New API: cc.has_header_symbol to check if a header defines a specific symbol

Also supports a 'prefix' keyword argument for feature checks such as _GNU_SOURCE
or for headers that need to be included first

mesonbuild/compilers.py

@@ -258,6 +258,9 @@ class Compiler():
     def has_header(self, *args, **kwargs):
         raise EnvironmentException('Language %s does not support header checks.' % self.language)
 
+    def has_header_symbol(self, *args, **kwargs):
+        raise EnvironmentException('Language %s does not support header symbol checks.' % self.language)
+
     def compiles(self, *args, **kwargs):
         raise EnvironmentException('Language %s does not support compile checks.' % self.language)
 
@@ -460,6 +463,13 @@ int someSymbolHereJustForFun;
 '''
         return self.compiles(templ % hname, extra_args)
 
+    def has_header_symbol(self, hname, symbol, prefix, extra_args=[]):
+        templ = '''{2}
+#include <{0}>
+int main () {{ {1}; }}'''
+        # Pass -O0 to ensure that the symbol isn't optimized away
+        return self.compiles(templ.format(hname, symbol, prefix), extra_args + ['-O0'])
+
     def compile(self, code, srcname, extra_args=[]):
         commands = self.get_exelist()
         commands.append(srcname)

mesonbuild/interpreter.py

@@ -575,6 +575,7 @@ class CompilerHolder(InterpreterObject):
                              'get_id': self.get_id_method,
                              'sizeof': self.sizeof_method,
                              'has_header': self.has_header_method,
+                             'has_header_symbol': self.has_header_symbol_method,
                              'run' : self.run_method,
                              'has_function' : self.has_function_method,
                              'has_member' : self.has_member_method,
@@ -752,6 +753,24 @@ class CompilerHolder(InterpreterObject):
         mlog.log('Has header "%s":' % string, h)
         return haz
 
+    def has_header_symbol_method(self, args, kwargs):
+        if len(args) != 2:
+            raise InterpreterException('has_header_symbol method takes exactly two arguments.')
+        check_stringlist(args)
+        hname = args[0]
+        symbol = args[1]
+        prefix = kwargs.get('prefix', '')
+        if not isinstance(prefix, str):
+            raise InterpreterException('Prefix argument of has_function must be a string.')
+        extra_args = self.determine_args(kwargs)
+        haz = self.compiler.has_header_symbol(hname, symbol, prefix, extra_args)
+        if haz:
+            h = mlog.green('YES')
+        else:
+            h = mlog.red('NO')
+        mlog.log('Header <{0}> has symbol "{1}":'.format(hname, symbol), h)
+        return haz
+
     def find_library_method(self, args, kwargs):
         if len(args) != 1:
             raise InterpreterException('find_library method takes one argument.')

test cases/common/111 has header symbol/meson.build

@@ -0,0 +1,18 @@
+project('has header symbol', 'c')
+
+cc = meson.get_compiler('c')
+
+assert (cc.has_header_symbol('stdio.h', 'int'), 'base types should always be available')
+assert (cc.has_header_symbol('stdio.h', 'printf'), 'printf function not found')
+assert (cc.has_header_symbol('stdio.h', 'FILE'), 'FILE structure not found')
+assert (cc.has_header_symbol('limits.h', 'INT_MAX'), 'INT_MAX define not found')
+assert (not cc.has_header_symbol('limits.h', 'guint64'), 'guint64 is not defined in limits.h')
+assert (not cc.has_header_symbol('stdlib.h', 'FILE'), 'FILE structure is defined in stdio.h, not stdlib.h')
+assert (not cc.has_header_symbol('stdlol.h', 'printf'), 'stdlol.h shouldn\'t exist')
+assert (not cc.has_header_symbol('stdlol.h', 'int'), 'shouldn\'t be able to find "int" with invalid header')
+
+# This is likely only available on Glibc, so just test for it
+if cc.has_function('ppoll')
+  assert (not cc.has_header_symbol('poll.h', 'ppoll'), 'ppoll should not be accessible without _GNU_SOURCE')
+  assert (cc.has_header_symbol('poll.h', 'ppoll', prefix : '#define _GNU_SOURCE'), 'ppoll should be accessible with _GNU_SOURCE')
+endif