Failure to expand macro in pragma pack for MS compatibility

[llvmbot]

Bugzilla Link	18576
Resolution	FIXED
Resolved on	Feb 20, 2014 17:01
Version	trunk
OS	All
Reporter	LLVM Bugzilla Contributor
CC	@rnk

Extended Description

MSVC uses directives that look like:

#pragma push(pack,_CRT_PACKING)

When requesting preprocessed output specified on the command-line to clang-cl ("/P"), the output does not expand _CRT_PACKING.

Reproduction steps:

1. Create a file with #include <windows.h>
2. clang-cl /P
3. Observe results in .i by searching for #pragma pack(push,_CRT_PACKING)

Expected Results:

• #pragma pack(push,_CRT_PACKING) should not be found and it should be #pragma pack(push,8)

Other notes:

• This was observed by trying to compile a file using pre-processed source output, so a good test case might be to #include <windows.h>, preprocess, then try to compile the preprocessed file. If successful, it's fixed.

[rnk]

This has also been bugging me since forever. We should really fix this. Warren, can you look at this?

[llvmbot]

Yeah, I'll do it after I Get CGRecordLayout fixed.

[rnk]

Fixed with a hack in r201821.

[rnk]

mentioned in issue llvm/llvm-bugzilla-archive#19529