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 bare 'let x: T;' with 1 <= size(T) <= 7 matched no zero-fill arm in
either stage (8B and >8B were already zeroed) - 'let c: [3]u8;' read
stack garbage. User-ruled zero-value semantics: cstage gate sz>8 ->
sz>0; wwstage zsz==8 arm hoisted above the fill-run arm (required -
8B would otherwise route into the run and diverge) and run gate
zsz>0. New 840 pin: dirty-frame probe rows, dual-dim (run + cs/ww
byte-id); discriminators fail exit-154 on pre-fix binaries.
Fused with the lib/bytes test conversion (rule 11): either half alone
turns 967 red. The old exit(signalled+10) wrapped a real 1782-count
ltrim failure to exit 0 - green depended on the garbage. Converted to
assert form (completes the 35/35 @test conversion); ltrim rows keep
the bare 'let c: [3]u8;' as the consumer proof of the fix.
