Assertion failed in insert_copy_and_fix_length

[sarranz]

This program

export fn fail() -> reg u64
{
  stack u64[1] a b;
  a[0] = 1;
  b[0:1] = #copy(a);
  reg u64 r;
  r = b[0];
  return r;
}

gives

Fatal error: exception File "src/insert_copy_and_fix_length.ml", line 75, characters 86-92: Assertion failed

[eponier]

Other issues with #copy:

• we cannot use subarrays in general (#copy(a[0:1]) does not assert false, but fail nonetheless)
• we cannot choose between for and while loops (is this a real problem?)