Hojun-Cho
64f0ddf01b
A primary-package top-level decl whose leaf also names a bundled module (`type sym` vs `import sym`; the lib/test->fnmatch->ascii -T floor's `ascii` module vs a `@test fn ascii`) collided in the flat scope: #23's installtop dup-check false-fired "duplicate fn/type" where cstage coexists. cstage keys the module name out of the value namespace by PROMOTING the same-leaf SK_USE in place to the value kind with use_alias=1 (cmd/wcc/check.c:2831/2848/2871/2907/2928/2951), so one correctly-kinded sym serves bare refs (call/structlit/var) while `name.member` still resolves the module via the `kind==SK_USE || use_alias` N_DOT guards (check.c:87/1337). This REVERSES wwstage's documented two-sym coexistence design (lib/ww/sym.ww scopelookupuselocal): keeping the SK_USE as a separate coexisting sym ripples into every bare-reference resolver (~25 scopelookup sites), and a missed site is a byte-id-consistent-but-wrong cat-A risk the gate cannot prove away — the same failure mode retired with the name-keyed variant-match cluster. The promote model is correct by construction: one sym of the right kind, identical to cstage. sym gains a use_alias field; the three N_DOT/N_CALL module-qualified guards honor use_alias. cstage installs every SK_USE in a dedicated first pass, so its value-arm promote is order-INDEPENDENT; wwstage installs in source order, so BOTH directions of the collision are promoted to reach cstage's identical single-sym end state: - use-before-value (`import aa` then `fn aa`): installtop promotes the pre-installed SK_USE to the value kind (use_alias=1). - value-before-use (`fn aa` then `import aa`): installdecl's N_USE arm promotes the pre-installed value sym in place (set use_alias=1, no coexisting SK_USE), mirroring cstage's self-import N_USE arm (check.c:2823-2834 `if (prev) prev->use_alias = 1`). Both orders compile + are cs/ww byte-identical AND byte-identical to each other. Cannot split: promote without the guards leaves `name.member` red on the promoted sym; the guards without promote are inert (no use_alias is ever set) — no bisect-clean intermediate. (#30) Pins (910/997): modfn_coexist_ok (use-before-value) AND modfn_coexist_vbu_ok (value-before-use) both accept on cstage + are cs/ww byte-id + run to exit 6 (bare fn and qualified module both resolve); the dup_fn row still rejects both stages (regression). fnmatch byte-id holds. The order-dependence is exactly what regresses silently, so both orders are pinned.