Hello,

I've created a simple db dynamic lib project.

dub.json:

{
	"name": "node-d-sample",
	"description": "A minimal D application.",
	"copyright": "Copyright © 2014, gabor",
	"authors": ["gabor"],
	"dependencies": {
	},
	"libs": [ "phobos2" ],
	"targetName": "node-d-sample",
	"targetPath": "lib",
	"targetType": "dynamicLibrary"
}

I have only one source, lib.d:

extern (C)
{
	int ping()
	{
		return 555;
	}
}

My system is a Mint x64, dub latest, dmd latest.

If I invoke "dub", then:

Building node-d-sample ~master configuration "library", build type debug.
Compiling using dmd...
Linking...
/usr/bin/ld: .dub/build/library-debug-linux.posix-x86_64-dmd_2066-44F775BF77E519551012EFF79429BBA3/node-d-sample.o: relocation R_X86_64_32 against `.rodata' can not be used when making a shared object; recompile with -fPIC
.dub/build/library-debug-linux.posix-x86_64-dmd_2066-44F775BF77E519551012EFF79429BBA3/node-d-sample.o: error adding symbols: Bad value
collect2: error: ld returned 1 exit status
--- errorlevel 1
FAIL .dub/build/library-debug-linux.posix-x86_64-dmd_2066-44F775BF77E519551012EFF79429BBA3/ node-d-sample dynamicLibrary
Error executing command run: dmd failed with exit code 1.

You need to add `-fPIC` to your compiler flags. In dub.json:

    ...,
    "dflags": ["-fPIC"]

On 12/14/2014 03:50 PM, Gabor Mezo wrote:
> Hello,
>
> I've created a simple db dynamic lib project.

https://github.com/D-Programming-Language/dub/issues/352

On Sunday, 14 December 2014 at 16:06:25 UTC, Martin Nowak wrote:
> On 12/14/2014 03:50 PM, Gabor Mezo wrote:
>> Hello,
>>
>> I've created a simple db dynamic lib project.
>
> https://github.com/D-Programming-Language/dub/issues/352

Thanks,

I've did this, it finally build, but something is still not good.

If I call externals from another application, and my D code allocates anything on heap, the calling process crashes with SIGSEV. I mean it works:

extern (C)
{
	int ping()
	{
		return 555;
	}
}

But it doesn't:

extern (C)
{
	int ping()
	{
                try { throw new Exception("foo"); } catch (Exception ex) { }
		return 555;
	}
}

or this one crashes too:

extern (C)
{
	int ping()
	{
                auto foo = new Object();
		return 555;
	}
}

I've opened an other thread instead, because this is a different
issue. It's there:

http://forum.dlang.org/thread/aycvoeaurrpmuehatdwp@forum.dlang.org#post-aycvoeaurrpmuehatdwp:40forum.dlang.org

On Sun, 14 Dec 2014 16:24:13 +0000
Gabor Mezo via Digitalmars-d <digitalmars-d@puremagic.com> wrote:

> On Sunday, 14 December 2014 at 16:06:25 UTC, Martin Nowak wrote:
> > On 12/14/2014 03:50 PM, Gabor Mezo wrote:
> >> Hello,
> >>
> >> I've created a simple db dynamic lib project.
> >
> > https://github.com/D-Programming-Language/dub/issues/352
> 
> Thanks,
> 
> I've did this, it finally build, but something is still not good.
> 
> If I call externals from another application, and my D code allocates anything on heap, the calling process crashes with SIGSEV.
did you called `rt_init()` for your dynamic library? you have to do
that in the calling process. and don't forget to call `rt_term()` on
exiting.

Thank you for your quick help, that was it.

I do (or at least I'm trying to do) hobbyist D programming as you guys, that's why I come here to cry at Sunday evening. :)

Ok, I'm almost there. It builds with DUB/DMD, I can allocate stuff on the heap, so far so good. But if I invoke:

dub --compiler=gdc

then I got:

Performing main compilation...
dub build "node-d-sample" --arch=x86_64 --compiler=gdc "--build=release"
Building package node-d-sample in /home/gabor/sandbox/node-d-sample/
Building node-d-sample ~master configuration "library", build type release.
Running gdc...
/usr/bin/ld: /usr/lib/gcc/x86_64-linux-gnu/4.9/libgphobos2.a(minfo.o): relocation R_X86_64_32 against `_D32TypeInfo_APxS6object10ModuleInfo6__initZ' can not be used when making a shared object; recompile with -fPIC
/usr/lib/gcc/x86_64-linux-gnu/4.9/libgphobos2.a: error adding symbols: Bad value
collect2: error: ld returned 1 exit status
FAIL .dub/build/library-release-linux.posix-x86_64-gdc_2065-33A38D9D3DC714C1501A18C957A2B35B/ node-d-sample dynamicLibrary
Error executing command build: gdc failed with exit code 1.

Exit code 2
Build complete -- 1 error, 0 warnings

or:

dub --compiler=ldmd2

then I got:

Performing main compilation...
dub build "node-d-sample" --arch=x86_64 --compiler=ldmd2 "--build=release"
The determined compiler type "ldc" doesn't match the expected type "dmd". This will probably result in build errors.
Building package node-d-sample in /home/gabor/sandbox/node-d-sample/
Building node-d-sample ~master configuration "library", build type release.
Running ldmd2...
/usr/bin/ld: /home/gabor/dev/ldc2-0.15.0-beta1-linux-x86_64/bin/../lib/libdruntime-ldc.a(eh.o): relocation R_X86_64_32 against `.rodata..str1' can not be used when making a shared object; recompile with -fPIC
/home/gabor/dev/ldc2-0.15.0-beta1-linux-x86_64/bin/../lib/libdruntime-ldc.a: error adding symbols: Bad value
collect2: error: ld returned 1 exit status
Error: /usr/bin/gcc failed with status: 1
FAIL .dub/build/library-release-linux.posix-x86_64-ldc_2066-212B345732639D80C27025028ED586A2/ node-d-sample dynamicLibrary
Error executing command build: ldmd2 failed with exit code 1.

Exit code 2
Build complete -- 1 error, 0 warnings

It seems DUB somehow eats dflags away for non DMD compilers. How the hell should I prevent this happen? Thanks.

On Sun, 14 Dec 2014 16:57:20 +0000
Gabor Mezo via Digitalmars-d <digitalmars-d@puremagic.com> wrote:

> Thank you for your quick help, that was it.
> 
> I do (or at least I'm trying to do) hobbyist D programming as you guys, that's why I come here to cry at Sunday evening. :)
ah, that's ok. but you'd better ask your questions in D.learning. not 'cause you're a beginner, but just 'cause D.learning has invalid name. it should be D.questions.

besides, when people see the question in "general", they tend to give shorter and less detailed answers than in "learning".

sorry for the noise, as i can't tell you anything about DUB.

Actually I'm practicing D for about three months but this C interfacing mumbo jumbo is still missing for me. Ok, I'm go there if I'm stuck, thanks.

On Sunday, 14 December 2014 at 16:57:24 UTC, Gabor Mezo wrote:
> /home/gabor/dev/ldc2-0.15.0-beta1-linux-x86_64/bin/../lib/libdruntime-ldc.a(eh.o): relocation R_X86_64_32 against `.rodata..str1' can not be used when making a shared object; recompile with -fPIC

Hm, the problem here is that LDC uses a static runtime build, while dynamic libraries require Phobos and druntime to be built as shared libraries. The latter has actually been supported since quite a few months now, but IIRC still isn't shipped as part of the binary packages: https://github.com/ldc-developers/ldc/issues/807

If you want to give it a try, you can quickly build LDC from source (http://wiki.dlang.org/Building_LDC_from_source) and pass the -DBUILD_SHARED_LIBS=ON flag to CMake. Building shared libraries should then succeed.

David