[Ada] Consolidate handling of implicit dereferences into semantic analysis

[Ada] Consolidate handling of implicit dereferences into semantic analysis

2020-06-11  Eric Botcazou  <ebotcazou@adacore.com>

gcc/ada/

	* checks.adb (Build_Discriminant_Checks): Build an explicit
	dereference when the type is an access type.
	* exp_atag.adb (Build_CW_Membership): Add explicit dereferences.
	(Build_Get_Access_Level): Likewise.
	(Build_Get_Alignment): Likewise.
	(Build_Inherit_Prims): Likewise.
	(Build_Get_Transportable): Likewise.
	(Build_Set_Size_Function): Likewise.
	* exp_ch3.adb (Build_Offset_To_Top_Function): Likewise.
	* exp_ch4.adb (Expand_Allocator_Expression): Likewise.
	(Expand_N_Indexed_Component ): Remove code dealing with implicit
	dereferences.
	(Expand_N_Selected_Component): Likewise.
	(Expand_N_Slice): Likewise.
	* exp_ch9.adb (Add_Formal_Renamings): Add explicit dereference.
	(Expand_Accept_Declarations): Likewise.
	(Build_Simple_Entry_Call): Remove code dealing with implicit
	dereferences.
	(Expand_N_Requeue_Statement): Likewise.
	* exp_disp.adb (Expand_Dispatching_Call): Build an explicit
	dereference when the controlling type is an access type.
	* exp_spark.adb (Expand_SPARK_N_Selected_Component): Delete.
	(Expand_SPARK_N_Slice_Or_Indexed_Component): Likewise.
	(Expand_SPARK): Do not call them.
	* sem_ch4.adb (Process_Implicit_Dereference_Prefix): Delete.
	(Process_Indexed_Component): Call Implicitly_Designated_Type
	to get the designated type for an implicit dereference.
	(Analyze_Overloaded_Selected_Component): Do not insert an
	explicit dereference here.
	(Analyze_Selected_Component): Likewise.
	(Analyze_Slice): Call Implicitly_Designated_Type to get the
	designated type for an implicit dereference.
	* sem_ch8.adb (Has_Components): New predicate extracted from...
	(Is_Appropriate_For_Record): ...this.  Delete.
	(Is_Appropriate_For_Entry_Prefix): Likewise.
	(Analyze_Renamed_Entry): Deal with implicit dereferences.
	(Find_Selected_Component): Do not insert an explicit dereference
	here.  Call Implicitly_Designated_Type to get the designated type
	for an implicit dereference.  Call Has_Components, Is_Task_Type
	and Is_Protected_Type directly.  Adjust test for error.
	* sem_res.adb (Resolve_Implicit_Dereference): New procedure.
	(Resolve_Call): Call Resolve_Indexed_Component last.
	(Resolve_Entry): Call Resolve_Implicit_Dereference on the prefix.
	(Resolve_Indexed_Component): Call Implicitly_Designated_Type to
	get the designated type for an implicit dereference and
	Resolve_Implicit_Dereference on the prefix at the end.
	(Resolve_Selected_Component): Likewise.
	(Resolve_Slice): Likewise.  Do not apply access checks here.
	* sem_util.ads (Implicitly_Designated_Type): Declare.
	* sem_util.adb (Copy_And_Maybe_Dereference): Simplify.
	(Implicitly_Designated_Type): New function.
	(Object_Access_Level): Fix typo.
	* sem_warn.adb (Check_Unset_Reference): Test Comes_From_Source
	on the original node.