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.
Widening a runtime f64 into a tagged slot pushed a stale AX as the
payload while the value sat in X0 — both stages shared the push bug
(float literals dodged it because TK_FLOAT loads AX too); the
divergent pop sides then produced different garbage. Spill the
payload from X0 (MOVSD) with the variant tag. Review item #49.
Both stages move in one commit: one emission contract; splitting
would leave the byte-id gates red between the halves.
The arg-drain loop checked node_isfloat before popping a widened
arg's GP words, so a float arg adjacent to a widened (tagged) arg
read the wrong stack slot: the f64 took the widened payload (#30), or
the float arm ate the tag word into X0 and the payload landed in DI
as the tag (#48). One missing branch, two manifestations — mirror
cstage's widen-first pop (cgen.c:9650-9665). Review items #30+#48
(fold reviewer-verified one-mechanism against the cstage twin).
