[Git][ghc/ghc][master] Use TcRnVDQInTermType in noNestedForallsContextsErr (#20115)
Marge Bot (@marge-bot)
gitlab at gitlab.haskell.org
Wed Oct 26 16:17:31 UTC 2022
Marge Bot pushed to branch master at Glasgow Haskell Compiler / GHC
Commits:
f60a1a62 by Vladislav Zavialov at 2022-10-26T12:17:14-04:00
Use TcRnVDQInTermType in noNestedForallsContextsErr (#20115)
When faced with VDQ in the type of a term, GHC generates the following
error message:
Illegal visible, dependent quantification in the type of a term
(GHC does not yet support this)
Prior to this patch, there were two ways this message could have been
generated and represented:
1. with the dedicated constructor TcRnVDQInTermType
(see check_type in GHC.Tc.Validity)
2. with the transitional constructor TcRnUnknownMessage
(see noNestedForallsContextsErr in GHC.Rename.Utils)
Not only this led to duplication of code generating the final SDoc,
it also made it tricky to track the origin of the error message.
This patch fixes the problem by using TcRnVDQInTermType exclusively.
- - - - -
8 changed files:
- compiler/GHC/Rename/Module.hs
- compiler/GHC/Rename/Utils.hs
- compiler/GHC/Tc/Errors/Ppr.hs
- compiler/GHC/Tc/Errors/Types.hs
- compiler/GHC/Tc/Validity.hs
- testsuite/tests/dependent/should_fail/T16326_Fail6.stderr
- testsuite/tests/dependent/should_fail/T16326_Fail8.stderr
- testsuite/tests/dependent/should_fail/T18271.stderr
Changes:
=====================================
compiler/GHC/Rename/Module.hs
=====================================
@@ -618,7 +618,8 @@ rnClsInstDecl (ClsInstDecl { cid_poly_ty = inst_ty, cid_binds = mbinds
Just (L _ cls) -> Right cls
Nothing -> Left
( getLocA head_ty'
- , hang (text "Illegal head of an instance declaration:"
+ , mkTcRnUnknownMessage $ mkPlainError noHints $
+ hang (text "Illegal head of an instance declaration:"
<+> quotes (ppr head_ty'))
2 (vcat [ text "Instance heads must be of the form"
, nest 2 $ text "C ty_1 ... ty_n"
@@ -681,9 +682,7 @@ rnClsInstDecl (ClsInstDecl { cid_poly_ty = inst_ty, cid_binds = mbinds
-- reach the typechecker, lest we encounter different errors that are
-- hopelessly confusing (such as the one in #16114).
bail_out (l, err_msg) = do
- addErrAt l $
- TcRnWithHsDocContext ctxt $
- mkTcRnUnknownMessage $ mkPlainError noHints err_msg
+ addErrAt l $ TcRnWithHsDocContext ctxt err_msg
pure $ mkUnboundName (mkTcOccFS (fsLit "<class>"))
rnFamEqn :: HsDocContext
=====================================
compiler/GHC/Rename/Utils.hs
=====================================
@@ -288,7 +288,7 @@ Note [No nested foralls or contexts in instance types] in GHC.Hs.Type).
-- "GHC.Rename.Module" and 'renameSig' in "GHC.Rename.Bind").
-- See @Note [No nested foralls or contexts in instance types]@ in
-- "GHC.Hs.Type".
-noNestedForallsContextsErr :: SDoc -> LHsType GhcRn -> Maybe (SrcSpan, SDoc)
+noNestedForallsContextsErr :: SDoc -> LHsType GhcRn -> Maybe (SrcSpan, TcRnMessage)
noNestedForallsContextsErr what lty =
case ignoreParens lty of
L l (HsForAllTy { hst_tele = tele })
@@ -297,9 +297,7 @@ noNestedForallsContextsErr what lty =
-- types of terms, so we give a slightly more descriptive error
-- message in the event that they contain visible dependent
-- quantification (currently only allowed in kinds).
- -> Just (locA l, vcat [ text "Illegal visible, dependent quantification" <+>
- text "in the type of a term"
- , text "(GHC does not yet support this)" ])
+ -> Just (locA l, TcRnVDQInTermType Nothing)
| HsForAllInvis{} <- tele
-> Just (locA l, nested_foralls_contexts_err)
L l (HsQualTy {})
@@ -307,6 +305,7 @@ noNestedForallsContextsErr what lty =
_ -> Nothing
where
nested_foralls_contexts_err =
+ mkTcRnUnknownMessage $ mkPlainError noHints $
what <+> text "cannot contain nested"
<+> quotes forAllLit <> text "s or contexts"
@@ -314,9 +313,7 @@ noNestedForallsContextsErr what lty =
addNoNestedForallsContextsErr :: HsDocContext -> SDoc -> LHsType GhcRn -> RnM ()
addNoNestedForallsContextsErr ctxt what lty =
whenIsJust (noNestedForallsContextsErr what lty) $ \(l, err_msg) ->
- addErrAt l $
- TcRnWithHsDocContext ctxt $
- mkTcRnUnknownMessage $ mkPlainError noHints err_msg
+ addErrAt l $ TcRnWithHsDocContext ctxt err_msg
{-
************************************************************************
=====================================
compiler/GHC/Tc/Errors/Ppr.hs
=====================================
@@ -364,12 +364,16 @@ instance Diagnostic TcRnMessage where
2 (text "type:" <+> quotes (ppr ty))
, hang (text "where the body of the forall has this kind:")
2 (quotes (pprKind kind)) ]
- TcRnVDQInTermType ty
+ TcRnVDQInTermType mb_ty
-> mkSimpleDecorated $ vcat
- [ hang (text "Illegal visible, dependent quantification" <+>
- text "in the type of a term:")
- 2 (pprType ty)
+ [ case mb_ty of
+ Nothing -> main_msg
+ Just ty -> hang (main_msg <> char ':') 2 (pprType ty)
, text "(GHC does not yet support this)" ]
+ where
+ main_msg =
+ text "Illegal visible, dependent quantification" <+>
+ text "in the type of a term"
TcRnBadQuantPredHead ty
-> mkSimpleDecorated $
hang (text "Quantified predicate must have a class or type variable head:")
=====================================
compiler/GHC/Tc/Errors/Types.hs
=====================================
@@ -915,7 +915,7 @@ data TcRnMessage where
dependent/should_fail/T17687
dependent/should_fail/T18271
-}
- TcRnVDQInTermType :: !Type -> TcRnMessage
+ TcRnVDQInTermType :: !(Maybe Type) -> TcRnMessage
{-| TcRnBadQuantPredHead is an error that occurs whenever a quantified predicate
lacks a class or type variable head.
=====================================
compiler/GHC/Tc/Validity.hs
=====================================
@@ -733,7 +733,7 @@ check_type ve (CastTy ty _) = check_type ve ty
--
-- Critically, this case must come *after* the case for TyConApp.
-- See Note [Liberal type synonyms].
-check_type ve@(ValidityEnv{ ve_tidy_env = env, ve_ctxt = ctxt
+check_type ve@(ValidityEnv{ ve_tidy_env = env
, ve_rank = rank, ve_expand = expand }) ty
| not (null tvbs && null theta)
= do { traceTc "check_type" (ppr ty $$ ppr rank)
@@ -745,9 +745,7 @@ check_type ve@(ValidityEnv{ ve_tidy_env = env, ve_ctxt = ctxt
-- Reject forall (a :: Eq b => b). blah
-- In a kind signature we don't allow constraints
- ; checkTcM (all (isInvisibleArgFlag . binderArgFlag) tvbs
- || vdqAllowed ctxt)
- (env, TcRnVDQInTermType (tidyType env ty))
+ ; checkVdqOK ve tvbs ty
-- Reject visible, dependent quantification in the type of a
-- term (e.g., `f :: forall a -> a -> Maybe a`)
@@ -938,6 +936,14 @@ checkConstraintsOK ve theta ty
checkTcM (all isEqPred theta) (env, TcRnConstraintInKind (tidyType env ty))
where env = ve_tidy_env ve
+checkVdqOK :: ValidityEnv -> [TyVarBinder] -> Type -> TcM ()
+checkVdqOK ve tvbs ty = do
+ checkTcM (vdqAllowed ctxt || no_vdq)
+ (env, TcRnVDQInTermType (Just (tidyType env ty)))
+ where
+ no_vdq = all (isInvisibleArgFlag . binderArgFlag) tvbs
+ ValidityEnv{ve_tidy_env = env, ve_ctxt = ctxt} = ve
+
{-
Note [Liberal type synonyms]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
=====================================
testsuite/tests/dependent/should_fail/T16326_Fail6.stderr
=====================================
@@ -1,5 +1,5 @@
-T16326_Fail6.hs:9:12: error:
+T16326_Fail6.hs:9:12: error: [GHC-51580]
Illegal visible, dependent quantification in the type of a term
(GHC does not yet support this)
In the definition of data constructor ‘MkFoo’
=====================================
testsuite/tests/dependent/should_fail/T16326_Fail8.stderr
=====================================
@@ -1,5 +1,5 @@
-T16326_Fail8.hs:7:10: error:
+T16326_Fail8.hs:7:10: error: [GHC-51580]
Illegal visible, dependent quantification in the type of a term
(GHC does not yet support this)
In an instance declaration
=====================================
testsuite/tests/dependent/should_fail/T18271.stderr
=====================================
@@ -1,5 +1,5 @@
-T18271.hs:7:19: error:
+T18271.hs:7:19: error: [GHC-51580]
Illegal visible, dependent quantification in the type of a term
(GHC does not yet support this)
In a deriving declaration
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/f60a1a62bf88ec787a5b5d1725129a24b6b81f4a
--
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/f60a1a62bf88ec787a5b5d1725129a24b6b81f4a
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