cross: Be more permissive about not-found exe_wrapper

We used to immediately try to use whatever exe_wrapper was defined in
the cross file, but some people generate the cross file once and use
it for several projects, most of which do not even need an exe wrapper
to build.

Now we're a bit more resilient. We quietly fall back to using
non-exe-wrapper paths for compiler checks and skip the sanity check.
However, if some code needs the exe wrapper, f.ex., if you run a built
executable using custom_target() or run_target(), we will error out
during setup.

Tests will, of course, continue to error out when you run them if the
exe wrapper was not found. We don't want people's tests to silently
"pass" (aka skip) because of a bad CI setup.

Closes https://github.com/mesonbuild/meson/issues/3562

This commit also adds a test for the behaviour of exe_wrapper in these
cases, and refactors the unit tests a bit for it.

1 files changed, 25 insertions, 9 deletions

diff --git a/run_tests.py b/run_tests.py
index af20ba2..6e441d3 100755
--- a/run_tests.py
+++ b/run_tests.py
@@ -29,6 +29,7 @@ from pathlib import Path
 import mesonbuild
 from mesonbuild import mesonlib
 from mesonbuild import mesonmain
+from mesonbuild import mtest
 from mesonbuild import mlog
 from mesonbuild.environment import detect_ninja
 
@@ -156,8 +157,17 @@ def get_fake_options(prefix):
     opts.cmd_line_options = {}
     return opts
 
-def should_run_linux_cross_tests():
-    return shutil.which('arm-linux-gnueabihf-gcc') and not platform.machine().lower().startswith('arm')
+def run_mtest_inprocess(commandlist):
+    old_stdout = sys.stdout
+    sys.stdout = mystdout = StringIO()
+    old_stderr = sys.stderr
+    sys.stderr = mystderr = StringIO()
+    try:
+        returncode = mtest.run(commandlist)
+    finally:
+        sys.stdout = old_stdout
+        sys.stderr = old_stderr
+    return returncode, mystdout.getvalue(), mystderr.getvalue()
 
 def run_configure_inprocess(commandlist):
     old_stdout = sys.stdout
@@ -203,7 +213,7 @@ if __name__ == '__main__':
     # Iterate over list in reverse order to find the last --backend arg
     backend = Backend.ninja
     cross = False
-    # FIXME: Convert to argparse
+    # FIXME: PLEASE convert to argparse
     for arg in reversed(sys.argv[1:]):
         if arg.startswith('--backend'):
             if arg.startswith('--backend=vs'):
@@ -212,6 +222,10 @@ if __name__ == '__main__':
                 backend = Backend.xcode
         if arg.startswith('--cross'):
             cross = True
+            if arg == '--cross=mingw':
+                cross = 'mingw'
+            elif arg == '--cross=arm':
+                cross = 'arm'
     # Running on a developer machine? Be nice!
     if not mesonlib.is_windows() and not mesonlib.is_haiku() and 'TRAVIS' not in os.environ:
         os.nice(20)
@@ -249,10 +263,12 @@ if __name__ == '__main__':
             returncode += subprocess.call(mesonlib.python_command + ['run_project_tests.py'] + sys.argv[1:], env=env)
         else:
             cross_test_args = mesonlib.python_command + ['run_cross_test.py']
-            print(mlog.bold('Running armhf cross tests.').get_text(mlog.colorize_console))
-            print()
-            returncode += subprocess.call(cross_test_args + ['cross/ubuntu-armhf.txt'], env=env)
-            print(mlog.bold('Running mingw-w64 64-bit cross tests.').get_text(mlog.colorize_console))
-            print()
-            returncode += subprocess.call(cross_test_args + ['cross/linux-mingw-w64-64bit.txt'], env=env)
+            if cross is True or cross == 'arm':
+                print(mlog.bold('Running armhf cross tests.').get_text(mlog.colorize_console))
+                print()
+                returncode += subprocess.call(cross_test_args + ['cross/ubuntu-armhf.txt'], env=env)
+            if cross is True or cross == 'mingw':
+                print(mlog.bold('Running mingw-w64 64-bit cross tests.').get_text(mlog.colorize_console))
+                print()
+                returncode += subprocess.call(cross_test_args + ['cross/linux-mingw-w64-64bit.txt'], env=env)
     sys.exit(returncode)