I supported clang-cl with BUILD_SHARED_LIBS

[durswd]

clang-cl (clang for msvc) can compiles static void foo(void) __attribute__ ((visibility(\"default\")));
But functions are not exported as DLL functions.
So these errors are caused.

undefined symbol: "void __cdecl google::ShutdownGoogleLogging(void)" (?ShutdownGoogleLogging@google@@YAXXZ)	logging_unittest	D:\Dev\glog\build_\lld-link	1	
undefined symbol: "void __cdecl google::RawLog__(int, char const *, int, char const *)" (?RawLog__@google@@YAXHPBDH0ZZ)	logging_unittest	D:\Dev\glog\build_\lld-link	1	
undefined symbol: "void __cdecl google::InstallFailureWriter(void (__cdecl *)(char const *, int))" (?InstallFailureWriter@google@@YAXP6AXPBDH@Z@Z)	signalhandler_unittest	D:\Dev\glog\build_\lld-link	1	

I made HAVE___ATTRIBUTE__VISIBILITY_DEFAULT disabled on MSVC.

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[durswd]

@googlebot I signed it!

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[shinh]

I think we are trying to avoid using vendor names explicitly. Maybe better to change the order of conditions?

if (HAVE___DECLSPEC)
 set (_EXPORT "__declspec(dllexport)")
 set (_IMPORT "__declspec(dllimport)")
elseif (HAVE___ATTRIBUTE__VISIBILITY_DEFAULT)
  ...
endif(HAVE___DECLSPEC)

[durswd]

Thank you for your suggestion. I changed it.

[shinh]

LGTM! We could create a follow-up patch if Sergiu (the owner of cmake build) or others have any comments.