cmake: fix Python executable with cmake

Currently, CMake has two ways of finding Python executables:
FindPythonInterp and FindPython/FindPython3. FindPythonInterp is
deprecated and may be removed at some point. Currently, python3native
sets PYTHON_EXECUTABLE, which FindPythonInterp uses. This is a problem
for a few reasons:

- Setting PYTHON_EXECUTABLE as an environment variable doesn't work, as
  CMake needs it to be set as an explicit CMake option via -D.
- Projects using the newer FindPython/FindPython3 don't pickup the right
  Python, as the newer routines use Python_EXECUTABLE and
  Python3_EXECUTABLE.

Fix this by setting PYTHON_EXECUTABLE, Python_EXECUTABLE, and
Python3_EXECUTABLE using -D options to EXTRA_OECMAKE.

The CMake routines are documented below:
https://cmake.org/cmake/help/latest/module/FindPythonInterp.html
https://cmake.org/cmake/help/latest/module/FindPython.html
https://cmake.org/cmake/help/latest/module/FindPython3.html

(From OE-Core rev: a22200a646eaf42cd4902a2fe3358d29717ac129)

Signed-off-by: Martin Kelly <mkelly@xevo.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

2 files changed, 3 insertions, 2 deletions

diff --git a/meta/classes/cmake.bbclass b/meta/classes/cmake.bbclass
index d91cf20130..94ed8061bb 100644
--- a/meta/classes/cmake.bbclass
+++ b/meta/classes/cmake.bbclass
@@ -175,6 +175,9 @@ cmake_do_configure() {
           -DCMAKE_INSTALL_LIBDIR:PATH=${@os.path.relpath(d.getVar('libdir'), d.getVar('prefix') + '/')} \
           -DCMAKE_INSTALL_INCLUDEDIR:PATH=${@os.path.relpath(d.getVar('includedir'), d.getVar('prefix') + '/')} \
           -DCMAKE_INSTALL_DATAROOTDIR:PATH=${@os.path.relpath(d.getVar('datadir'), d.getVar('prefix') + '/')} \
+          -DPYTHON_EXECUTABLE:PATH=${PYTHON} \
+          -DPython_EXECUTABLE:PATH=${PYTHON} \
+          -DPython3_EXECUTABLE:PATH=${PYTHON} \
           -DLIB_SUFFIX=${@d.getVar('baselib').replace('lib', '')} \
           -DCMAKE_INSTALL_SO_NO_EXE=0 \
           -DCMAKE_TOOLCHAIN_FILE=${WORKDIR}/toolchain.cmake \
diff --git a/meta/classes/python3native.bbclass b/meta/classes/python3native.bbclass
index 182c11aa2e..d98fb4c758 100644
--- a/meta/classes/python3native.bbclass
+++ b/meta/classes/python3native.bbclass
@@ -1,8 +1,6 @@
 inherit python3-dir
 
 PYTHON="${STAGING_BINDIR_NATIVE}/python3-native/python3"
-# PYTHON_EXECUTABLE is used by cmake
-PYTHON_EXECUTABLE="${PYTHON}"
 EXTRANATIVEPATH += "python3-native"
 DEPENDS_append = " python3-native "