Commit a0908440 authored by simonpj's avatar simonpj
Browse files

[project @ 2003-10-27 14:08:04 by simonpj]

Improve duplicate-instance reporting; swap inst-env param order
parent 7222d3c0
......@@ -540,40 +540,40 @@ tcExtendLocalInstEnv :: [DFunId] -> TcM a -> TcM a
-- Add new locally-defined instances
tcExtendLocalInstEnv dfuns thing_inside
= do { traceDFuns dfuns
; eps <- getEps
; env <- getGblEnv
; dflags <- getDOpts
; inst_env' <- foldlM (extend dflags (eps_inst_env eps))
(tcg_inst_env env)
dfuns
; inst_env' <- foldlM (addInst dflags) (tcg_inst_env env) dfuns
; let env' = env { tcg_insts = dfuns ++ tcg_insts env,
tcg_inst_env = inst_env' }
; setGblEnv env' thing_inside }
where
extend dflags pkg_ie home_ie dfun
= do { checkNewInst dflags (home_ie, pkg_ie) dfun
; return (extendInstEnv home_ie dfun) }
checkNewInst :: DynFlags -> (InstEnv, InstEnv) -> DFunId -> TcM ()
-- Check that the proposed new instance is OK
checkNewInst dflags ies dfun
= do { -- Check functional dependencies
case checkFunDeps ies dfun of
addInst :: DynFlags -> InstEnv -> DFunId -> TcM InstEnv
-- Check that the proposed new instance is OK,
-- and then add it to the home inst env
addInst dflags home_ie dfun
= do { -- Load imported instances, so that we report
-- duplicates correctly
pkg_ie <- loadImportedInsts cls tys
-- Check functional dependencies
; case checkFunDeps (pkg_ie, home_ie) dfun of
Just dfuns -> funDepErr dfun dfuns
Nothing -> return ()
-- Check for duplicate instance decls
; let { (matches, _) = lookupInstEnv dflags (pkg_ie, home_ie) cls tys
; dup_dfuns = [dup_dfun | (_, (_, dup_tys, dup_dfun)) <- matches,
isJust (matchTys (mkVarSet tvs) tys dup_tys)] }
-- Find memebers of the match list which
-- dfun itself matches. If the match is 2-way, it's a duplicate
; case dup_dfuns of
dup_dfun : _ -> dupInstErr dfun dup_dfun
[] -> return ()
}
-- OK, now extend the envt
; return (extendInstEnv home_ie dfun) }
where
(tvs, _, cls, tys) = tcSplitDFunTy (idType dfun)
(matches, _) = lookupInstEnv dflags ies cls tys
dup_dfuns = [dup_dfun | (_, (_, dup_tys, dup_dfun)) <- matches,
isJust (matchTys (mkVarSet tvs) tys dup_tys)]
-- Find memebers of the match list which
-- dfun itself matches. If the match is 2-way, it's a duplicate
traceDFuns dfuns
= traceTc (text "Adding instances:" <+> vcat (map pp dfuns))
......
......@@ -250,8 +250,8 @@ thing we are looking up can have an arbitrary "flexi" part.
\begin{code}
lookupInstEnv :: DynFlags
-> (InstEnv, -- Home-package inst-env
InstEnv) -- External package inst-env
-> (InstEnv -- External package inst-env
,InstEnv) -- Home-package inst-env
-> Class -> [Type] -- What we are looking for
-> ([(TyVarSubstEnv, InstEnvElt)], -- Successful matches
[Id]) -- These don't match but do unify
......@@ -265,7 +265,7 @@ lookupInstEnv :: DynFlags
-- but Foo [Int] is a unifier. This gives the caller a better chance of
-- giving a suitable error messagen
lookupInstEnv dflags (home_ie, pkg_ie) cls tys
lookupInstEnv dflags (pkg_ie, home_ie) cls tys
| not (null all_unifs) = (all_matches, all_unifs) -- This is always an error situation,
-- so don't attempt to pune the matches
| otherwise = (pruned_matches, [])
......@@ -362,7 +362,7 @@ checkFunDeps :: (InstEnv, InstEnv) -> DFunId
-> Maybe [DFunId] -- Nothing <=> ok
-- Just dfs <=> conflict with dfs
-- Check wheher adding DFunId would break functional-dependency constraints
checkFunDeps (home_ie, pkg_ie) dfun
checkFunDeps (pkg_ie, home_ie) dfun
| null bad_fundeps = Nothing
| otherwise = Just bad_fundeps
where
......
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