2016-04-27  Ed Schonberg  <schonberg@adacore.com>

	* sem_util.ads, sem_util.adb (Is_Null_Record_Type): New predicate
	to determine whether a record type is a null record.
	* sem_ch3.adb (Analyze_Object_Declaration): If the type is a
	null record and there is no expression in the declaration,
	no predicate check applies to the object.

2016-04-27  Hristian Kirtchev  <kirtchev@adacore.com>

	* sem_ch7.adb (Analyze_Package_Body_Helper): The body of an
	instantiated package should not cause freezing of previous contracts.

2016-04-27  Ed Schonberg  <schonberg@adacore.com>

	* sem_dim.adb (Analyze_Dimension): Handle subtype declarations
	that do not come from source.
	(Analyze_Dimension_Subtype_Declaration): Allow confirming
	dimensions on subtype entity, either inherited from base type
	or provided by aspect specification.

2016-04-27  Ed Schonberg  <schonberg@adacore.com>

	* s-gearop.ads (Matrix_Vector_Solution, Matrix_Matrix_Solution):
	Add scalar formal object Zero, to allow detection and report
	when the matrix is singular.
	* s-gearop.adb (Matrix_Vector_Solution, Matrix_Matrix_Solution):
	Raise Constraint_Error if the Forward_Eliminate pass has
	determined that determinant is Zero.o
	* s-ngrear.adb (Solve): Add actual for Zero in corresponding
	instantiations.
	* s-ngcoar.adb (Solve): Ditto.

From-SVN: r235499