Commit e83fa2eb authored by simonpj's avatar simonpj
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[project @ 2003-02-20 16:02:57 by simonpj]

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parent 3194c528
......@@ -629,6 +629,18 @@ tcMethods clas inst_tyvars inst_tyvars' dfun_theta' inst_tys'
-- Solution: make meth_insts available, so that 'then' refers directly
-- to the local 'bind' rather than going via the dictionary.
-- BUT WATCH OUT! If the method type mentions the class variable, then
-- this optimisation is not right. Consider
-- class C a where
-- op :: Eq a => a
-- instance C Int where
-- op = op
-- The occurrence of 'op' on the rhs gives rise to a constraint
-- op at Int
-- The trouble is that the 'meth_inst' for op, which is 'available', also
-- looks like 'op at Int'. But they are not the same.
all_insts = avail_insts ++ catMaybes meth_insts
xtve = inst_tyvars `zip` inst_tyvars'
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