Unignore most warnings on POSIX in build/SConscript.main.

base/compiler_specific.h

 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef BASE_COMPILER_SPECIFIC_H_
 #define BASE_COMPILER_SPECIFIC_H_
 
 #include "build/build_config.h"
 
 #if defined(COMPILER_MSVC)
@@ skipping 10 matching lines @@
 // http://msdn.microsoft.com/en-us/library/d9x1s805.aspx
 
 // MSVC_SUPPRESS_WARNING disables warning |n| for the remainder of the line and
 // for the next line of the source file.
 #define MSVC_SUPPRESS_WARNING(n) __pragma(warning(suppress:n))
 
 // MSVC_PUSH_DISABLE_WARNING pushes |n| onto a stack of warnings to be disabled.
 // The warning remains disabled until popped by MSVC_POP_WARNING.
 #define MSVC_PUSH_DISABLE_WARNING(n) __pragma(warning(push)) \
                                      __pragma(warning(disable:n))
+
+// MSVC_PUSH_WARNING_LEVEL pushes |n| as the global warning level.  The level
+// remains in effect until popped by MSVC_POP_WARNING().  Use 0 to disable all
+// warnings.
+#define MSVC_PUSH_WARNING_LEVEL(n) __pragma(warning(push, n))
+
+// Pop effects of innermost MSVC_PUSH_* macro.
 #define MSVC_POP_WARNING() __pragma(warning(pop))
 
 // Allows |this| to be passed as an argument in constructor initializer lists.
 // This uses push/pop instead of the seemingly simpler suppress feature to avoid
 // having the warning be disabled for more than just |code|.
 //
 // Example usage:
 // Foo::Foo() : x(NULL), ALLOW_THIS_IN_INITIALIZER_LIST(y(this)), z(3) {}
 //
 // Compiler warning C4355: 'this': used in base member initializer list:
 // http://msdn.microsoft.com/en-us/library/3c594ae3(VS.80).aspx
 #define ALLOW_THIS_IN_INITIALIZER_LIST(code) MSVC_PUSH_DISABLE_WARNING(4355) \
                                              code \
                                              MSVC_POP_WARNING()
 
 #else  // COMPILER_MSVC
 
 #define MSVC_SUPPRESS_WARNING(n)
 #define MSVC_PUSH_DISABLE_WARNING(n)
+#define MSVC_PUSH_WARNING_LEVEL(n)
 #define MSVC_POP_WARNING()
 #define ALLOW_THIS_IN_INITIALIZER_LIST(code) code
 
 #endif  // COMPILER_MSVC
 
 #endif  // BASE_COMPILER_SPECIFIC_H_