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[Git][ghc/ghc][wip/sjakobi/T27732-type-data-field-annotations] Reject `~` and UNPACK annotations on type data fields
by Simon Jakobi (＠sjakobi) 22 Aug '26

22 Aug '26

Simon Jakobi pushed to branch wip/sjakobi/T27732-type-data-field-annotations at Glasgow Haskell Compiler / GHC Commits: 76238d25 by Simon Jakobi at 2026-08-22T03:15:38+02:00 Reject `~` and UNPACK annotations on type data fields Widen restriction (R3) of Note [Type data declarations] to any strictness or unpackedness annotation — none of them make sense at the type level — and generalize the check and error message accordingly. Fixes #27732 Assisted-by: Claude Fable 5 - - - - - 15 changed files: - + changelog.d/27732 - compiler/GHC/Rename/Module.hs - compiler/GHC/Tc/Errors/Types.hs - docs/users_guide/exts/type_data.rst - + testsuite/tests/type-data/should_fail/T27732a.hs - + testsuite/tests/type-data/should_fail/T27732a.stderr - + testsuite/tests/type-data/should_fail/T27732b.hs - + testsuite/tests/type-data/should_fail/T27732b.stderr - + testsuite/tests/type-data/should_fail/T27732c.hs - + testsuite/tests/type-data/should_fail/T27732c.stderr - + testsuite/tests/type-data/should_fail/T27732d.hs - + testsuite/tests/type-data/should_fail/T27732d.stderr - testsuite/tests/type-data/should_fail/TDStrictnessGADT.stderr - testsuite/tests/type-data/should_fail/TDStrictnessH98.stderr - testsuite/tests/type-data/should_fail/all.T Changes: ===================================== changelog.d/27732 ===================================== @@ -0,0 +1,8 @@ +section: language +synopsis: Reject `~` and UNPACK annotations on type data fields +description: + ``type data`` declarations (:extension:`TypeData`) now reject any + strictness or unpackedness annotation on constructor fields. + Previously only ``!`` was rejected. +mrs: !16563 +issues: #27732 ===================================== compiler/GHC/Rename/Module.hs ===================================== @@ -71,7 +71,6 @@ import GHC.Data.Graph.Directed ( SCC, flattenSCC, Node(..) , stronglyConnCompFromEdgedVerticesUniq ) import GHC.Data.OrdList import qualified GHC.LanguageExtensions as LangExt -import GHC.Core.DataCon ( isSrcStrict ) import Control.Monad import Data.Bifunctor ( first ) @@ -2116,8 +2115,8 @@ rnDataDefn doc (HsDataDefn { dd_cType = cType, dd_ctxt = context, dd_cons = cond = do { ; when (has_labelled_fields condecl) $ failWith $ TcRnTypeDataForbids TypeDataForbidsLabelledFields - ; when (has_strictness_flags condecl) $ - failWith $ TcRnTypeDataForbids TypeDataForbidsStrictnessAnnotations + ; when (has_field_annotations condecl) $ + failWith $ TcRnTypeDataForbids TypeDataForbidsFieldAnnotations } has_labelled_fields (ConDeclGADT { con_g_args = RecConGADT _ _ }) = True @@ -2125,13 +2124,16 @@ rnDataDefn doc (HsDataDefn { dd_cType = cType, dd_ctxt = context, dd_cons = cond = not (null (unLoc flds)) has_labelled_fields _ = False - has_strictness_flags condecl - = any isSrcStrict (con_arg_bangs condecl) + has_field_annotations condecl + = any is_annotated (con_arg_fields condecl) + where + is_annotated (CDF { cdf_bang = bang, cdf_unpack = unpack }) + = bang /= NoSrcStrict || unpack /= NoSrcUnpack - con_arg_bangs (ConDeclGADT { con_g_args = PrefixConGADT _ args }) = map cdf_bang args - con_arg_bangs (ConDeclH98 { con_args = PrefixCon _ args }) = map cdf_bang args - con_arg_bangs (ConDeclH98 { con_args = InfixCon _ arg1 arg2 }) = [cdf_bang arg1, cdf_bang arg2] - con_arg_bangs _ = [] + con_arg_fields (ConDeclGADT { con_g_args = PrefixConGADT _ args }) = args + con_arg_fields (ConDeclH98 { con_args = PrefixCon _ args }) = args + con_arg_fields (ConDeclH98 { con_args = InfixCon _ arg1 arg2 }) = [arg1, arg2] + con_arg_fields _ = [] {- Note [Type data declarations] @@ -2166,8 +2168,9 @@ preceded by `type`, with the following restrictions: (R2) There are no labelled fields. Perhaps these could be supported using type families, but they are omitted for now. -(R3) There are no strictness flags, because they don't make sense at - the type level. +(R3) There are no strictness or unpackedness annotations (!, ~, + {-# UNPACK #-}, {-# NOUNPACK #-}), because they don't make sense + at the type level. (R4) The types of the constructors contain no constraints. ===================================== compiler/GHC/Tc/Errors/Types.hs ===================================== @@ -2865,6 +2865,10 @@ data TcRnMessage where type-data/should_fail/TDRecordsH98 type-data/should_fail/TDStrictnessGADT type-data/should_fail/TDStrictnessH98 + type-data/should_fail/T27732a + type-data/should_fail/T27732b + type-data/should_fail/T27732c + type-data/should_fail/T27732d -} TcRnTypeDataForbids :: !TypeDataForbids -> TcRnMessage @@ -4523,15 +4527,15 @@ data ZonkerMessage where data TypeDataForbids = TypeDataForbidsDatatypeContexts | TypeDataForbidsLabelledFields - | TypeDataForbidsStrictnessAnnotations + | TypeDataForbidsFieldAnnotations | TypeDataForbidsDerivingClauses deriving Generic instance Outputable TypeDataForbids where - ppr TypeDataForbidsDatatypeContexts = text "Data type contexts" - ppr TypeDataForbidsLabelledFields = text "Labelled fields" - ppr TypeDataForbidsStrictnessAnnotations = text "Strictness flags" - ppr TypeDataForbidsDerivingClauses = text "Deriving clauses" + ppr TypeDataForbidsDatatypeContexts = text "Data type contexts" + ppr TypeDataForbidsLabelledFields = text "Labelled fields" + ppr TypeDataForbidsFieldAnnotations = text "Strictness or unpackedness annotations" + ppr TypeDataForbidsDerivingClauses = text "Deriving clauses" -- | Specifies which back ends can handle a requested foreign import or export type ExpectedBackends = [Backend] ===================================== docs/users_guide/exts/type_data.rst ===================================== @@ -33,7 +33,7 @@ either an ordinary algebraic data type or a GADT, prefixed with the keyword ``type``, except that it may not contain a datatype context (even with :extension:`DatatypeContexts`), labelled fields, -strictness flags, or +:ref:`strictness <strict-haskell>` or :ref:`unpackedness <unpack-pragma>` annotations, or a ``deriving`` clause. The only constraints permitted in the types of constructors are ===================================== testsuite/tests/type-data/should_fail/T27732a.hs ===================================== @@ -0,0 +1,4 @@ +{-# LANGUAGE TypeData, LazyFieldAnnotations #-} +module T27732a where + +type data T a = Cons ~a ===================================== testsuite/tests/type-data/should_fail/T27732a.stderr ===================================== @@ -0,0 +1,3 @@ +T27732a.hs:4:17: error: [GHC-67297] + Strictness or unpackedness annotations are not allowed in type data declarations. + ===================================== testsuite/tests/type-data/should_fail/T27732b.hs ===================================== @@ -0,0 +1,5 @@ +{-# LANGUAGE TypeData, LazyFieldAnnotations #-} +module T27732b where + +type data T a where + Cons :: ~a -> T a ===================================== testsuite/tests/type-data/should_fail/T27732b.stderr ===================================== @@ -0,0 +1,3 @@ +T27732b.hs:5:6: error: [GHC-67297] + Strictness or unpackedness annotations are not allowed in type data declarations. + ===================================== testsuite/tests/type-data/should_fail/T27732c.hs ===================================== @@ -0,0 +1,4 @@ +{-# LANGUAGE TypeData #-} +module T27732c where + +type data T a = Cons {-# UNPACK #-} a ===================================== testsuite/tests/type-data/should_fail/T27732c.stderr ===================================== @@ -0,0 +1,3 @@ +T27732c.hs:4:17: error: [GHC-67297] + Strictness or unpackedness annotations are not allowed in type data declarations. + ===================================== testsuite/tests/type-data/should_fail/T27732d.hs ===================================== @@ -0,0 +1,4 @@ +{-# LANGUAGE TypeData #-} +module T27732d where + +type data T a = Cons {-# NOUNPACK #-} a ===================================== testsuite/tests/type-data/should_fail/T27732d.stderr ===================================== @@ -0,0 +1,3 @@ +T27732d.hs:4:17: error: [GHC-67297] + Strictness or unpackedness annotations are not allowed in type data declarations. + ===================================== testsuite/tests/type-data/should_fail/TDStrictnessGADT.stderr ===================================== @@ -1,3 +1,3 @@ +TDStrictnessGADT.hs:5:6: error: [GHC-67297] + Strictness or unpackedness annotations are not allowed in type data declarations. -TDStrictnessGADT.hs:5:6: [GHC-67297] - Strictness flags are not allowed in type data declarations. ===================================== testsuite/tests/type-data/should_fail/TDStrictnessH98.stderr ===================================== @@ -1,3 +1,3 @@ +TDStrictnessH98.hs:4:17: error: [GHC-67297] + Strictness or unpackedness annotations are not allowed in type data declarations. -TDStrictnessH98.hs:4:17: [GHC-67297] - Strictness flags are not allowed in type data declarations. ===================================== testsuite/tests/type-data/should_fail/all.T ===================================== @@ -13,3 +13,7 @@ test('TDStrictnessGADT', normal, compile_fail, ['']) test('TDStrictnessH98', normal, compile_fail, ['']) test('TDTagToEnum', normal, compile_fail, ['']) test('T22332b', normal, compile_fail, ['']) +test('T27732a', normal, compile_fail, ['']) +test('T27732b', normal, compile_fail, ['']) +test('T27732c', normal, compile_fail, ['']) +test('T27732d', normal, compile_fail, ['']) View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/76238d25514b322b45939e8ec9bce78… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/76238d25514b322b45939e8ec9bce78… You're receiving this email because of your account on gitlab.haskell.org. 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[Git][ghc/ghc][wip/sjakobi/T27732-type-data-field-annotations] Reject `~` and UNPACK annotations on type data fields
by Simon Jakobi (＠sjakobi) 22 Aug '26

22 Aug '26

Simon Jakobi pushed to branch wip/sjakobi/T27732-type-data-field-annotations at Glasgow Haskell Compiler / GHC Commits: 96a5f054 by Simon Jakobi at 2026-08-22T01:37:46+02:00 Reject `~` and UNPACK annotations on type data fields Widen restriction (R3) of Note [Type data declarations] to any strictness or unpackedness annotation — none of them make sense at the type level — and generalize the check and error message accordingly. Fixes #27732 Assisted-by: Claude Fable 5 - - - - - 15 changed files: - + changelog.d/27732 - compiler/GHC/Rename/Module.hs - compiler/GHC/Tc/Errors/Types.hs - docs/users_guide/exts/type_data.rst - + testsuite/tests/type-data/should_fail/T27732a.hs - + testsuite/tests/type-data/should_fail/T27732a.stderr - + testsuite/tests/type-data/should_fail/T27732b.hs - + testsuite/tests/type-data/should_fail/T27732b.stderr - + testsuite/tests/type-data/should_fail/T27732c.hs - + testsuite/tests/type-data/should_fail/T27732c.stderr - + testsuite/tests/type-data/should_fail/T27732d.hs - + testsuite/tests/type-data/should_fail/T27732d.stderr - testsuite/tests/type-data/should_fail/TDStrictnessGADT.stderr - testsuite/tests/type-data/should_fail/TDStrictnessH98.stderr - testsuite/tests/type-data/should_fail/all.T Changes: ===================================== changelog.d/27732 ===================================== @@ -0,0 +1,8 @@ +section: language +synopsis: Reject `~` and UNPACK annotations on type data fields +description: + ``type data`` declarations (:extension:`TypeData`) now reject any + strictness or unpackedness annotation on constructor fields. + Previously only ``!`` was rejected. +mrs: !16563 +issues: #27732 ===================================== compiler/GHC/Rename/Module.hs ===================================== @@ -71,7 +71,7 @@ import GHC.Data.Graph.Directed ( SCC, flattenSCC, Node(..) , stronglyConnCompFromEdgedVerticesUniq ) import GHC.Data.OrdList import qualified GHC.LanguageExtensions as LangExt -import GHC.Core.DataCon ( isSrcStrict ) +import GHC.Core.DataCon ( SrcStrictness(..), SrcUnpackedness(..) ) import Control.Monad import Data.Bifunctor ( first ) @@ -2116,8 +2116,8 @@ rnDataDefn doc (HsDataDefn { dd_cType = cType, dd_ctxt = context, dd_cons = cond = do { ; when (has_labelled_fields condecl) $ failWith $ TcRnTypeDataForbids TypeDataForbidsLabelledFields - ; when (has_strictness_flags condecl) $ - failWith $ TcRnTypeDataForbids TypeDataForbidsStrictnessAnnotations + ; when (has_field_annotations condecl) $ + failWith $ TcRnTypeDataForbids TypeDataForbidsFieldAnnotations } has_labelled_fields (ConDeclGADT { con_g_args = RecConGADT _ _ }) = True @@ -2125,13 +2125,16 @@ rnDataDefn doc (HsDataDefn { dd_cType = cType, dd_ctxt = context, dd_cons = cond = not (null (unLoc flds)) has_labelled_fields _ = False - has_strictness_flags condecl - = any isSrcStrict (con_arg_bangs condecl) + has_field_annotations condecl + = any is_annotated (con_arg_fields condecl) + where + is_annotated (CDF { cdf_bang = bang, cdf_unpack = unpack }) + = bang /= NoSrcStrict || unpack /= NoSrcUnpack - con_arg_bangs (ConDeclGADT { con_g_args = PrefixConGADT _ args }) = map cdf_bang args - con_arg_bangs (ConDeclH98 { con_args = PrefixCon _ args }) = map cdf_bang args - con_arg_bangs (ConDeclH98 { con_args = InfixCon _ arg1 arg2 }) = [cdf_bang arg1, cdf_bang arg2] - con_arg_bangs _ = [] + con_arg_fields (ConDeclGADT { con_g_args = PrefixConGADT _ args }) = args + con_arg_fields (ConDeclH98 { con_args = PrefixCon _ args }) = args + con_arg_fields (ConDeclH98 { con_args = InfixCon _ arg1 arg2 }) = [arg1, arg2] + con_arg_fields _ = [] {- Note [Type data declarations] @@ -2166,8 +2169,9 @@ preceded by `type`, with the following restrictions: (R2) There are no labelled fields. Perhaps these could be supported using type families, but they are omitted for now. -(R3) There are no strictness flags, because they don't make sense at - the type level. +(R3) There are no strictness or unpackedness annotations (!, ~, + {-# UNPACK #-}, {-# NOUNPACK #-}), because they don't make sense + at the type level. (R4) The types of the constructors contain no constraints. ===================================== compiler/GHC/Tc/Errors/Types.hs ===================================== @@ -2865,6 +2865,10 @@ data TcRnMessage where type-data/should_fail/TDRecordsH98 type-data/should_fail/TDStrictnessGADT type-data/should_fail/TDStrictnessH98 + type-data/should_fail/T27732a + type-data/should_fail/T27732b + type-data/should_fail/T27732c + type-data/should_fail/T27732d -} TcRnTypeDataForbids :: !TypeDataForbids -> TcRnMessage @@ -4523,15 +4527,15 @@ data ZonkerMessage where data TypeDataForbids = TypeDataForbidsDatatypeContexts | TypeDataForbidsLabelledFields - | TypeDataForbidsStrictnessAnnotations + | TypeDataForbidsFieldAnnotations | TypeDataForbidsDerivingClauses deriving Generic instance Outputable TypeDataForbids where - ppr TypeDataForbidsDatatypeContexts = text "Data type contexts" - ppr TypeDataForbidsLabelledFields = text "Labelled fields" - ppr TypeDataForbidsStrictnessAnnotations = text "Strictness flags" - ppr TypeDataForbidsDerivingClauses = text "Deriving clauses" + ppr TypeDataForbidsDatatypeContexts = text "Data type contexts" + ppr TypeDataForbidsLabelledFields = text "Labelled fields" + ppr TypeDataForbidsFieldAnnotations = text "Strictness or unpackedness annotations" + ppr TypeDataForbidsDerivingClauses = text "Deriving clauses" -- | Specifies which back ends can handle a requested foreign import or export type ExpectedBackends = [Backend] ===================================== docs/users_guide/exts/type_data.rst ===================================== @@ -33,7 +33,7 @@ either an ordinary algebraic data type or a GADT, prefixed with the keyword ``type``, except that it may not contain a datatype context (even with :extension:`DatatypeContexts`), labelled fields, -strictness flags, or +:ref:`strictness <strict-haskell>` or :ref:`unpackedness <unpack-pragma>` annotations, or a ``deriving`` clause. The only constraints permitted in the types of constructors are ===================================== testsuite/tests/type-data/should_fail/T27732a.hs ===================================== @@ -0,0 +1,4 @@ +{-# LANGUAGE TypeData, LazyFieldAnnotations #-} +module T27732a where + +type data T a = Cons ~a ===================================== testsuite/tests/type-data/should_fail/T27732a.stderr ===================================== @@ -0,0 +1,3 @@ +T27732a.hs:4:17: error: [GHC-67297] + Strictness or unpackedness annotations are not allowed in type data declarations. + ===================================== testsuite/tests/type-data/should_fail/T27732b.hs ===================================== @@ -0,0 +1,5 @@ +{-# LANGUAGE TypeData, LazyFieldAnnotations #-} +module T27732b where + +type data T a where + Cons :: ~a -> T a ===================================== testsuite/tests/type-data/should_fail/T27732b.stderr ===================================== @@ -0,0 +1,3 @@ +T27732b.hs:5:6: error: [GHC-67297] + Strictness or unpackedness annotations are not allowed in type data declarations. + ===================================== testsuite/tests/type-data/should_fail/T27732c.hs ===================================== @@ -0,0 +1,4 @@ +{-# LANGUAGE TypeData #-} +module T27732c where + +type data T a = Cons {-# UNPACK #-} a ===================================== testsuite/tests/type-data/should_fail/T27732c.stderr ===================================== @@ -0,0 +1,3 @@ +T27732c.hs:4:17: error: [GHC-67297] + Strictness or unpackedness annotations are not allowed in type data declarations. + ===================================== testsuite/tests/type-data/should_fail/T27732d.hs ===================================== @@ -0,0 +1,4 @@ +{-# LANGUAGE TypeData #-} +module T27732d where + +type data T a = Cons {-# NOUNPACK #-} a ===================================== testsuite/tests/type-data/should_fail/T27732d.stderr ===================================== @@ -0,0 +1,3 @@ +T27732d.hs:4:17: error: [GHC-67297] + Strictness or unpackedness annotations are not allowed in type data declarations. + ===================================== testsuite/tests/type-data/should_fail/TDStrictnessGADT.stderr ===================================== @@ -1,3 +1,3 @@ +TDStrictnessGADT.hs:5:6: error: [GHC-67297] + Strictness or unpackedness annotations are not allowed in type data declarations. -TDStrictnessGADT.hs:5:6: [GHC-67297] - Strictness flags are not allowed in type data declarations. ===================================== testsuite/tests/type-data/should_fail/TDStrictnessH98.stderr ===================================== @@ -1,3 +1,3 @@ +TDStrictnessH98.hs:4:17: error: [GHC-67297] + Strictness or unpackedness annotations are not allowed in type data declarations. -TDStrictnessH98.hs:4:17: [GHC-67297] - Strictness flags are not allowed in type data declarations. ===================================== testsuite/tests/type-data/should_fail/all.T ===================================== @@ -13,3 +13,7 @@ test('TDStrictnessGADT', normal, compile_fail, ['']) test('TDStrictnessH98', normal, compile_fail, ['']) test('TDTagToEnum', normal, compile_fail, ['']) test('T22332b', normal, compile_fail, ['']) +test('T27732a', normal, compile_fail, ['']) +test('T27732b', normal, compile_fail, ['']) +test('T27732c', normal, compile_fail, ['']) +test('T27732d', normal, compile_fail, ['']) View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/96a5f05492ab4f5ed4c9f0d999afff1… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/96a5f05492ab4f5ed4c9f0d999afff1… You're receiving this email because of your account on gitlab.haskell.org. 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[Git][ghc/ghc][wip/sjakobi/T27732-type-data-field-annotations] Reject `~` and UNPACK annotations on type data fields
by Simon Jakobi (＠sjakobi) 22 Aug '26

22 Aug '26

Simon Jakobi pushed to branch wip/sjakobi/T27732-type-data-field-annotations at Glasgow Haskell Compiler / GHC Commits: 728dcc2e by Simon Jakobi at 2026-08-22T00:06:33+02:00 Reject `~` and UNPACK annotations on type data fields Widen restriction (R3) of Note [Type data declarations] to any strictness or unpackedness annotation — none of them make sense at the type level — and generalize the check and error message accordingly. Fixes #27732 Assisted-by: Claude Fable 5 - - - - - 15 changed files: - + changelog.d/27732 - compiler/GHC/Rename/Module.hs - compiler/GHC/Tc/Errors/Types.hs - docs/users_guide/exts/type_data.rst - + testsuite/tests/type-data/should_fail/T27732a.hs - + testsuite/tests/type-data/should_fail/T27732a.stderr - + testsuite/tests/type-data/should_fail/T27732b.hs - + testsuite/tests/type-data/should_fail/T27732b.stderr - + testsuite/tests/type-data/should_fail/T27732c.hs - + testsuite/tests/type-data/should_fail/T27732c.stderr - + testsuite/tests/type-data/should_fail/T27732d.hs - + testsuite/tests/type-data/should_fail/T27732d.stderr - testsuite/tests/type-data/should_fail/TDStrictnessGADT.stderr - testsuite/tests/type-data/should_fail/TDStrictnessH98.stderr - testsuite/tests/type-data/should_fail/all.T Changes: ===================================== changelog.d/27732 ===================================== @@ -0,0 +1,8 @@ +section: language +synopsis: Reject `~` and UNPACK annotations on type data fields +description: + ``type data`` declarations (:extension:`TypeData`) now reject any + strictness or unpackedness annotation on constructor fields. + Previously only ``!`` was rejected. +mrs: !16536 +issues: #27732 ===================================== compiler/GHC/Rename/Module.hs ===================================== @@ -71,7 +71,7 @@ import GHC.Data.Graph.Directed ( SCC, flattenSCC, Node(..) , stronglyConnCompFromEdgedVerticesUniq ) import GHC.Data.OrdList import qualified GHC.LanguageExtensions as LangExt -import GHC.Core.DataCon ( isSrcStrict ) +import GHC.Core.DataCon ( SrcStrictness(..), SrcUnpackedness(..) ) import Control.Monad import Data.Bifunctor ( first ) @@ -2116,8 +2116,8 @@ rnDataDefn doc (HsDataDefn { dd_cType = cType, dd_ctxt = context, dd_cons = cond = do { ; when (has_labelled_fields condecl) $ failWith $ TcRnTypeDataForbids TypeDataForbidsLabelledFields - ; when (has_strictness_flags condecl) $ - failWith $ TcRnTypeDataForbids TypeDataForbidsStrictnessAnnotations + ; when (has_field_annotations condecl) $ + failWith $ TcRnTypeDataForbids TypeDataForbidsFieldAnnotations } has_labelled_fields (ConDeclGADT { con_g_args = RecConGADT _ _ }) = True @@ -2125,13 +2125,16 @@ rnDataDefn doc (HsDataDefn { dd_cType = cType, dd_ctxt = context, dd_cons = cond = not (null (unLoc flds)) has_labelled_fields _ = False - has_strictness_flags condecl - = any isSrcStrict (con_arg_bangs condecl) + has_field_annotations condecl + = any is_annotated (con_arg_fields condecl) + where + is_annotated (CDF { cdf_bang = bang, cdf_unpack = unpack }) + = bang /= NoSrcStrict || unpack /= NoSrcUnpack - con_arg_bangs (ConDeclGADT { con_g_args = PrefixConGADT _ args }) = map cdf_bang args - con_arg_bangs (ConDeclH98 { con_args = PrefixCon _ args }) = map cdf_bang args - con_arg_bangs (ConDeclH98 { con_args = InfixCon _ arg1 arg2 }) = [cdf_bang arg1, cdf_bang arg2] - con_arg_bangs _ = [] + con_arg_fields (ConDeclGADT { con_g_args = PrefixConGADT _ args }) = args + con_arg_fields (ConDeclH98 { con_args = PrefixCon _ args }) = args + con_arg_fields (ConDeclH98 { con_args = InfixCon _ arg1 arg2 }) = [arg1, arg2] + con_arg_fields _ = [] {- Note [Type data declarations] @@ -2166,8 +2169,9 @@ preceded by `type`, with the following restrictions: (R2) There are no labelled fields. Perhaps these could be supported using type families, but they are omitted for now. -(R3) There are no strictness flags, because they don't make sense at - the type level. +(R3) There are no strictness or unpackedness annotations (!, ~, + {-# UNPACK #-}, {-# NOUNPACK #-}), because they don't make sense + at the type level. (R4) The types of the constructors contain no constraints. ===================================== compiler/GHC/Tc/Errors/Types.hs ===================================== @@ -2865,6 +2865,10 @@ data TcRnMessage where type-data/should_fail/TDRecordsH98 type-data/should_fail/TDStrictnessGADT type-data/should_fail/TDStrictnessH98 + type-data/should_fail/T27732a + type-data/should_fail/T27732b + type-data/should_fail/T27732c + type-data/should_fail/T27732d -} TcRnTypeDataForbids :: !TypeDataForbids -> TcRnMessage @@ -4523,15 +4527,15 @@ data ZonkerMessage where data TypeDataForbids = TypeDataForbidsDatatypeContexts | TypeDataForbidsLabelledFields - | TypeDataForbidsStrictnessAnnotations + | TypeDataForbidsFieldAnnotations | TypeDataForbidsDerivingClauses deriving Generic instance Outputable TypeDataForbids where - ppr TypeDataForbidsDatatypeContexts = text "Data type contexts" - ppr TypeDataForbidsLabelledFields = text "Labelled fields" - ppr TypeDataForbidsStrictnessAnnotations = text "Strictness flags" - ppr TypeDataForbidsDerivingClauses = text "Deriving clauses" + ppr TypeDataForbidsDatatypeContexts = text "Data type contexts" + ppr TypeDataForbidsLabelledFields = text "Labelled fields" + ppr TypeDataForbidsFieldAnnotations = text "Strictness or unpackedness annotations" + ppr TypeDataForbidsDerivingClauses = text "Deriving clauses" -- | Specifies which back ends can handle a requested foreign import or export type ExpectedBackends = [Backend] ===================================== docs/users_guide/exts/type_data.rst ===================================== @@ -33,7 +33,7 @@ either an ordinary algebraic data type or a GADT, prefixed with the keyword ``type``, except that it may not contain a datatype context (even with :extension:`DatatypeContexts`), labelled fields, -strictness flags, or +:ref:`strictness <strict-haskell>` or :ref:`unpackedness <unpack-pragma>` annotations, or a ``deriving`` clause. The only constraints permitted in the types of constructors are ===================================== testsuite/tests/type-data/should_fail/T27732a.hs ===================================== @@ -0,0 +1,4 @@ +{-# LANGUAGE TypeData, LazyFieldAnnotations #-} +module T27732a where + +type data T a = Cons ~a ===================================== testsuite/tests/type-data/should_fail/T27732a.stderr ===================================== @@ -0,0 +1,3 @@ +T27732a.hs:4:17: error: [GHC-67297] + Strictness or unpackedness annotations are not allowed in type data declarations. + ===================================== testsuite/tests/type-data/should_fail/T27732b.hs ===================================== @@ -0,0 +1,5 @@ +{-# LANGUAGE TypeData, LazyFieldAnnotations #-} +module T27732b where + +type data T a where + Cons :: ~a -> T a ===================================== testsuite/tests/type-data/should_fail/T27732b.stderr ===================================== @@ -0,0 +1,3 @@ +T27732b.hs:5:6: error: [GHC-67297] + Strictness or unpackedness annotations are not allowed in type data declarations. + ===================================== testsuite/tests/type-data/should_fail/T27732c.hs ===================================== @@ -0,0 +1,4 @@ +{-# LANGUAGE TypeData #-} +module T27732c where + +type data T a = Cons {-# UNPACK #-} a ===================================== testsuite/tests/type-data/should_fail/T27732c.stderr ===================================== @@ -0,0 +1,3 @@ +T27732c.hs:4:17: error: [GHC-67297] + Strictness or unpackedness annotations are not allowed in type data declarations. + ===================================== testsuite/tests/type-data/should_fail/T27732d.hs ===================================== @@ -0,0 +1,4 @@ +{-# LANGUAGE TypeData #-} +module T27732d where + +type data T a = Cons {-# NOUNPACK #-} a ===================================== testsuite/tests/type-data/should_fail/T27732d.stderr ===================================== @@ -0,0 +1,3 @@ +T27732d.hs:4:17: error: [GHC-67297] + Strictness or unpackedness annotations are not allowed in type data declarations. + ===================================== testsuite/tests/type-data/should_fail/TDStrictnessGADT.stderr ===================================== @@ -1,3 +1,3 @@ +TDStrictnessGADT.hs:5:6: error: [GHC-67297] + Strictness or unpackedness annotations are not allowed in type data declarations. -TDStrictnessGADT.hs:5:6: [GHC-67297] - Strictness flags are not allowed in type data declarations. ===================================== testsuite/tests/type-data/should_fail/TDStrictnessH98.stderr ===================================== @@ -1,3 +1,3 @@ +TDStrictnessH98.hs:4:17: error: [GHC-67297] + Strictness or unpackedness annotations are not allowed in type data declarations. -TDStrictnessH98.hs:4:17: [GHC-67297] - Strictness flags are not allowed in type data declarations. ===================================== testsuite/tests/type-data/should_fail/all.T ===================================== @@ -13,3 +13,7 @@ test('TDStrictnessGADT', normal, compile_fail, ['']) test('TDStrictnessH98', normal, compile_fail, ['']) test('TDTagToEnum', normal, compile_fail, ['']) test('T22332b', normal, compile_fail, ['']) +test('T27732a', normal, compile_fail, ['']) +test('T27732b', normal, compile_fail, ['']) +test('T27732c', normal, compile_fail, ['']) +test('T27732d', normal, compile_fail, ['']) View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/728dcc2e4be9f8d5df8b38db3e88029… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/728dcc2e4be9f8d5df8b38db3e88029… You're receiving this email because of your account on gitlab.haskell.org. 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[Git][ghc/ghc] Pushed new branch wip/sjakobi/T27732-type-data-field-annotations
by Simon Jakobi (＠sjakobi) 22 Aug '26

22 Aug '26

Simon Jakobi pushed new branch wip/sjakobi/T27732-type-data-field-annotations at Glasgow Haskell Compiler / GHC -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/tree/wip/sjakobi/T27732-type-data-fiel… You're receiving this email because of your account on gitlab.haskell.org. Manage all notifications: https://gitlab.haskell.org/-/profile/notifications | Help: https://gitlab.haskell.org/help

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[Git][ghc/ghc][wip/sjakobi/T16836-implicit-field-strictness] Add -Wimplicit-field-strictness (#16836)
by Simon Jakobi (＠sjakobi) 22 Aug '26

22 Aug '26

Simon Jakobi pushed to branch wip/sjakobi/T16836-implicit-field-strictness at Glasgow Haskell Compiler / GHC Commits: 303103cb by Simon Jakobi at 2026-08-21T23:20:31+02:00 Add -Wimplicit-field-strictness (#16836) This opt-in warning fires when a data constructor field lacks an explicit strictness annotation (`!` or `~`). It complements the LazyFieldAnnotations extension (4762a8bf30f) from GHC proposal 752, which makes `~` annotations available for this purpose. Deciding which fields to report requires their levity, so the check runs after typechecking. To keep the noise down, the diagnostic is emitted once per data declaration, grouped by constructor. Closes #16836. Assisted-by: Claude Fable 5 - - - - - 20 changed files: - + changelog.d/implicit-field-strictness-warning - changelog.d/lazy-field-annotations - compiler/GHC/Driver/Flags.hs - compiler/GHC/Driver/Session.hs - compiler/GHC/Tc/Errors/Ppr.hs - compiler/GHC/Tc/Errors/Types.hs - compiler/GHC/Tc/TyCl.hs - compiler/GHC/Types/Error/Codes.hs - compiler/GHC/Types/Hint.hs - compiler/GHC/Types/Hint/Ppr.hs - docs/users_guide/exts/strict.rst - docs/users_guide/using-warnings.rst - + testsuite/tests/warnings/should_compile/T16836a.hs - + testsuite/tests/warnings/should_compile/T16836a.stderr - + testsuite/tests/warnings/should_compile/T16836b.hs - + testsuite/tests/warnings/should_compile/T16836c.hs - + testsuite/tests/warnings/should_compile/T16836c.stderr - + testsuite/tests/warnings/should_compile/T16836d.hs - + testsuite/tests/warnings/should_compile/T16836d.stderr - testsuite/tests/warnings/should_compile/all.T Changes: ===================================== changelog.d/implicit-field-strictness-warning ===================================== @@ -0,0 +1,10 @@ +section: compiler +synopsis: Add `-Wimplicit-field-strictness` +issues: #16836 +mrs: !16555 + +description: { + The new opt-in warning :ghc-flag:`-Wimplicit-field-strictness` reports + data constructor fields that lack an explicit strictness annotation + (``!`` or ``~``). +} ===================================== changelog.d/lazy-field-annotations ===================================== @@ -11,4 +11,7 @@ description: { continues to control the default strictness of unannotated fields. See `GHC Proposal #752 <https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0752-l…>`_. + + Also note the new opt-in :ghc-flag:`-Wimplicit-field-strictness` warning, which + reports fields lacking an explicit annotation. } ===================================== compiler/GHC/Driver/Flags.hs ===================================== @@ -1142,6 +1142,7 @@ data WarningFlag = | Opt_WarnUnrecognisedModifiers -- ^ @since 10.0 | Opt_WarnSemaphoreOpenFailure -- Since 10.0.1 | Opt_WarnDefaultedCallStack -- ^ @since 10.2 + | Opt_WarnImplicitFieldStrictness -- ^ @since 10.2 deriving (Eq, Ord, Show, Enum, Bounded) -- | Return the names of a WarningFlag @@ -1251,6 +1252,7 @@ warnFlagNames wflag = case wflag of Opt_WarnTypeEqualityRequiresOperators -> "type-equality-requires-operators" :| [] Opt_WarnMissingRoleAnnotations -> "missing-role-annotations" :| [] Opt_WarnImplicitRhsQuantification -> "implicit-rhs-quantification" :| [] + Opt_WarnImplicitFieldStrictness -> "implicit-field-strictness" :| [] Opt_WarnIncompleteExportWarnings -> "incomplete-export-warnings" :| [] Opt_WarnIncompleteRecordSelectors -> "incomplete-record-selectors" :| [] Opt_WarnBadlyLevelledTypes -> "badly-levelled-types" :| [] ===================================== compiler/GHC/Driver/Session.hs ===================================== @@ -2449,6 +2449,7 @@ wWarningFlagsDeps = [minBound..maxBound] >>= \x -> case x of Opt_WarnUnrecognisedModifiers -> warnSpec x Opt_WarnSemaphoreOpenFailure -> warnSpec x Opt_WarnDefaultedCallStack -> warnSpec x + Opt_WarnImplicitFieldStrictness -> warnSpec x warningGroupsDeps :: [(Deprecation, FlagSpec WarningGroup)] warningGroupsDeps = map mk warningGroups ===================================== compiler/GHC/Tc/Errors/Ppr.hs ===================================== @@ -1384,6 +1384,21 @@ instance Diagnostic TcRnMessage where hang (text "Missing role annotation" <> colon) 2 (text "type role" <+> ppr name <+> hsep (map ppr roles)) + TcRnImplicitFieldStrictness _lazy_anns cons -> mkSimpleDecorated $ + hang (text "These constructor fields lack an explicit strictness annotation" <> colon) + 2 (vcat (map ppr_con cons)) + where + ppr_con (con, fields) = + bullet <+> text "In" <+> quotes (ppr con) <> colon <+> ppr_fields fields + ppr_fields fields + | let names = [n | ImplicitStrictnessRecField n <- fields] + , not (null names) + = text "field" <> plural names <+> quotedListWithAnd (map ppr names) + | otherwise + = let poss = [i | ImplicitStrictnessPosField i <- fields] + in text "field" <> plural poss + <+> unquotedListWith (text "and") (map int poss) + TcRnIllformedTypePattern p -> mkSimpleDecorated $ hang (text "Ill-formed type pattern:") 2 (ppr p) @@ -2693,6 +2708,8 @@ instance Diagnostic TcRnMessage where -> ErrorWithoutFlag TcRnMissingRoleAnnotation{} -> WarningWithFlag Opt_WarnMissingRoleAnnotations + TcRnImplicitFieldStrictness{} + -> WarningWithFlag Opt_WarnImplicitFieldStrictness TcRnIllegalInvisTyVarBndr{} -> ErrorWithoutFlag TcRnIllegalWildcardTyVarBndr{} @@ -3428,6 +3445,12 @@ instance Diagnostic TcRnMessage where -> noHints TcRnMissingRoleAnnotation{} -> noHints + TcRnImplicitFieldStrictness lazy_anns _ + -> SuggestExplicitFieldStrictness + : [ useExtensionInOrderTo + (text "to allow" <+> quotes (char '~') <+> text "annotations") + LangExt.LazyFieldAnnotations + | not lazy_anns ] TcRnIllegalInvisTyVarBndr{} -> [suggestExtension LangExt.TypeAbstractions] TcRnIllegalWildcardTyVarBndr{} ===================================== compiler/GHC/Tc/Errors/Types.hs ===================================== @@ -123,6 +123,7 @@ module GHC.Tc.Errors.Types ( , TypeSyntax(..) , typeSyntaxExtension , SuggestLinear(..) + , ImplicitStrictnessField(..) -- * Errors for hs-boot and signature files , BadBootDecls(..) @@ -4235,6 +4236,23 @@ data TcRnMessage where -} TcRnMissingRoleAnnotation :: Name -> [Role] -> TcRnMessage + + {-| TcRnImplicitFieldStrictness is a warning that occurs when a data + constructor field lacks an explicit strictness annotation (@!@ or @~@) + + Controlled by flags: + - Wimplicit-field-strictness + + Test cases: + T16836a, T16836b, T16836c, T16836d + + -} + TcRnImplicitFieldStrictness + :: Bool -- ^ whether @LazyFieldAnnotations@ is enabled + -> [(Name, [ImplicitStrictnessField])] + -- ^ per data constructor, the fields lacking annotations + -> TcRnMessage + {-| TcRnPatersonCondFailure is an error that occurs when an instance declaration fails to conform to the Paterson conditions. Which particular condition fails depends on the constructor of PatersonCondFailure @@ -6399,6 +6417,14 @@ data PatSynInvalidRhsReason | PatSynUnboundVar !Name deriving (Generic) +-- | A constructor field lacking an explicit strictness annotation, as +-- reported by 'TcRnImplicitFieldStrictness'. +data ImplicitStrictnessField + -- | A record field + = ImplicitStrictnessRecField FieldLabelString + -- | A positional argument (1-based index) + | ImplicitStrictnessPosField Int + data BadFieldAnnotationReason where {-| A lazy data type field annotation (~) was used without enabling the extension LazyFieldAnnotations. ===================================== compiler/GHC/Tc/TyCl.hs ===================================== @@ -5022,6 +5022,17 @@ checkValidTyCon tc ; mapM_ (checkValidDataCon dflags ex_ok tc) data_cons ; mapM_ (checkPartialRecordField data_cons) (tyConFieldLabels tc) + ; warn_implicit_strictness <- woptM Opt_WarnImplicitFieldStrictness + ; when (warn_implicit_strictness + && not (isNewTyCon tc) + && not (isTypeDataTyCon tc)) $ + case mapMaybe conImplicitStrictnessFields data_cons of + [] -> return () + offenders -> + do { lazy_anns <- xoptM LangExt.LazyFieldAnnotations + ; addDiagnosticTc $ + TcRnImplicitFieldStrictness lazy_anns offenders } + -- Check that fields with the same name share a type ; mapM_ check_fields groups }} where @@ -5072,6 +5083,30 @@ checkValidTyCon tc res2 = dataConOrigResTy con2 fty2 = dataConFieldType con2 lbl +-- | For a given data constructor, collect the fields to report for +-- @-Wimplicit-field-strictness@. +-- +-- Returns 'Nothing' if there are none, otherwise the constructor's +-- 'Name' together with the offending fields. +-- +-- Only fields whose type is known to be lifted are collected: unlifted +-- fields are unconditionally strict, and annotating one with @!@ or +-- @~@ would trigger @-Wredundant-strictness-flags@. +conImplicitStrictnessFields :: DataCon -> Maybe (Name, [ImplicitStrictnessField]) +conImplicitStrictnessFields con + | null fields = Nothing + | otherwise = Just (dataConName con, fields) + where + fld_refs = case dataConFieldLabels con of + [] -> map ImplicitStrictnessPosField [1..] + lbls -> map (ImplicitStrictnessRecField . flLabel) lbls + fields = [ ref + | (ref, arg_ty, HsSrcBang _ _ NoSrcStrict) + <- zip3 fld_refs + (map scaledThing (dataConOrigArgTys con)) + (dataConSrcBangs con) + , typeLevity_maybe arg_ty == Just Lifted ] + checkPartialRecordField :: [DataCon] -> FieldLabel -> TcM () -- Checks the partial record field selector, and warns. -- See Note [Checking partial record field] ===================================== compiler/GHC/Types/Error/Codes.hs ===================================== @@ -542,6 +542,7 @@ type family GhcDiagnosticCode c = n | n -> c where GhcDiagnosticCode "TcRnNegativeNumTypeLiteral" = 93632 GhcDiagnosticCode "TcRnUnusedQuantifiedTypeVar" = 54180 GhcDiagnosticCode "TcRnMissingRoleAnnotation" = 65490 + GhcDiagnosticCode "TcRnImplicitFieldStrictness" = 47032 GhcDiagnosticCode "TcRnUntickedPromotedThing" = 49957 GhcDiagnosticCode "TcRnIllegalBuiltinSyntax" = 39716 ===================================== compiler/GHC/Types/Hint.hs ===================================== @@ -343,6 +343,14 @@ data GhcHint -} | SuggestAddStandaloneKindSignature Name + {-| Suggests to annotate each constructor field with explicit strictness + (@!@ or @~@). + + Triggered by: 'GHC.Tc.Errors.Types.TcRnImplicitFieldStrictness' + Test case(s): warnings/should_compile/T16836a + -} + | SuggestExplicitFieldStrictness + {-| Suggests the user to fill in the wildcard constraint to disambiguate which constraint that is. ===================================== compiler/GHC/Types/Hint/Ppr.hs ===================================== @@ -185,6 +185,9 @@ instance Outputable GhcHint where -> text "Use a standalone deriving declaration instead" SuggestAddStandaloneKindSignature name -> text "Add a standalone kind signature for" <+> quotes (ppr name) + SuggestExplicitFieldStrictness + -> text "Annotate each field with" <+> quotes (char '!') + <+> text "(strict) or" <+> quotes (char '~') <+> text "(lazy)" SuggestFillInWildcardConstraint -> text "Fill in the wildcard constraint yourself" SuggestAppropriateTHTick ns ===================================== docs/users_guide/exts/strict.rst ===================================== @@ -194,6 +194,9 @@ The ``~`` annotation must be written in prefix form:: See `GHC Proposal #229 <https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0229-w…>`__ for the precise rules. +See also :ghc-flag:`-Wimplicit-field-strictness`, which warns about +fields lacking an explicit annotation. + .. _strict-data: Strict-by-default data types ===================================== docs/users_guide/using-warnings.rst ===================================== @@ -2505,6 +2505,21 @@ of ``-W(no-)*``. In other words the type-class role cannot be accidentally left representational or phantom, which could affected the code correctness. +.. ghc-flag:: -Wimplicit-field-strictness + :shortdesc: warn when constructor fields lack explicit strictness annotations + :type: dynamic + :reverse: -Wno-implicit-field-strictness + :category: + + :since: 10.2.1 + :default: off + + .. index:: + single: strictness annotations, missing + + This warning reports data constructor fields that lack an explicit + strictness annotation (``!`` or ``~``). + .. ghc-flag:: -Wimplicit-rhs-quantification :shortdesc: warn when type variables on the RHS of a type synonym are implicitly quantified :type: dynamic ===================================== testsuite/tests/warnings/should_compile/T16836a.hs ===================================== @@ -0,0 +1,37 @@ +{-# OPTIONS_GHC -Wimplicit-field-strictness #-} +{-# LANGUAGE GADTs #-} +{-# LANGUAGE TypeFamilies #-} +{-# LANGUAGE TypeOperators #-} +module T16836a where + +-- plain multi-constructor data +-- warns for both constructors +data T a = MkT a Bool + | MkT2 !Int a + +-- record with a shared field group +-- warns for x, y and z; not for b +data R = MkR { x, y :: Int, z :: Char, b :: !Bool } + +-- infix constructor +-- warns for the first argument +data I = Int :+: !Bool + +-- GADT syntax +-- warns for the first argument +data G a where + MkG :: Int -> !Bool -> G a + +-- GADT record syntax +-- warns for gx +data GR a where + MkGR :: { gx :: Int, gy :: !Bool } -> GR a + +-- data family instance +-- warns +data family F a +data instance F Int = MkF Char + +-- fully annotated +-- doesn't warn +data S = MkS !Int !Bool ===================================== testsuite/tests/warnings/should_compile/T16836a.stderr ===================================== @@ -0,0 +1,55 @@ +T16836a.hs:9:1: warning: [GHC-47032] [-Wimplicit-field-strictness] + • These constructor fields lack an explicit strictness annotation: + • In ‘MkT’: fields 1 and 2 + • In ‘MkT2’: field 2 + • In the data type declaration for ‘T’ + Suggested fixes: + • Annotate each field with ‘!’ (strict) or ‘~’ (lazy) + • Use the ‘LazyFieldAnnotations’ extension (implied by ‘StrictData’) + to allow ‘~’ annotations + +T16836a.hs:14:1: warning: [GHC-47032] [-Wimplicit-field-strictness] + • These constructor fields lack an explicit strictness annotation: + • In ‘MkR’: fields ‘x’, ‘y’ and ‘z’ + • In the data type declaration for ‘R’ + Suggested fixes: + • Annotate each field with ‘!’ (strict) or ‘~’ (lazy) + • Use the ‘LazyFieldAnnotations’ extension (implied by ‘StrictData’) + to allow ‘~’ annotations + +T16836a.hs:18:1: warning: [GHC-47032] [-Wimplicit-field-strictness] + • These constructor fields lack an explicit strictness annotation: + • In ‘:+:’: field 1 + • In the data type declaration for ‘I’ + Suggested fixes: + • Annotate each field with ‘!’ (strict) or ‘~’ (lazy) + • Use the ‘LazyFieldAnnotations’ extension (implied by ‘StrictData’) + to allow ‘~’ annotations + +T16836a.hs:22:1: warning: [GHC-47032] [-Wimplicit-field-strictness] + • These constructor fields lack an explicit strictness annotation: + • In ‘MkG’: field 1 + • In the data type declaration for ‘G’ + Suggested fixes: + • Annotate each field with ‘!’ (strict) or ‘~’ (lazy) + • Use the ‘LazyFieldAnnotations’ extension (implied by ‘StrictData’) + to allow ‘~’ annotations + +T16836a.hs:27:1: warning: [GHC-47032] [-Wimplicit-field-strictness] + • These constructor fields lack an explicit strictness annotation: + • In ‘MkGR’: field ‘gx’ + • In the data type declaration for ‘GR’ + Suggested fixes: + • Annotate each field with ‘!’ (strict) or ‘~’ (lazy) + • Use the ‘LazyFieldAnnotations’ extension (implied by ‘StrictData’) + to allow ‘~’ annotations + +T16836a.hs:33:1: warning: [GHC-47032] [-Wimplicit-field-strictness] + • These constructor fields lack an explicit strictness annotation: + • In ‘MkF’: field 1 + • In the data family instance declaration for ‘F’ + Suggested fixes: + • Annotate each field with ‘!’ (strict) or ‘~’ (lazy) + • Use the ‘LazyFieldAnnotations’ extension (implied by ‘StrictData’) + to allow ‘~’ annotations + ===================================== testsuite/tests/warnings/should_compile/T16836b.hs ===================================== @@ -0,0 +1,25 @@ +{-# OPTIONS_GHC -Wimplicit-field-strictness #-} +{-# LANGUAGE GADTs #-} +{-# LANGUAGE TypeFamilies #-} +{-# LANGUAGE TypeData #-} +{-# LANGUAGE EmptyDataDecls #-} +{-# LANGUAGE LazyFieldAnnotations #-} +module T16836b where + +-- fully annotated declarations don't warn +data T a = MkT ~a !Bool +data R = MkR { x, y :: !Int, z :: ~Char } +data G a where + MkG :: !Int -> ~Bool -> G a +data family F a +data instance F Int = MkF !Char + +-- newtypes can't have annotations; exempt +newtype N = MkN Int + +-- 'type data' can't have annotations; exempt +type data TD = MkTD Bool + +-- no fields, nothing to annotate +data E +data Nullary = A | B ===================================== testsuite/tests/warnings/should_compile/T16836c.hs ===================================== @@ -0,0 +1,6 @@ +{-# OPTIONS_GHC -Wimplicit-field-strictness #-} +{-# LANGUAGE StrictData #-} +module T16836c where + +-- unannotated fields warn under StrictData too +data T a = MkT a !Bool ~Char ===================================== testsuite/tests/warnings/should_compile/T16836c.stderr ===================================== @@ -0,0 +1,6 @@ +T16836c.hs:6:1: warning: [GHC-47032] [-Wimplicit-field-strictness] + • These constructor fields lack an explicit strictness annotation: + • In ‘MkT’: field 1 + • In the data type declaration for ‘T’ + Suggested fix: Annotate each field with ‘!’ (strict) or ‘~’ (lazy) + ===================================== testsuite/tests/warnings/should_compile/T16836d.hs ===================================== @@ -0,0 +1,20 @@ +{-# OPTIONS_GHC -Wimplicit-field-strictness #-} +{-# LANGUAGE MagicHash #-} +{-# LANGUAGE UnboxedTuples #-} +{-# LANGUAGE UnliftedDatatypes #-} +module T16836d where + +import GHC.Exts + +-- unlifted fields can't be usefully annotated; exempt +data P = MkP Int# (# Int, Int #) + +type UD :: UnliftedType +data UD = MkUD + +-- a field of an unlifted data type is exempt too +data Q = MkQ UD + +-- mixed constructor +-- warns only for the lifted field 2 +data M = MkM Int# Int ===================================== testsuite/tests/warnings/should_compile/T16836d.stderr ===================================== @@ -0,0 +1,9 @@ +T16836d.hs:20:1: warning: [GHC-47032] [-Wimplicit-field-strictness] + • These constructor fields lack an explicit strictness annotation: + • In ‘MkM’: field 2 + • In the data type declaration for ‘M’ + Suggested fixes: + • Annotate each field with ‘!’ (strict) or ‘~’ (lazy) + • Use the ‘LazyFieldAnnotations’ extension (implied by ‘StrictData’) + to allow ‘~’ annotations + ===================================== testsuite/tests/warnings/should_compile/all.T ===================================== @@ -91,3 +91,7 @@ test('T25901_imp_unused_3', [extra_files(['T25901_helper_3.hs'])], multimod_comp test('T25901_imp_unused_4', normal, compile, ['-Wunused-imports']) test('T25901_imp_dodgy_1', [extra_files(['T25901_helper_1.hs'])], multimod_compile, ['T25901_imp_dodgy_1', '-v0 -Wdodgy-imports']) test('T25901_imp_dodgy_2', [extra_files(['T25901_helper_2.hs'])], multimod_compile, ['T25901_imp_dodgy_2', '-v0 -Wdodgy-imports']) +test('T16836a', normal, compile, ['']) +test('T16836b', normal, compile, ['']) +test('T16836c', normal, compile, ['']) +test('T16836d', normal, compile, ['']) View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/303103cb9015da0e1c42335d0d6c787… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/303103cb9015da0e1c42335d0d6c787… You're receiving this email because of your account on gitlab.haskell.org. 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[Git][ghc/ghc][wip/jeltsch/improve-closure-property-check] Re-implement the home unit closure check
by Wolfgang Jeltsch (＠jeltsch) 22 Aug '26

22 Aug '26

Wolfgang Jeltsch pushed to branch wip/jeltsch/improve-closure-property-check at Glasgow Haskell Compiler / GHC Commits: 2341f9e0 by Wolfgang Jeltsch at 2026-08-21T21:51:29+03:00 Re-implement the home unit closure check Resolves #27051. - - - - - 5 changed files: - compiler/GHC/Driver/Downsweep.hs - compiler/GHC/Driver/Errors/Ppr.hs - compiler/GHC/Driver/Errors/Types.hs - compiler/GHC/Unit/Env.hs - compiler/GHC/Unit/External/Index.hs Changes: ===================================== compiler/GHC/Driver/Downsweep.hs ===================================== @@ -54,7 +54,6 @@ import GHC.Runtime.Context import Language.Haskell.Syntax.ImpExp import GHC.Types.UnresolvedImport -import GHC.Data.Graph.Directed import GHC.Data.FastString import GHC.Data.Maybe ( expectJust ) import qualified GHC.Data.Maybe as M @@ -77,7 +76,7 @@ import GHC.Types.Target import GHC.Types.SourceFile import GHC.Types.SourceError import GHC.Types.SrcLoc -import GHC.Types.Unique.Map +import GHC.Types.Unique.Set import GHC.Types.PkgQual import GHC.Types.Basic @@ -91,6 +90,7 @@ import GHC.Unit.Module.Graph import GHC.Unit.Module.Deps import qualified GHC.Unit.Home.Graph as HUG import GHC.Unit.Module.Stage +import GHC.Unit.External.Index import Data.Either ( partitionEithers, lefts ) import qualified Data.Map as Map @@ -260,11 +260,9 @@ downsweep hsc_env diag_wrapper msg old_summaries maybe_base_graph excl_mods allo imps_cache <- newIORef Map.empty (root_errs, root_summaries) <- rootSummariesParallel n_jobs hsc_env diag_wrapper msg (getRootSummary excl_mods summ_cache imps_cache) - let closure_errs = checkHomeUnitsClosed unit_env - unit_env = hsc_unit_env hsc_env - - all_errs = closure_errs ++ root_errs - + let unit_env = hsc_unit_env hsc_env + closure_errs <- checkHomeUnitsClosed unit_env + let all_errs = closure_errs ++ root_errs case all_errs of [] -> do (downsweep_errs, downsweep_nodes) <- @@ -933,52 +931,66 @@ rootSummariesParallel n_jobs hsc_env diag_wrapper msg get_summary = do -- * Check/validate properties and error out -------------------------------------------------------------------------------- --- | This function checks then important property that if both p and q are home units --- then any dependency of p, which transitively depends on q is also a home unit. --- --- See Note [Multiple Home Units], section 'Closure Property'. -checkHomeUnitsClosed :: UnitEnv -> [DriverMessages] -checkHomeUnitsClosed ue - | Set.null bad_unit_ids = [] - | otherwise = [singleMessage $ mkPlainErrorMsgEnvelope rootLoc $ DriverHomePackagesNotClosed (Set.toList bad_unit_ids)] +-- | Checks whether the given unit environment has the closure property. See +-- the section “Closure Property” in @Note [Multiple Home Units]@. +checkHomeUnitsClosed :: UnitEnv -> IO [DriverMessages] +checkHomeUnitsClosed unit_env = do + unit_infos <- globalUnits <$> readIORef (uic_index (ue_uic unit_env)) + return $ case offending_dependencies unit_infos of + [] -> [] + offenders -> [ + singleMessage $ + mkPlainErrorMsgEnvelope error_source_span $ + DriverHomePackagesNotClosed offenders + ] where - home_id_set = HUG.allUnits $ ue_home_unit_graph ue - bad_unit_ids = upwards_closure Set.\\ home_id_set {- Remove all home units reached, keep only bad nodes -} - rootLoc = mkGeneralSrcSpan (fsLit "<command line>") - downwards_closure :: Graph (Node UnitId UnitId) - downwards_closure = graphFromEdgedVerticesUniq graphNodes + home_unit_data :: [(UnitId, HomeUnitEnv)] + home_unit_data = HUG.unitEnv_assocs (ue_home_unit_graph unit_env) - inverse_closure = graphReachability $ transposeG downwards_closure + home_units :: UniqSet UnitId + home_units = mkUniqSet (map fst home_unit_data) - upwards_closure = Set.fromList $ map node_key $ allReachableMany inverse_closure [DigraphNode uid uid [] | uid <- Set.toList home_id_set] + referenced_external_units :: [UnitId] + referenced_external_units + = concatMap (map (toUnitId . fst) . explicitUnits . homeUnitEnv_units . snd) + home_unit_data - all_unit_direct_deps :: UniqMap UnitId (Set.Set UnitId) - all_unit_direct_deps - = HUG.unitEnv_foldWithKey go emptyUniqMap $ ue_home_unit_graph ue - where - go rest this this_uis = - plusUniqMap_C Set.union - (addToUniqMap_C Set.union external_depends this (Set.fromList $ this_deps)) - rest - where - external_depends = mapUniqMap (Set.fromList . unitDepends) (unitInfoMap this_units) - this_units = homeUnitEnv_units this_uis - this_deps = [ toUnitId unit | (unit,Just _) <- explicitUnits this_units] - - graphNodes :: [Node UnitId UnitId] - graphNodes = go Set.empty home_id_set - where - go done todo - = case Set.minView todo of - Nothing -> [] - Just (uid, todo') - | Set.member uid done -> go done todo' - | otherwise -> case lookupUniqMap all_unit_direct_deps uid of - Nothing -> pprPanic "uid not found" (ppr (uid, all_unit_direct_deps)) - Just depends -> - let todo'' = (depends Set.\\ done) `Set.union` todo' - in DigraphNode uid uid (Set.toList depends) : go (Set.insert uid done) todo'' + offending_dependencies :: GlobalUnitInfoMap -> [(UnitId, UnitId)] + offending_dependencies unit_infos + = collect emptyUniqSet referenced_external_units + where + + collect :: UniqSet UnitId -> [UnitId] -> [(UnitId, UnitId)] + collect _ [] = [] + collect processed (current : remaining) + | current `elementOfUniqSet` processed + = collect processed remaining + | otherwise + = let + + needed :: [UnitId] + needed | Just current_infos <- unitInfosOfUnitId current unit_infos + = concatMap unitDepends current_infos + | otherwise + = pprPanic "Unit not found during closure property check" + (ppr current) + + current_offenders :: [(UnitId, UnitId)] + current_offenders + | current `elementOfUniqSet` home_units + = [] + | otherwise + = map ((,) current) $ + nonDetEltsUniqSet $ + mkUniqSet needed `intersectUniqSets` home_units + + in + current_offenders ++ collect (addOneToUniqSet processed current) + (needed ++ remaining) + + error_source_span :: SrcSpan + error_source_span = mkGeneralSrcSpan (fsLit "<command line>") -------------------------------------------------------------------------------- -- * Enable Code Gen for Template Haskell ===================================== compiler/GHC/Driver/Errors/Ppr.hs ===================================== @@ -235,10 +235,17 @@ instance Diagnostic DriverMessage where "but no output will be generated.") $$ (text "There is no module named" <+> quotes (ppr mod_name) <> text ".")) - DriverHomePackagesNotClosed needed_unit_ids - -> mkSimpleDecorated $ vcat ([text "Home units are not closed." - , text "It is necessary to also load the following units:" ] - ++ map (\uid -> text "-" <+> ppr uid) needed_unit_ids) + DriverHomePackagesNotClosed offending_dependencies + -> mkSimpleDecorated $ + hang (text "Some units are not loaded but depend on loaded units.") + 4 + (vcat (map pprDependency offending_dependencies)) + where + + pprDependency :: (UnitId, UnitId) -> SDoc + pprDependency (external_unit, home_unit) + = ppr external_unit <+> arrow <+> ppr home_unit + DriverInterfaceError reason -> diagnosticMessage (ifaceDiagnosticOpts opts) reason DriverInconsistentDynFlags msg ===================================== compiler/GHC/Driver/Errors/Types.hs ===================================== @@ -369,7 +369,7 @@ data DriverMessage where DriverRedirectedNoMain :: !ModuleName -> DriverMessage - DriverHomePackagesNotClosed :: ![UnitId] -> DriverMessage + DriverHomePackagesNotClosed :: ![(UnitId, UnitId)] -> DriverMessage DriverInterfaceError :: !IfaceMessage -> DriverMessage ===================================== compiler/GHC/Unit/Env.hs ===================================== @@ -443,13 +443,11 @@ The flow: Closure Property ---------------- -You must perform a clean cut of the dependency graph. - -> Any dependency which is not a home unit must not (transitively) depend on a home unit. - -For example, if you have three packages p, q and r, then if p depends on q which -depends on r then it is illegal to load both p and r as home units but not q, -because q is a dependency of the home unit p which depends on another home unit r. +A unit environment must have the closure property, which means that, whenever +some units @h₁@ and @h₂@ have been loaded as home units, @h₁@ does not directly +or indirectly depend on an external unit that directly or indirectly depends +on @h₂@. 'GHC.Driver.Downsweep.checkHomeUnitsClosed' checks whether a given unit +environment indeed has this property. Offsetting Paths ---------------- ===================================== compiler/GHC/Unit/External/Index.hs ===================================== @@ -64,6 +64,7 @@ module GHC.Unit.External.Index ( -- * 'GlobalUnitInfoMap' GlobalUnitInfoMap, lookupGlobalUnitInfoMap, + unitInfosOfUnitId, emptyGlobalUnitInfoMap, mkGlobalUnitInfoMap, -- * 'GlobalUnitKey' @@ -287,6 +288,12 @@ lookupGlobalUnitInfoMap (GlobalUnitKey uid abiHash) (GlobalUnitInfoMap globalMap Nothing -> Nothing Just sameUnitId -> Map.lookup abiHash sameUnitId +-- | Lookup all 'UnitInfo' entries of a given 'UnitId'. This can result in more +-- than one 'UnitInfo' only if the given 'UnitId' is a conflicting one. +unitInfosOfUnitId :: UnitId -> GlobalUnitInfoMap -> Maybe [UnitInfo] +unitInfosOfUnitId uid (GlobalUnitInfoMap globalMap) = + Map.elems <$> lookupUniqMap globalMap uid + mkGlobalUnitInfoMap :: [(UnitId, UnitInfo)] -> GlobalUnitInfoMap mkGlobalUnitInfoMap unitInfos = GlobalUnitInfoMap $ listToUniqMap_C Map.union (map mkEntry unitInfos) View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/2341f9e03d2a1d3f51ce582051206e0… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/2341f9e03d2a1d3f51ce582051206e0… You're receiving this email because of your account on gitlab.haskell.org. Manage all notifications: https://gitlab.haskell.org/-/profile/notifications | Help: https://gitlab.haskell.org/help

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[Git][ghc/ghc][wip/jeltsch/improve-closure-property-check] 13 commits: testsuite: Use sigkill in process009.
by Wolfgang Jeltsch (＠jeltsch) 22 Aug '26

22 Aug '26

Wolfgang Jeltsch pushed to branch wip/jeltsch/improve-closure-property-check at Glasgow Haskell Compiler / GHC Commits: fed942ac by Andreas Klebinger at 2026-08-17T12:11:57-04:00 testsuite: Use sigkill in process009. SIGHUB might have been blocked by a (grand)*parent of the test. In such cases the test would fail as the python process would simply exist gracefully instead of committing to a premature end. By using SIGKILL we can rely on the signal not being blocked, fixing #27578 in the process. - - - - - 574c875f by Andreas Klebinger at 2026-08-17T12:12:39-04:00 Simplify comparison in DFM.hs Fixes #27669 - - - - - d8f1a2a3 by Alan Zimmerman at 2026-08-17T12:13:18-04:00 TTG: Add extension points to BooleanFormula They are currently unused, but will be used for exact print annotations next, allowing us to get rid of LocatedBF / SrcSpanAnnBF - - - - - 93a2b20f by Andreas Klebinger at 2026-08-18T04:31:04-04:00 Fix a number of incorrect module references: Fix module reference in Note [DataCon wrappers are conlike]. Fix module reference in Note [Detailed InertCans Invariants]. Fix module reference in Note [GHC's data format representations]. Fix module reference in Note [Grand plan for static forms]. Fix module reference in Note [How tuples work]. Fix module reference in Note [Solved dictionaries]. Fix module reference in Note [Stacktraces from Info Table Provenance Entries (IPE based stack unwinding)]. Fix module reference in Note [The VarBndr type and its uses]. Found the incorrect references with a llm. - - - - - eb0dfb01 by Simon Jakobi at 2026-08-18T04:31:44-04:00 ci: Run stack-hadrian-build only in full-ci pipelines The job exists to catch changes that break hadrian/build-stack (#18726), but nothing in the pipeline depends on it, and it can only break when hadrian's dependencies change. Restricting it to full-ci (like hadrian-multi) still covers marge-bot merge batches, so such breakage cannot reach master unnoticed, while ordinary validate pipelines skip the job. Assisted-by: Claude Fable 5 - - - - - b9160962 by Simon Jakobi at 2026-08-20T14:57:52-04:00 testsuite: Show baseline sample count and range in perf failures A perf baseline is the mean of all samples recorded for a commit, and it prints as a single number, hiding how far the samples spread. When the spread is wide, this can indicate an unstable metric that isn't actually useful as a signal for the perf tests. For example, in #27602, T27336's peak_megabytes_allocated baseline showed as 757 when the underlying samples were 605 and 909. When the baseline is averaged from more than one sample, say so in the failure output: the one-line stat-failure reason shows the sample range, and the detail block lists the raw samples. Single-sample baselines print exactly as before. Context: #27602 Assisted-by: Claude Fable 5 - - - - - a4979877 by Simon Jakobi at 2026-08-20T14:57:52-04:00 testsuite: Fold Baseline into CommitMetric A Baseline was just a CommitMetric plus the commit it came from, built by copying fields across. Since get_commit_metric already knows that commit, record it on CommitMetric itself and drop Baseline. This also collapses both branches of find_baseline into plain returns. Assisted-by: Claude Fable 5 - - - - - 99fb8d68 by Simon Jakobi at 2026-08-20T14:57:52-04:00 ci: Clarify comment on pushing perf notes after failures Context: #27602 Assisted-by: Claude Fable 5 - - - - - 2ca87972 by Alan Zimmerman at 2026-08-20T14:58:36-04:00 EPA: Remove LocatedBC / SrcSpanBF The custom annotations are now in the BooleanFormula TTG extension points, so LBooleanFormula can now use the standard LocatedA. - - - - - d2bc32aa by Simon Peyton Jones at 2026-08-21T12:59:26-04:00 Better handling of serialisation of wired-in names Fixes #27501 - - - - - d2795ffc by Alan Zimmerman at 2026-08-21T13:00:05-04:00 EPA: Remove NoEpTok/NoEpUniTok, using an unhelpful SrcSpan instead Also introduce helper functions noEpTok and noEpUniTok to serve as simple replacements in code inserting an token annotation without location information. - - - - - 0972cf68 by Wolfgang Jeltsch at 2026-08-21T21:04:47+03:00 Improve documentation related to the closure property - - - - - 95a4624b by Wolfgang Jeltsch at 2026-08-21T21:45:16+03:00 Re-implement the home unit closure check Resolves #27051. - - - - - 71 changed files: - .gitlab-ci.yml - .gitlab/ci.sh - compiler/GHC/Builtin.hs - compiler/GHC/Builtin/WiredIn/Types.hs - compiler/GHC/CmmToAsm/Format.hs - compiler/GHC/Core/Class.hs - compiler/GHC/CoreToIface.hs - compiler/GHC/Data/BooleanFormula.hs - compiler/GHC/Data/Word64Map/Internal.hs - compiler/GHC/Data/Word64Map/Lazy.hs - compiler/GHC/Data/Word64Map/Strict.hs - compiler/GHC/Data/Word64Map/Strict/Internal.hs - compiler/GHC/Driver/Downsweep.hs - compiler/GHC/Driver/Errors/Ppr.hs - compiler/GHC/Driver/Errors/Types.hs - compiler/GHC/Driver/GenerateCgIPEStub.hs - compiler/GHC/Hs.hs - compiler/GHC/Hs/Dump.hs - compiler/GHC/Hs/Utils.hs - compiler/GHC/Iface/Binary.hs - compiler/GHC/Iface/Ext/Ast.hs - compiler/GHC/Iface/Syntax.hs - compiler/GHC/Iface/Tidy/StaticPtrTable.hs - compiler/GHC/IfaceToCore.hs - compiler/GHC/Parser.y - compiler/GHC/Parser/Annotation.hs - compiler/GHC/Parser/PostProcess.hs - compiler/GHC/Tc/Solver/InertSet.hs - compiler/GHC/Tc/TyCl/Class.hs - compiler/GHC/Types/Id/Make.hs - compiler/GHC/Types/Unique/DFM.hs - compiler/GHC/Types/Var.hs - compiler/GHC/Unit/Env.hs - compiler/GHC/Unit/External/Index.hs - compiler/Language/Haskell/Syntax/BooleanFormula.hs - compiler/Language/Haskell/Syntax/Extension.hs - testsuite/driver/perf_notes.py - testsuite/driver/testglobals.py - testsuite/tests/ghc-api/exactprint/T22919.stderr - testsuite/tests/ghc-api/exactprint/Test20239.stderr - testsuite/tests/ghc-api/exactprint/ZeroWidthSemi.stderr - testsuite/tests/haddock/should_compile_flag_haddock/T17544.stderr - testsuite/tests/haddock/should_compile_flag_haddock/T17544_kw.stderr - testsuite/tests/haddock/should_compile_flag_haddock/T24221.stderr - testsuite/tests/module/mod185.stderr - testsuite/tests/parser/should_compile/DumpParsedAst.stderr - testsuite/tests/parser/should_compile/DumpParsedAstComments.stderr - testsuite/tests/parser/should_compile/DumpRenamedAst.stderr - testsuite/tests/parser/should_compile/DumpSemis.stderr - testsuite/tests/parser/should_compile/DumpTypecheckedAst.stderr - testsuite/tests/parser/should_compile/KindSigs.stderr - testsuite/tests/parser/should_compile/T14189.stderr - testsuite/tests/parser/should_compile/T15323.stderr - testsuite/tests/parser/should_compile/T20452.stderr - testsuite/tests/parser/should_compile/T20718.stderr - testsuite/tests/parser/should_compile/T20718b.stderr - testsuite/tests/parser/should_compile/T20846.stderr - testsuite/tests/parser/should_compile/T23315/T23315.stderr - testsuite/tests/printer/AnnotationNoListTuplePuns.stdout - testsuite/tests/printer/T18791.stderr - testsuite/tests/printer/Test20297.stdout - testsuite/tests/printer/Test24533.stdout - testsuite/tests/process/process009.hs - testsuite/tests/process/process009.stdout - utils/check-exact/ExactPrint.hs - utils/check-exact/Parsers.hs - utils/check-exact/Transform.hs - utils/check-exact/Utils.hs - utils/haddock/haddock-api/src/Haddock/Backends/Xhtml/Decl.hs - utils/haddock/haddock-api/src/Haddock/Interface/Rename.hs - utils/haddock/haddock-api/src/Haddock/Types.hs The diff was not included because it is too large. View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/af6db0b6b81b12ddcbd35644c836be… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/af6db0b6b81b12ddcbd35644c836be… You're receiving this email because of your account on gitlab.haskell.org. Manage all notifications: https://gitlab.haskell.org/-/profile/notifications | Help: https://gitlab.haskell.org/help

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[Git][ghc/ghc] Pushed new branch wip/davide/io_uring
by David Eichmann (＠DavidEichmann) 22 Aug '26

22 Aug '26

David Eichmann pushed new branch wip/davide/io_uring at Glasgow Haskell Compiler / GHC -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/tree/wip/davide/io_uring You're receiving this email because of your account on gitlab.haskell.org. Manage all notifications: https://gitlab.haskell.org/-/profile/notifications | Help: https://gitlab.haskell.org/help

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[Git][ghc/ghc][master] EPA: Remove NoEpTok/NoEpUniTok, using an unhelpful SrcSpan instead
by Marge Bot (＠marge-bot) 22 Aug '26

22 Aug '26

Marge Bot pushed to branch master at Glasgow Haskell Compiler / GHC Commits: d2795ffc by Alan Zimmerman at 2026-08-21T13:00:05-04:00 EPA: Remove NoEpTok/NoEpUniTok, using an unhelpful SrcSpan instead Also introduce helper functions noEpTok and noEpUniTok to serve as simple replacements in code inserting an token annotation without location information. - - - - - 35 changed files: - compiler/GHC/Hs.hs - compiler/GHC/Hs/Dump.hs - compiler/GHC/Hs/Utils.hs - compiler/GHC/Parser.y - compiler/GHC/Parser/Annotation.hs - compiler/GHC/Parser/PostProcess.hs - testsuite/tests/ghc-api/exactprint/T22919.stderr - testsuite/tests/ghc-api/exactprint/Test20239.stderr - testsuite/tests/ghc-api/exactprint/ZeroWidthSemi.stderr - testsuite/tests/haddock/should_compile_flag_haddock/T17544.stderr - testsuite/tests/haddock/should_compile_flag_haddock/T17544_kw.stderr - testsuite/tests/haddock/should_compile_flag_haddock/T24221.stderr - testsuite/tests/module/mod185.stderr - testsuite/tests/parser/should_compile/DumpParsedAst.stderr - testsuite/tests/parser/should_compile/DumpParsedAstComments.stderr - testsuite/tests/parser/should_compile/DumpRenamedAst.stderr - testsuite/tests/parser/should_compile/DumpSemis.stderr - testsuite/tests/parser/should_compile/DumpTypecheckedAst.stderr - testsuite/tests/parser/should_compile/KindSigs.stderr - testsuite/tests/parser/should_compile/T14189.stderr - testsuite/tests/parser/should_compile/T15323.stderr - testsuite/tests/parser/should_compile/T20452.stderr - testsuite/tests/parser/should_compile/T20718.stderr - testsuite/tests/parser/should_compile/T20718b.stderr - testsuite/tests/parser/should_compile/T20846.stderr - testsuite/tests/parser/should_compile/T23315/T23315.stderr - testsuite/tests/printer/AnnotationNoListTuplePuns.stdout - testsuite/tests/printer/T18791.stderr - testsuite/tests/printer/Test20297.stdout - testsuite/tests/printer/Test24533.stdout - utils/check-exact/ExactPrint.hs - utils/check-exact/Parsers.hs - utils/check-exact/Transform.hs - utils/check-exact/Utils.hs - utils/haddock/haddock-api/src/Haddock/Types.hs The diff was not included because it is too large. View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/d2795ffc9abb4d44d08b84ca4559f8e… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/d2795ffc9abb4d44d08b84ca4559f8e… You're receiving this email because of your account on gitlab.haskell.org. Manage all notifications: https://gitlab.haskell.org/-/profile/notifications | Help: https://gitlab.haskell.org/help

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[Git][ghc/ghc][master] Better handling of serialisation of wired-in names
by Marge Bot (＠marge-bot) 22 Aug '26

22 Aug '26

Marge Bot pushed to branch master at Glasgow Haskell Compiler / GHC Commits: d2bc32aa by Simon Peyton Jones at 2026-08-21T12:59:26-04:00 Better handling of serialisation of wired-in names Fixes #27501 - - - - - 2 changed files: - compiler/GHC/Builtin.hs - compiler/GHC/Iface/Binary.hs Changes: ===================================== compiler/GHC/Builtin.hs ===================================== @@ -27,8 +27,7 @@ module GHC.Builtin ( knownKeyOccName, knownKeyOccName_maybe, -- * Known names - lookupWiredInKnownKeyName, - lookupKnownNameInfo, + wiredInNamesMap, lookupKnownNameInfo, -- * Random other things maybeCharLikeCon, maybeIntLikeCon, @@ -45,7 +44,6 @@ module GHC.Builtin ( import GHC.Prelude -import GHC.Builtin.Uniques import GHC.Builtin.PrimOps import GHC.Builtin.PrimOps.Ids import GHC.Builtin.WiredIn.Types @@ -76,9 +74,6 @@ import GHC.Data.List.SetOps import GHC.Data.FastString import qualified GHC.Data.List.Infinite as Inf -import Control.Applicative ((<|>)) - - {- ********************************************************************* * * @@ -624,7 +619,7 @@ See also wiredInNames :: [Name] wiredInNames | debugIsOn - , Just badNamesDoc <- knownKeyNamesOkay all_names + , Just badNamesDoc <- wiredInNamesOkay all_names = pprPanic "badAllKnownKeyNames" badNamesDoc | otherwise = all_names @@ -672,8 +667,8 @@ wiredInNames -- | Check the known-key names list of consistency. -- (a) Unique is in-range -- (b) Distinct uniques -knownKeyNamesOkay :: [Name] -> Maybe SDoc -knownKeyNamesOkay all_names +wiredInNamesOkay :: [Name] -> Maybe SDoc +wiredInNamesOkay all_names | ns@(_:_) <- filter (not . isValidKnownKeyUnique . getUnique) all_names = Just $ text " Out-of-range known-key uniques: " <> brackets (pprWithCommas (ppr . nameOccName) ns) @@ -697,15 +692,6 @@ knownKeyNamesOkay all_names text ": " <> brackets (pprWithCommas (ppr . nameOccName) ns) --- | Given a 'Unique' lookup its associated 'Name' if it corresponds to a --- wired-in thing. --- --- See Note [Symbol table representation of names] for when this function is --- used to reconstruct a wired-in name from its unique -lookupWiredInKnownKeyName :: Unique -> Maybe Name -lookupWiredInKnownKeyName u = - knownUniqueTupleName u <|> lookupUFM_Directly wiredInNamesMap u - -- | Maps 'Unique's to wired-in known-key names. -- -- The type is @UniqFM Name Name@ to denote that the 'Unique's used ===================================== compiler/GHC/Iface/Binary.hs ===================================== @@ -32,7 +32,9 @@ module GHC.Iface.Binary ( import GHC.Prelude -import GHC.Builtin ( knownKeyOccMap, lookupWiredInKnownKeyName ) +import GHC.Builtin ( knownKeyOccMap, wiredInNamesMap ) +import GHC.Builtin.Uniques( knownUniqueTupleName ) + import GHC.Utils.Panic import GHC.Utils.Binary as Binary import GHC.Utils.Outputable @@ -41,6 +43,7 @@ import GHC.Types.Name import GHC.Types.Unique import GHC.Types.SrcLoc import GHC.Types.Name.Cache +import GHC.Types.Unique.FM import GHC.Unit import GHC.Unit.Module.ModIface @@ -721,25 +724,84 @@ getSymbolTable bh name_cache = do {- Note [Symbol table representation of names] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -An occurrence of a name in an interface file is serialized as a single 32-bit -word. The format of this word is: - 00xxxxxx xxxxxxxx xxxxxxxx xxxxxxxx - A normal name. x is an index into the symbol table - 10xxxxxx xxyyyyyy yyyyyyyy yyyyyyyy - A wired-in name. x is the Unique's Char, y is the int part. We assume that - all wired-in known-key uniques fit in this space. This is asserted by - GHC.Builtin.knownKeyNamesOkay. - -During serialization we check for tuples or wired-in things with 'lookupWiredInKnownKeyName'. -During deserialization we use 'lookupWiredInKnownKeyName' to get from the -unique back to its tuple or corresponding Name. We use the same oracle function -in both directions to make sure it is symmetric. - -Tuples are a special case of wired-in names that we can construct from the -unique alone (see 'knownUniqueTupleName'). Tuples aren't included in the -wired-in names map: see Note [Infinite families of known-key names]. +For serialisation we divide Names into two classes: + * Compact Names are serialised simply as their unique. + * Non-compact Names are entered into the Symbol Table of the interface file, + and serialised as the index into that table + +In more detail: +* Compact Names comprise + - All WiredIn Names + - All Names related to tuples, whether WiredIn or not. See (ST2) below. + +* The key property of a compact Name is that GHC can compute the Name from + its Unique, via `lookupCompactName`: + - For most wired-in names, we look up in the `wiredInNameMap`. + - For names related to tuples, we use `knownUniqueTupleName` + Tuples aren't included in the wired-in names map: see (ST1) below + +* Serialisation is done by `putName`: + - When we serialise a compact Name, + we serialise it as a single 32-bit word: + 10xxxxxx xxyyyyyy yyyyyyyy yyyyyyyy + where xxxx is the tag, and yyyy is the payload. + The function `wiredInNamesOkay` checks that the wired-in names all have + uniques that fit into the `yyy` field. + + - When we serialise a non-compact name: + - We look it up in the (stateful, growing) symbol table + - If it not there we add it to the symbol table + - We serialise the occurrenc to a single 32-bit word: + 00xxxxxx xxxxxxxx xxxxxxxx xxxxxxxx + where `xxxxx` is an index into the symbol table. + +* Deserialision is done by `getName`. We read a 32-bit word + - If the MSB is `10` it must be a compact name, so we use + `lookupCompactName` to get from the Unique to the Name. + - If the MSB is `00` it must be a non-compact Name, + so we look it up in the symbol table. + +Wrinkles: + +(ST1) There are many, many tuple types and constructors, so we don't put + them in the wiredInNameMap. Instead we put them in a distinct part of the + Unique namespace, and provide + knownUniqueTupleName :: Unique -> Maybe Name + to identify such a Unique and map it to the corresponding Name. + See Note [Infinite families of known-key names]. + +(ST2) A wired-in data constructor, like (#,#) has a related, also wired-in + (promoted) type constructor; see `mkPromotedDataCon`. That type constructor + in turn contains its `TyConRepName` (e.g. $tc'(#,#)) to support Typeable. + + That `TyConRepName` is built by `mkPrelTyConRepName`, but it is /not/ + wired-in. Why not? Because its definition involves fingerprints etc. (Maybe + it could be made wired-in, but it would tricky, and there is no point.) + + Nevertheless, although it is not wired-in, it is /compact/; that is, we can + serialise and de-serialise it using the mechanisms above. + + This idea is, however, entirely optional. You could delete the line in + `isCompactName` that tests for `knownUniqueTupleName` and then the + TyConRepNames would be serialised as non-compact names, and everything would + work. Fewer tests, but Typeable-heavy code might have bigger interface files. -} +isCompactName :: Name -> Bool +-- See Note [Symbol table representation of names] +isCompactName n + | isWiredInName n = True -- This will catch tuples too! + | isJust (knownUniqueTupleName (nameUnique n)) = True -- Optional: see wrinkle (ST2) + | otherwise = False + +lookupCompactName :: Unique -> Name +-- See Note [Symbol table representation of names] +lookupCompactName u + | Just n <- knownUniqueTupleName u = n -- See wrinkle (ST1) + | Just n <- lookupUFM_Directly wiredInNamesMap u = n + | otherwise = pprPanic "lookupCompactName" (ppr u $$ char tag $$ ppr ix) + where + (tag, ix) = unpkUniqueGrimily u -- See Note [Symbol table representation of names] putName :: BinSymbolTable -> WriteBinHandle -> Name -> IO () @@ -747,7 +809,7 @@ putName BinSymbolTable{ bin_symtab_map = symtab_map_ref, bin_symtab_next = symtab_next } bh name - | Just _ <- lookupWiredInKnownKeyName (nameUnique name) + | isCompactName name , let (c, u) = unpkUniqueGrimily (nameUnique name) -- INVARIANT: (ord c) fits in 8 bits = -- assert (u < 2^(22 :: Int)) put_ bh (0x80000000 @@ -783,16 +845,10 @@ getSymtabName symtab bh = do i :: Word32 <- get bh case i .&. 0xC0000000 of 0x00000000 -> return $! symtab ! fromIntegral i - - 0x80000000 -> - let + 0x80000000 -> return $! lookupCompactName u + where tag = chr (fromIntegral ((i .&. 0x3FC00000) `shiftR` 22)) ix = fromIntegral i .&. 0x003FFFFF u = mkUniqueGrimilyWithTag tag ix - in - return $! case lookupWiredInKnownKeyName u of - Nothing -> pprPanic "getSymtabName:unknown known-key unique" - (ppr i $$ ppr u $$ char tag $$ ppr ix) - Just n -> n _ -> pprPanic "getSymtabName:unknown name tag" (ppr i) View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/d2bc32aa4ac13ae1cc1770e6f11db73… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/d2bc32aa4ac13ae1cc1770e6f11db73… You're receiving this email because of your account on gitlab.haskell.org. 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