello,

I've tried to enable cross-compilation in Coin for QtWebKit 5.212 to improve
platform coverage in each build, however I've faced following problem.

Our Linux cross-compilation platform is Boot2Qt which is based on meta-qt5
Yocto layer. QtWebKit uses CMake internally, and Qt cmake config files on
this platform rely on environment variable OE_QMAKE_PATH_HOST_BINS
(see patch[1]). However, qmake-based builds seem to work fine without this
variable.

I suppose that patch[1] is wrong. Can we revert it in Yocto images used in Coin?


[1] https://github.com/meta-qt5/meta-qt5/blob/268429962056a12e0e899612dafb433c257af5cf/recipes-qt/qt5/qtbase/0006-Pretend-Qt5-wasn-t-found-if-OE_QMAKE_PATH_EXTERNAL_H.patch

You can see that this patch avtually checks OE_QMAKE_PATH_EXTERNAL_HOST_BINS
CMake variable instead of environment; in
sysroots/x86_64-pokysdk-linux/usr/share/cmake/OEToolchainConfig.cmake.d/OEQt5Toolchain.cmake
this cmake variable is set to $ENV{OE_QMAKE_PATH_HOST_BINS}, there is no
similar file for Aarch64 sysroot and there is no way to guess it's location in the build
system without hardcoding. Anyway it won't help, because subject variable isn't set.

-- 
Regards,
Konstantin