2017-09-06  Raphael Amiard  <amiard@adacore.com>

	* a-chtgop.ads, a-chtgop.adb: Add versions of First and Next with
	Position parameter. If supplied, use it to provide efficient iteration.
	* a-cohase.ads, a-cohase.adb, a-cihama.ads, a-cihama.adb,
	a-cohama.ads, a-cohama.adb: Add/Use Position to provide efficient
	iteration.

2017-09-06  Ed Schonberg  <schonberg@adacore.com>

	* exp_util.adb (Build_Allocate_Deallocate_Proc): If the
	designated type is class-wide and the expression is an unchecked
	conversion, preserve the conversion when checking the tag of the
	designated object, to prevent spurious semantic errors when the
	expression in the conversion has an untagged type (for example
	an address attribute).

From-SVN: r251757