Is there a way to have the C Preprocessor resolve macros in an #error statement?

Question

Just as the title says. I want to use a preprocessor macro in the text of an #error statement:

#define SOME_MACRO 1

#if SOME_MACRO != 0
    #error \"SOME_MACRO          


        

Answer 1

In Visual Studio you can use pragmamessage as follows:

#define STRING2(x) #x
#define STRING(x) STRING2(x)

#define SOME_MACRO 1

#if SOME_MACRO != 0
    #pragma message ( "SOME_MACRO was not 0; it was " STRING(SOME_MACRO) )
    #error SOME_MACRO was not 0;
#endif

This will generate two messages, but you'll get the value of SOME_MACRO. In G++ use the following instead (from comments: g++ version 4.3.4 works well with parenthesis as in the code above):

#pragma message "SOME_MACRO was not 0; it was " STRING(SOME_MACRO)