2011-11-04 Robert Dewar <dewar@adacore.com>

	* gnat_rm.texi: Minor reformatting.

2011-11-04  Matthew Heaney  <heaney@adacore.com>

	* a-convec.adb, a-coinve.adb, a-cobove.adb (Merge): Raise PE
	when Target and Source denote same non-empty object
	* a-cdlili.adb, a-cidlli.adb, a-cbdlli.adb (Merge): Ditto

2011-11-04  Robert Dewar  <dewar@adacore.com>

	* exp_attr.adb: Minor reformatting.

2011-11-04  Ed Schonberg  <schonberg@adacore.com>

	* exp_ch5.adb (Expand_Assign_Record): Do not generate a
	discriminant assignment within an initialization proc if the
	record is an unchecked union, as it can only come from the
	initialization of an unchecked union component.

2011-11-04  Robert Dewar  <dewar@adacore.com>

	* gnat_ugn.texi: Minor reformatting.

2011-11-04  Robert Dewar  <dewar@adacore.com>

	* par-labl.adb (Rewrite_As_Loop): Generate info msg rather than
	warning message.

2011-11-04  Robert Dewar  <dewar@adacore.com>

	* exp_ch4.adb: Minor code reorganization (remove junk obsolete
	var Save_Space).



git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@180954 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 15 insertions, 1 deletions

diff --git a/gcc/ada/a-cdlili.adb b/gcc/ada/a-cdlili.adb
index 326c74b0785..8b513222ef8 100644
--- a/gcc/ada/a-cdlili.adb
+++ b/gcc/ada/a-cdlili.adb
@@ -515,10 +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)";