C strange warning.

http://pastebin.com/3js28CTR
$> gcc main.c
If tata(char|short|float c) => warning
If tata(int|long|double c) => nothing

Does somebody could explain why exactly ? =)

But in the 6.7.5.3.14, I read that the empty list in a function declarator that is not part of a definition of that function specifies that no information about the number or types of the parameters is supplied.
Unless my english is very bad (and I know it probably is), it means that the declaration of each argument isn't required in the pointer argument list, no ?