[Bug c++/18605] New: __attribute__ ((format (printf, ...))) doesn't work in C++ methods

[mkaufmann at student dot ethz dot ch]

[This bug has already been reported in 1998 to the mailing list. Please look
there for more explanations: http://gcc.gnu.org/ml/gcc-bugs/1998-08/msg00434.html ]

__attribute__(format(printf, ...)) works for C procedures, but not for C++
methods. g++ counts the implicit "this" parameter, and therefore g++ only
accepts declarations with wrong numbers:

// This works, but should not:
void printMessage(const char* format, ...) __attribute__((format(printf,2,3)));

// This should work, but g++ prints the error "format string arg not a string type":
GCC bug workaround: Use __attribute__((format(printf,1,2)));


Example program:

#include <stdio.h>
#include <stdarg.h>

class Test
{
  public:
	void printMessage(const char* format, ...) __attribute__((format(printf,1,2)));
};

void Test::printMessage(const char* format, ...)
{
	va_list ap;
	va_start(ap, format);
	::vprintf(format, ap);
	va_end(ap);
}

int main (int argc, char* argv[])
{
	long l = 1000;
	Test test;

	test.printMessage("This should give a warning if compiled with '-Wformat':
%d\n", l);
	return 0;
}

-- 
           Summary: __attribute__ ((format (printf, ...))) doesn't work in
                    C++ methods
           Product: gcc
           Version: 3.3.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: mkaufmann at student dot ethz dot ch
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18605