rhstaggedabicall's N_DOT arm re-derived the field type via dotfieldtnode
(a base-ident-only structlookup walk) then asked istaggedtype. The
checker now stamps the field's resolved type on the N_DOT node itself
(check.ww struct-field arm), so read src.type_ directly. typeistagged(nil)
is false, preserving the old ft==nil bail.
Polarity DOWN per rule 10: cstage's gate was already wide. cg_widen_tagged_
store reads src->type inline, NAMED-resolved, then tests TY_TAGGED
(cmd/w6c/cgen.c:1302-1305) -- no standalone helper. Pre-trim wwstage's
gate was NARROWER (dotfieldtnode required base==N_IDENT, firing only for
`ident.field`); reading src.type_ also fires for chained-dot bases
(`a.b.c`) since the checker stamps N_DOT.type_ at any depth. This aligns
wwstage UP to cstage's existing coverage. Byte-id 990-997 green confirms
the widened shape does not occur in bootstrap sources -- byte-id-neutral.
Drops one dotfieldtnode caller; the *node-returning callers
(typenodeprimresolved, indexvaluetnode, matchscrutt) stay until their
consumers migrate to *tinfo (the closing dotfield* deletion follows once
none need *node). First clean slice of that consumer migration; same
g/h-style stamp read as #55/#56.
Known pre-existing gap (filed, not introduced here): neither stage's
chained-DOT read path has a tagged-union leaf branch, so a chained-dot
tagged ABI source would store stale DX/CX/R8. Symmetric across stages
(byte-id stays green); the retained `cgdot loads AX=tag, DX=word0, ...`
comment is accurate only for ident.field bases.
make test 133/133 (quiescent tree, byte-id 990-997 green).
Hojun-Cho
8ccda588c6