Suppressing warnings for a printf-like function in C-CodePudding

I have a legacy logging printf-like function in C:

namespace legacy
{
    void DoLog(const char* format,...);
}

If is only visible if a corresponding macro is defined (this is legacy too):

#ifdef LOG
# define Log legacy::DoLog
#else
# define Log /* Nothing */
#endif

I have some C code, which calls this log like:

Log("Logging started!");

When the LOG macro is not defined, Log("Something"); turns into ("Something"); which is unused code.

I need to suppress these warnings in GCC, and do it only once, of course, so I wrap Log into MyLog as #define MyLog Log and try this:

#define MyLog(...) \
    _Pragma("GCC diagnostic push"); \
    _Pragma("GCC diagnostic ignored \"-Wunused-value\""); \
    Log(__VA_ARGS__); \
    _Pragma("GCC diagnostic pop");

But these pragmas for some reason do not have any effect
https://gcc.gnu.org/onlinedocs/cpp/Pragmas.html
https://gcc.gnu.org/onlinedocs/gcc/Diagnostic-Pragmas.html

I would better use inline C wrapper with templates for the perfect wrapping, but I cannot cope with it yet...

Any suggestions how to suppress these warnings?

Thank you in advance!

CodePudding user response：

Use

#define Log(...)

and then Log("Logging started!"); expands to just ; instead of ("Logging started!");

CodePudding user response：

I managed to come to the two following solutions:

C style inline function, with suppressed warnings and basic Windows and Linux platform definitions used:

template<typename... Args>
inline void MyLog(const char* format, Args... args)
{
#ifndef LOG
# ifdef _MSC_VER // Windows
#  pragma warning(push)
#  pragma warning(disable: 4548)
# elif defined(__GNUC__) // Linux
#  pragma GCC diagnostic push
#  pragma GCC diagnostic ignored "-Wunused-value"
# endif
#endif
    Log(format, (args,...));
#ifndef LOG
# ifdef _MSC_VER // Windows
#  pragma warning(pop)
# elif defined(__GNUC__) // Linux
#  pragma GCC diagnostic pop
# endif
#endif
}

C style wrapper macro, even without any warnings suppression needed (thanks to @KamilCuk and @user253751):

#ifndef LOG
# define MyLog(...)
#else
# define MyLog(...) Log(__VA_ARGS__)
#endif