mesonlib: handle meson exe wrappers

There are cases when it is useful to wrap the main meson executable with
a script that sets up environment variables, passes --cross-file, etc.
For example, in a Yocto SDK, we need to point to the right meson.cross
so that everything "just works", and we need to alter CC, CXX, etc. In
such cases, it can happen that the "meson" found in the path is actually
a wrapper script that invokes the real meson, which may be in another
location (e.g. "meson.real" or similar).

Currently, in such a situation, meson gets confused because it tries to
invoke itself using the "meson" executable (which points to the wrapper
script) instead of the actual meson (which may be called "meson.real" or
similar). In fact, the wrapper script is not necessarily even Python, so
the whole thing fails.

Fix this by using Python imports to directly find mesonmain.py instead
of trying to detect it heuristically. In addition to fixing the wrapper
issue, this should make the detection logic much more robust.

1 files changed, 4 insertions, 9 deletions

diff --git a/run_project_tests.py b/run_project_tests.py
index 3801432..644c6c3 100755
--- a/run_project_tests.py
+++ b/run_project_tests.py
@@ -41,7 +41,7 @@ import re
 from run_unittests import get_fake_options, run_configure
 
 from run_tests import get_backend_commands, get_backend_args_for_dir, Backend
-from run_tests import ensure_backend_detects_changes
+from run_tests import ensure_backend_detects_changes, setup_pythonpath
 
 
 class BuildStep(Enum):
@@ -88,12 +88,6 @@ no_meson_log_msg = 'No meson-log.txt found.'
 
 system_compiler = None
 
-meson_command = os.path.join(os.getcwd(), 'meson')
-if not os.path.exists(meson_command):
-    meson_command += '.py'
-    if not os.path.exists(meson_command):
-        raise RuntimeError('Could not find main Meson script to run.')
-
 class StopException(Exception):
     def __init__(self):
         super().__init__('Stopped by user')
@@ -324,7 +318,7 @@ def _run_test(testdir, test_build_dir, install_dir, extra_args, compiler, backen
     if pass_libdir_to_test(testdir):
         gen_args += ['--libdir', 'lib']
     gen_args += [testdir, test_build_dir] + flags + test_args + extra_args
-    (returncode, stdo, stde) = run_configure(meson_command, gen_args)
+    (returncode, stdo, stde) = run_configure(mesonlib.meson_command, gen_args)
     try:
         logfile = Path(test_build_dir, 'meson-logs', 'meson-log.txt')
         mesonlog = logfile.open(errors='ignore', encoding='utf-8').read()
@@ -647,7 +641,7 @@ def check_format():
                 check_file(fullname)
 
 def check_meson_commands_work():
-    global backend, meson_command, compile_commands, test_commands, install_commands
+    global backend, compile_commands, test_commands, install_commands
     testdir = PurePath('test cases', 'common', '1 trivial').as_posix()
     with AutoDeletedDir(tempfile.mkdtemp(prefix='b ', dir='.')) as build_dir:
         print('Checking that configuring works...')
@@ -692,6 +686,7 @@ if __name__ == '__main__':
     setup_commands(options.backend)
 
     detect_system_compiler()
+    setup_pythonpath()
     script_dir = os.path.split(__file__)[0]
     if script_dir != '':
         os.chdir(script_dir)