Drop the `!TY_ARRAY` exclusion in the bare-let no-rhs zero-fill (cgen.c
N_LET else + cgenstmt.ww cglet, both gated `sz>8 && !TY_ARRAY`) so an
uninit `[N]T` array local zero-fills like every other composite (Go-zero
per user ruling). The zero-fill extent is the array's chased ABI size
(lu->size / chased tinfo.size, rule-13 — never a hardcoded count*esz),
NOT the slot-padded letslotsize, so a non-8-multiple array ([20]u8 = 20)
zeroes its exact bytes instead of over-zeroing to the 24B slot. The
unrolled MOVQ/MOVL/MOVB run mirrors the existing composite path; the
largest real local array ([256]u8) is 32 MOVQs (pathbuf[4096] is a
module GLOBAL, BSS-filled — never on this stack path, so no large-fill
case exists).
Closes a gate-blind #263-class bug: `let a: [3]int;` (no init) read
whatever the stack held — a clean frame masked it (fresh stack = 0), a
dirtied frame exposed it (d_array=165 garbage). BOTH stages emitted no
fill, both-wrong-IDENTICAL, so the cs==ww byte-id net could not see it.
The load-bearing net is therefore a RUNTIME dirtied-stack zero-read
(944_array_zeroinit_run: array-elem / narrow [4]u32 / non-8-mult [20]u8
/ 2D + an initialized control), not asm presence.
Deliberate byte-id EVENT: every uninit-array source site gains zero-fill
insns, so the 990-997 .s MOVE vs the prior tree; cs==ww HOLDS (both add
the identical insns). The 990-997 byte-id + 995 self-rebuild staying
GREEN is the fixpoint proof — it proves every uninit compiler-array is
write-before-read, so the zero-fill is purely additive and the
ww1->ww2->ww3 self-rebuild fixpoint holds by construction. w6c/wwdump
main.combined.ww regenerated (cgenstmt.ww embeds there).
#84 is ARRAY-ONLY; the no-default reject-set (uninit tagged / plain-*T)
is split to #113, parked behind a ruling — selfhost relies on the
current (void|T) zero-fill (the "not-set-yet" idiom).
Hojun-Cho
00d9580c9f