Fix warnings in test/std/language.support

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@242624 91177308-0d34-0410-b5e6-96231b3b80d8

test/libcxx/compiler.py

@@ -150,3 +150,14 @@ class CXXCompiler(object):
         cmd, out, err, rc = self.compile(os.devnull, out=os.devnull,
                                          flags=flags)
         return rc == 0
+
+    def addCompileFlagIfSupported(self, flag):
+        if isinstance(flag, list):
+            flags = list(flag)
+        else:
+            flags = [flag]
+        if self.hasCompileFlag(flags):
+            self.compile_flags += flags
+            return True
+        else:
+            return False

test/libcxx/test/config.py

@@ -570,10 +570,9 @@ class Configuration(object):
     def configure_warnings(self):
         enable_warnings = self.get_lit_bool('enable_warnings', False)
         if enable_warnings:
-            self.cxx.compile_flags += ['-Wsystem-headers', '-Wall', '-Werror']
-            if ('clang' in self.config.available_features or
-                'apple-clang' in self.config.available_features):
-                self.cxx.compile_flags += ['-Wno-user-defined-literals']
+            self.cxx.compile_flags += ['-D_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER',
+                '-Wall', '-Werror']
+            self.cxx.addCompileFlagIfSupported('-Wno-user-defined-literals')
 
     def configure_sanitizer(self):
         san = self.get_lit_conf('use_sanitizer', '').strip()