Application crash

[Double_D]

I finally isolated my problem to the use of __FUNCTION__ (a predefined macro) in the following code:

#define debug_printf(debug,lvl,x) do { \
                                        if ( ! __debug_printf_check( debug, lvl ) ){ \
                                            __debug_lock(); \
                                            __debug_printf ( "%s:%s:%d: ",__FILE__, __FUNCTION__, __LINE__); \
                                            __debug_printf x ; \
                                            __debug_unlock();\
                                        }\
                                    } while(0)

where __debug_printf is defined as follows:

void __debug_printf(const char * format, ... )
{
    //int diagnostic = 1;
    
    va_list ap;
    
    //if (diagnostic)
        //return;
    
    if (output_enabled & CONSOLE_OUTPUT){
        va_start (ap, format);
        vfprintf ( stderr, format, ap );     
        va_end(ap);
    }
    
    if (output_enabled & UI_OUTPUT){
        va_start (ap, format);
        ui_debug_printf( format, &ap);
        va_end(ap);
    }
    
    if ( output_enabled & FILE_OUTPUT){
        va_start (ap, format );
        if (fp != NULL) vfprintf ( fp, format, ap );
        va_end (ap);
    }
    
}

The program wouldn't crash on every invocation of __debug__printf, but it would consistently crash at the same point in our code.  __FUNCTION__ is actually redundant, since FILE and LINE are given, so I removed any reference to __FUNCTION__ and the crash problem disappeared.  It was a pain to find this bug.

[menchar]

Are you using C99?

C99 added the   __func__   mechanism, I think the  __FUNCTION__  macro is something NI did.

Even if you're using C99, it's not certain that NI would have implemented __func__.    __func__ is actualy a block scope local (stack) variable, not a macro, so you may get better behavior with it if it's available.

But like you say you know the file and line so it's not really needed.