Improving std.regex(p)

[Don]

bearophile wrote:
> Lars T. Kyllingstad:
>> Does anyone know what the current limitations on CTFE are?
> 
> One less if this works and gets accepted:
> http://d.puremagic.com/issues/show_bug.cgi?id=3050
> 
> Bye,
> bearophile

It's a great piece of work, but the rest of the CTFE mechanics are not 
ready for that patch.
The one which is blocking everything in CTFE is bug 1330. At present, 
CTFE uses copy-on-write, and that doesn't work with reference types.
Fixing that is going to require large changes throughout the compiler, 
so I've been holding off on that one. Meanwhile I've been trying to fix 
all the non-reference bugs in CTFE and assembling a comprehensive test 
suite.

So to answer the original question -- the main things that don't work in 
CTFE that are allowable in safe D are classes, exceptions, and built-in 
features which are implemented in the runtime rather than in the 
compiler (including array operations).