[Ada] Hashed container Cursor type predefined equality non-conformance

gcc/ada/

	* libgnat/a-cohase.ads (Cursor): Synchronize comments for the Cursor
	type definition to be consistent with identical definitions in other
	container packages. Add additional comments regarding the importance of
	maintaining the "Position" component for predefined equality.
	* libgnat/a-cohama.ads (Cursor): Likewise.
	* libgnat/a-cihama.ads (Cursor): Likewise.
	* libgnat/a-cohase.adb (Find, Insert): Ensure that Cursor objects
	always have their "Position" component set to ensure predefined
	equality works as required.
	* libgnat/a-cohama.adb (Find, Insert): Likewise.
	* libgnat/a-cihama.adb (Find, Insert): Likewise.

gcc/testsuite/

	* gnat.dg/containers2.adb: New test.

6 files changed, 49 insertions, 6 deletions

diff --git a/gcc/ada/libgnat/a-cihama.adb b/gcc/ada/libgnat/a-cihama.adb
index 7a490d5..50adea1 100644
--- a/gcc/ada/libgnat/a-cihama.adb
+++ b/gcc/ada/libgnat/a-cihama.adb
@@ -522,7 +522,8 @@ is
          return No_Element;
       end if;
 
-      return Cursor'(Container'Unrestricted_Access, Node, Hash_Type'Last);
+      return Cursor'
+        (Container'Unrestricted_Access, Node, HT_Ops.Index (HT, Node));
    end Find;
 
    --------------------
@@ -748,6 +749,7 @@ is
       end if;
 
       Position.Container := Container'Unchecked_Access;
+      Position.Position := HT_Ops.Index (HT, Position.Node);
    end Insert;
 
    procedure Insert
diff --git a/gcc/ada/libgnat/a-cihama.ads b/gcc/ada/libgnat/a-cihama.ads
index ccf5f4e..f896167 100644
--- a/gcc/ada/libgnat/a-cihama.ads
+++ b/gcc/ada/libgnat/a-cihama.ads
@@ -363,8 +363,22 @@ private
 
    type Cursor is record
       Container : Map_Access;
+      --  Access to this cursor's container
+
       Node      : Node_Access;
+      --  Access to the node pointed to by this cursor
+
       Position  : Hash_Type := Hash_Type'Last;
+      --  Position of the node in the buckets of the container. If this is
+      --  equal to Hash_Type'Last, then it will not be used. Position is
+      --  not requried by the implementation, but improves the efficiency
+      --  of various operations.
+      --
+      --  However, this value must be maintained so that the predefined
+      --  equality operation acts as required by RM A.18.4-18/2, which
+      --  states: "The predefined "=" operator for type Cursor returns True
+      --  if both cursors are No_Element, or designate the same element
+      --  in the same container."
    end record;
 
    procedure Write
diff --git a/gcc/ada/libgnat/a-cohama.adb b/gcc/ada/libgnat/a-cohama.adb
index 9c4e51a..fb46e07 100644
--- a/gcc/ada/libgnat/a-cohama.adb
+++ b/gcc/ada/libgnat/a-cohama.adb
@@ -478,7 +478,8 @@ is
          return No_Element;
       end if;
 
-      return Cursor'(Container'Unrestricted_Access, Node, Hash_Type'Last);
+      return Cursor'
+        (Container'Unrestricted_Access, Node, HT_Ops.Index (HT, Node));
    end Find;
 
    --------------------
@@ -635,6 +636,7 @@ is
       end if;
 
       Position.Container := Container'Unrestricted_Access;
+      Position.Position := HT_Ops.Index (HT, Position.Node);
    end Insert;
 
    procedure Insert
@@ -677,6 +679,7 @@ is
       end if;
 
       Position.Container := Container'Unrestricted_Access;
+      Position.Position := HT_Ops.Index (HT, Position.Node);
    end Insert;
 
    procedure Insert
diff --git a/gcc/ada/libgnat/a-cohama.ads b/gcc/ada/libgnat/a-cohama.ads
index 21b6935..c6e377c 100644
--- a/gcc/ada/libgnat/a-cohama.ads
+++ b/gcc/ada/libgnat/a-cohama.ads
@@ -465,7 +465,15 @@ private
 
       Position  : Hash_Type := Hash_Type'Last;
       --  Position of the node in the buckets of the container. If this is
-      --  equal to Hash_Type'Last, then it will not be used.
+      --  equal to Hash_Type'Last, then it will not be used. Position is
+      --  not requried by the implementation, but improves the efficiency
+      --  of various operations.
+      --
+      --  However, this value must be maintained so that the predefined
+      --  equality operation acts as required by RM A.18.4-18/2, which
+      --  states: "The predefined "=" operator for type Cursor returns True
+      --  if both cursors are No_Element, or designate the same element
+      --  in the same container."
    end record;
 
    procedure Read
diff --git a/gcc/ada/libgnat/a-cohase.adb b/gcc/ada/libgnat/a-cohase.adb
index 0131f73..aac5b1b 100644
--- a/gcc/ada/libgnat/a-cohase.adb
+++ b/gcc/ada/libgnat/a-cohase.adb
@@ -605,13 +605,13 @@ is
    is
       HT   : Hash_Table_Type renames Container'Unrestricted_Access.HT;
       Node : constant Node_Access := Element_Keys.Find (HT, Item);
-
    begin
       if Node = null then
          return No_Element;
       end if;
 
-      return Cursor'(Container'Unrestricted_Access, Node, Hash_Type'Last);
+      return Cursor'
+        (Container'Unrestricted_Access, Node, HT_Ops.Index (HT, Node));
    end Find;
 
    --------------------
@@ -763,9 +763,11 @@ is
       Position  : out Cursor;
       Inserted  : out Boolean)
    is
+      HT : Hash_Table_Type renames Container'Unrestricted_Access.HT;
    begin
       Insert (Container.HT, New_Item, Position.Node, Inserted);
       Position.Container := Container'Unchecked_Access;
+      Position.Position := HT_Ops.Index (HT, Position.Node);
    end Insert;
 
    procedure Insert
@@ -1998,7 +2000,7 @@ is
             return No_Element;
          else
             return Cursor'
-              (Container'Unrestricted_Access, Node, Hash_Type'Last);
+              (Container'Unrestricted_Access, Node, HT_Ops.Index (HT, Node));
          end if;
       end Find;
 
diff --git a/gcc/ada/libgnat/a-cohase.ads b/gcc/ada/libgnat/a-cohase.ads
index a0aca52..c1415b5 100644
--- a/gcc/ada/libgnat/a-cohase.ads
+++ b/gcc/ada/libgnat/a-cohase.ads
@@ -537,8 +537,22 @@ private
 
    type Cursor is record
       Container : Set_Access;
+      --  Access to this cursor's container
+
       Node      : Node_Access;
+      --  Access to the node pointed to by this cursor
+
       Position  : Hash_Type := Hash_Type'Last;
+      --  Position of the node in the buckets of the container. If this is
+      --  equal to Hash_Type'Last, then it will not be used. Position is
+      --  not requried by the implementation, but improves the efficiency
+      --  of various operations.
+      --
+      --  However, this value must be maintained so that the predefined
+      --  equality operation acts as required by RM A.18.7-17/2, which
+      --  states: "The predefined "=" operator for type Cursor returns True
+      --  if both cursors are No_Element, or designate the same element
+      --  in the same container."
    end record;
 
    procedure Write