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Date: Thu, 5 Nov 2015 15:57:39 -0800 (PST)
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Subject: Problems Linking With a C++ Lib
From: Aurele <aurele.vitali@gmail.com>
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Xref: news.eternal-september.org comp.lang.ada:28223
Date: 2015-11-05T15:57:39-08:00
List-Id: <comp.lang.ada>

Hi all, I've developed a DirectInput Windows wrapper library in C and I'm trying to link it with an Ada main (Adacore GPS environment) but I keep getting the following error: 

undefined reference to `DI_InitDirectInput@8'

I used C to develop this wrapper because its uses DirectX "API Methods" which is not supported in Ada (well at least I think its not). The wrapper is simple and implemented using MS Visual Studio.  Here is the C code sample:

extern "C" {																	
int DI_InitDirectInput( HWND hWnd, HINSTANCE hInstance );
int DI_InitDirectInput( HWND hWnd, HINSTANCE hInstance )
  {
  ...
  };
}

In Ada, I've created the following spec for the library:

package DI is
  function DI_InitDirectInput( hW    : hWnd; 
                               hInst : hInstance ) return Bool;
private
    pragma import( C, DI_InitDirectInput, "DI_InitDirectInput" );
end DI;

I use the following linker switches when building the main body:

  package Linker is
    for Default_Switches ("ada") use ( "-LE:\Lib", "-lDirectInput" );
  end Linker;

GPS (or the builder) finds the library but not the reference.  The library works well if I use the ObjectAda IDE to build the main.

Any thoughts?