Feature request: more stable looping control flow

[ssyram]

Eurydice requires looping pattern matching to resugar the loops, e.g.,

let iter = ...::into_iter(&sth);
while true {
  let x = ...::next(&iter);
  match x {
    None -> break;
    Some ? -> ?
  }
}
?rest

However, there are cases when the ?rest things are put directly into the None case, this is correct wrt the control-flow, but it will escape from the resugaring patterns. Would it be possible to avoid such cases and have some more stable looping control flow?

[Nadrieril]

That's definitely something we'd like to fix. Do you happen to have small examples that give bad control-flow today?

[ssyram]

Some internal codes caused this, I tried just now, but could not re-produce an easy example... It would be great if there is some theoretical guarantee on this?