pub fn shape_transition(from: ShapeId, property_hash: u32) -> Option<ShapeId>Expand description
Transition a shape by adding a new property.
Consults the ambient shape table. Returns None if no scope is active,
if the dictionary-mode threshold (>64 properties) would be exceeded, or
if from is not present in the active table (e.g. a stale shape_id
carried over from a different ambient handle — a HashMapData built
under the process-default handle and later mutated inside a per-VM
scope). When a transition is recorded, it is also appended to the
ambient table’s transition log for JIT shape-guard invalidation.