PR c++/11517
	* call.c (build_conditional_expr): Use perform_implicit_conversion
	and error_operand_p.  Robustify.
	* typeck.c (build_unary_op): Use perform_implicit_conversion.

	PR c++/11517
	* g++.dg/expr/cond2.C: New test.

From-SVN: r69715