cstage rejected a deref-less function-pointer call `f(21)` (f: *fn...) with
"calling non-function" while wwstage accepted it and ran correctly -- a
cs!=ww divergence. Hare auto-dereferences a pointer callee to its fn type
before the call. Peel one pointer level after the named-type chase so
cstage accepts a `*fn` callee, matching wwstage and Hare.
One level only, deliberately: the #181-cgen indirect-call path lowers the
callee VALUE as the target (CALL AX), which is the fn address for a single
`*fn` but only the address-of the fn-ptr for `**fn`. A multi-level peel
would accept `**fn` past what cgen can lower -- a silent both-stage
miscompile (returns garbage). cstage stays loud on `**fn` (rule 7);
wwstage's loop-accept of all levels (check.ww:3763) is the over-permissive
side, filed for align-down plus the deeper cgen multi-level autoderef.
Surfaced by the codegen miscompile hunt (finding C6a). Pinned by
test/lang/fnptr_derefless_call_test.ww (deref-less + canonical (*f)(21),
multi-arg, alias-chain, tuple-return; reverting the peel reds the
deref-less rows at compile).
Hojun-Cho
e515a08fb7