vec::init and tail should return slices

[brson]

Right now they return a new vector.

[ghost]

Can you say a bit more about this? I see from the code they return the result of calling the slice function but that does indeed appear to copy the vector. Do you mean that they should return a view?

[brson]

The word 'slice' here is overloaded. &[T] is a 'slice' and the slice function is old and, imo, incorrectly returns new vectors instead of slices.

To be fair though, some people have advocated using 'view' to mean &[T] and leaving slice as is. I think that is a minority opinion though. In either case, I think init and tail should return &[T].

[sanxiyn]

Did #5213 fix this?

[erickt]

@sanxiyn: Yep! Closing...