[Buildroot] [PATCH v14 4/5] package/pkg-meson.mk: set Python sysconfigdata

[aduskett at gmail.com <aduskett@gmail.com>]

From: Adam Duskett <Aduskett@gmail.com>

meson has support for Python dependencies, to e.g. build Python modules.
It parses Python's sysconfig module to find the appropriate
configuration variables. However, the sysconfig module is the one for
the host, _not_ for the target. Therefore, wrong values may be set. Many
of them get overridden anyway by the cross-compilation.conf. One
particular one that is problematic is that it uses the python-XXX.pc
pkg-config file for the host instead of the target, because it
explicitly sets the PKG_CONFIG_LIBDIR found in sysconfig.

Use the same trick as for python package: pass PYTHONPATH,
PYTHONNOUSERSITE and _PYTHON_SYSCONFIGDATA_NAME in the environment to
point to staging instead of host. This ensures the sysconfig from the
target is used instead of the one from the host.

An alternative would be to patch meson to not use the PKG_CONFIG_LIBDIR
from sysconfig. However, it is likely that other problems will pop up at
some point because of using the wrong sysconfig.

Note that this approach will still break things when meson needs to
build something for the host during a target build.

Signed-off-by: Adam Duskett <Aduskett@gmail.com>
---
Changes v1 -> v14:
  - Add this patch to the series.

 package/pkg-meson.mk | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/package/pkg-meson.mk b/package/pkg-meson.mk
index 184a22a44a..b6360fb738 100644
--- a/package/pkg-meson.mk
+++ b/package/pkg-meson.mk
@@ -84,6 +84,9 @@ define $(2)_CONFIGURE_CMDS
 	    ) \
 	    package/meson/cross-compilation.conf.in \
 	    > $$($$(PKG)_SRCDIR)/build/cross-compilation.conf
+	_PYTHON_SYSCONFIGDATA_NAME="$$(if $$(BR2_PACKAGE_PYTHON3),$$(PKG_PYTHON_SYSCONFIGDATA_NAME),_sysconfigdata)" \
+	PYTHONPATH="$$(if $$(BR2_PACKAGE_PYTHON3),$$(PYTHON3_PATH),$$(PYTHON_PATH))" \
+	PYTHONNOUSERSITE=1 \
 	PATH=$$(BR_PATH) $$($$(PKG)_CONF_ENV) $$(MESON) \
 		--prefix=/usr \
 		--libdir=lib \
-- 
2.21.0