The #258 borrow desugar lowers `let s: []T = arr` to a runtime
`arr[0:len]` (N_SLICE over the array base) so the slice header is built
at run time. That is only meaningful for a LOCAL let — a fn body
executes the borrow. A module-level let is static data with no runtime
to run the borrow; its rhs must stay the raw N_ARRLIT so cgen can
materialize it as DATA.
cstage splits this by checker: clet (the desugar site, check.c:1993)
runs only from cstmt (local statements); module-level lets are checked
in check_file pass-2 (check.c:2549) which never desugars. wwstage runs
ONE checkletassign for both — function-body lets via resolvewalk's
post-order walk (a block scope is pushed, c.cur != c.top) and top-level
lets via checkfile pass-2 (no scope pushed, c.cur == c.top). Mirror
cstage's split by gating the desugar call on `c.cur != c.top` (the same
module-scope test as check.ww:184). The #130 module-level assignability
check in checkletassign is untouched.
Without this, a module-level `let g: []u8 = [1u8,2u8,3u8]` reached cgen
as N_SLICE in wwstage but N_ARRLIT in cstage — the cs!=ww shape that
blocked #10 part-a's wwstage data-emission. Locals stay byte-identical
(named-array->slice still works, exit 8 both stages); selfhost combined
.ww regenerated.
Hojun-Cho
ad00114c7f