I want to update a library with new symbols (ie partial recompilation):

libmylib.so : compiled from bar.d and foo.d

now update the file foo.d

dmd -c -fPIC foo.d -offoo.o

clang++ -o libmylib_update.so foo.o -shared -Wl,-lmylib

When trying to dlopen libmylib_update.so from C++ it fails with: The module 'foo' is already defined in 'libmylib.so'

(it somehow works when the dlopen is called from D)

How would I achieve that?

On Thursday, 1 December 2016 at 22:05:06 UTC, Timothee Cour wrote:
> I want to update a library with new symbols (ie partial recompilation):
>
> libmylib.so : compiled from bar.d and foo.d
>
> now update the file foo.d
>
> dmd -c -fPIC foo.d -offoo.o
>
> clang++ -o libmylib_update.so foo.o -shared -Wl,-lmylib
>
> When trying to dlopen libmylib_update.so from C++ it fails with: The module 'foo' is already defined in 'libmylib.so'
>
> (it somehow works when the dlopen is called from D)
>
> How would I achieve that?

Have a look at what `trace -E d_executable args` and `trace -E c++_executable args`
print on startup and grep for dlopen calls and the like.

> Have a look at what `trace -E d_executable args` and `trace -E c++_executable args`
> print on startup and grep for dlopen calls and the like.

do you mean strace?
I have trace on OSX but I'm asking for linux.

On Saturday, 10 December 2016 at 02:39:33 UTC, timotheecour wrote:
>> Have a look at what `trace -E d_executable args` and `trace -E c++_executable args`
>> print on startup and grep for dlopen calls and the like.
>
> do you mean strace?
> I have trace on OSX but I'm asking for linux.

Looking at the code for $checkModuleCollisions in druntime [src/rt/sections_elf_shared.d:859]:

```
 * Check for module collisions. A module in a shared library collides
 * with an existing module if it's ModuleInfo is interposed (search
 * symbol interposition) by another DSO.  Therefor two modules with the
 * same name do not collide if their DSOs are in separate symbol resolution
 * chains.
```

Not exactly sure what that means nor how to fix my issue:

```
void some_fun(){
  handle=dlopen2("path/liblib.so", RTLD_LAZY | RTLD_LOCAL);
  // error: The module 'foo' is already defined in 'libmylib.so'
}
```

How would I modify the code to avoid this?