PR c++/39551
	* gcc/cp/call.c (build_over_call): Set TREE_NO_WARNING on the
	compiler-generated INDIRECT_REF expression.
	* gcc/cp/cvt.c (convert_to_void): Emit warning when stripping off
	INDIRECT_REF.
	* gcc/testsuite/g++.dg/warn/Wunused-13.C: New testcase.

From-SVN: r146132