[Ada] Refine logic to set Needs_Activation_Record on subprogram types

2018-05-30  Ed Schonberg  <schonberg@adacore.com>

gcc/ada/

	* sem_ch3.adb (Access_Subprogram_Declaration): The flag
	Needs_Activation_Record is only needed on a subprogram type, not on a
	pointer to such.
	* sem_res.adb (Resolve_Selected_Component): If the context type and the
	component type are anonymous access to subprograms, use the component
	type to obtain the proper value of Needs_Activation_Record flag for the
	expression.

From-SVN: r260932

gcc/ada/ChangeLog

+2018-05-30  Ed Schonberg  <schonberg@adacore.com>
+
+	* sem_ch3.adb (Access_Subprogram_Declaration): The flag
+	Needs_Activation_Record is only needed on a subprogram type, not on a
+	pointer to such.
+	* sem_res.adb (Resolve_Selected_Component): If the context type and the
+	component type are anonymous access to subprograms, use the component
+	type to obtain the proper value of Needs_Activation_Record flag for the
+	expression.
+
 2018-05-30  Eric Botcazou  <ebotcazou@adacore.com>
 
 	* gcc-interface/trans.c (gnat_to_gnu) <N_Assignment_Statement>: Add

gcc/ada/sem_ch3.adb

@@ -1307,11 +1307,9 @@ package body Sem_Ch3 is
 
       --  If the access_to_subprogram is not declared at the library level,
       --  it can only point to subprograms that are at the same or deeper
-      --  accessibility level. All such might require an activation record
-      --  when compiling for C.
+      --  accessibility level. The corresponding subprogram type might
+      --  require an activation record when compiling for C.
 
-      Set_Needs_Activation_Record  (T_Name,
-                                      not Is_Library_Level_Entity (T_Name));
       Set_Needs_Activation_Record  (Desig_Type,
                                       not Is_Library_Level_Entity (T_Name));
 

gcc/ada/sem_res.adb

@@ -10118,6 +10118,17 @@ package body Sem_Res is
          Set_Etype (N, Typ);
          Set_Entity_With_Checks (S, Comp1);
 
+         --  The type of the context and that of the component are
+         --  compatible and in general identical, but if they are anonymous
+         --  access_to_subprogram types the relevwnt type is that of the
+         --  component. Thid matters in Unnest_Subprograms mode, where the
+         --  relevant context is the one in which the type is declared. not
+         --  the point of use. this determines what activation record to use.
+
+         if Ekind (Typ) = E_Anonymous_Access_Subprogram_Type then
+            Set_Etype (N, Etype (Comp1));
+         end if;
+
       else
          --  Resolve prefix with its type