delta/haskell.git - gitlab.haskell.org: ghc/ghc.git

	Commit message (Collapse)	Author	Age	Files	Lines
*	Fix egregious error in eta-reduction of data families	Simon Peyton Jones	2015-12-04	1	-0/+11
	This terrible and long-standing bug was shown up by Trac #11148. We are trying to eta-reduce a data family instance, so that we can then derive Functor or Generic. But we were assuming, for absolutely not reason whatsoever, that the type variables were lined up in a convenient order. The fact that it ever worked was a fluke. This patch fixes it properly. Main change is in eta_reduce in TcInstDcls.tcDataFamInstDecl