Run the following command on your source file:
gcc -fpreprocessed -dD -E test.c
Thanks to KennyTM for finding the right flags. Here’s the result for completeness:
test.c:
#define foo bar
foo foo foo
#ifdef foo
#undef foo
#define foo baz
#endif
foo foo
/* comments? comments. */
// c++ style comments
gcc -fpreprocessed -dD -E test.c
:
#define foo bar
foo foo foo
#ifdef foo
#undef foo
#define foo baz
#endif
foo foo