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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Building an encapsulated library that uses GNAT sockets under Windows
Date: Thu, 21 Apr 2016 14:59:35 +0200
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Xref: news.eternal-september.org comp.lang.ada:30217
Date: 2016-04-21T14:59:35+02:00
List-Id: <comp.lang.ada>

It seems I finally found a way to build it. The solution is quite 
perplexing. I would be glad if anybody could shed some light on it.

An encapsulated library requires that -lws2_32 -lwsock32 appeared *both* 
at the beginning and the end of the linker command line. Only then no 
"undefined reference" messages appear.

For this build this program:
--------------------------------------- gcc_wrapper.adb ---
with Ada.Command_Line;  use Ada.Command_Line;
with Ada.Exceptions;    use Ada.Exceptions;
with Ada.Text_IO;       use Ada.Text_IO;
with GNAT.OS_Lib;       use GNAT.OS_Lib;

procedure GCC_Wrapper is
    Prefix : String_List :=
             (  new String'("-lwsock32"),
                new String'("-lws2_32")
             );
    Options : String_List (1..Argument_Count);
begin
    for No in 1..Argument_Count loop
       Options (No) := new String'(Argument (No));
    end loop;
    declare
       List : String_List := Prefix & Options & Prefix;
    begin
       Put ("gcc.exe");
       for No in List'Range loop
          Put (" " & List (No).all);
       end loop;
       New_Line;
       Set_Exit_Status (Exit_Status (Spawn ("gcc.exe", List)));
    end;
exception
    when Error : others =>
       Put_Line
       (  Standard_Error,
          "Fault: " & Exception_Information (Error)
       );
       Set_Exit_Status (2);
end GCC_Wrapper;
--------------------------------------- gcc_wrapper.adb ---

The project file must contain:

    package Linker is
       for Driver use "<absolute-path-to>/gcc_wrapper.exe";
    end Linker;

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de