Making AssertError a singleton

[Jonathan M Davis via Digitalmars-d]

On Monday, 12 December 2016 at 15:51:07 UTC, Andrei Alexandrescu 
wrote:
> Here it is:
>
> https://github.com/dlang/druntime/pull/1710
>
> It relieves code that uses assert from needing the GC. I think 
> all Errors should be singletons - multiple objects in that 
> hierarchy arguably make no sense. But of course there are many 
> situations out there. If this breaks your code, please holler.

I don't know if that would actually work with polymorphic 
contracts in classes. It also could be problematic with unit 
tests - especially unit tests that catch AssertErrors (e.g. if 
someone wants to test the contracts).

I also fail to see how this fixes much of anything. If the issue 
is avoiding the GC, it doesn't matter if the program is being 
killed. If the issue is avoiding even linking in the GC, doesn't 
that mean that druntime isn't being used (in which case, doing 
this in druntime is pointless)? So, I don't see how such a change 
would matter for either scenario, and I don't know why else it 
would be of any value.

And if we fix it so that exceptions don't need the GC (which is 
arguably needed for @nogc to be widely used), then this whole 
problem goes away anyway. So, I'm inclined to argue that we just 
fix _that_ problem and not worry about the fact that assert 
currently triggers the GC on failure.

- Jonathan M Davis