The N_TUPLE expr arm built its TY_TUPLE with size 0 (only the
annotated N_TTUPLE resolve_type route computed the layout), and
type_default passes TY_TUPLE through, so an inferred
`let t = (4: size, 2: size)` planted a 0-size local at offset 0 —
the element stores landed on the saved BP/RIP and main segfaulted
on RET (cstage; the arg shape instead fell to the global-symbol
path and link-failed). wwstage (exprtype N_TUPLE -> tinfofornode)
was runtime-correct throughout — cstage aligns UP to it; all
fixed shapes are now byte-id. Slot rule mirrors the N_TTUPLE twin
and cgen tuple_eslot, with untyped elements sized at their
type_default (element types stay untyped for the consumer-side
assignability contract).
7 table rows in 941 pin the class (cast/bare/mixed/float elems,
destructure-from-local, call-arg, nested); each fails at master
e8977a4 cstage (segfault or link-fail + byte-id NO).
Hojun-Cho
24e02b259c