Wwstage's slotsize had a catch-all `return 8` for any N_TNAME where
primsize's `> 0` guard failed. `primsize("void") == 0` (correct —
void is zero-sized per cmd/wcc/type.c:46), so void landed on the
catch-all. (void | !void) then sized as `8 (tag) + max(8, 8) = 16`
instead of `8 + 0 = 8`, and the phantom payload word made
cgwidentaggedstore spill DX for the let-init — diverging from
cstage's `8`-byte slot.
Two narrow additions per rule 10 (align wwstage DOWN to cstage):
1. N_TBANG case at the top of slotsize, recurse on .lhs. Mirrors
cstage resolve_type N_TBANG which copies the underlying type's
size unchanged.
2. `void => 0` in N_TNAME BEFORE the primsize guard, so the SSoT
matches cmd/wcc/type.c:46.
757_letbind_void_bang_void exercises three shapes — void-arm,
invalid-arm, full natural-form fromutf8 — and pins cstage/wwstage
asm byte-identity per row.
lib/strings/strings.ww fromutf8 WHY-comment drops the Bug-B
SIGSEGV caveat (measurement artifact: original test linked without
rt/start.s; RET popped argc). Keeps #19 dependency for the
eventual collapse to `utf8.validate(in)?`.
Hare matches ww's design (void zero-sized, !T inherits T's
layout); this is a pure wwstage implementation gap, not a
divergence to argue about.
Hojun-Cho
f8770d1502