ada: Adding support to defer the addition of extra formals

ada: Adding support to defer the addition of extra formals

Add support to create the extra formals when the underlying type
of some formal type or return type of a subprogram, subprogram type
or entry is not available when the entity is frozen. For example,
when a function that returns a private type is frozen before the
full-view of its private type is analyzed.

gcc/ada/ChangeLog:

	* einfo.ads (Extra_Formals): Complete documentation.
	(Has_First_Controlling_Parameter_Aspect): Place it in alphabetical order.
	(Has_Frozen_Extra_Formals): New attribute.
	* gen_il-fields.ads (Has_Frozen_Extra_Formals): New entity field.
	* gen_il-gen-gen_entities.adb (Has_Frozen_Extra_Formals): Adding new
	entity flag to subprograms, subprogram types, and and entries.
	* gen_il-internals.adb (Image): Adding Has_Frozen_Extra_Formals.
	* exp_ch3.adb (Build_Array_Init_Proc): Freeze its extra formals.
	(Build_Init_Procedure): Freeze its extra formals.
	(Expand_Freeze_Record_Type): For tagged types with foreign convention
	create the extra formals of primitives with convention Ada.
	* exp_ch6.ads (Create_Extra_Actuals): New subprogram.
	* exp_ch6.adb (Check_BIP_Actuals): Adding assertions.
	(Create_Extra_Actuals): New subprogram that factorizes code from
	Expand_Call_Helper.
	(Expand_Call_Helper): Adding support to defer the addition of extra
	actuals. Move the code that adds the extra actuals to a new subprogram.
	(Is_Unchecked_Union_Equality): Renamed as Is_Unchecked_Union_Predefined_
	Equality_Call.
	* exp_ch7.adb (Create_Finalizer): Freeze its extra formals.
	(Wrap_Transient_Expression): Link the temporary with its relocated
	expression to facilitate locating the expression in the expanded code.
	* exp_ch9.ads (Expand_N_Entry_Declaration): Adding one formal.
	* exp_ch9.adb (Expand_N_Entry_Declaration): Defer the expansion of
	the entry if the extra formals are not available; analyze the built
	declarations for the record type that holds all the parameters if
	the expansion of the entry declaration was deferred.
	* exp_disp.adb (Expand_Dispatching_Call): Handle deferred extra formals.
	(Set_CPP_Constructors): Freeze its extra formals.
	* freeze.adb (Freeze_Entity): Create the extra actuals of acccess to
	subprograms whose designated type is a subprogram type.
	(Freeze_Subprogram): Adjust assertion to support deferred extra formals,
	and freeze extra formals of non-dispatching subprograms with foreign
	convention. Added assertion to check matching of formals in thunks.
	* sem_aux.adb (Get_Called_Entity): Adding documentation.
	* sem_ch3.adb (Analyze_Full_Type_Declaration): Create the extra formals
	of deferred subprograms, subprogram types and entries; create also the
	extra actuals of deferred calls.
	* sem_ch6.ads (Freeze_Extra_Formals): New subprogram.
	(Deferred_Extra_Formals_Support): New package.
	* sem_ch6.adb (Analyze_Subprogram_Body_Helper): Create the extra formals
	of subprograms without separate spec.
	(Add_Extra_Formal): Add documentation.
	(Has_Extra_Formals): Removed.
	(Parent_Subprogram): Adding documentation.
	(Create_Extra_Formals): Defer adding extra formals if the underlying_type
	of some formal type or return type is not available.
	(Extra_Formals_Match_OK): Add missing check on the extra formals of
	unchecked unions.
	(Freeze_Extra_Formals): New subprogram.
	(Deferred_Extra_Formals_Support): New package.
	* sem_ch9.adb (Analyze_Entry_Declaration): Freeze its extra formals.
	* sem_ch13.adb (New_Put_Image_Subprogram): ditto.
	* sem_util.ads (Is_Unchecked_Union_Equality): New subprogram.
	* sem_util.adb (Is_Unchecked_Union_Equality): ditto.