compilers/clike: Speedup cross_compute_int

Expand the expression passed into cross_compute_int using the
preprocessor first and then try to evaluate the expanded expression
using the host machine compiler and test if the result is valid.

Co-authored-by: Charles Brunet <[email protected]>

mesonbuild/compilers/mixins/clike.py

@@ -476,6 +476,21 @@ def cross_compute_int(self, expression: str, low: T.Optional[int], high: T.Optio
             if self._compile_int(f'{expression} == {guess}', prefix, env, extra_args, dependencies):
                 return guess
 
+        # Try to expand the expression and evaluate it on the build machines compiler
+        if self.language in env.coredata.compilers.build:
+            try:
+                expanded, _ = self.get_define(expression, prefix, env, extra_args, dependencies, False)
+                evaluate_expanded = f'''
+                #include <stdio.h>
+                #include <stdint.h>
+                int main(void) {{ int expression = {expanded}; printf("%d", expression); return 0; }}'''
+                run = env.coredata.compilers.build[self.language].run(evaluate_expanded, env)
+                if run and run.compiled and run.returncode == 0:
+                    if self._compile_int(f'{expression} == {run.stdout}', prefix, env, extra_args, dependencies):
+                        return int(run.stdout)
+            except mesonlib.EnvironmentException:
+                pass
+
         # If no bounds are given, compute them in the limit of int32
         maxint = 0x7fffffff
         minint = -0x80000000

unittests/linuxcrosstests.py

@@ -46,6 +46,15 @@ def test_cflags_cross_environment_pollution(self):
         compdb = self.get_compdb()
         self.assertNotIn('-DBUILD_ENVIRONMENT_ONLY', compdb[0]['command'])
 
+    def test_cross_compute_int(self):
+        '''
+        Test that compute int works even in environments that that do not have
+        exe_wrapper to run built executables.
+        '''
+        testdir = os.path.join(self.common_test_dir, '134 compute int')
+        self.init(testdir)
+        self.build()
+
     def test_cross_file_overrides_always_args(self):
         '''
         Test that $lang_args in cross files always override get_always_args().