Prior to this change, calling a protocol function with an opaque type
would yield a warning, as Dialyzer concludes that the impl_for/1
function can't handle opaque arguments, since all clauses would
destructure their arguments in some way.
By adding a catch-all clause that does not destructure its argument,
Dialyzer no longer draws this conclusion, and the warnings go away.
As noted in the protocol.ex comment, this is technically a hack as it
relies on Dialyzer not being smart enough. However, I would not expect
it to break soon, if ever.
Signed-off-by: José Valim <jose.valim@plataformatec.com.br>
Magnus Lång
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