Sjoerd Visscher pushed to branch wip/T18570 at Glasgow Haskell Compiler / GHC Commits: f05d68b2 by Sjoerd Visscher at 2025-06-27T21:00:38+02:00 Fix field type mismatch error handling - - - - - 4 changed files: - compiler/GHC/Tc/TyCl.hs - testsuite/tests/typecheck/should_fail/CommonFieldTypeMismatch.stderr - testsuite/tests/typecheck/should_fail/T12083a.stderr - testsuite/tests/typecheck/should_fail/T9739.stderr Changes: ===================================== compiler/GHC/Tc/TyCl.hs ===================================== @@ -4787,6 +4787,7 @@ checkValidTyCl tc = setSrcSpan (getSrcSpan tc) $ addTyConCtxt tc $ recoverM recovery_code $ + checkNoErrs $ do { traceTc "Starting validity for tycon" (ppr tc) ; checkValidTyCon tc ; checkTyConConsistentWithBoot tc -- See Note [TyCon boot consistency checking] @@ -4991,7 +4992,7 @@ checkValidTyCon tc check_fields ((label, con1) :| other_fields) -- These fields all have the same name, but are from -- different constructors in the data type - = recoverM (return ()) $ mapM_ checkOne other_fields + = mapM_ checkOne other_fields -- Check that all the fields in the group have the same type -- NB: this check assumes that all the constructors of a given -- data type use the same type variables @@ -5001,8 +5002,10 @@ checkValidTyCon tc lbl = flLabel label checkOne (_, con2) -- Do it both ways to ensure they are structurally identical - = do { checkFieldCompat lbl con1 con2 res1 res2 fty1 fty2 - ; checkFieldCompat lbl con2 con1 res2 res1 fty2 fty1 } + = do { ((), no_errs) <- askNoErrs $ + checkFieldCompat lbl con1 con2 res1 res2 fty1 fty2 + ; when no_errs $ + checkFieldCompat lbl con2 con1 res2 res1 fty2 fty1 } where res2 = dataConOrigResTy con2 fty2 = dataConFieldType con2 lbl @@ -5029,8 +5032,10 @@ checkPartialRecordField all_cons fld checkFieldCompat :: FieldLabelString -> DataCon -> DataCon -> Type -> Type -> Type -> Type -> TcM () checkFieldCompat fld con1 con2 res1 res2 fty1 fty2 - = do { checkTc (isJust mb_subst1) (TcRnCommonFieldResultTypeMismatch con1 con2 fld) - ; checkTc (isJust mb_subst2) (TcRnCommonFieldTypeMismatch con1 con2 fld) } + = if isNothing mb_subst1 + then addErrTc $ TcRnCommonFieldResultTypeMismatch con1 con2 fld + else when (isNothing mb_subst2) $ + addErrTc $ TcRnCommonFieldTypeMismatch con1 con2 fld where mb_subst1 = tcMatchTy res1 res2 mb_subst2 = tcMatchTyX (expectJust mb_subst1) fty1 fty2 ===================================== testsuite/tests/typecheck/should_fail/CommonFieldTypeMismatch.stderr ===================================== @@ -2,10 +2,3 @@ CommonFieldTypeMismatch.hs:3:1: error: [GHC-91827] • Constructors A1 and A2 give different types for field ‘fld’ • In the data type declaration for ‘A’ -CommonFieldTypeMismatch.hs:4:8: error: [GHC-83865] - • Couldn't match type ‘[Char]’ with ‘Int’ - Expected: Int - Actual: String - • In the expression: fld - In an equation for ‘fld’: fld A2 {fld = fld} = fld - ===================================== testsuite/tests/typecheck/should_fail/T12083a.stderr ===================================== @@ -1,4 +1,3 @@ - T12083a.hs:6:1: error: [GHC-91510] • Illegal qualified type: Num a => a • In the type synonym declaration for ‘Constrd’ @@ -12,3 +11,20 @@ T12083a.hs:10:26: error: [GHC-25709] In the data type declaration for ‘ExistentiallyLost’ Suggested fix: Enable any of the following extensions: ‘ExistentialQuantification’ or ‘GADTs’ + +T12083a.hs:15:5: error: [GHC-27958] + • Could not deduce ‘ATF1 (p0, p1) ~ p0’ + arising from a superclass required to satisfy ‘TC (p0, p1)’, + arising from a type ambiguity check for + the type signature for ‘uie_handlers’ + from the context: TC u + bound by the type signature for: + uie_handlers :: forall u. TC u => ADT Int + at T12083a.hs:15:5-28 + The type variables ‘p0’, ‘p1’ are ambiguous + • In the ambiguity check for ‘uie_handlers’ + To defer the ambiguity check to use sites, enable AllowAmbiguousTypes + When checking the class method: + uie_handlers :: forall u. TC u => ADT Int + In the class declaration for ‘TC’ + ===================================== testsuite/tests/typecheck/should_fail/T9739.stderr ===================================== @@ -1,4 +1,3 @@ - T9739.hs:4:1: error: [GHC-29210] • Superclass cycle for ‘Class1’ one of whose superclasses is ‘Class3’ @@ -7,6 +6,22 @@ T9739.hs:4:1: error: [GHC-29210] Suggested fix: Perhaps you intended to use the ‘UndecidableSuperClasses’ extension +T9739.hs:7:3: error: [GHC-39999] + • Could not deduce ‘Class1 t0’ + arising from a superclass required to satisfy ‘Class3 t0’, + arising from a type ambiguity check for + the type signature for ‘class2’ + from the context: (Class2 t a, Class3 t) + bound by the type signature for: + class2 :: forall t a m. (Class2 t a, Class3 t) => a -> m + at T9739.hs:7:3-32 + The type variable ‘t0’ is ambiguous + • In the ambiguity check for ‘class2’ + To defer the ambiguity check to use sites, enable AllowAmbiguousTypes + When checking the class method: + class2 :: forall t a m. (Class2 t a, Class3 t) => a -> m + In the class declaration for ‘Class2’ + T9739.hs:9:1: error: [GHC-29210] • Superclass cycle for ‘Class3’ one of whose superclasses is ‘Class1’ @@ -14,3 +29,4 @@ T9739.hs:9:1: error: [GHC-29210] • In the class declaration for ‘Class3’ Suggested fix: Perhaps you intended to use the ‘UndecidableSuperClasses’ extension + View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/f05d68b257f64624a82619580396dd2c... -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/f05d68b257f64624a82619580396dd2c... You're receiving this email because of your account on gitlab.haskell.org.