ada: Compile time crash on limited object in extended return

This patch fixes an error in the compiler whereby using an extended return on
an object of limited tagged type which extends a tagged protected type may lead
to a compile-time crash.

gcc/ada/ChangeLog:

	* exp_ch3.adb (Build_Assignment): Add condition to fetch corresponding
	record types for concurrent tagged types.

1 files changed, 17 insertions, 5 deletions

diff --git a/gcc/ada/exp_ch3.adb b/gcc/ada/exp_ch3.adb
index 3dd4d9c..9d61d41 100644
--- a/gcc/ada/exp_ch3.adb
+++ b/gcc/ada/exp_ch3.adb
@@ -2692,11 +2692,23 @@ package body Exp_Ch3 is
            and then Tagged_Type_Expansion
            and then Nkind (Exp_Q) /= N_Raise_Expression
          then
-            Append_To (Res,
-              Make_Tag_Assignment_From_Type
-                (Default_Loc,
-                 New_Copy_Tree (Lhs, New_Scope => Proc_Id),
-                 Underlying_Type (Typ)));
+            --  Get the relevant type for the call to
+            --  Make_Tag_Assignment_From_Type, which, for concurrent types is
+            --  their corresponding record.
+
+            declare
+               T : Entity_Id := Underlying_Type (Typ);
+            begin
+               if Ekind (T) in E_Protected_Type | E_Task_Type then
+                  T := Corresponding_Record_Type (T);
+               end if;
+
+               Append_To (Res,
+                 Make_Tag_Assignment_From_Type
+                   (Default_Loc,
+                    New_Copy_Tree (Lhs, New_Scope => Proc_Id),
+                    T));
+            end;
          end if;
 
          --  Adjust the component if controlled except if it is an aggregate