Migrating D front end to D - post Dconf

[Jonathan M Davis]

On Saturday, May 11, 2013 19:56:00 Walter Bright wrote:
> At least for dmd, we keep all the old binaries up and downloadable for that
> reason.

That helps considerably, though if the compiler is old enough, that won't work 
for Linux due to glibc changes and whatnot. I expect that my particular 
situation is quite abnormal, but I thought that it was worth raising the point 
that if you're compiler has to compile itself, then changes to the language 
(and anything else the compiler depends on) can be that much more costly, so 
it may be worth minimizing what the compiler depends on (as Daniel is 
suggesting).

As we increase our stability, the likelihood of problems will be less, but 
we'll probably never eliminate them. Haskell's case is as bad as it is because 
they released a new standard for it and did it in a way that it doesn't 
necessarily work to build the old one anymore (and if it does, it tends to be 
a pain). It would be akin to if dmd were building itself when we went from D1 
to D2, and the new compiler could only compile D1 when certain flags were used, 
and those flags were overly complicated to boot. So, it's much worse than 
simply going from one version of the compiler to the next.

- Jonathan M Davis