PR c++/67942 - diagnose placement new buffer overflow

PR c++/67942 - diagnose placement new buffer overflow

gcc/cp/
	* cp/init.c (warn_placement_new_too_small): Avoid assuming
	the size of the first operand of placement new or its type
	is known.

gcc/testsuite/
	* g++.dg/warn/Wplacement-new-size.C: Exercise placement new
	invocations where the size of the destination buffer object
	or its type (or both) is unknown.

From-SVN: r229831