The concrete→tagged arm walked variants with typeeqast-only, rejecting
widenings that aren't strict surface-eq: NAMED-aliased variants, nested
tagged inside a variant, and concrete → variant after the wrap-induced
exprtype reshape that Commit 3 (#41, variadic wrap re-land) introduces.
Replace the walk with a recursive isassignable call per variant, mirroring
harec tagged_select_subtype (ref/harec/src/types.c:702-739, recursive
type_is_assignable at :718; invoked from the TAGGED arm at :1110-1112)
and the byte-id cstage precedent at cmd/wcc/type.c:298-299. The recursive
call's leading typeeqast (check.ww:2257) preserves the #55 surface-nominal
fast path; the #57 bare-vs-qualified TNAME residual is unchanged.
No new test: the new widen path is dormant pre-Commit-3; existing
tagged-union tests cover the surface-eq fast path. Commit 3's fmttest
exercise will exercise the recursive widen for free.
Closes 39 cascade errors that fire once #41 lands.
Hojun-Cho
e662156574