The wcc test drivers ran `ww build <bare-/tmp src>` with no -o, so the
compiler's <stem>.sepwork scratch landed beside the source and was never
cleaned: unbounded /tmp growth (2195 stale dirs observed) that fills tmpfs
and fabricates phantom test failures + silent harness aborts, and for
in-repo fixture builds leaked .sepwork into the tracked tree.
Each leaking build now writes its source + output inside a per-invocation
tmpdir, passes -o <tmpdir>/<stem> so the .sepwork lands inside it, and
rm -rf's the tmpdir on every exit path -- including fopen-fail and the
expected-fail reject builds (scratch is mkdir'd before the build can fail).
`ww run` and explicit-`-o`/byte-id helpers are left as-is; the 990/993
byte-id comparison logic is byte-for-byte unchanged.
Two items filed separately (this commit holds the no-Makefile / no-main.c
rail):
- #13: a stale <src>.s byte-id readback (749) silently no-ops since
separate-compile emits .s to <ostem>.sepwork/__root.s; documented inline.
- #14: build-system Makefile recipes build selfhost/cmd/*/main.ww with no
-o and leak main.sepwork in-tree (bounded, gitignored; own commit).
One concern -- sepwork leak hygiene -- across 228 drivers; uniform
transform applied per-file and two-round reviewed. make test: all 402
passed, zero net-new /tmp scratch, zero test-driven in-repo .sepwork.
A bodied fn with a bare C-style `...` was silently accepted by cstage
and SEGFAULTED wwstage (resolvefnbody walked a typeless `...` param).
Gate it: bare C-`...` is allowed only on bodiless decls (extern /
@symbol prototypes), the real FFI path; Hare-style `T...` is unaffected.
ww restricts C-`...` to bodiless decls pending vastart/vaarg/vaend
builtins (#16); harec permits bodied C-variadic fns (check.c:3656) -- a
documented divergence, reopened when #16 lands.
Test 852 runs both stages; its reject rows require the gate's diagnostic
(not merely a nonzero exit), so a crash can't pass them vacuously.
