compiler: Add compute_int functionality.

Fixes #435

2 files changed, 43 insertions, 0 deletions

diff --git a/mesonbuild/compilers.py b/mesonbuild/compilers.py
index 8c2bb92..d1a564b 100644
--- a/mesonbuild/compilers.py
+++ b/mesonbuild/compilers.py
@@ -1010,6 +1010,34 @@ class CCompiler(Compiler):
                 return i
         raise EnvironmentException('Cross-compile check overflowed')
 
+    def cross_compute_int(self, fragment, prefix, env, extra_args=None, dependencies=None):
+        if extra_args is None:
+            extra_args = []
+        fargs = {'prefix': prefix, 'fragment': fragment}
+        t = '''#include <stdio.h>
+        {prefix}
+        int temparray[{size}-({fragment})];'''
+        return self._bisect_compiles(t, fargs, env, extra_args, dependencies)
+
+    def compute_int(self, fragment, prefix, env, extra_args=None, dependencies=None):
+        if extra_args is None:
+            extra_args = []
+        fargs = {'prefix': prefix, 'fragment': fragment}
+        if self.is_cross:
+            return self.cross_compute_int(fragment, prefix, env, extra_args, dependencies)
+        t = '''#include<stdio.h>
+        {prefix}
+        int main(int argc, char **argv) {{
+            printf("%ld\\n", (long)({fragment}));
+            return 0;
+        }};'''
+        res = self.run(t.format(**fargs), env, extra_args, dependencies)
+        if not res.compiled:
+            return -1
+        if res.returncode != 0:
+            raise EnvironmentException('Could not run compute_int test binary.')
+        return int(res.stdout)
+
     def cross_sizeof(self, element, prefix, env, extra_args=None, dependencies=None):
         if extra_args is None:
             extra_args = []
diff --git a/mesonbuild/interpreter.py b/mesonbuild/interpreter.py
index 07b5c40..dca7934 100644
--- a/mesonbuild/interpreter.py
+++ b/mesonbuild/interpreter.py
@@ -631,6 +631,7 @@ class CompilerHolder(InterpreterObject):
         self.methods.update({'compiles': self.compiles_method,
                              'links': self.links_method,
                              'get_id': self.get_id_method,
+                             'compute_int': self.compute_int_method,
                              'sizeof': self.sizeof_method,
                              'has_header': self.has_header_method,
                              'has_header_symbol': self.has_header_symbol_method,
@@ -822,6 +823,20 @@ class CompilerHolder(InterpreterObject):
         mlog.log('Checking for type "', mlog.bold(typename), '": ', hadtxt, sep='')
         return had
 
+    def compute_int_method(self, args, kwargs):
+        if len(args) != 1:
+            raise InterpreterException('Compute_int takes exactly one argument.')
+        check_stringlist(args)
+        fragment = args[0]
+        prefix = kwargs.get('prefix', '')
+        if not isinstance(prefix, str):
+            raise InterpreterException('Prefix argument of compute_int must be a string.')
+        extra_args = self.determine_args(kwargs)
+        deps = self.determine_dependencies(kwargs)
+        res = self.compiler.compute_int(fragment, prefix, self.environment, extra_args, deps)
+        mlog.log('Computing int of "%s": %d' % (fragment, res))
+        return res
+
     def sizeof_method(self, args, kwargs):
         if len(args) != 1:
             raise InterpreterException('Sizeof takes exactly one argument.')