Is there any way you do something like...
#define { { printf("%s,%s",_FUNCTION_, _LINE_); {
this won't compile. But I'm wondering if there is some kind of trick to effectively get the same functionality? (other than writing a tool to hook at the preprocessing step)
The point of doing this is a pondering on how to get a poor mans code coverage.
It's certainly not possible with a macro. The name of a macro must be an identifier. The brace characters are punctuators, not identifiers.
I've seen this done (not that I endorse it...) with #define BEGIN ... and #define END ....
e.g.
void foo(void)
BEGIN
stuff();
END
You can't change the way the compiler interprets {}'s. It's an assumption that they make to be able to syntaxically determine if the code is correct and what it is supposed to do.
If you indeed would like to do something like that, I suggest doing a search-and-replace on "{" "{ MY_MACRO;"
Get rich-man's code coverage with the tools discussed in these questions, particularly gcov, which is part of GCC.