[Ada] Protect analysis of Indexing aspect against cascaded errors

2019-08-13  Arnaud Charlet  <charlet@adacore.com>

gcc/ada/

	* sem_ch13.adb (Check_Iterator_Functions): Protect against
	cascaded errors.

From-SVN: r274351

gcc/ada/ChangeLog

+2019-08-13  Arnaud Charlet  <charlet@adacore.com>
+
+	* sem_ch13.adb (Check_Iterator_Functions): Protect against
+	cascaded errors.
+
 2019-08-13  Ed Schonberg  <schonberg@adacore.com>
 
 	* sem_ch8.adb (Analyze_Subprogram_Renaming): Do no suppress mode

gcc/ada/sem_ch13.adb

@@ -4653,10 +4653,12 @@ package body Sem_Ch13 is
          end if;
 
          if not Is_Overloaded (Expr) then
-            if not Check_Primitive_Function (Entity (Expr)) then
+            if Entity (Expr) /= Any_Id
+              and then not Check_Primitive_Function (Entity (Expr))
+            then
                Error_Msg_NE
                  ("aspect Indexing requires a function that applies to type&",
-                   Entity (Expr), Ent);
+                  Entity (Expr), Ent);
             end if;
 
             --  Flag the default_iterator as well as the denoted function.