Incompatible argument type conversion using macro - c

Question

I am trying to use a single macro argument (provided by third party) to display a string with placeholders and values of those place holder.
#define DBG1(AR1) do{ \
printf(AR1); \
}while(0);
int main()
{
int varDummy = 123;
/* Expecting Test Message 123*/
DBG1(("Test Message %d\r\n", varDummy));
return 0;
}
Notice the argument of DBG1 ("Test Message %d\r\n", varDummy) is in parentheses and is being treated whole as a string i.e. const char* and error shows up that varDummy not allowed to be converted due to it's int type.
In the actual code the argument of DBG1 has different number of place holders (%d, %x...) and respective values which have to be printed. Apparently I am unable to display the passed string along with its place holder values.
In the real code I have the following macro from third party
LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_recvfrom(%d, %p, %"SZT_F", 0x%x, ..)\n", s, mem, len, flags));
/* discarding the first argument */
#define LWIP_DEBUGF(debug, message) do{ \
DBG1(message) \
}while(0);
Please note this is a resource constrained embedded system.

Answer 1

Notice the argument of DBG1 ("Test Message %d\r\n", varDummy) is in parentheses …
This problem is at the same time the solution. Since there are already parentheses, you need not supply them in your DBG1 macro and can change printf(AR1); \ to printf AR1; \. Besides that, you can simplify the macro to
#define DBG1(AR1) printf AR1;
(since you can't change the LWIP_DEBUGF macro from third party, we unfortunately have to keep the semicolon).

Answer 2

You can use a temporary buffer to hold the adjointed string, something like this:
#define DBG1(AR1) do{\
printf(AR1);\
} while(0)
#define BUFFER_SIZE 100
int main()
{
int varDummy = 123;
char buffer[BUFFER_SIZE];
sprintf(buffer, "Test Message %d\r\n", varDummy);
/* Expecting Test Message 123*/
DBG1(buffer);
return 0;
}

Answer 3

Notice the argument of DBG1 is in parentheses
Yeah that's the problem, you are calling printf(("Test Message %d\r\n", varDummy)); where the inner parentheses has turned the , from a function argument separator into the comma operator. The comma operator discards the left operand and returns the right. Which is int, a type incompatible with the format string of printf, which explains the compiler error.
Instead you should be using a variadic macro:
#define DBG1(AR1,...) printf(AR1, __VA_ARGS__)
...
DBG1("Test Message %d\r\n", varDummy);
The do-while(0) trick is pointless to use in this case.
Please note this is a resource constrained embedded system.
Then you shouldn't be using stdio.h or variadic functions in the first place. Instead, design your own product-specific logging module. Writing a little snippet that spits out strings on UART isn't rocket science.
Similarly, parsing raw binary data from UART isn't rocket science either, so you don't actually need the string conversion, just a decent terminal program on the PC.