How to know (in GCC) when given macro/preprocessor symbol gets declared?

Question

Suppose I have #define foo in various header files. It may expand to some different things. I would like to know (when compiling a .cc file) when a #define is encountered, t

Answer 1

It wont help you find where it was defined but you can see the definition for a particular file by using the -E -dM flags

g++ -E -dM file.cpp | grep MACRO