RFC: Value range propagation for if-else

[bearophile via Digitalmars-d]

Lionello Lunesu:

>> ubyte foo(immutable int x)
>> in {
>>     assert(x >= 0 && x <= ubyte.max);
>> } body {
>>     return x;
>> }
>
> Yeah, I wanted to support "assert" as well, but it doesn't 
> create a scope so it'll be a bit trickier to implement.

If you have an assert in a pre-condition and the argument is 
const, then the body{} is the scope you look for.

Bye,
bearophile