Fix cross environment pollution.

Environment variables like CFLAGS and LDFLAGS should not affect the
cross environment.

Fixes #1772

mesonbuild/backend/backends.py

@@ -405,9 +405,10 @@ def generate_basic_compiler_args(self, target, compiler, no_warn_args=False):
         # Add compile args added using add_global_arguments()
         # These override per-project arguments
         commands += self.build.get_global_args(compiler)
-        # Compile args added from the env: CFLAGS/CXXFLAGS, etc. We want these
-        # to override all the defaults, but not the per-target compile args.
-        commands += self.environment.coredata.external_args[compiler.get_language()]
+        if not target.is_cross:
+            # Compile args added from the env: CFLAGS/CXXFLAGS, etc. We want these
+            # to override all the defaults, but not the per-target compile args.
+            commands += self.environment.coredata.external_args[compiler.get_language()]
         # Always set -fPIC for shared libraries
         if isinstance(target, build.SharedLibrary):
             commands += compiler.get_pic_args()

mesonbuild/backend/ninjabackend.py

@@ -2266,9 +2266,10 @@ def generate_link(self, target, outfile, outname, obj_list, linker, extra_args=[
             # Add link args added using add_global_link_arguments()
             # These override per-project link arguments
             commands += self.build.get_global_link_args(linker)
-            # Link args added from the env: LDFLAGS. We want these to
-            # override all the defaults but not the per-target link args.
-            commands += self.environment.coredata.external_link_args[linker.get_language()]
+            if not target.is_cross:
+                # Link args added from the env: LDFLAGS. We want these to
+                # override all the defaults but not the per-target link args.
+                commands += self.environment.coredata.external_link_args[linker.get_language()]
 
         # Now we will add libraries and library paths from various sources
 

mesonbuild/backend/vs2010backend.py

@@ -759,11 +759,12 @@ def gen_vcxproj(self, target, ofname, guid):
         for l, args in self.build.global_args.items():
             if l in file_args:
                 file_args[l] += args
-        # Compile args added from the env: CFLAGS/CXXFLAGS, etc. We want these
-        # to override all the defaults, but not the per-target compile args.
-        for l, args in self.environment.coredata.external_args.items():
-            if l in file_args:
-                file_args[l] += args
+        if not target.is_cross:
+            # Compile args added from the env: CFLAGS/CXXFLAGS, etc. We want these
+            # to override all the defaults, but not the per-target compile args.
+            for l, args in self.environment.coredata.external_args.items():
+                if l in file_args:
+                    file_args[l] += args
         for args in file_args.values():
             # This is where Visual Studio will insert target_args, target_defines,
             # etc, which are added later from external deps (see below).
@@ -901,9 +902,10 @@ def gen_vcxproj(self, target, ofname, guid):
             # Add link args added using add_global_link_arguments()
             # These override per-project link arguments
             extra_link_args += self.build.get_global_link_args(compiler)
-            # Link args added from the env: LDFLAGS. We want these to
-            # override all the defaults but not the per-target link args.
-            extra_link_args += self.environment.coredata.external_link_args[compiler.get_language()]
+            if not target.is_cross:
+                # Link args added from the env: LDFLAGS. We want these to
+                # override all the defaults but not the per-target link args.
+                extra_link_args += self.environment.coredata.external_link_args[compiler.get_language()]
             # Only non-static built targets need link args and link dependencies
             extra_link_args += target.link_args
             # External deps must be last because target link libraries may depend on them.

mesonbuild/compilers.py

@@ -957,15 +957,16 @@ def _get_compiler_check_args(self, env, extra_args, dependencies, mode='compile'
             args += self.get_linker_debug_crt_args()
         # Read c_args/cpp_args/etc from the cross-info file (if needed)
         args += self.get_cross_extra_flags(env, link=(mode == 'link'))
-        if mode == 'preprocess':
-            # Add CPPFLAGS from the env.
-            args += env.coredata.external_preprocess_args[self.language]
-        elif mode == 'compile':
-            # Add CFLAGS/CXXFLAGS/OBJCFLAGS/OBJCXXFLAGS from the env
-            args += env.coredata.external_args[self.language]
-        elif mode == 'link':
-            # Add LDFLAGS from the env
-            args += env.coredata.external_link_args[self.language]
+        if not self.is_cross:
+            if mode == 'preprocess':
+                # Add CPPFLAGS from the env.
+                args += env.coredata.external_preprocess_args[self.language]
+            elif mode == 'compile':
+                # Add CFLAGS/CXXFLAGS/OBJCFLAGS/OBJCXXFLAGS from the env
+                args += env.coredata.external_args[self.language]
+            elif mode == 'link':
+                # Add LDFLAGS from the env
+                args += env.coredata.external_link_args[self.language]
         args += self.get_compiler_check_args()
         # extra_args must override all other arguments, so we add them last
         args += extra_args

run_tests.py

@@ -153,7 +153,7 @@ def is_cross_build(self):
     print('Running unittests.\n')
     units = ['InternalTests', 'AllPlatformTests']
     if mesonlib.is_linux():
-        units += ['LinuxlikeTests']
+        units += ['LinuxlikeTests', 'LinuxArmCrossCompileTests']
     elif mesonlib.is_windows():
         units += ['WindowsTests']
     # Can't pass arguments to unit tests, so set the backend to use in the environment

run_unittests.py

@@ -1531,6 +1531,27 @@ def test_run_installed(self):
         env['LD_LIBRARY_PATH'] = installed_libdir
         self.assertEqual(subprocess.call(installed_exe, env=env), 0)
 
+class LinuxArmCrossCompileTests(BasePlatformTests):
+    '''
+    Tests that verify cross-compilation to Linux/ARM
+    '''
+    def setUp(self):
+        super().setUp()
+        src_root = os.path.dirname(__file__)
+        self.meson_command += ['--cross=' + os.path.join(src_root, 'cross', 'ubuntu-armhf.txt')]
+
+    def test_cross_environment_pollution(self):
+        '''
+        Test that CFLAGS and the like don't pollute the cross environment. This
+        can't be an ordinary test case because we need to inspect the compiler
+        database.
+        '''
+        testdir = os.path.join(self.common_test_dir, '3 static')
+        os.environ['CFLAGS'] = '-DBUILD_ENVIRONMENT_ONLY'
+        self.init(testdir)
+        compdb = self.get_compdb()
+        self.assertNotIn('-DBUILD_ENVIRONMENT_ONLY', compdb[0]['command'])
+
 class RewriterTests(unittest.TestCase):
 
     def setUp(self):