emitObjcDefinedPropertySetter now dispatches on objcPropertyKind to
emit the right runtime ops per Apple's ARC contract:
- assign → bare store (primitives, explicitly opted-out object slots).
- strong → load old; objc_retain(new); store new; objc_release(old).
Apple's runtime treats release(NULL) as a safe no-op, so
no explicit null-check on the old value.
- weak → objc_storeWeak(field_addr, val) — handles first-store
(init) and re-store (destroy + init) atomically. Registers
the slot with libobjc's side-table; the runtime auto-nils
it when the target deallocates.
- copy → [val copy] (sends `copy` selector — returns retained per
the NSCopying contract); load old; store the copied
instance; release old.
Side-effect on the weak path: even with the bare-load getter still in
place (loaded directly from the slot), weak reads work because Apple's
runtime side-table-nils the slot at target dealloc. The getter
improvement via objc_loadWeakRetained is the next commit and is
needed for race-safe reads (between load and use, the target could
deinit on another thread); for the single-threaded test scenarios
the bare load is sufficient.
ffi-objc-arc-02-strong-property advances from "child dealloc'd at
midpoint" to "unbalanced; alloc=2 dealloc=1" — strong setter now
retains, but the M4.B-dealloc cleanup hasn't landed so the child
held by the property isn't released when the parent deallocates.
Final commit (M4.B dealloc) closes the loop.
ffi-objc-arc-03-weak-property turns fully green: storeWeak +
auto-nil side-table do the work.
189/189 example tests pass; chess on iOS-sim green.
f4faef97dd