* constexpr.c (potential_constant_expression_1) <case RANGE_FOR_STMT>:
	Recur into RANGE_FOR_INIT_STMT.
	* cp-tree.def: Add RANGE_FOR_INIT_STMT to RANGE_FOR_STMT.
	* cp-tree.h (RANGE_FOR_INIT_STMT): Define.
	* dump.c (cp_dump_tree) <case RANGE_FOR_STMT>: Also dump
	RANGE_FOR_INIT_STMT.
	* pt.c (tsubst_expr) <case RANGE_FOR_STMT>: Recur into
	RANGE_FOR_INIT_STMT.
	* semantics.c (begin_range_for_stmt): Adjust call to build_stmt.
	Do put the init statement in RANGE_FOR_INIT_STMT.
	(finish_range_for_decl): Pop it for templates.

	* g++.dg/cpp2a/range-for11.C: New test.
	* g++.dg/cpp2a/range-for12.C: New test.
	* g++.dg/cpp2a/range-for13.C: New test.
	* g++.dg/cpp2a/range-for14.C: New test.
	* g++.dg/cpp2a/range-for15.C: New test.
	* g++.dg/cpp2a/range-for16.C: New test.
	* g++.dg/cpp2a/range-for17.C: New test.
	* g++.dg/cpp2a/range-for18.C: New test.
	* g++.dg/parse/error61.C (foo): Adjust dg-error.

From-SVN: r264158