https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64644
--- Comment #2 from Harald van Dijk <harald at gigawatt dot nl> --- Yep, thanks, testing that on 4.9.2 seems to give the right results. I see it covered by existing tests in at least gcc/testsuite/g++.old-deja/g++.law/union4.C and gcc/testsuite/g++.old-deja/g++.law/union4.C. I'll re-test with GCC 5 soonish (later in the week, probably), change dg-warning to dg-error where appropriate, and check if there's already a test to make sure it remains a warning without -pedantic-errors. A question, though: I see that like many other existing warnings, this doesn't handle -Werror=pedantic. Is that something that should be addressed as well, or is that something that should at some later point be handled for all relevant warnings at once?
