cg_dotbase_addr / dotbaseaddr rejected a non-ident inner, so a chained
base (`o.p.m[i]` / `o.i.m[i]` / `o.a.b.m[i]`) fell to cgexpr(base) which
auto-derefs the array field's first 8 bytes AS a pointer -> garbage base
-> segfault (base64 fillobuf `s.enc.encmap[...]` blocker). Extend the one
helper per stage to accept a chained inner: a new cg_dotchain_addr /
dotchainaddr recovers the container base via the dot-chain spine (recurse
to &x, deref when x is a *struct, sum field offsets), keeping the same
no-AX/no-stack spill contract. dotbaseaddr then takes the pointer VALUE of
inner when viaptr, else its ADDRESS, and adds the field offset. One fix
closes every op (index r/w, addr-of, slice, compound) since all route
through the helper. Symmetric cs==ww byte-id.
test/949: +22 rows. Chained-PTR (rd/wr/addr/slice x2/compound), deeper
(value+ptr leaf links, triple-pointer exercising the internal deref),
non-u8 esz stride (i32 addr+slice), and single-level controls — all
byte-id. The chained VALUE-container arm (`o.i.m`) is run-only (byteid=0):
it needs a value nested-struct instance, which trips THREE orthogonal
pre-existing cs!=ww emission divergences (bare-let zero-init policy,
global DATAW byte count, i32 element-load opcode in the index fallback)
unrelated to #253. Run correctness proves the segfault is gone for that
cell; byte-id there awaits the separate wwstage value-nested-struct fix.
Hojun-Cho
585ec50676