We ICEd when returning a stmt expr that ends with an overloaded
function, because instantiate_type did not know what to do with
STMT_EXPRs.  And it shouldn't have to: the expected type of a stmt
expr cannot be used to resolve its value: an unresolved overload
cannot supply the result of a stmt expr.  Catch that and report the
error in the stmt expr before we have a chance to instantiate it.

for  gcc/cp/ChangeLog

	PR c++/84492
	* semantics.c (finish_stmt_expr_expr): Reject unresolved
	overloads used as stmt expr values.

for  gcc/testsuite/ChangeLog

	PR c++/84492
	* g++.dg/pr84492.C: New.

From-SVN: r258269