2011-11-06 Basile Starynkevitch <basile@starynkevitch.net>

	MELT branch merged with trunk rev 181026 using svnmerge



git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/branches/melt-branch@181034 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 47 insertions, 1 deletions

diff --git a/gcc/ada/a-cdlili.adb b/gcc/ada/a-cdlili.adb
index 497a1112d43..8b513222ef8 100644
--- a/gcc/ada/a-cdlili.adb
+++ b/gcc/ada/a-cdlili.adb
@@ -146,6 +146,27 @@ package body Ada.Containers.Doubly_Linked_Lists is
       Insert (Container, No_Element, New_Item, Count);
    end Append;
 
+   ------------
+   -- Assign --
+   ------------
+
+   procedure Assign (Target : in out List; Source : List) is
+      Node : Node_Access;
+
+   begin
+      if Target'Address = Source'Address then
+         return;
+      end if;
+
+      Target.Clear;
+
+      Node := Source.First;
+      while Node /= null loop
+         Target.Append (Node.Element);
+         Node := Node.Next;
+      end loop;
+   end Assign;
+
    -----------
    -- Clear --
    -----------
@@ -206,6 +227,17 @@ package body Ada.Containers.Doubly_Linked_Lists is
       return Find (Container, Item) /= No_Element;
    end Contains;
 
+   ----------
+   -- Copy --
+   ----------
+
+   function Copy (Source : List) return List is
+   begin
+      return Target : List do
+         Target.Assign (Source);
+      end return;
+   end Copy;
+
    ------------
    -- Delete --
    ------------
@@ -483,10 +515,24 @@ package body Ada.Containers.Doubly_Linked_Lists is
          LI, RI : Cursor;
 
       begin
-         if Target'Address = Source'Address then
+
+         --  The semantics of Merge changed slightly per AI05-0021. It was
+         --  originally the case that if Target and Source denoted the same
+         --  container object, then the GNAT implementation of Merge did
+         --  nothing. However, it was argued that RM05 did not precisely
+         --  specify the semantics for this corner case. The decision of the
+         --  ARG was that if Target and Source denote the same non-empty
+         --  container object, then Program_Error is raised.
+
+         if Source.Is_Empty then
             return;
          end if;
 
+         if Target'Address = Source'Address then
+            raise Program_Error with
+              "Target and Source denote same non-empty container";
+         end if;
+
          if Target.Busy > 0 then
             raise Program_Error with
               "attempt to tamper with cursors of Target (list is busy)";