Repairing BigInt const

[Don]

Matthias Walter wrote:
> Hi all,
> 
> as it seems, the current version of BigInt is not capable of const, i.e.
> BigInt(1) + const(BigInt)(1) does not work.
> 
> Is there already an effort to fix this or would it make sense if I had
> taken some time to create a fix for it? I have no idea of all the asm in
> the x86 specialization but as const is an interface thing, I should be
> able to figure out everything without that knowledge. Or are there
> general design problems, such that this would be a waste of time?
> 
> Matthias

It's been prevented by some compiler bugs. The changes to pure in 2.050 
were triggered by attempts to make BigInt pure. 2.051 will include 
several fixes to nothrow.

Note that const is transitive (unlike C++), so it isn't just an 
interface thing.