[Ada] Validate_Access_Subprogram_Instance: check if not null types match

2019-12-16  Ghjuvan Lacambre  <lacambre@adacore.com>

gcc/ada/

	* sem_ch12.adb (Validate_Access_Subprogram_Instance): Add
	Can_Never_Be_Null checks.

From-SVN: r279413

gcc/ada/ChangeLog

+2019-12-16  Ghjuvan Lacambre  <lacambre@adacore.com>
+
+	* sem_ch12.adb (Validate_Access_Subprogram_Instance): Add
+	Can_Never_Be_Null checks.
+
 2019-12-16  Eric Botcazou  <ebotcazou@adacore.com>
 
 	* doc/gnat_rm/implementation_defined_pragmas.rst (VFA): Document

gcc/ada/sem_ch12.adb

@@ -12303,6 +12303,12 @@ package body Sem_Ch12 is
             Error_Msg_NE
               ("actual for formal & must have convention %", Actual, Gen_T);
          end if;
+
+         if Can_Never_Be_Null (A_Gen_T) /= Can_Never_Be_Null (Act_T) then
+            Error_Msg_NE
+               ("non null exclusion of actual and formal & do not match",
+               Actual, Gen_T);
+         end if;
       end Validate_Access_Subprogram_Instance;
 
       -----------------------------------