[Rd] How do you debug the R implementation?

[Mick Jordan]

This is a question for the folks who are developing the C part of the R 
implementation, and not about R debugging.

I'm curious what tools developers use to debug the C implementation on 
Mac OS and Linux (my two platforms). And, if you happen to use gdb, 
whether anyone has any macros to simplify seeing inside the R internal 
data structures.

Thanks
Mick Jordan