The following code (excerpted from Microsoft's DirectX header XAudio2.h) fails to compile with Windows compatibility: #define DECLSPEC_UUID_WRAPPER(x) __declspec(uuid(#x)) #define DEFINE_CLSID(className, l, w1, w2, b1, b2, b3, b4, b5, b6, b7, b8) \ class DECLSPEC_UUID_WRAPPER(l##-##w1##-##w2##-##b1##b2##-##b3##b4##b5##b6##b7##b8) className DEFINE_CLSID(XAudio2, 5a508685, a254, 4fba, 9b, 82, 9a, 24, b0, 03, 06, af); //DEFINE_CLSID(XAudio2,5a508685,a254,4fba,9b,82,9a,24,b0,03,06,af); This results in: % clang++ -fms-extensions -Wno-invalid-token-paste -c clang.cpp clang.cpp:6:1: error: uuid attribute contains a malformed GUID DEFINE_CLSID(XAudio2, 5a508685, a254, 4fba, 9b, 82, 9a, 24, b0, 03, 06, af); ^ clang.cpp:4:8: note: expanded from macro 'DEFINE_CLSID' class DECLSPEC_UUID_WRAPPER(l##-##w1##-##w2##-##b1##b2##-##b3##b4##b5##b6##b7##b8) className ^ clang.cpp:1:50: note: expanded from macro 'DECLSPEC_UUID_WRAPPER' #define DECLSPEC_UUID_WRAPPER(x) __declspec(uuid(#x)) ^ <scratch space>:16:1: note: expanded from here "5a508685- a254- 4fba- 9b82- 9a24b00306af" ^ 1 error generated. When using the commented DEFINE_CLSID-line without the spaces, the code compiles successfully.
Yeah, I see the issue. I can't find this GUID in the Win 7.0A SDK, the Win 8.0 SDK, or the Win 8.1 SDK. Where exactly did you encounter this issue? I don't want to add another compatibility hack unless it's a bug in a recent, widely used header.
If this is just a problem in the 2010 June Direct X SDK, then I'd rather encourage people to migrate to the Win8 SDK than add this hack. The xaudio2.h header in the Win 8 SDK doesn't appear to have this problem.
>Where exactly did you encounter this issue? In the copy of the DirectX headers in the Unreal Engine which seem to be the June 2010 SDK. I noticed that a recent commit there included a workaround for clang's behavior[*] and thought I'd file a bug report. [*] https://github.com/EpicGames/UnrealEngine/commit/701ad40823134d909081d70e83dea3a149a355ed (I'm afraid it's a private repository; you'll need to register an account at Epic Games to get access)
Hey this is Mike Fricker at Epic. I've been tracking the progress of Clang on Windows and updating Unreal Engine to support that as a build target as a background project. As of last weekend the Unreal Editor is now able to be fully compiled on Windows under Clang (requires LLVM r231657.) Upgrading to a newer DirectX SDK is not really an option. There are a slew of PC titles that use the June 2010 DirectX SDK specifically for DirectX 9 support on Windows XP and Windows 7, which is not available in the newer SDKs. The Unreal Engine codebase is actually an excellent test case for LLVM on all platforms. There are actually a number of other issues we've observed and can reproduce. I'll work with the team to get those entered into your database. --Mike
Honestly I would have thought that leading and trailing spaces were trimmed from arguments during macro expansion. Another thing: This location in the preprocessor backtrace looks a bit weird: | <scratch space>:16:1 (In reply to comment #4) > I'll work with the team to get those entered into your database. Please do!
OK, if the June 2010 SDK is still super widely used, then we probably want to do something here.
Fixed by r235186: [MSVC] Mimic MSVC whitespace collapse for incompatible token pasting The workaround is simple but a little ugly. Let me know if there's any fallout.