Visual studio __VA_ARGS__ issue

Question

I run cl /P test.cpp, the file and result is as following.

test.cpp

#define FiltedLog( ...) \\
    if (logDetail) \\
        MP_LOG(LOG_INFO,  __VA_ARGS_         


        

Answer 1

Yes, this is a longstanding bug in the Visual C++ preprocessor. To work around it, use indirection:

#define INDIRECT_EXPAND(m, args) m args

#define FiltedLog( ...) \
    if (logDetail) \
        INDIRECT_EXPAND(MP_LOG, (LOG_INFO, __VA_ARGS__));

(Do note that __PRETTY_FUNCTION__ is a nonstandard extension that is not supported by Visual C++.)