How does the C preprocessor handle circular dependencies?

Question

I want to know how the C preprocessor handles circular dependencies (of #defines). This is my program:

#define ONE TWO 
#define TWO THREE
#defi         


        

Answer 1

https://gcc.gnu.org/onlinedocs/cpp/Self-Referential-Macros.html#Self-Referential-Macros answers the question about self referential macros.

The crux of the answer is that when the pre-processor finds self referential macros, it doesn't expand them at all.

I suspect, the same logic is used to prevent expansion of circularly defined macros. Otherwise, the preprocessor will be in an infinite expansion.