--- a/gcc/ada/libgnat/a-dhfina.ads	Thu Oct 25 07:37:49 2018 +0900
+++ b/gcc/ada/libgnat/a-dhfina.ads	Thu Feb 13 11:34:05 2020 +0900
@@ -6,41 +6,101 @@
 --                                                                          --
 --                                 S p e c                                  --
 --                                                                          --
--- This specification is derived from the Ada Reference Manual for use with --
--- GNAT.  In accordance with the copyright of that document, you can freely --
--- copy and modify this specification,  provided that if you redistribute a --
--- modified version,  any changes that you have made are clearly indicated. --
+--          Copyright (C) 2004-2019, Free Software Foundation, Inc.         --
+--                                                                          --
+-- GNAT is free software;  you can  redistribute it  and/or modify it under --
+-- terms of the  GNU General Public License as published  by the Free Soft- --
+-- ware  Foundation;  either version 3,  or (at your option) any later ver- --
+-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
+-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
+-- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
+--                                                                          --
+-- As a special exception under Section 7 of GPL version 3, you are granted --
+-- additional permissions described in the GCC Runtime Library Exception,   --
+-- version 3.1, as published by the Free Software Foundation.               --
+--                                                                          --
+-- In particular,  you can freely  distribute your programs  built with the --
+-- GNAT Pro compiler, including any required library run-time units,  using --
+-- any licensing terms  of your choosing.  See the AdaCore Software License --
+-- for full details.                                                        --
+--                                                                          --
+-- GNAT was originally developed  by the GNAT team at  New York University. --
+-- Extensive contributions were provided by Ada Core Technologies Inc.      --
 --                                                                          --
 ------------------------------------------------------------------------------
 
 package Ada.Directories.Hierarchical_File_Names is
-   pragma Unimplemented_Unit;
 
    function Is_Simple_Name (Name : String) return Boolean;
+   --  Returns True if Name is a simple name, and returns False otherwise.
 
    function Is_Root_Directory_Name (Name : String) return Boolean;
+   --  Returns True if Name is syntactically a root (a directory that cannot
+   --  be decomposed further), and returns False otherwise.
 
    function Is_Parent_Directory_Name (Name : String) return Boolean;
+   --  Returns True if Name can be used to indicate symbolically the parent
+   --  directory of any directory, and returns False otherwise.
 
    function Is_Current_Directory_Name (Name : String) return Boolean;
+   --  Returns True if Name can be used to indicate symbolically the directory
+   --  itself for any directory, and returns False otherwise.
 
    function Is_Full_Name (Name : String) return Boolean;
+   --  Returns True if the leftmost directory part of Name is a root, and
+   --  returns False otherwise.
 
    function Is_Relative_Name (Name : String) return Boolean;
+   --  Returns True if Name allows the identification of an external file
+   --  (including directories and special files) but is not a full name, and
+   --  returns False otherwise.
 
    function Simple_Name (Name : String) return String
      renames Ada.Directories.Simple_Name;
+   --  Returns the simple name portion of the file name specified by Name. The
+   --  exception Name_Error is propagated if the string given as Name does not
+   --  allow the identification of an external file (including directories and
+   --  special files).
 
    function Containing_Directory (Name : String) return String
      renames Ada.Directories.Containing_Directory;
+   --  Returns the name of the containing directory of the external file
+   --  (including directories) identified by Name. If more than one directory
+   --  can contain Name, the directory name returned is implementation-defined.
+   --  The exception Name_Error is propagated if the string given as Name does
+   --  not allow the identification of an external file. The exception
+   --  Use_Error is propagated if the external file does not have a containing
+   --  directory.
 
    function Initial_Directory (Name : String) return String;
+   --  Returns the leftmost directory part in Name. That is, it returns a root
+   --  directory name (for a full name), or one of a parent directory name, a
+   --  current directory name, or a simple name (for a relative name). The
+   --  exception Name_Error is propagated if the string given as Name does not
+   --  allow the identification of an external file (including directories and
+   --  special files).
 
    function Relative_Name (Name : String) return String;
+   --  Returns the entire file name except the Initial_Directory portion. The
+   --  exception Name_Error is propagated if the string given as Name does not
+   --  allow the identification of an external file (including directories and
+   --  special files), or if Name has a single part (this includes if any of
+   --  Is_Simple_Name, Is_Root_Directory_Name, Is_Parent_Directory_Name, or
+   --  Is_Current_Directory_Name are True).
 
    function Compose
      (Directory      : String := "";
       Relative_Name  : String;
       Extension      : String := "") return String;
+   --  Returns the name of the external file with the specified Directory,
+   --  Relative_Name, and Extension. The exception Name_Error is propagated if
+   --  the string given as Directory is not the null string and does not allow
+   --  the identification of a directory, or if Is_Relative_Name
+   --  (Relative_Name) is False, or if the string given as Extension is not
+   --  the null string and is not a possible extension, or if Extension is not
+   --  the null string and Simple_Name (Relative_Name) is not a base name.
+   --
+   --  The result of Compose is a full name if Is_Full_Name (Directory) is
+   --  True; result is a relative name otherwise.
 
 end Ada.Directories.Hierarchical_File_Names;