On Windows, x86.

http://dl.dropbox.com/u/9218759/DLL_Imports.zip

fail_build.bat runs:
dmd driver.d mydll.lib -I%cd%\include\
but linking fails:
driver.obj(driver)
 Error 42: Symbol Undefined _D5mydll12__ModuleInfoZ
--- errorlevel 1

work_build.bat runs:
dmd driver.d mydll.lib %cd%\include\mydll.di
and this succeeds.

So passing the .di file explicitly works, but via the import switch it does not.

Here's a non-DLL example which works fine when using header files and an import switch: http://dl.dropbox.com/u/9218759/importsWorkUsually.zip

So unless I'm missing something this looks like a linker bug?

On 3/12/2011 5:24 PM, Andrej Mitrovic wrote:
> driver.obj(driver)
>   Error 42: Symbol Undefined _D5mydll12__ModuleInfoZ
> --- errorlevel 1

Your dll is exporting a different symbol: _D5mydll3fooFiZi
Do you have the .def file and the command line used to build the DLL?

On 3/12/2011 9:15 PM, Bekenn wrote:
> On 3/12/2011 5:24 PM, Andrej Mitrovic wrote:
>> driver.obj(driver)
>> Error 42: Symbol Undefined _D5mydll12__ModuleInfoZ
>> --- errorlevel 1
>
> Your dll is exporting a different symbol: _D5mydll3fooFiZi
> Do you have the .def file and the command line used to build the DLL?
I believe _D5mydll12__ModuleInfoZ is supposed to be exported by the compiler.

It contains static constructor and unittest information used by the runtime to initialize it.

Actually passing that .di file compiles it in statically, and the exe ends up not needing the DLL.

It's a bit too late for me to thinker with the linker, I'll have a clearer head tomorrow.

My commands to compile were:
dmd -ofmydll.dll mydll.d
dmd -o- -Hdinclude mydll.d
dmd driver.d mydll.lib -I%cd%\include

On 3/12/2011 7:02 PM, Andrej Mitrovic wrote:
> My commands to compile were:
> dmd -ofmydll.dll mydll.d
> dmd -o- -Hdinclude mydll.d
> dmd driver.d mydll.lib -I%cd%\include

Thanks.

I've tried several things, but can't get the _D5mydll12__ModuleInfoZ symbol to show up at all.  The behavior is the same with and without a .def file (I tried a few versions).  I even went back to http://www.digitalmars.com/d/2.0/dll.html and copied everything
in the "D code calling D code in DLLs" section verbatim.  After fixing a few compilation errors (the web page's version of concat needs its arguments qualified with "in"), I ended up with the exact same problem you're experiencing.

I'd definitely call this a bug.

On 3/12/2011 11:39 PM, Bekenn wrote:
> On 3/12/2011 7:02 PM, Andrej Mitrovic wrote:
>> My commands to compile were:
>> dmd -ofmydll.dll mydll.d
>> dmd -o- -Hdinclude mydll.d
>> dmd driver.d mydll.lib -I%cd%\include
>
> Thanks.
>
> I've tried several things, but can't get the _D5mydll12__ModuleInfoZ
> symbol to show up at all. The behavior is the same with and without a
> .def file (I tried a few versions). I even went back to
> http://www.digitalmars.com/d/2.0/dll.html and copied everything
> in the "D code calling D code in DLLs" section verbatim. After fixing a
> few compilation errors (the web page's version of concat needs its
> arguments qualified with "in"), I ended up with the exact same problem
> you're experiencing.
>
> I'd definitely call this a bug.

Probably unrelated, but this same issue showed up in the GDC backend. Apparently, the compiler tried to be smart about exporting ModuleInfo only for those modules that needed it.  The fix was to always export it regardless.