patch applied (ghc): Fix Trac #3017: ensure that we quantify over
enough type variables when equalities are involved
Simon Peyton Jones
simonpj at microsoft.com
Wed Feb 11 12:57:07 EST 2009
Wed Feb 11 09:47:33 PST 2009 simonpj at microsoft.com
* Fix Trac #3017: ensure that we quantify over enough type variables when equalities are involved
The function FunDeps.grow was not doing the right thing when type equality
constraints were involved. That wasn't really its fault: its input was
being filtered by fdPredsOfInsts.
To fix this I did a bit of refactoring, so that the (revolting) fdPredsOfInsts
is now less important (maybe we can get rid of it in due course). The 'grow'
function moves from FunDeps to
The main comments are with the first of these, in
Note [Growing the tau-tvs using constraints] in Inst.
Push to the branch if conflict free.
M ./compiler/basicTypes/VarSet.lhs -1 +8
M ./compiler/typecheck/Inst.lhs -5 +45
M ./compiler/typecheck/TcMType.lhs -1 +24
M ./compiler/typecheck/TcSimplify.lhs -3 +3
M ./compiler/typecheck/TcTyClsDecls.lhs -2 +1
M ./compiler/types/FunDeps.lhs -39 +1
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