[PATCH V2] python3native, pythonnative: export PYTHON_LIBRARY and PYTHON_INCLUDE_DIR

[Khem Raj <raj.khem@gmail.com>]

packages can use

find_package(PythonInterp REQUIRED)
find_package(PythonLibs REQUIRED)

while we control PYTHON pointing to native py3 the libs and include
directories will then point to build host version, which can result in
unexpected combination and if we are lucky we get errors if its quite
different e.g. py2 libs/includes and py3 executable

This variable can be then used to export PYTHON_LIBRARY and
PYTHON_INCLUDE_DIR so that above find_packages can work correctly

see [1] for how it happens in cmake

LLDB uses it see [2]

[1] https://github.com/Kitware/CMake/blob/master/Modules/FindPythonLibs.cmake
[2] https://github.com/llvm/llvm-project/blob/master/lldb/cmake/modules/LLDBConfig.cmake#L226

Signed-off-by: Khem Raj <raj.khem@gmail.com>
---
v2: Use PYTHON_DIR variable

 meta/classes/python3native.bbclass | 8 ++++++++
 meta/classes/pythonnative.bbclass  | 8 ++++++++
 2 files changed, 16 insertions(+)

diff --git a/meta/classes/python3native.bbclass b/meta/classes/python3native.bbclass
index a3acaf61bb..768302488b 100644
--- a/meta/classes/python3native.bbclass
+++ b/meta/classes/python3native.bbclass
@@ -9,6 +9,14 @@ DEPENDS_append = " python3-native "
 export STAGING_INCDIR
 export STAGING_LIBDIR
 
+# Packages can use
+# find_package(PythonInterp REQUIRED)
+# find_package(PythonLibs REQUIRED)
+# which ends up using libs/includes from build host
+# Therefore pre-empt that effort
+export PYTHON_LIBRARY="${STAGING_LIBDIR}/${PYTHON_DIR}"
+export PYTHON_INCLUDE_DIR="${STAGING_INCDIR}/${PYTHON_DIR}"
+
 export _PYTHON_SYSCONFIGDATA_NAME="_sysconfigdata"
 
 # suppress host user's site-packages dirs.
diff --git a/meta/classes/pythonnative.bbclass b/meta/classes/pythonnative.bbclass
index ae6600cd15..604423b80e 100644
--- a/meta/classes/pythonnative.bbclass
+++ b/meta/classes/pythonnative.bbclass
@@ -12,6 +12,14 @@ DEPENDS_append = " python-native "
 export STAGING_INCDIR
 export STAGING_LIBDIR
 
+# Packages can use
+# find_package(PythonInterp REQUIRED)
+# find_package(PythonLibs REQUIRED)
+# which ends up using libs/includes from build host
+# Therefore pre-empt that effort
+export PYTHON_LIBRARY="${STAGING_LIBDIR}/${PYTHON_DIR}"
+export PYTHON_INCLUDE_DIR="${STAGING_INCDIR}/${PYTHON_DIR}"
+
 # suppress host user's site-packages dirs.
 export PYTHONNOUSERSITE = "1"
 
-- 
2.23.0