re PR c++/64644 ("warning: anonymous union with no members" should be an error with -pedantic-errors)

/cp
2017-09-15  Manuel Lopez-Ibanez  <manu@gcc.gnu.org>
	    Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/64644
	* decl2.c (finish_anon_union): Complain about "anonymous union with
	no members" with a pedwarn.

/testsuite
2017-09-15  Manuel Lopez-Ibanez  <manu@gcc.gnu.org>
	    Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/64644
	* g++.dg/other/anon-union4.C: New.
	* g++.old-deja/g++.law/union4.C: Adjust.
	* g++.old-deja/g++.other/anon1.C: Likewise.

Co-Authored-By: Paolo Carlini <paolo.carlini@oracle.com>

From-SVN: r252835