Cstage's cmd/w6c/cgen.c:6363-6411 special-cases `let s: []T =
alloc([], n)!;` to inline rt_alloc + null-check + exit(1) + slice
header build, avoiding a generic call-then-store path. Wwstage's
cglet had no mirror — pre-#31 the path was rejected at check, but
once #31 made the check side accept it, the cgen side would have
silently miscompiled. Mirror added at cgenstmt.ww cglet rhs head,
emitting byte-identical asm.
Element size goes through elemsizeofc so str (16), structs, and
tagged aliases all match cstage's lu->sub->size uniformly — the
defensive path matters because check today only allows []u8, but
relaxing that is its own task.
Test exercises the path: writes to s[0] and s[15], reads back. Would
SIGSEGV on a junk header. 994 + 995 byte-identity green.
Hojun-Cho
30a0856fe5