PEGO
A270: Shared Empty Capture Frame
A scope with no capture slots needs no fresh frame storage. One immutable empty frame can represent it.
Mechanism and Invariants
The frame is shared only for zero-slot scopes and is never written. Captured scopes keep their own slot arrays and rollback. Plain calls can leave a caller's frame current, while generic zero-slot invocations use the empty owner. Complete layout collectors must count required dead/nil slots before deciding a scope is empty.
Scope and State
Default capture-free scope representation in closure, both VMs, generated Go Node/typed Go and TypeScript.
Reference Control
No shared-empty-frame-only comparator is maintained. Plain-call or layout controls affect a larger route.
Evidence and Implementation
Record 001 lists the empty-frame mechanism among combined changes; 019 measures a broader capture-free call path. Neither provides a current isolated empty-frame effect.
Source owners: emptyFrame and
invokePlain, newFrame, generated empty frame,
Parser.newFrame.
The comparison policy distinguishes same-source controls, historical changes and full checkpoints.