[COMMITTED] ada: Fix couple of issues with arrays indexed by enumeration type

["Marc Poulhiès" <poulhies@adacore.com>]

From: Eric Botcazou <ebotcazou@adacore.com>

The first one is that Remove_Warning_Messages reinstates the Original_Node
of an N_Raise_Constraint_Error node in the tree for no clear reasons, and
the Original_Node may contain constructs whose expansion has been stopped
when the Constraint_Error was asserted, eventually causing gigi to stop.

The second one is that a path in Build_Array_Aggr_Code.Gen_Loop does not
copy the loop bounds, unlike other paths, thus triggering a sharing issue.

gcc/ada/

	* errout.adb (Remove_Warning_Messages.Check_For_Warning): Do not
	reinstate the Original_Node in the tree.
	* exp_aggr.adb (Build_Array_Aggr_Code.Gen_Loop): Copy the bounds
	on all paths.

Tested on x86_64-pc-linux-gnu, committed on master.

---
 gcc/ada/errout.adb   | 16 +++-------------
 gcc/ada/exp_aggr.adb |  4 ++--
 2 files changed, 5 insertions(+), 15 deletions(-)

diff --git a/gcc/ada/errout.adb b/gcc/ada/errout.adb
index 85931552970..5730a543ee1 100644
--- a/gcc/ada/errout.adb
+++ b/gcc/ada/errout.adb
@@ -3383,23 +3383,13 @@ package body Errout is
             E := Errors.Table (E).Next;
          end loop;
 
+         --  Warnings may have been posted on subexpressions of original tree
+
          if Nkind (N) = N_Raise_Constraint_Error
            and then Is_Rewrite_Substitution (N)
            and then No (Condition (N))
          then
-            --  Warnings may have been posted on subexpressions of the original
-            --  tree. We place the original node back on the tree to remove
-            --  those warnings, whose sloc do not match those of any node in
-            --  the current tree. Given that we are in unreachable code, this
-            --  modification to the tree is harmless.
-
-            if Is_List_Member (N) then
-               Set_Condition (N, Original_Node (N));
-               Check_All_Warnings (Condition (N));
-            else
-               Rewrite (N, Original_Node (N));
-               Check_All_Warnings (N);
-            end if;
+            Check_All_Warnings (Original_Node (N));
          end if;
 
          return OK;
diff --git a/gcc/ada/exp_aggr.adb b/gcc/ada/exp_aggr.adb
index 185705544e9..dde49d1e289 100644
--- a/gcc/ada/exp_aggr.adb
+++ b/gcc/ada/exp_aggr.adb
@@ -2058,7 +2058,7 @@ package body Exp_Aggr is
          --  to do that if we already have the base type at hand.
 
          if Etype (L) = Index_Base then
-            L_L := L;
+            L_L := New_Copy_Tree (L);
          else
             L_L :=
               Make_Qualified_Expression (Loc,
@@ -2067,7 +2067,7 @@ package body Exp_Aggr is
          end if;
 
          if Etype (H) = Index_Base then
-            L_H := H;
+            L_H := New_Copy_Tree (H);
          else
             L_H :=
               Make_Qualified_Expression (Loc,
-- 
2.34.1