matchscrutt's N_DOT branch resolved the field type via the dotfieldtnode
AST walk + resolvetagged; post-#66 the N_DOT node carries the field tinfo
on .type_, so return the scrutinee node directly and let cgmatch gate on
istaggedtype(scrutt) instead of scrutt.kind == N_TTAGGED. All six scrutt
consumers read .type_ (peeling TY_NAMED), none reads node structure, so a
value node vs a type node is invisible downstream; the istaggedtype guard
preserves the old nil-for-non-tagged contract.
Symmetry-improving (rule 10): cstage derives the dispatch type from s->type
with one unconditional NAMED-peel (cmd/w6c/cgen.c:4847-4850; the N_IDENT
check at :4854 is only the slot-offset fast-path). The old dotfieldtnode
required base.kind == N_IDENT -- a restriction cstage never had -- so the
chained-dot widening this enables matches cstage (out-of-corpus, #14).
Drops matchscrutt's dotfieldtnode caller (external callers 2->1; the
indexvaluetnode:1084 internal recursion remains, and the cgassign tagged-
store sites still need the node-keyed resolvetagged machinery, so neither
walker is deletable yet -- store-migration + #61d follow). N_DOT-match
coverage: 693/694/695/700/744 (runtime). byte-id 990-997 unchanged, 134/134.
Hojun-Cho
aec48e8c13