Add support of --version command line switch.

source/gnatdoc/gnatdoc-command_line.adb

@@ -21,9 +21,13 @@ with VSS.Strings.Conversions;
 
 with GNATdoc.Comments.Options;
 with GNATdoc.Options;
+with GNATdoc.Version;
 
 with GPR2.Options;
 with GPR2.Project.Registry.Exchange;
+with VSS.Strings.Formatters;
+with VSS.Strings.Formatters.Strings;
+with VSS.Strings.Templates;
 
 package body GNATdoc.Command_Line is
 
@@ -32,6 +36,11 @@ package body GNATdoc.Command_Line is
       Long_Name   => "help",
       Description => "Display help information");
 
+   Version_Option            : constant VSS.Command_Line.Binary_Option :=
+     (Short_Name  => <>,
+      Long_Name   => "version",
+      Description => "Display version");
+
    Backend_Option            : constant VSS.Command_Line.Value_Option :=
      (Short_Name  => <>,
       Long_Name   => "backend",
@@ -121,6 +130,7 @@ package body GNATdoc.Command_Line is
    procedure Initialize is
    begin
       Parser.Add_Option (Help_Option);
+      Parser.Add_Option (Version_Option);
       Parser.Add_Option (Print_Gpr_Registry_Option);
       Parser.Add_Option (Style_Option);
       Parser.Add_Option (Backend_Option);
@@ -173,6 +183,20 @@ package body GNATdoc.Command_Line is
          VSS.Command_Line.Report_Message (Parser.Help_Text);
       end if;
 
+      if Parser.Is_Specified (Version_Option) then
+         declare
+            Template : constant
+              VSS.Strings.Templates.Virtual_String_Template :=
+                "GNATdoc {}";
+
+         begin
+            VSS.Command_Line.Report_Error
+              (Template.Format
+                 (VSS.Strings.Formatters.Strings.Image
+                      (GNATdoc.Version.Version_String)));
+         end;
+      end if;
+
       --  Process `--print-gpr-registry` if specified
 
       if Parser.Is_Specified (Print_Gpr_Registry_Option) then

source/gnatdoc/gnatdoc-version.ads

@@ -0,0 +1,23 @@
+------------------------------------------------------------------------------
+--                    GNAT Documentation Generation Tool                    --
+--                                                                          --
+--                       Copyright (C) 2024, AdaCore                        --
+--                                                                          --
+-- This 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.  This software is distributed in the hope  that it will be useful, --
+-- but WITHOUT ANY WARRANTY;  without even the implied warranty of MERCHAN- --
+-- TABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public --
+-- License for  more details.  You should have  received  a copy of the GNU --
+-- General  Public  License  distributed  with  this  software;   see  file --
+-- COPYING3.  If not, go to http://www.gnu.org/licenses for a complete copy --
+-- of the license.                                                          --
+------------------------------------------------------------------------------
+
+package GNATdoc.Version is
+
+   Version_String : VSS.Strings.Virtual_String :=
+     "%VERSION% (%DATE%)";
+
+end GNATdoc.Version;