Hojun-Cho
f8d2f92316
Class A silent miscompile, latent until two modules export the same struct leaf name. Wwstage's structlookup (selfhost/cmd/wcc/cgenutil.ww) walked c.structs head-first by sname, returning the FIRST match. cgdot's *struct field-load branch handed it inner.str (the bare leaf from a parsed N_TPTR whose inner is N_TNAME) and the head-pick silently emitted the wrong-module field offset — a displacement against BX that loaded whatever the colliding-module struct happened to align there. Cstage carries no sister bug: resolve_typename (cmd/wcc/check.c:65) already routes bare-leaf TY_STRUCT names through scope_lookup_prefer per c->cur_mod, and cgen.c reads fi.foff off the typed Sym — cs vs ws asm diverged on every bare- leaf collision but no in-tree corpus declares two same-leaf structs, so 995_self_rebuild stayed green (same surfacing pattern as #4a enumlookup post-strings). Fifth leaf of the trio leaf-name lookup graduation (after #27 aliaslookup, #28/#31 fnparams/fnretlookupmod, #4a enumlookup): structlookup grows a same-module-first walk before the head-walk fallback, mirroring aliaslookup's two-pass shape. No structlookupmod variant — pkg.S collapses at parse time (lib/ww/parse/parse.ww joindotted) into a single N_TNAME str routed through the existing embedded-dot smod==pkg branch, so there's no cgdot-style N_DOT consumer surface to add a *mod variant for (deferred per rob until one surfaces). No cstage symmetric fix needed for the same reason the bug doesn't surface there. 734_struct_modshadow pins the fix with 2 rows: row 1 bare-leaf in module M must fold against M's own S even with another module's same-leaf S at the head of c.structs (asserts the matching field- load disp inside the right TEXT sym + bad disp NOT-presence anti- check + byte-id between stages); row 2 pkg-qualified alpha.S from inside alpha is defensive coverage of the pre-existing embedded-dot smod==pkg branch — same path pre/post-fix (no sentinel-flip on this commit), pinned here so a future regression to the embedded-dot lookup is caught.