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fix cyclic detection of partial strings in StackfulPreOrderHeapIter (#3050)

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This commit is contained in:
Mark Thom
2025-08-21 22:52:25 -07:00
parent c5389dbbf2
commit b2cfc8b6f2
2 changed files with 26 additions and 31 deletions
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41
src/heap_iter.rs
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@@ -445,24 +445,17 @@ impl<'a, ElideLists: ListElisionPolicy> StackfulPreOrderHeapIter<'a, ElideLists>
let cell = *cell;
let tail_idx = self.heap.scan_slice_to_str(vh).tail_idx;
// forward the current PStrLoc cell if the zero
// byte at the end of the string buffer
// is marked
let buf_bytes = self.heap[tail_idx - 1].into_bytes();
if self.heap[tail_idx - 1].get_mark_bit() {
self.read_cell_mut(h).set_forwarding_bit(true);
self.stack.push(h);
if buf_bytes[7] != 0u8 {
let cell = self.read_cell_mut(h);
cell.set_forwarding_bit(true);
continue;
} else {
self.heap[tail_idx - 1].set_mark_bit(true);
}
// now mark it as if were a HeapCellValue, even
// though it's not! this is fine as long as its tag
// is never inspected, which it isn't.
self.push_if_unmarked(
IterStackLoc::iterable_loc(tail_idx - 1, HeapOrStackTag::Heap),
);
self.stack.push(IterStackLoc::mark_loc(tail_idx, HeapOrStackTag::Heap));
self.stack.push(IterStackLoc::iterable_loc(tail_idx - 1, HeapOrStackTag::Heap));
self.stack.push(IterStackLoc::pending_mark_loc(tail_idx, HeapOrStackTag::Heap));
return Some(cell);
}
@@ -1959,10 +1952,6 @@ mod tests {
unmark_cell_bits!(iter.next().unwrap()),
pstr_loc_as_cell!(heap_index!(3) + 2)
);
assert_eq!(
unmark_cell_bits!(iter.next().unwrap()),
pstr_loc_as_cell!(heap_index!(3) + 2)
);
assert_eq!(iter.next(), None);
}
@@ -2177,8 +2166,14 @@ mod tests {
);
assert_eq!(iter.heap.slice_to_str(0, "a string".len()), "a string");
assert_eq!(iter.next().unwrap(), pstr_loc_as_cell!(0));
assert_eq!(iter.next().unwrap(), empty_list_as_cell!());
assert_eq!(
unmark_cell_bits!(iter.next().unwrap()),
pstr_loc_as_cell!(0)
);
assert_eq!(
unmark_cell_bits!(iter.next().unwrap()),
empty_list_as_cell!()
);
assert_eq!(iter.next(), None);
}
@@ -2554,10 +2549,6 @@ mod tests {
unmark_cell_bits!(iter.next().unwrap()),
pstr_loc_as_cell!(heap_index!(3) + 2)
);
assert_eq!(
unmark_cell_bits!(iter.next().unwrap()),
pstr_loc_as_cell!(heap_index!(3) + 2)
);
assert_eq!(
unmark_cell_bits!(iter.next().unwrap()),
pstr_loc_as_cell!(heap_index!(3))