Never unify a SigTyVar with a non-tyvar type (fixes Trac #7786)
authorSimon Peyton Jones <simonpj@microsoft.com>
Mon, 22 Apr 2013 11:50:24 +0000 (12:50 +0100)
committerSimon Peyton Jones <simonpj@microsoft.com>
Mon, 22 Apr 2013 11:54:50 +0000 (12:54 +0100)
commit6ebab3df7e68f8325ef60111c0c7755dd6ffcc91
tree767dd1979763728b9f24d5b74aae93acf395170d
parent28c14617606661d639c6f7676034c45e4bcab4f1
Never unify a SigTyVar with a non-tyvar type (fixes Trac #7786)

This unwanted unification was happening in the zonking phase
which un-flattens type-function applications (TcMType.zonkFlats,
try_zonk_fun_eq).  The main unifier is careful to make the check,
but I'd forgotten it here.  That in turn led to a very confusing
error message.
compiler/typecheck/TcMType.lhs