record-method-dispatch was rebound with (set! record-method-dispatch ...) in six
files, each wrapping the previous binding, so precedence was whatever the rt.ss
load order happened to be — the true outermost arm was inst-time's Date arm, not
the one you'd guess. A type-gated wrapper that only whitelists its own methods
then errored on everything else, stealing universal Object methods from the arms
beneath it: (.getClass (java.util.Date.)) threw "No method getClass on Date",
same for File, while (class ...) and (.getClass "s") worked.
Replace the wrapper stack with an ordered list of arms (register-method-arm!,
ascending priority), each returning 'pass to defer. getClass is now one arm at
the top reached by every value, so it can't be shadowed; the three duplicate
getClass checks (dot-forms, host-static, base) collapse into it. Each former
wrapper is an arm at an explicit priority instead of an implicit load-order slot.
A library can register its own arm rather than set!-wrapping the dispatcher.
Runtime only, no re-mint. make test green (0 new/stale divergences), +1 corpus
row for getClass on Date/File.
0b07b376bb