2009-11-30 Thomas Quinot <quinot@adacore.com>

	* g-sechas.adb: Minor reformatting

2009-11-30  Matthew Heaney  <heaney@adacore.com>

	* a-crbtgo.adb (Delete_Fixup): Add comments explaining why predicates
	were removed.
	* a-cdlili.adb (Vet): Remove always-true predicates.



git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@154823 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 19 insertions, 0 deletions

diff --git a/gcc/ada/a-crbtgo.adb b/gcc/ada/a-crbtgo.adb
index cd14b90491d..c8ddcff02a5 100644
--- a/gcc/ada/a-crbtgo.adb
+++ b/gcc/ada/a-crbtgo.adb
@@ -49,6 +49,8 @@ package body Ada.Containers.Red_Black_Trees.Generic_Operations is
    procedure Left_Rotate  (Tree : in out Tree_Type; X : Node_Access);
    procedure Right_Rotate (Tree : in out Tree_Type; Y : Node_Access);
 
+--  Why is all the following code commented out ???
+
 --     ---------------------
 --     -- Check_Invariant --
 --     ---------------------
@@ -171,8 +173,15 @@ package body Ada.Containers.Red_Black_Trees.Generic_Operations is
                if Right (W) = null
                  or else Color (Right (W)) = Black
                then
+                  --  As a condition for setting the color of the left child to
+                  --  black, the left child access value must be non-null. A
+                  --  truth table analysis shows that if we arrive here, that
+                  --  condition holds, so there's no need for an explicit test.
+                  --  The assertion is here to document what we know is true.
+
                   pragma Assert (Left (W) /= null);
                   Set_Color (Left (W), Black);
+
                   Set_Color (W, Red);
                   Right_Rotate (Tree, W);
                   W := Right (Parent (X));
@@ -206,8 +215,16 @@ package body Ada.Containers.Red_Black_Trees.Generic_Operations is
 
             else
                if Left (W) = null or else Color (Left (W)) = Black then
+
+                  --  As a condition for setting the color of the right child
+                  --  to black, the right child access value must be non-null.
+                  --  A truth table analysis shows that if we arrive here, that
+                  --  condition holds, so there's no need for an explicit test.
+                  --  The assertion is here to document what we know is true.
+
                   pragma Assert (Right (W) /= null);
                   Set_Color (Right (W), Black);
+
                   Set_Color (W, Red);
                   Left_Rotate (Tree, W);
                   W := Left (Parent (X));
@@ -246,6 +263,8 @@ package body Ada.Containers.Red_Black_Trees.Generic_Operations is
            "attempt to tamper with cursors (container is busy)";
       end if;
 
+      --  Why are these all commented out ???
+
 --    pragma Assert (Tree.Length > 0);
 --    pragma Assert (Tree.Root /= null);
 --    pragma Assert (Tree.First /= null);