Currently (on OSX) I can runtime load a D dll from a C program, but not from a D program, which seems silly.

Is it possible to runtime load a D shared library as a standalone (ie without sharing GC, runtime or any other data), treating it as if we were loading from a C program (making no attempt at sharing druntime or otherwise).

What do I need to change in druntime to make this possible?

Try compiling your library with -defaultlib= (leaving it blank after the equal sign). Then it might work by not loading the symbols for phobos etc twice - they will only be linked into the main program.

On Wed, Feb 26, 2014 at 1:20 PM, Adam D. Ruppe <destructionator@gmail.com>wrote:

> Try compiling your library with -defaultlib= (leaving it blank after the equal sign). Then it might work by not loading the symbols for phobos etc twice - they will only be linked into the main program.
>

Thanks, but I don't see how that would help treating the D dll as a standalone library with its own GC/druntime etc. Once again, I'm doing runtime loading (via dlopen+friends) not load-time linking (via -L-lfoo compile flags).

Furthermore, the following:
dmd -oflibfoo.dylib -shared -defaultlib= foo.d
results in link errors (because of '-defaultlib= ')

and I also tried:
dmd -offoo.o -c foo.d
gcc foo.o -shared -o libfoo.dylib -Wl,-flat_namespace -Wl,-undefined
-Wl,suppress

followed by runtime loading it in a D program (via dlopen) but not
surprisingly this crashes.

On 02/26/2014 10:16 PM, Timothee Cour wrote:
> Currently (on OSX) I can runtime load a D dll from a C program, but not
> from a D program, which seems silly.
>
> Is it possible to runtime load a D shared library as a standalone (ie
> without sharing GC, runtime or any other data), treating it as if we
> were loading from a C program (making no attempt at sharing druntime or
> otherwise).
>
> What do I need to change in druntime to make this possible?
>
Depends on why it doesn't work.

On Fri, Feb 28, 2014 at 10:27 AM, Martin Nowak <code@dawg.eu> wrote:

> On 02/26/2014 10:16 PM, Timothee Cour wrote:
>
>> Currently (on OSX) I can runtime load a D dll from a C program, but not from a D program, which seems silly.
>>
>> Is it possible to runtime load a D shared library as a standalone (ie without sharing GC, runtime or any other data), treating it as if we were loading from a C program (making no attempt at sharing druntime or otherwise).
>>
>> What do I need to change in druntime to make this possible?
>>
>>  Depends on why it doesn't work.
>


Here's an example.
If it works from inside C++ there should be a way to make it work from
inside D isn't there?  (eg by isolating the GC of the shared library from
the GC of the main program, etc).

main.d:
call a D shared library via dlopen/dlsym
foo.d:
extern(C) void foo(){
  printf("inside_foo\n"); //ok
  import core.runtime;
  bool ret=Runtime.initialize();//will segfault below with or without that
  assert(ret);//ok
  int[]a;
  a.length=2;//segfault
}


dmd -g -oflibfoo.dylib -shared foo.d
dmd -g -oftest main.d
./test
#Loading shared libraries isn't yet supported on OSX.
#inside_foo
#segfault at first occurence of gc (a.length=2 above)

under lldb:

* thread #1: test D2rt12sections_osx9tlsOffsetFPvZm + 109, stop reason =
EXC_BAD_ACCESS (code=EXC_I386_GPFLT)
    frame #0: test D2rt12sections_osx9tlsOffsetFPvZm + 109
    frame #1:  test __tls_get_addr + 20
    frame #2:  libfoo.dylib _d_arraysetlengthT + 3701
 ...

Filed as https://issues.dlang.org/show_bug.cgi?id=12792.