Switch with previous parameter: Wrong char count with macros

#define BAZ 12345
int foo(int bar, int baz = BAZ);

Try to replace baz with previous parameter. This results in:

int foo(int baz = BAZ);, int bar

It looks like the character count is based on the macro expansion.

I found this out with a more common example:

int foo(Foo *bar = NULL, Foo *baz = NULL);

NULL is defined to be __null, that breaks it...