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Simon Peyton Jones authored
I found (Trac #14175) that the tidying we do when reporting type error messages could cause a well-kinded type to become ill-kinded. Reason: we initialised the tidy-env with a completely un-zonked TidyEnv accumulated in the TcLclEnv as we come across lexical type-varialbe bindings. Solution: zonk them. But I ended up refactoring a bit: * Get rid of tcl_tidy :: TidyEnv altogether * Instead use tcl_bndrs :: TcBinderStack This used to contain only Ids, but now I've added those lexically scoped TyVars too. * Change names: TcIdBinderStack -> TcBinderStack TcIdBinder -> TcBinder extendTcIdBndrs -> extendTcBinderStack * Now tcInitTidyEnv can grab those TyVars from the tcl_bndrs, zonk, and tidy them. The only annoyance is that I had to add TcEnv.hs-boot, to break the recursion between the zonking code and the TrRnMonad functions like addErrTc that call tcInitTidyEnv. Tiresome, but in fact that file existed already.
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