1 files changed, 26 insertions, 0 deletions

diff --git a/gcc/ada/a-rbtgso.ads b/gcc/ada/a-rbtgso.ads
index 4c3d668f719..c39dc6e3fce 100644
--- a/gcc/ada/a-rbtgso.ads
+++ b/gcc/ada/a-rbtgso.ads
@@ -59,25 +59,51 @@ package Ada.Containers.Red_Black_Trees.Generic_Set_Operations is
    pragma Pure;
 
    procedure Union (Target : in out Tree_Type; Source : Tree_Type);
+   --  Attempts to insert each element of Source in Target. If Target is
+   --  busy then Program_Error is raised. We say "attempts" here because
+   --  if these are unique-element sets, then the insertion should fail
+   --  (not insert a new item) when the insertion item from Source is
+   --  equivalent to an item already in Target. If these are multisets
+   --  then of course the attempt should always succeed.
 
    function Union (Left, Right : Tree_Type) return Tree_Type;
+   --  Makes a copy of Left, and attempts to insert each element of
+   --  Right into the copy, then returns the copy.
 
    procedure Intersection (Target : in out Tree_Type; Source : Tree_Type);
+   --  Removes elements from Target that are not equivalent to items in
+   --  Source. If Target is busy then Program_Error is raised.
 
    function Intersection (Left, Right : Tree_Type) return Tree_Type;
+   --  Returns a set comprising all the items in Left equivalent to items in
+   --  Right.
 
    procedure Difference (Target : in out Tree_Type; Source : Tree_Type);
+   --  Removes elements from Target that are equivalent to items in Source. If
+   --  Target is busy then Program_Error is raised.
 
    function Difference (Left, Right : Tree_Type) return Tree_Type;
+   --  Returns a set comprising all the items in Left not equivalent to items
+   --  in Right.
 
    procedure Symmetric_Difference
      (Target : in out Tree_Type;
       Source : Tree_Type);
+   --  Removes from Target elements that are equivalent to items in Source, and
+   --  inserts into Target items from Source not equivalent elements in
+   --  Target. If Target is busy then Program_Error is raised.
 
    function Symmetric_Difference (Left, Right : Tree_Type) return Tree_Type;
+   --  Returns a set comprising the union of the elements in Left not
+   --  equivalent to items in Right, and the elements in Right not equivalent
+   --  to items in Left.
 
    function Is_Subset (Subset : Tree_Type; Of_Set : Tree_Type) return Boolean;
+   --  Returns False if Subset contains at least one element not equivalent to
+   --  any item in Of_Set; returns True otherwise.
 
    function Overlap (Left, Right : Tree_Type) return Boolean;
+   --  Returns True if at least one element of Left is equivalent to an item in
+   --  Right; returns False otherwise.
 
 end Ada.Containers.Red_Black_Trees.Generic_Set_Operations;