cmake: handle arguments in the [binaries] section of the machine file

Sometimes, the machine file can include compiler command line options,
in order to pick the correct multilib.  For example, Meson uses "$cc
--print-search-dirs" to find the library search path, where $cc is the
cc from the machine file.  Because the outputs of "gcc -m32
--print-search-dirs" and "gcc --print-search-dirs" are different, this
only works if you have

   [binaries]
   cc = ['gcc', '-m32']

in the machine file.  Right now, however, the cmake module assumes that
the compiler listed in the machine file is either a compiler, or a
"launcher" followed by the compiler.  Check if the second argument
starts with a slash (for Microsoft-like compilers) or a dash (for
everyone else), and if so presume that the CMAKE_*_COMPILER_LAUNCHER
need not be defined.

2 files changed, 49 insertions, 6 deletions

diff --git a/mesonbuild/cmake/toolchain.py b/mesonbuild/cmake/toolchain.py
index 50ff10c..316f57c 100644
--- a/mesonbuild/cmake/toolchain.py
+++ b/mesonbuild/cmake/toolchain.py
@@ -16,6 +16,7 @@ from pathlib import Path
 from .traceparser import CMakeTraceParser
 from ..envconfig import CMakeSkipCompilerTest
 from ..mesonlib import MachineChoice
+from ..compilers import VisualStudioLikeCompiler
 from .common import language_map, cmake_get_generator_args
 from .. import mlog
 
@@ -27,6 +28,7 @@ from textwrap import dedent
 if T.TYPE_CHECKING:
     from .executor import CMakeExecutor
     from ..environment import Environment
+    from ..compilers import Compiler
 
 class CMakeExecScope(Enum):
     SUBPROJECT = 'subproject'
@@ -182,21 +184,30 @@ class CMakeToolchain:
 
         # Set the compiler variables
         for lang, comp_obj in self.compilers.items():
-            exe_list = [make_abs(x) for x in comp_obj.get_exelist()]
             prefix = 'CMAKE_{}_'.format(language_map.get(lang, lang.upper()))
 
+            exe_list = comp_obj.get_exelist()
             if not exe_list:
                 continue
-            elif len(exe_list) == 2:
-                defaults[prefix + 'COMPILER']          = [exe_list[1]]
-                defaults[prefix + 'COMPILER_LAUNCHER'] = [exe_list[0]]
-            else:
-                defaults[prefix + 'COMPILER'] = exe_list
+
+            if len(exe_list) >= 2 and not self.is_cmdline_option(comp_obj, exe_list[1]):
+                defaults[prefix + 'COMPILER_LAUNCHER'] = [make_abs(exe_list[0])]
+                exe_list = exe_list[1:]
+
+            exe_list[0] = make_abs(exe_list[0])
+            defaults[prefix + 'COMPILER'] = exe_list
             if comp_obj.get_id() == 'clang-cl':
                 defaults['CMAKE_LINKER'] = comp_obj.get_linker_exelist()
 
         return defaults
 
+    @staticmethod
+    def is_cmdline_option(compiler: 'Compiler', arg: str) -> bool:
+        if isinstance(compiler, VisualStudioLikeCompiler):
+            return arg.startswith('/')
+        else:
+            return arg.startswith('-')
+
     def update_cmake_compiler_state(self) -> None:
         # Check if all variables are already cached
         if self.cmakestate.languages.issuperset(self.compilers.keys()):
diff --git a/unittests/linuxliketests.py b/unittests/linuxliketests.py
index 991a0c2..81cca06 100644
--- a/unittests/linuxliketests.py
+++ b/unittests/linuxliketests.py
@@ -1697,3 +1697,35 @@ class LinuxlikeTests(BasePlatformTests):
         obj_files = p.stdout.strip().split('\n')
         self.assertEqual(len(obj_files), 1)
         self.assertTrue(obj_files[0].endswith('-prelink.o'))
+
+    def do_one_test_with_nativefile(self, testdir, args):
+        testdir = os.path.join(self.common_test_dir, testdir)
+        with tempfile.TemporaryDirectory() as d:
+            p = Path(d) / 'nativefile'
+            with p.open('wt', encoding='utf-8') as f:
+                f.write(f'''[binaries]
+                    c = {args}
+                    ''')
+            self.init(testdir, extra_args=['--native-file=' + str(p)])
+            self.build()
+
+    def test_cmake_multilib(self):
+        '''
+        Test that the cmake module handles multilib paths correctly.
+        '''
+        # Verify that "gcc -m32" works
+        try:
+            self.do_one_test_with_nativefile('1 trivial', "['gcc', '-m32']")
+        except subprocess.CalledProcessError as e:
+            raise SkipTest('Not GCC, or GCC does not have the -m32 option')
+        self.wipe()
+
+        # Verify that cmake works
+        try:
+            self.do_one_test_with_nativefile('../cmake/1 basic', "['gcc']")
+        except subprocess.CalledProcessError as e:
+            raise SkipTest('Could not build basic cmake project')
+        self.wipe()
+
+        # If so, we can test that cmake works with "gcc -m32"
+        self.do_one_test_with_nativefile('../cmake/1 basic', "['gcc', '-m32']")