gcc/c-family/ChangeLog:
	PR c++/87504
	* c-warn.c (get_outermost_macro_expansion): New function.
	(spelled_the_same_p): Use it to unwind the macro expansions, and
	compare the outermost macro in each nested expansion, rather than
	the innermost.

gcc/testsuite/ChangeLog:
	PR c++/87504
	* c-c++-common/Wtautological-compare-8.c: New test.

From-SVN: r267299