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.
An error-first tagged union -- error variant at tag 0, success at tag 1+,
e.g. (myerr | u16) -- was silently miscompiled by wwstage: the try/propagate
codegen hardcoded success = tag 0, so the actual success value (tag 1)
failed the CMPQ $0 and fell to the error path -> exit(1) instead of the
value (44). cstage was correct (computes the success tag via
cg_tagged_success_tag = first non-error variant).
wwstage-only: a successtag/successvariant helper (mirroring cstage) replaces
the hardcoded tag-0 / first-param assumption at all four try sites --
cgtryprop (?), cgtryunw (!), and the two latent shift sites cgtrytupleshift
+ cgtrytaggedshift (which bite an error-first union with an aggregate
success payload). Success-first unions (the Hare idiom + what the selfhost
uses) keep successtag=0 -> CMPQ $0 unchanged -> byte-id-neutral on 990-997.
cstage untouched (w6c md5 unchanged).
byte-id 990-997 8/8. test/wcc/825 table-driven (errfirst must/prop +
tuple-success + success-first control). A separate nested-tagged-union
construction divergence is filed (#10/#125).
