[avr-gcc-list] Question regarding the format attribute

[PAZ]

One really useful feature of the gcc compiler is the ability to check whether the arguments in a ‘printf’ like function correspond with its format string:

 

    int MY_printf(char *format, ...) __attribute__((format (printf,1,2)));

 

This will generate a warning if the function is called for example like ‘MY_printf(”%s”, 1234);’

 

Unfortunately, this feature does not work when program memory constants are used in the definition:

 

    int MY_printf(PGM_P *format, ...) __attribute__((format (printf,1,2)));

 

The call ‘MY_printf(PSTR(”%s”), 1234);’ no longer gives the desired warning that there is a mismatch between the printf like format and the argument list.

 

This can be explained by arguing that a ‘printf’ formatted function must have a (char *) argument for its specified format parameter.

It’s a real bummer though that the format attribute does not work with functions that are declared as above. Note that the compiler does not throw a error if you do.

 

Any thoughts ?

 

Regards

 

Peter