Linking with a non-default druntime

[Basile B.]

On Sunday, 30 September 2018 at 19:03:17 UTC, Per Nordlöw wrote:
> How can I link my dmd-compiled program with a specific version 
> of the druntime?

druntime is within libphobos. So you must change this.

>
> I need this when experimenting with a new GC.

Did you try what i proposed earlier ? Until the handlers are 
plugged there can be a fallback to the manual allocs.

For example you start with the manual implementation and add 
handlers + fallback for every functions, like here for malloc

```
     __gshared void* function(size_t, uint, const TypeInfo) 
nothrow mallocHandler;
     void* malloc(size_t size, uint bits, const TypeInfo ti) 
nothrow
     {
         if (mallocHandler) // experimental stuff
         {
             return mallocHandler(size, bits, ti);
         }
         else // fallback until handler is assigned
         {
             void* p = cstdlib.malloc(size);
             if (size && p is null)
                 onOutOfMemoryError();
             return p;
         }
     }
```

this way you can very easily change-compile-test, without 
recompiling the whole runtime and phobos each time.