From 60f4aa3d033451da1daed159d9cb8780bf56e724 Mon Sep 17 00:00:00 2001 From: Manuel M T Chakravarty Date: Mon, 18 Sep 2006 23:15:42 +0000 Subject: [PATCH] Check for repeated tyvars in AT family decls Sat Aug 26 19:49:55 EDT 2006 Manuel M T Chakravarty * Check for repeated tyvars in AT family decls --- compiler/rename/RnSource.lhs | 27 ++++++++++++++++++++++++--- 1 file changed, 24 insertions(+), 3 deletions(-) diff --git a/compiler/rename/RnSource.lhs b/compiler/rename/RnSource.lhs index e29c2fe..344ae35 100644 --- a/compiler/rename/RnSource.lhs +++ b/compiler/rename/RnSource.lhs @@ -43,7 +43,7 @@ import SrcLoc ( Located(..), unLoc, noLoc ) import DynFlags ( DynFlag(..) ) import Maybes ( seqMaybe ) import Maybe ( isNothing, isJust ) -import Monad ( liftM ) +import Monad ( liftM, when ) import BasicTypes ( Boxity(..) ) \end{code} @@ -787,8 +787,11 @@ rnATs ats = mapFvRn (wrapLocFstM rn_at) ats rnTyClDecl tydecl rn_at _ = panic "RnSource.rnATs: invalid TyClDecl" - lookupIdxVars _ tyvars cont = mappM lookupIdxVar tyvars >>= cont - -- + lookupIdxVars _ tyvars cont = + do { checkForDups tyvars; + ; tyvars' <- mappM lookupIdxVar tyvars + ; cont tyvars' + } -- Type index variables must be class parameters, which are the only -- type variables in scope at this point. lookupIdxVar (L l tyvar) = @@ -796,9 +799,27 @@ rnATs ats = mapFvRn (wrapLocFstM rn_at) ats name' <- lookupOccRn (hsTyVarName tyvar) return $ L l (replaceTyVarName tyvar name') + -- Type variable may only occur once. + -- + checkForDups [] = return () + checkForDups (L loc tv:ltvs) = + do { setSrcSpan loc $ + when (hsTyVarName tv `ltvElem` ltvs) $ + addErr (repeatedTyVar tv) + ; checkForDups ltvs + } + + rdrName `ltvElem` [] = False + rdrName `ltvElem` (L _ tv:ltvs) + | rdrName == hsTyVarName tv = True + | otherwise = rdrName `ltvElem` ltvs + noPatterns = text "Default definition for an associated synonym cannot have" <+> text "type pattern" +repeatedTyVar tv = ptext SLIT("Illegal repeated type variable") <+> + quotes (ppr tv) + -- This data decl will parse OK -- data T = a Int -- treating "a" as the constructor. -- 1.7.10.4