Remove block argument from loop

[asterite]

Introducing a block argument here was a mistake. Some people now want the loop index to be a different value. But the worse thing is that the loop index can silently overflow. And if we ever change the language to raise on overflow, this could eventually break some long running programs like servers (and that wouldn't be nice).

loop is intended to be a cute syntax sugar for while true while also allowing you to keep the variable inside the loop local to the block.

Closes #5975

[straight-shoota]

Wow, the counter var was never actually used in the compiler and stdlib?

[RX14]

@straight-shoota i didn't even realise loop do had an index lol

[Willamin]

In the event anyone wants this feature back, I've put together a shard to replace this functionality. When the compiler eventually raises an exception on integer overflows, I'll patch my shard to handle that accordingly.

Sidenote: the ability for me to bring a small feature like this back is one of my favorite features of Crystal! 😄

[straight-shoota]

@Willamin I don't think this is helpful. That behaviour was removed for a reason. If you want to use a short cut to have looping block with an incrementing counter, it should have a different name at least.
And it hardly makes any sense to require a shard for such a simple six line method.

I'll patch my shard to handle that accordingly.

What would that be? If there was a way to deal with that which would work for every use case, it could've stayed in the stdlib implementation.

[RX14]

When the compiler eventually raises an exception on integer overflows, I'll patch my shard to handle that accordingly.

and do what? reset back to 0? That's even worse than raising!