exp_ch4.adb (Expand_N_Selected_Component): If the component is the discriminant of a constrained subtype...

	* exp_ch4.adb (Expand_N_Selected_Component): If the component is the
	discriminant of a constrained subtype, analyze the copy of the
	corresponding constraint, because in some cases it may be only
	partially analyzed.
	Removes long-lived ??? comments.

	* exp_ch7.adb (Establish_Transient_Scope): Remove complex code that
	handled controlled or secondary-stack expressions within the
	iteration_scheme of a loop.

	* sem_ch5.adb (Analyze_Iteration_Scheme): Build a block to evaluate
	bounds that may contain functions calls, to prevent memory leaks when
	the bound contains a call to a function that uses the secondary stack.
	(Check_Complex_Bounds): Subsidiary of Analyze_Iteration_Scheme, to
	generate temporaries for loop bounds that might contain function calls
	that require secondary stack and/or finalization actions.

	* sem_ch4.adb (Analyze_Indexed_Component_Form): If the prefix is a
	selected component and the selector is overloadable (not just a
	function) treat as function call, Analyze_Call will disambiguate if
	necessary.
	(Analyze_Selected_Component): Do not generate an actual subtype for the
	selected component if expansion is disabled. The actual subtype is only
	needed for constraint checks.
	(Analyze_Allocator): If restriction No_Streams is set, then do
	not permit objects to be declared of a stream type, or of a
	composite type containing a stream.

	* restrict.ads: Remove the a-stream entry from Unit_Array, since
	No_Streams no longer prohibits with'ing this package.

	* sem_ch3.adb (Build_Derived_Record_Type): If the parent type has
	discriminants, but the parent base has unknown discriminants, there is
	no discriminant constraint to inherit. Such a discrepancy can arise
	when the actual for a formal type with unknown discriminants is a
	similar private type whose full view has discriminants.
	(Analyze_Object_Declaration): If restriction No_Streams is set, then
	do not permit objects to be declared of a stream type, or of a
	composite type containing a stream.

From-SVN: r90906