Fragile ABI

[R Grocott]

On Friday, 17 August 2012 at 13:42:27 UTC, Michel Fortin wrote:
> It's certainly doable if you put it at the right place. But 
> druntime is not the one in charge of dynamic linking: the 
> dynamic linker from the OS is, so that's the ideal place to do 
> such a thing. If you want to do it in druntime it'll be a huge 
> hassle, if doable at all it'll probably break easily. But on 
> the OS side you hit a rock because of different approach to 
> dynamic linking (Windows does not really have a dynamic linker).

So basically, any system to create a more sensible ABI needs to 
built on top of the C ABI, name mangling, editable vtables, and 
nothing else? Ouch.

If druntime can't detect whether symbols were dynamically or 
statically linked, does that mean that your system would add an 
overhead to *all* virtual function calls, not just those which 
call into a dynamic library? If so, that'd be a pretty strong 
argument against implementing anything like it, unless it's 
something which has to be explicitly switched on (using, say, an 
"extern(D_FlexibleABI)" statement).