Stefan Koch:
The problem with vrp for non-static immutable values is, that vrp becomes a runtime-thing and I would like to avoid that! Tracking the range of a Variable at runtime could cause significant overhead!
Nope, the value range tracking is purely compile-time.
2. implementation is not straight-forward and bugs could be hard to find.
It's much better to remove bugs from the compiler than from an unbound amount of user code that uses casts incorrectly.
3. Code that relays on this may not be easy to read,
I don't believe this. Please show one or more examples.
and it may be hard for the programmer to see why a particular assignment does not need a cast!
And this is bad because?
But if we have much logic and control-flow between the assignment and the definition of the assigning variable then not haveing an explicit cast could cause a bit of puzzlement.
I think most D programmers are used to C/C++ coding, that doesn't require most of those casts. I don't think that "puzzlement" is real, or problematic.
Bye, bearophile
