ada: Resolve ACATS compilation and execution issues with container aggregates

ada: Resolve ACATS compilation and execution issues with container aggregates

This change set addresses various compilation and execution problems
encountered in the draft ACATS tests for container aggregates:

C435001 (container aggregates with Assign_Indexed)
C435002 (container aggregates with Add_Unnamed)
C435003 (container aggregates with Add_Named)
C435004 (container aggregates with Assign_Indexed and Add_Unnamed)

gcc/ada/

	* exp_aggr.adb (Expand_Container_Aggregate): Add top-level
	variables Choice_{Lo|Hi} and Int_Choice_{Lo|Hi} used for
	determining the low and high bounds of component association
	choices. Replace code for determining whether we have an indexed
	aggregate with call to new function Sem_Aggr.Is_Indexed_Aggregate.
	Remove test of whether Empty_Subp is a function, since it must be
	a function. Move Default and Count_Type to be locals of a new
	block enclosing the code that creates the object to hold the
	aggregate length, and set them according to the default and type
	of the Empty function's parameter when present (and to Empty and
	Standard_Natural otherwise). Use Siz_Exp for the aggregate length
	when set, and use Empty's default length when available, and use
	zero for the length otherwise. In generating the call to the
	New_Indexed function, use the determined lower and upper bounds if
	determined earlier by Aggregate_Size, and otherwise compute those
	from the index type's lower bound and the determined aggregate
	length. In the case where a call to Empty is generated and the
	function has a formal parameter, pass the value saved in Siz_Decl
	(otherwise the parameter list is empty). Remove code specific to
	making a parameterless call to the Empty function. Extend the code
	for handling positional container aggregates to account for types
	that define Assign_Indexed, rather than just Add_Unnamed, and in
	the case of indexed aggregates, create a temporary object to hold
	values of the aggregate's key index, and initialize and increment
	that temporary for each call generated to the Assign_Indexed
	procedure. For named container aggregates that have key choices
	given by ranges, call Expand_Range_Component to generate a loop
	that will call the appropriate insertion procedure for each value
	of the range. For indexed aggregates with a Component_Associations
	list, set and use the Assign_Indexed procedure for each component
	association, whether or not there's an iterator specification.
	(Add_Range_Size): Add code to determine the low and high bounds of
	the range and capture those in up-level variables when their value
	is less than or greater than (respectively) the current minimum
	and maximum bounds values.
	(Aggregate_Size): Separately handle the case where a single choice
	is of a discrete type, and call Add_Range_Size to take its value
	into consideration for determination of min and max bounds of the
	aggregate. Add comments in a couple of places.
	(Build_Siz_Exp): Remove the last sentence and "???" from the
	comment that talks about accumulating nonstatic sizes, since that
	sentence seems to be obsolete. Record the low and high bound
	values in Choice_Lo and Choice_Hi in the case of a nonstatic
	range.
	(Expand_Iterated_Component): Set the Defining_Identifier of the
	iterator specification to the Loop_Id in the
	N_Iterated_Component_Association case.
	(Expand_Range_Component): Procedure unnested from the block
	handling indexed aggregates in Expand_Container_Aggregate, and
	moved to top level of that procedure so it can also be called for
	Add_Named cases. A formal parameter Insert_Op is added, and
	existing calls to this procedure are changed to pass the
	appropriate insertion procedure's Entity.
	* sem_aggr.ads: Add with_clause for Sinfo.Nodes.
	(Is_Indexed_Aggregate): New function for use by
	Resolve_Container_Aggregate and Expand_Container_Aggregate.
	* sem_aggr.adb: Add with_clause for Sem_Ch5. Move with_clause for
	Sinfo.Nodes to sem_aggr.ads.
	(Is_Indexed_Aggregate): New function to determine whether a
	container aggregate is a container aggregate (replacing local
	variable of the same name in Resolve_Container_Aggregate).
	(Resolve_Iterated_Association): Remove part of comment saying that
	a Key_Expression is always present. Set Parent field of the copy
	of a component association with a loop parameter specification. On
	the setting of Loop_Param_Id, account for a
	Loop_Parameter_Specification being changed into an
	Iterator_Specification as a result of being analyzed. Only call
	Preanalyze_And_Resolve on Key_Expr when a key expression is
	actually present. Remove loop for handling choices for the case of
	an N_Component_Association with a Defining_Identifier (there
	shouldn't be more than one choice in this case, and add an
	assertion to ensure that). Also add code here to handle the case
	where the choice is a function call, creating an
	iterator_specification analyzing it, and call
	Resolve_Iterated_Association recursively to process it. Add error
	check to enforce RM22 4.3.5(27), which requires that the type of
	the loop parameter must be the same as the key type when there is
	no key expression and the aggregate is an indexed aggregate or has
	an Add_Named op.
	(Resolve_Container_Aggregate): In the Add_Unnamed case, call
	Resolve_Iterated_Association for both
	N_Iterated_Element_Association and N_Component_Association (rather
	than just the latter). Remove error check for nonstatic choices in
	component associations in Add_Named cases (multiple named
	nonstatic associations are fine except in indexed aggregates).
	Remove local variable Is_Indexed_Aggregate, replaced with new
	library-level function of the same name, and add test of
	Is_Indexed_Aggregate in the case where the aggregate type has an
	Assign_Indexed operation, as a guard for doing error checks for
	indexed aggregates. For indexed aggregate resolution, do not call
	Analyze_And_Resolve on the expression of an
	N_Component_Association in the "box association" case. Move error
	checks for indexed aggregates with iterated associations that flag
	cases where an association is a loop_parameter_specification with
	an iterator filter or a key expression (violation of RM22
	4.3.5(28/5)), from the loop that checks for contiguous and
	nonoverlapping choices and into the preceding association loop
	after the call to Resolve_Iterated_Association. The RM reference
	is added to the error-message strings.