2014-07-30  Ed Schonberg  <schonberg@adacore.com>

	* freeze.adb (Check_Expression_Function): At the freeze point
	of an expression function, verify that the expression in the
	function does not contain references to any deferred constants
	that have no completion yet.
	(Freeze_Expression, Freeze_Before): call
	Check_Expression_Function.
	* a-ciorse.ads: Add Reference_Control_Type to detect tampering.
	* a-ciorse.adb: Add Adjust and Finalize routines for
	Reference_Control_Type. Use it in the construction of Reference
	and Constant_Reference values.

From-SVN: r213287