Can't return from inside a block

[pcwalton]

iterFunc({|| ret; }) does not return from the outer function.

Maybe we'll just have accept this, since in the absence of non-local control flow, there's no nice way to implement such returns.

[brson]

This translates now, but incorrectly, acting like a continue statement.

[catamorphism]

Here's a code example that reproduces it:

use std;
import std::uint;

fn foo() {
  for each (uint i in uint::range(0u, 10u)) { 
    if (i > 5u) {
      ret;
    }
  }
  fail "Shouldn't have reached this point";
}

fn main() {
  foo();
  log_err "Okay!";
}

The problem is that the ret inside the for-each loop is returning from the closure that trans generates automatically for the loop body, not from foo. That's why it acts like a continue.

I was going to try fixing this, but it's not obvious to me how to (there's no other case when you're returning from more than one nested scope at once), so I'm changing it back to unassigned.

[marijnh]

Iterators are out. Rewording the bug title to apply to blocks.

[graydon]

Duplicated (in much more detail) by #1619, closing.