cstage cbinop routes every comparison through unify_arith
(cmd/wcc/check.c:952), which loud-rejects an error-typed operand
paired with a differing type (e.g. strconv.invalid != i32). wwstage
binoptype returned bool for comparisons without any unify step, so it
silently accepted a program cstage rejects -- a rule-10 break (align
the leaner-but-leniner wwstage DOWN to cstage).
Scope the rejection to an error operand (varianterr) mismatched with
the other (typeeqast) so the broad differing-types diagnostic -- whose
typeeqast-vs-cstage-type_eq asymmetry risk could reject valid bootstrap
code -- stays out of wwstage. Covers the whole comparison family
(EQ/NEQ/LT/LE/GT/GE), all of which cstage routes through unify_arith.
Found by impl-strconv3 writing the strconv test. Gate-blind: the
bootstrap never compares an error type to an int, so byte-id stayed
green while the stages disagreed on what's a valid program.
test/wcc/949_errtype_compare.c: both drivers reject invalid !=/==/< i32
(K_BUILDERR); same-error-type and plain-int compares still accept on
both stages + cs==ww byte-id (K_RUN). 12/12.
Hojun-Cho
dbc169a025