tail call causes memory leak in certain circumstances

[ghost]

The following code

use std;
import std._vec;

fn inner(vec[int] dummy, int t) -> int {
  if (t > 0) {
    be inner(dummy, t - 1);
  }
  else {
    ret 0;
  }
}

fn main() {
  inner(vec(1), 1);
}

gives
rt: fatal, 'leaked memory in rust main loop (1 objects)' failed, rt/memory_region.cpp:99 1 objects
Without the 'dummy' vector it is OK, i.e.
fn inner(int t) -> int {
if (t > 0) {
be inner(t - 1);
}
else {
ret 0;
}
}

fn main() {
  inner(1);
}

[graydon]

Ah, it's leaking the argument slots to the slot the tail-call is originating from. Nice minimal case, thanks!

Found the problem, adding further-reduced test plus fix shortly.

[graydon]

Er, the function the tail-call is originating from. Sigh, mondays.

[graydon]

Fix leaking arg slots on tail calls. Closed by bc646d0.