[Buildroot] [git commit branch/2022.02.x] meson-package: prevent cmake find_package() picking up host libraries

[Peter Korsgaard]

commit: https://git.buildroot.net/buildroot/commit/?id=e35d7f2ed4cd0e2bab9d1003246cba951689e8bd
branch: https://git.buildroot.net/buildroot/commit/?id=refs/heads/2022.02.x

The meson build system uses (1) pkg-config and (2) cmake find_package to locate
dependencies and stops only if a package is found. Cmake uses a toolchain file
that is generated by meson from the existing configuration [1].

The cmake toolchain file misses CMAKE_FIND_ROOT_PATH and CMAKE_FIND_ROOT_PATH_*
settings, and find_package() falls back to the default behaviour and looks for
dependencies on the build machine (the Buildroot HOST_DIR).

Use a feature introduced in meson 0.56.0 [2] to pass the Buildroot toolchain
file to cmake instead of using a meson-generated one.

Fixes the following build failures:
http://autobuild.buildroot.org/results/056/05673ed04c6f044f1b56b9d5342d61653be43a18/
http://autobuild.buildroot.org/results/f0a/f0a9e719114f19dc9d20622ed85dd4f8e968c20f/
http://autobuild.buildroot.org/results/527/527ee199813abbacd61c3fa32b517ea60af60659/

[1[ see mesonbuild/cmake/toolchain.py
[2] see https://mesonbuild.com/CMake-module.html#cross-compilation

Signed-off-by: Andreas Ziegler <br015 at umbiko.net>
Signed-off-by: Yann E. MORIN <yann.morin.1998 at free.fr>
(cherry picked from commit 6ab8b1e26386527659c27d9b194a0915e1ff6c34)
Signed-off-by: Peter Korsgaard <peter at korsgaard.com>
---
 package/pkg-meson.mk                   | 1 +
 support/misc/cross-compilation.conf.in | 3 +++
 2 files changed, 4 insertions(+)

diff --git a/package/pkg-meson.mk b/package/pkg-meson.mk
index 9e70d49b60..f1390a18d0 100644
--- a/package/pkg-meson.mk
+++ b/package/pkg-meson.mk
@@ -81,6 +81,7 @@ define PKG_MESON_CROSSCONFIG_SED
         -e "s%@TARGET_CXXFLAGS@%$(call make-sq-comma-list,$($(strip $(2))))%g" \
         -e "s%@BR2_CMAKE@%$(BR2_CMAKE)%g" \
         -e "s%@PKGCONF_HOST_BINARY@%$(HOST_DIR)/bin/pkgconf%g" \
+        -e "s%@HOST_DIR@%$(HOST_DIR)%g" \
         -e "s%@STAGING_DIR@%$(STAGING_DIR)%g" \
         -e "s%@STATIC@%$(if $(BR2_STATIC_LIBS),true,false)%g" \
         $(TOPDIR)/support/misc/cross-compilation.conf.in
diff --git a/support/misc/cross-compilation.conf.in b/support/misc/cross-compilation.conf.in
index 1977a83501..235e5a8495 100644
--- a/support/misc/cross-compilation.conf.in
+++ b/support/misc/cross-compilation.conf.in
@@ -26,6 +26,9 @@ needs_exe_wrapper = true
 sys_root = '@STAGING_DIR@'
 pkg_config_libdir = '@STAGING_DIR@/usr/lib/pkgconfig:@STAGING_DIR@/usr/share/pkgconfig'
 pkg_config_static = '@STATIC@'
+# enable meson build to pass a toolchain file to cmake
+cmake_toolchain_file = '@HOST_DIR@/share/buildroot/toolchainfile.cmake'
+cmake_defaults = false
 
 [host_machine]
 system = 'linux'