ARM Cross-compiling QtWebEngine: Fails on ninja rebuilding

AJCote

Here is the logs about the failure:

wrote build.ninja.
bootstrap complete.  rebuilding...
Traceback (most recent call last):
  File "/root/.conan/data/qt/5.15.9/ajcote/testing/source/qt/qtwebengine/src/3rdparty/ninja/configure.py", line 684, in <module>
    subprocess.check_call(rebuild_args)
  File "/usr/lib/python2.7/subprocess.py", line 185, in check_call
    retcode = call(*popenargs, **kwargs)
  File "/usr/lib/python2.7/subprocess.py", line 172, in call
    return Popen(*popenargs, **kwargs).wait()
  File "/usr/lib/python2.7/subprocess.py", line 394, in __init__
    errread, errwrite)
  File "/usr/lib/python2.7/subprocess.py", line 1047, in _execute_child
    raise child_exception
OSError: [Errno 2] No such file or directory
Project ERROR: NINJA build error!
Makefile:81: recipe for target 'sub-ninja-pro-make_first' failed
make[3]: *** [sub-ninja-pro-make_first] Error 3

It looks related to a missing python2 library, but I can't tell which one. Any ideas where to start the investigation?
Or is it possible to skip this part (of building ninja) because I already have it?

Thank you for your suggestions

EDIT:
I fixed the detection of ninja during the dependencies detection and the building of ninja is now skipped. However, it is now blocked on the linking of 'gn':

Project MESSAGE: /root/.conan/data/qt/5.15.9/ajcote/testing/source/qt/qtwebengine/src/3rdparty/gn/build/gen.py --no-last-commit-position --out-path /root/.conan/data/qt/5.15.9/ajcote/testing/build/2067b3f195cf6679f70b77b2487fc5f31f6cc207/qtwebengine/src/3rdparty/gn/out/Release --cc "/usr/bin/gcc" --cxx "/usr/bin/g++" --ld "/usr/bin/g++"
[0/187] CXX base/files/scoped_temp_dir.omake[4]: Entering directory '/root/.conan/data/qt/5.15.9/ajcote/testing/build/2067b3f195cf6679f70b77b2487fc5f31f6cc207/qtwebengine/src/buildtools'
make[4]: Nothing to be done for 'first'.
make[4]: Leaving directory '/root/.conan/data/qt/5.15.9/ajcote/testing/build/2067b3f195cf6679f70b77b2487fc5f31f6cc207/qtwebengine/src/buildtools'
[187/187] LINK gn
FAILED: gn
/usr/bin/g++ -O3 -fdata-sections -ffunction-sections -Wl,--gc-sections -Wl,-strip-all -Wl,--as-needed -static-libstdc++ -pthread -o gn -Wl,--start-group tools/gn/gn_main.o base.a gn_lib.a -Wl,--end-group -ldl
base.a: error adding symbols: Archive has no index; run ranlib to add one
collect2: error: ld returned 1 exit status
ninja: build stopped: subcommand failed.
Project ERROR: GN build error!
Makefile:98: recipe for target 'sub-gn-pro-make_first' failed
make[3]: *** [sub-gn-pro-make_first] Error 3
make[3]: Leaving directory '/root/.conan/data/qt/5.15.9/ajcote/testing/build/2067b3f195cf6679f70b77b2487fc5f31f6cc207/qtwebengine/src/buildtools'
Makefile:53: recipe for target 'sub-buildtools-make_first' failed
make[2]: *** [sub-buildtools-make_first] Error 2
make[2]: Leaving directory '/root/.conan/data/qt/5.15.9/ajcote/testing/build/2067b3f195cf6679f70b77b2487fc5f31f6cc207/qtwebengine/src'
Makefile:48: recipe for target 'sub-src-make_first' failed
make[1]: *** [sub-src-make_first] Error 2
make[1]: Leaving directory '/root/.conan/data/qt/5.15.9/ajcote/testing/build/2067b3f195cf6679f70b77b2487fc5f31f6cc207/qtwebengine'
Makefile:532: recipe for target 'module-qtwebengine-make_first' failed
make: *** [module-qtwebengine-make_first] Error 2

EDIT 2: The linking of 'gn' is fixed with this patch: https://codereview.qt-project.org/c/qt/qtwebengine/+/411914

However, the rebuilding of ninja is still failing when it is not provided by the host OS.