Making MzScheme extensions using VC++ 5.0?

[Paul Fernhout <pdfernhout@kurtz-fernhout.com>]

(I mentioned this issue in a previous post, but I tried again and
thought I'd ask the question more directly with more information.)

I'm having difficulties compiling an extension for MzScheme.
It's basically the "Hello World" extension from the documentation.

I have Microsoft Visual C++ 5.0 installed under NT 4.0 SP 3. 
No SP installed for VC++ 5.0 I think 
(although there is a 100MB one from Microsoft).
(I know there is a VC 6.0, but I'm trying to avoid sending Redmond more
money than I have to.)

Using, mzc the file compiles OK, but in the link stage I get:
.\mzdyn.obj : error : Internal error during Pass1

So, I made my own project to build an Win32 DLL.
I left the default options for everything.
One exception, I got this link warning for the debug version:
LINK : warning 
LNK4098: defaultlib "LIBC" conflicts with use of other libs; use
/NODEFAULTLIB:library

So, I added
LIBC
under Link: 
Catagory: Input
to "Ignore Libraries" field.

I am now able to build a DLL using the debug settings. Under release, I
get the same error as before under mzc:
  .\mzdyn.obj : error : Internal error during Pass1

Trying to load this Debug verion of the DLL, 
(load-extension "c:/PdfScheme/TestDll.dll")
I got a load error from DrScheme:

load-extension: "c:/PdfScheme/TestDll.dll" is not an extension (The
specified procedure could not be found.; errno=127)

I look at the DLL some more, and try this:
"g:/program Files/devstudio/vc/bin/dumpbin.exe" /exports 
debug/testdll.dll
which shows me that there are no exported functions in the DLL.

I look at "escheme.h" and it only declares the two core functions
"extern". There is no declaration for Win32 that they are exported from
a DLL.

So I modify the code to be the following:

===============================================
#define SCHEME_DIRECT_EMBEDDED 0
#include "c:\plt\collects\mzscheme\include\scheme.h"
extern __declspec( dllexport ) Scheme_Object
*scheme_initialize(Scheme_Env *global_env);
extern __declspec( dllexport ) Scheme_Object *scheme_reload(Scheme_Env
*global_env);

//#include "c:\plt\collects\mzscheme\include\escheme.h"

Scheme_Object *scheme_reload(Scheme_Env *env)
{
  /* When the extension is loaded, return a Scheme string: */
  return scheme_make_string("Hello, world!");
}

Scheme_Object *scheme_initialize(Scheme_Env *env)
{
  /* First load is same as every load: */
  return scheme_reload(env);
}
======================================================

This builds under Debug (same error still for release), but DrScheme
still gives me:
 
load-extension: "c:/PdfScheme/TestDll.dll" is not an extension (The
specified procedure could not be found.; errno=127)

when I try to load it. I tried shutting down DrScheme (do I have to on a
second try if the first failed?) and trying the load again, but still
the same error.

Any suggestions?  It seems that the "escheme.h" header is insufficient
for Windows. I think the alternative is to have a seperate export file,
so maybe mzc fools the linker with some sort of other approach somehow
and then the header may be adequate.

Any suggestions how to proceed from this point?

Does anyone have a complete stand-alone simple project to build a DLL
that works under VC 5.0 I could try?

Or is it time to switch to GCC? If so, can someone first confirm it does
work under GCC for Win NT? I would think the dllexport would still be
needed even then in the declaration (although I've only used GCC for
other platforms than Win32).

-Paul Fernhout
Kurtz-Fernhout Software 
=========================================================
Developers of custom software and educational simulations
Creators of the Garden with Insight(TM) garden simulator
http://www.kurtz-fernhout.com