Hojun-Cho d56b7ca946 w6c+wwstage: narrow int/rune array-literal elements to the declared type (#251)
`let a:[4]u8=[65,66,67,68]`, `def D:[4]u8=['A',..]`, and `enc{m=[65,..]}`
rejected with "init [4]i32 not assignable to declared [4]u8": an array
literal's element type came from the elements via type_default (int-lit
-> i32, rune-lit -> rune) with no declared-element-type propagation. The
scalar path already narrows (`let c:u8='A'`); only array aggregation at
the let/def/struct-field sites #130 (test 920) left unwired did not.

Fix = the int/rune analogue of coerce_floatlit, realised as the EXISTING
#130 accept-if-fits range-check — NOT a node-type restamp. cgen drives
the array element WIDTH from the declared type at every site (cgen.c
local-let lu->sub, emit_array_data d->type), so a restamp would be dead
code (the array literal keeps its [N]i32/[N]rune node type; the cs==ww
byte-id gate confirms the bytes emit u8-wide regardless). Per element:
foldable int/rune literal -> defcastfits range-check vs declared T
(in-range accept, out-of-range REJECT loud, rule-7); non-foldable ->
type_assignable / isassignable.

cstage (check.c): wire arrlit_init_fits into clet (local let),
struct-field-init, and def-init — the three sites the #130 module-let
path already covered.

wwstage (check.ww): factor checkletassign's inline #130 block into
checkarrlitfits and call it from the let path, the def path, and a
TARGETED array-field walk in the N_STRUCTLIT arm. This also closes a
pre-existing rule-7 wwstage over-accept: the def path ran NO init
assignability check and the N_STRUCTLIT head-stamp parks field
assignability (#23), so out-of-range / str array elements silently
over-accepted (a truncating miscompile) at those two sites. The
struct-field walk is the array-field accept-if-fits ONLY — it reuses the
stable N_TSTRUCT field-list walk (astoffset precedent), isolated from
the broader parked #23 field-assignability walk.

Regenerated w6c + wwdump combined.ww (embed check.ww). New test 951
covers let/def/struct-field x int/rune accept (run + cs==ww byte-id) and
out-of-range/str reject (both stages). test-unit 237 + smoke green.
2026-06-02 01:53:57 +09:00
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