Commit fe108ff1 authored by simonpj@microsoft.com's avatar simonpj@microsoft.com
Browse files

Improve error reporting in Core Lint

parent 2f0d9b27
......@@ -235,7 +235,7 @@ lintCoreExpr (Let (Rec pairs) body)
where
bndrs = map fst pairs
lintCoreExpr (App fun (Type ty))
lintCoreExpr e@(App fun (Type ty))
-- This is like 'let' for types
-- It's needed when dealing with desugarer output for GADTs. Consider
-- data T = forall a. T a (a->Int) Bool
......@@ -260,7 +260,8 @@ lintCoreExpr (App fun (Type ty))
-- False -> fail)
-- ) a
-- Now the inner case look as though it has incompatible branches.
= go fun [ty]
= addLoc (AnExpr e) $
go fun [ty]
where
go (App fun (Type ty)) tys
= do { go fun (ty:tys) }
......@@ -278,9 +279,9 @@ lintCoreExpr (App fun (Type ty))
; lintCoreArgs fun_ty (map Type tys) }
lintCoreExpr e@(App fun arg)
= do { ty <- lintCoreExpr fun
= do { fun_ty <- lintCoreExpr fun
; addLoc (AnExpr e) $
lintCoreArg ty arg }
lintCoreArg fun_ty arg }
lintCoreExpr (Lam var expr)
= addLoc (LambdaBodyOf var) $
......@@ -336,14 +337,14 @@ lintCoreArgs ty (a : args) =
do { res <- lintCoreArg ty a
; lintCoreArgs res args }
lintCoreArg ty a@(Type arg_ty) =
lintCoreArg fun_ty a@(Type arg_ty) =
do { arg_ty <- lintTy arg_ty
; lintTyApp ty arg_ty }
; lintTyApp fun_ty arg_ty }
lintCoreArg fun_ty arg =
-- Make sure function type matches argument
do { arg_ty <- lintCoreExpr arg
; let err = mkAppMsg fun_ty arg_ty
; let err = mkAppMsg fun_ty arg_ty arg
; case splitFunTy_maybe fun_ty of
Just (arg,res) ->
do { checkTys arg arg_ty err
......@@ -449,7 +450,8 @@ lintCoreAlt scrut_ty alt_ty alt@(DataAlt con, args, rhs)
addInScopeVars args $ -- Put the args in scope before lintBinder,
-- because the Ids mention the type variables
if isVanillaDataCon con then
do { mapM lintBinder args
do { addLoc (CasePat alt) $ do
{ mapM lintBinder args
-- FIX! Add check that all args are Ids.
-- Check the pattern
-- Scrutinee type must be a tycon applicn; checked by caller
......@@ -457,11 +459,12 @@ lintCoreAlt scrut_ty alt_ty alt@(DataAlt con, args, rhs)
-- NB: args must be in scope here so that the lintCoreArgs line works.
-- NB: relies on existential type args coming *after* ordinary type args
; con_type <- lintTyApps (dataConRepType con) tycon_arg_tys
; con_type <- lintTyApps (dataConRepType con) tycon_arg_tys
-- Can just map Var as we know that this is a vanilla datacon
; con_result_ty <- lintCoreArgs con_type (map Var args)
; checkTys con_result_ty scrut_ty (mkBadPatMsg con_result_ty scrut_ty)
-- Check the RHS
; con_result_ty <- lintCoreArgs con_type (map Var args)
; checkTys con_result_ty scrut_ty (mkBadPatMsg con_result_ty scrut_ty)
}
-- Check the RHS
; checkAltExpr rhs alt_ty }
else -- GADT
......@@ -472,10 +475,13 @@ lintCoreAlt scrut_ty alt_ty alt@(DataAlt con, args, rhs)
; case coreRefineTys in_scope con tvs scrut_ty of {
Nothing -> return () ; -- Alternative is dead code
Just (refine, _) -> updateTvSubstEnv (composeTvSubst in_scope refine subst_env) $
do { tvs' <- mapM lintTy (mkTyVarTys tvs)
; con_type <- lintTyApps (dataConRepType con) tvs'
; mapM lintBinder ids -- Lint Ids in the refined world
; lintCoreArgs con_type (map Var ids)
do { addLoc (CasePat alt) $ do
{ tvs' <- mapM lintTy (mkTyVarTys tvs)
; con_type <- lintTyApps (dataConRepType con) tvs'
; mapM lintBinder ids -- Lint Ids in the refined world
; lintCoreArgs con_type (map Var ids)
}
; let refined_alt_ty = substTy (mkTvSubst in_scope refine) alt_ty
-- alt_ty is already an OutType, so don't re-apply
-- the current substitution. But we must apply the
......@@ -545,7 +551,8 @@ data LintLocInfo
= RhsOf Id -- The variable bound
| LambdaBodyOf Id -- The lambda-binder
| BodyOfLetRec [Id] -- One of the binders
| CaseAlt CoreAlt -- Pattern of a case alternative
| CaseAlt CoreAlt -- Case alternative
| CasePat CoreAlt -- *Pattern* of the case alternative
| AnExpr CoreExpr -- Some expression
| ImportedUnfolding SrcLoc -- Some imported unfolding (ToDo: say which)
\end{code}
......@@ -656,7 +663,10 @@ dumpLoc (AnExpr e)
= (noSrcLoc, text "In the expression:" <+> ppr e)
dumpLoc (CaseAlt (con, args, rhs))
= (noSrcLoc, text "In a case alternative:" <+> parens (ppr con <+> ppr args))
= (noSrcLoc, text "In a case alternative:" <+> parens (ppr con <+> pp_binders args))
dumpLoc (CasePat (con, args, rhs))
= (noSrcLoc, text "In the pattern of a case alternative:" <+> parens (ppr con <+> pp_binders args))
dumpLoc (ImportedUnfolding locn)
= (locn, brackets (ptext SLIT("in an imported unfolding")))
......@@ -721,11 +731,12 @@ mkBadAltMsg scrut_ty alt
------------------------------------------------------
-- Other error messages
mkAppMsg :: Type -> Type -> Message
mkAppMsg fun arg
mkAppMsg :: Type -> Type -> CoreExpr -> Message
mkAppMsg fun_ty arg_ty arg
= vcat [ptext SLIT("Argument value doesn't match argument type:"),
hang (ptext SLIT("Fun type:")) 4 (ppr fun),
hang (ptext SLIT("Arg type:")) 4 (ppr arg)]
hang (ptext SLIT("Fun type:")) 4 (ppr fun_ty),
hang (ptext SLIT("Arg type:")) 4 (ppr arg_ty),
hang (ptext SLIT("Arg:")) 4 (ppr arg)]
mkKindErrMsg :: TyVar -> Type -> Message
mkKindErrMsg tyvar arg_ty
......
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