#15290: QuantifiedConstraints: panic "addTcEvBind NoEvBindsVar" -------------------------------------+------------------------------------- Reporter: goldfire | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.1 Component: Compiler | Version: 8.4.3 Resolution: | Keywords: | QuantifiedConstraints Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: quantified- | constraints/T15290, T15290a Blocked By: | Blocking: 9123, 14883 Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by simonpj): Thanks for putting this in the right place. I think your patch should work now; and I tried this which seems even better {{{ diff --git a/compiler/typecheck/TcGenDeriv.hs b/compiler/typecheck/TcGenDeriv.hs index b944520..736eb14 100644 --- a/compiler/typecheck/TcGenDeriv.hs +++ b/compiler/typecheck/TcGenDeriv.hs @@ -1668,13 +1668,12 @@ gen_Newtype_binds loc cls inst_tvs inst_tys rhs_ty [] rhs_expr] where Pair from_ty to_ty = mkCoerceClassMethEqn cls inst_tvs inst_tys rhs_ty meth_id - meth_RDR = getRdrName meth_id + (_, _, from_tau) = tcSplitSigmaTy from_ty rhs_expr = nlHsVar (getRdrName coerceId) - `nlHsAppType` from_ty - `nlHsAppType` to_ty - `nlHsApp` nlHsVar meth_RDR + `nlHsApp` (nlHsVar meth_RDR `nlExprWithTySig` from_tau) + `nlExprWithTySig` to_ty mk_atf_inst :: TyCon -> TcM FamInst mk_atf_inst fam_tc = do @@ -1703,11 +1702,6 @@ gen_Newtype_binds loc cls inst_tvs inst_tys rhs_ty rep_cvs' = toposortTyVars rep_cvs pp_lhs = ppr (mkTyConApp fam_tc rep_lhs_tys) -nlHsAppType :: LHsExpr GhcPs -> Type -> LHsExpr GhcPs -nlHsAppType e s = noLoc (HsAppType hs_ty e) - where - hs_ty = mkHsWildCardBndrs $ nlHsParTy (typeToLHsType s) - nlExprWithTySig :: LHsExpr GhcPs -> Type -> LHsExpr GhcPs nlExprWithTySig e s = noLoc $ ExprWithTySig hs_ty $ parenthesizeHsExpr sigPrec e }}} I like this because it feels more uniform: two type signatures rather that one type signature and two type applications. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15290#comment:26 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler