I am about 50% certain I am missing something obvious. I'm playing with DLLs in D, and following the example here:

http://digitalmars.com/d/dll.html

The end result of this tutorial are some D source files:

dll.d
mydll.d
mydll2.d
test.d

and also a .def file (mydll.def), a .lib file (mydll.lib), and of course the .dll (mydll.dll). The command

C:>dmd test.d mydll.lib

goes fine, and the resultant executable works fine.

Fine.

Now I want to call this DLL from a C program. First, I re-wrote mydll.d and mydll2.d and recompiled the DLL and the test executable:

[mydll.d]
export extern(C) void dllprint();

[mydll2.d]
module mydll;
export extern(C)
void dllprint() { printf("hello dll world\n"); }

The original .exe still works. Fine. Then I wrote a C header file and a test2.c:

[mydll.h]
__declspec(dllimport) void dllprint(void);

[test2.c]
#include "mydll.h"

int main(int argc, char* argv[]) {
    dllprint();
    return 0;
}

This does not work. I am using MinGW 3.4.2. The following command works:

C:>gcc -c test2.c

test2.o is generated without issue. However:

C:>gcc -L. -lmydll test2.o
./mydll.dll: file not recognized: File format not recognized
collect2: ld returned 1 exit status

The linker fails. Again, I'm pretty sure I'm missing something obvious. Any help?

-Kirk McDonald

Kirk McDonald wrote:
[...]
> 
> This does not work. I am using MinGW 3.4.2. The following command works:
> 
> C:>gcc -c test2.c
> 
> test2.o is generated without issue. However:
> 
> C:>gcc -L. -lmydll test2.o
> ./mydll.dll: file not recognized: File format not recognized
> collect2: ld returned 1 exit status
> 
> The linker fails. Again, I'm pretty sure I'm missing something obvious. Any help?
> 
> -Kirk McDonald

First of all I'd try the using dmc/optlink instead of gcc. I haven't tried this but dmd on win does have some issues with object/lib file compatibility (at least with VS).

BCS wrote:
> First of all I'd try the using dmc/optlink instead of gcc. I haven't tried this but dmd on win does have some issues with object/lib file compatibility (at least with VS).

Interesting. That did it:

C:>dmc -c test2.c

C:>dmc test2.obj mydll.lib
link test2,,,mydll+user32+kernel32/noi;

C:>test2
hello dll world

Are there any plans to fix this? Is this perceived as a serious problem?

-Kirk McDonald

"Kirk McDonald" <kirklin.mcdonald@gmail.com> wrote in message news:e506jv$9gv$1@digitaldaemon.com...
>
> Are there any plans to fix this? Is this perceived as a serious problem?

I would actually put this down to gcc not recognising the .lib format you generated. Have a look at the mingw/cygwin gcc specs. I'm sure you have to generate gcc specific .a files, or at least gcc specific .lib files from the .def file. IIRC there is a tutorial on the Net about creating dll's with Mingw, might be worth looking at that to see what is going on.

M

If you want a dll, and you're staticly linking it, you have to create an import library from the dll...

To link dynamically, you'll typically use LoadLibrary(), etc. at least on Windows.

-[Unknown]


> BCS wrote:
>> First of all I'd try the using dmc/optlink instead of gcc. I haven't tried this but dmd on win does have some issues with object/lib file compatibility (at least with VS).
> 
> Interesting. That did it:
> 
> C:>dmc -c test2.c
> 
> C:>dmc test2.obj mydll.lib
> link test2,,,mydll+user32+kernel32/noi;
> 
> C:>test2
> hello dll world
> 
> Are there any plans to fix this? Is this perceived as a serious problem?
> 
> -Kirk McDonald