Repository : ssh://darcs.haskell.org//srv/darcs/ghc On branch : master
http://hackage.haskell.org/trac/ghc/changeset/3394d49af13697626145aca6d80b65ae8661418c >--------------------------------------------------------------- commit 3394d49af13697626145aca6d80b65ae8661418c Author: Simon Peyton Jones <simo...@microsoft.com> Date: Wed Dec 19 17:37:27 2012 +0000 Pass the correct inst_tys argument to dataConCannotMatch, in mkRecSelBinds This fixes Trac #7503. >--------------------------------------------------------------- compiler/typecheck/TcTyClsDecls.lhs | 16 ++++++++++------ 1 files changed, 10 insertions(+), 6 deletions(-) diff --git a/compiler/typecheck/TcTyClsDecls.lhs b/compiler/typecheck/TcTyClsDecls.lhs index 0523dcd..46a9445 100644 --- a/compiler/typecheck/TcTyClsDecls.lhs +++ b/compiler/typecheck/TcTyClsDecls.lhs @@ -272,8 +272,7 @@ kcTyClGroup decls -- Step 1: Bind kind variables for non-synonyms ; let (syn_decls, non_syn_decls) = partition (isSynDecl . unLoc) decls - ; initial_kinds <- - getInitialKinds TopLevel non_syn_decls + ; initial_kinds <- getInitialKinds TopLevel non_syn_decls ; traceTc "kcTyClGroup: initial kinds" (ppr initial_kinds) -- Step 2: Set initial envt, kind-check the synonyms @@ -1553,7 +1552,7 @@ mkRecSelBind (tycon, sel_name) -- Add catch-all default case unless the case is exhaustive -- We do this explicitly so that we get a nice error message that -- mentions this particular record selector - deflt | not (any is_unused all_cons) = [] + deflt | all dealt_with all_cons = [] | otherwise = [mkSimpleMatch [L loc (WildPat placeHolderType)] (mkHsApp (L loc (HsVar (getName rEC_SEL_ERROR_ID))) (L loc (HsLit msg_lit)))] @@ -1561,9 +1560,14 @@ mkRecSelBind (tycon, sel_name) -- Do not add a default case unless there are unmatched -- constructors. We must take account of GADTs, else we -- get overlap warning messages from the pattern-match checker - is_unused con = not (con `elem` cons_w_field - || dataConCannotMatch inst_tys con) - inst_tys = tyConAppArgs data_ty + -- NB: we need to pass type args for the *representation* TyCon + -- to dataConCannotMatch, hence the calculation of inst_tys + -- This matters in data families + -- data instance T Int a where + -- A :: { fld :: Int } -> T Int Bool + -- B :: { fld :: Int } -> T Int Char + dealt_with con = con `elem` cons_w_field || dataConCannotMatch inst_tys con + inst_tys = substTyVars (mkTopTvSubst (dataConEqSpec con1)) (dataConUnivTyVars con1) unit_rhs = mkLHsTupleExpr [] msg_lit = HsStringPrim $ unsafeMkByteString $ _______________________________________________ Cvs-ghc mailing list Cvs-ghc@haskell.org http://www.haskell.org/mailman/listinfo/cvs-ghc
