A rejected program emits no .s, so the test-lang-byteid (T2) gate cannot
cover wwstage-reject -- yet the retired C twins asserted that BOTH stages
reject with the same diagnostic. runww's //ww:error arm was cstage-only,
so migrating reject rows onto it would silently drop the wwstage-reject
coverage the C twins carried.
Run w6c_ww (wwstage) alongside w6c (cstage) on each //ww:error case and
require both to fail with the shared diagnostic body present. The body is
identical across stages; only cstage's leading prefix differs, so the
substring matches the body alone (no file:line). An ERROR row now reports
PASS dual / FAIL cstage / FAIL wwstage. w6c_ww resolves off the same $BIN
as the C twins -- no new harness threading.
Two pilot reject cases (runww_dup_main_reject, runww_dup_type_reject)
exercise the dual-stage path; the wwstage leg is proven non-vacuous (a
cstage-rejects/wwstage-accepts case reports FAIL wwstage).
Prerequisite for migrating fold-3 reject rows onto runww.
Hojun-Cho
d48b53d04d