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[Git][ghc/ghc] Deleted branch wip/bump-submodules-2603
by Cheng Shao (＠TerrorJack) 10 Apr '26

10 Apr '26

Cheng Shao deleted branch wip/bump-submodules-2603 at Glasgow Haskell Compiler / GHC -- You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/10.1] 7 commits: Release notes for GHC 10.0
by Zubin (＠wz1000) 10 Apr '26

10 Apr '26

Zubin pushed to branch wip/10.1 at Glasgow Haskell Compiler / GHC Commits: 9ad47b85 by Zubin Duggal at 2026-04-10T14:43:10+05:30 Release notes for GHC 10.0 - - - - - 6521096a by Zubin Duggal at 2026-04-10T14:43:10+05:30 Bump ghc-prim version to 0.14.0 - - - - - fe6aad3a by Zubin Duggal at 2026-04-10T14:43:10+05:30 Bump template-haskell to 2.25.0.0; update submodule exceptions for TH 2.25 - - - - - 83cc93e9 by Zubin Duggal at 2026-04-10T14:43:10+05:30 Bump GHC version to 10.0 - - - - - 6e966202 by Zubin Duggal at 2026-04-10T14:43:36+05:30 Bump base to 4.23.0.0; update submodules for base 4.24 upper bound - - - - - 77758465 by Zubin Duggal at 2026-04-10T14:43:37+05:30 Bump GHC version to 10.1; update submodules template-haskell-lift and template-haskell-quasiquoter for ghc-internal 10.200 - - - - - 4638ffef by Zubin Duggal at 2026-04-10T14:43:37+05:30 Use changelog.d for release notes (#26002) GHC now uses a fragment-based changelog workflow using a custom script adapted from https://codeberg.org/fgaz/changelog-d. Contributors add a file in changelog.d/ for each user-facing change. At release time, these are assembled into release notes for sphinx (in RST) format, using the tool. New hadrian `changelog` target to generate changelogs CI job to validate changelog entries for MRs unless skipped with ~"no-changelog" label Teach sphinx about ghc-mr: extlink to link to MRs Remove `ghc-package-list` from sphinx, and implement it in changelog-d instead (Fixes #26476). (cherry picked from commit 989c07249978f418dfde1353abfad453f024d61a) - - - - - 64 changed files: - .gitlab-ci.yml - .gitlab/issue_templates/release_tracking.md - .gitlab/merge_request_templates/Default.md - + changelog.d/changelog-entries - + changelog.d/config - compiler/ghc.cabal.in - configure.ac - − docs/users_guide/10.0.1-notes.rst - + docs/users_guide/10.2.1-notes.rst - − docs/users_guide/9.16.1-notes.rst - docs/users_guide/conf.py - docs/users_guide/ghc_config.py.in - − docs/users_guide/ghc_packages.py - docs/users_guide/release-notes.rst - ghc/ghc-bin.cabal.in - hadrian/hadrian.cabal - hadrian/src/CommandLine.hs - hadrian/src/Main.hs - hadrian/src/Packages.hs - + hadrian/src/Rules/Changelog.hs - hadrian/src/Rules/Documentation.hs - hadrian/src/Rules/Test.hs - hadrian/src/Settings/Default.hs - libraries/array - libraries/base/base.cabal.in - libraries/deepseq - libraries/directory - libraries/exceptions - libraries/filepath - libraries/ghc-boot-th/ghc-boot-th.cabal.in - libraries/ghc-boot/ghc-boot.cabal.in - libraries/ghc-compact/ghc-compact.cabal - libraries/ghc-experimental/ghc-experimental.cabal.in - libraries/ghc-prim/changelog.md - libraries/ghc-prim/ghc-prim.cabal - libraries/ghci/ghci.cabal.in - libraries/haskeline - libraries/hpc - libraries/os-string - libraries/parsec - libraries/process - libraries/semaphore-compat - libraries/stm - libraries/template-haskell-lift - libraries/template-haskell-quasiquoter - libraries/template-haskell/template-haskell.cabal.in - libraries/terminfo - libraries/unix - m4/fp_setup_project_version.m4 - m4/fptools_ghc_version.m4 - testsuite/mk/boilerplate.mk - testsuite/tests/linters/Makefile - testsuite/tests/linters/all.T - + testsuite/tests/linters/changelog-d.stdout - + utils/changelog-d/ChangelogD.hs - + utils/changelog-d/LICENSE - + utils/changelog-d/README.md - + utils/changelog-d/changelog-d.cabal - utils/haddock/haddock-api/haddock-api.cabal - utils/haddock/haddock-api/src/Haddock/InterfaceFile.hs - utils/haddock/haddock-library/haddock-library.cabal - utils/haddock/haddock-test/haddock-test.cabal - utils/haddock/haddock.cabal - utils/hsc2hs The diff was not included because it is too large. View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/bc104b4ed67bc0968c9c38b19e4aba… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/bc104b4ed67bc0968c9c38b19e4aba… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/10.1] 9 commits: hadrian: Add template-haskell-lift and template-haskell-quasiquoter to ghci-multi targets
by Zubin (＠wz1000) 10 Apr '26

10 Apr '26

Zubin pushed to branch wip/10.1 at Glasgow Haskell Compiler / GHC Commits: c78d1a8c by Zubin Duggal at 2026-04-10T13:33:14+05:30 hadrian: Add template-haskell-lift and template-haskell-quasiquoter to ghci-multi targets - - - - - 5eca095b by Zubin Duggal at 2026-04-10T13:33:14+05:30 Bump os-string submodule to 2.0.10 - - - - - 60583c7d by Zubin Duggal at 2026-04-10T13:33:14+05:30 Release notes for GHC 10.0 - - - - - 62ba2dfc by Zubin Duggal at 2026-04-10T13:33:14+05:30 Bump ghc-prim version to 0.14.0 - - - - - 09419f5e by Zubin Duggal at 2026-04-10T13:33:14+05:30 Bump template-haskell to 2.25.0.0; update submodule exceptions for TH 2.25 - - - - - 79da036d by Zubin Duggal at 2026-04-10T13:33:14+05:30 Bump GHC version to 10.0 - - - - - 25cddb6d by Zubin Duggal at 2026-04-10T13:33:14+05:30 Bump base to 4.23.0.0; update submodules for base 4.24 upper bound - - - - - 4ae1c2d8 by Zubin Duggal at 2026-04-10T13:33:14+05:30 Bump GHC version to 10.1; update submodules template-haskell-lift and template-haskell-quasiquoter for ghc-internal 10.200 - - - - - bc104b4e by Zubin Duggal at 2026-04-10T13:33:14+05:30 Use changelog.d for release notes (#26002) GHC now uses a fragment-based changelog workflow using a custom script adapted from https://codeberg.org/fgaz/changelog-d. Contributors add a file in changelog.d/ for each user-facing change. At release time, these are assembled into release notes for sphinx (in RST) format, using the tool. New hadrian `changelog` target to generate changelogs CI job to validate changelog entries for MRs unless skipped with ~"no-changelog" label Teach sphinx about ghc-mr: extlink to link to MRs Remove `ghc-package-list` from sphinx, and implement it in changelog-d instead (Fixes #26476). (cherry picked from commit 989c07249978f418dfde1353abfad453f024d61a) - - - - - 65 changed files: - .gitlab-ci.yml - .gitlab/issue_templates/release_tracking.md - .gitlab/merge_request_templates/Default.md - + changelog.d/changelog-entries - + changelog.d/config - compiler/ghc.cabal.in - configure.ac - − docs/users_guide/10.0.1-notes.rst - + docs/users_guide/10.2.1-notes.rst - − docs/users_guide/9.16.1-notes.rst - docs/users_guide/conf.py - docs/users_guide/ghc_config.py.in - − docs/users_guide/ghc_packages.py - docs/users_guide/release-notes.rst - ghc/ghc-bin.cabal.in - hadrian/hadrian.cabal - hadrian/src/CommandLine.hs - hadrian/src/Main.hs - hadrian/src/Packages.hs - + hadrian/src/Rules/Changelog.hs - hadrian/src/Rules/Documentation.hs - hadrian/src/Rules/Test.hs - hadrian/src/Rules/ToolArgs.hs - hadrian/src/Settings/Default.hs - libraries/array - libraries/base/base.cabal.in - libraries/deepseq - libraries/directory - libraries/exceptions - libraries/filepath - libraries/ghc-boot-th/ghc-boot-th.cabal.in - libraries/ghc-boot/ghc-boot.cabal.in - libraries/ghc-compact/ghc-compact.cabal - libraries/ghc-experimental/ghc-experimental.cabal.in - libraries/ghc-prim/changelog.md - libraries/ghc-prim/ghc-prim.cabal - libraries/ghci/ghci.cabal.in - libraries/haskeline - libraries/hpc - libraries/os-string - libraries/parsec - libraries/process - libraries/semaphore-compat - libraries/stm - libraries/template-haskell-lift - libraries/template-haskell-quasiquoter - libraries/template-haskell/template-haskell.cabal.in - libraries/terminfo - libraries/unix - m4/fp_setup_project_version.m4 - m4/fptools_ghc_version.m4 - testsuite/mk/boilerplate.mk - testsuite/tests/linters/Makefile - testsuite/tests/linters/all.T - + testsuite/tests/linters/changelog-d.stdout - + utils/changelog-d/ChangelogD.hs - + utils/changelog-d/LICENSE - + utils/changelog-d/README.md - + utils/changelog-d/changelog-d.cabal - utils/haddock/haddock-api/haddock-api.cabal - utils/haddock/haddock-api/src/Haddock/InterfaceFile.hs - utils/haddock/haddock-library/haddock-library.cabal - utils/haddock/haddock-test/haddock-test.cabal - utils/haddock/haddock.cabal - utils/hsc2hs The diff was not included because it is too large. View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/510a4ac7b8ac302ce4f4e389936c19… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/510a4ac7b8ac302ce4f4e389936c19… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/10.1] 4 commits: Bump GHC version to 10.0
by Zubin (＠wz1000) 10 Apr '26

10 Apr '26

Zubin pushed to branch wip/10.1 at Glasgow Haskell Compiler / GHC Commits: f2fb4a35 by Zubin Duggal at 2026-04-10T10:09:29+05:30 Bump GHC version to 10.0 - - - - - fa9e64e8 by Zubin Duggal at 2026-04-10T10:09:30+05:30 Bump base to 4.23.0.0; update submodules for base 4.24 upper bound - - - - - 9ed5abb8 by Zubin Duggal at 2026-04-10T10:09:30+05:30 Bump GHC version to 10.1; update submodules template-haskell-lift and template-haskell-quasiquoter for ghc-internal 10.200 - - - - - 510a4ac7 by Zubin Duggal at 2026-04-10T10:09:30+05:30 Use changelog.d for release notes (#26002) GHC now uses a fragment-based changelog workflow using a custom script adapted from https://codeberg.org/fgaz/changelog-d. Contributors add a file in changelog.d/ for each user-facing change. At release time, these are assembled into release notes for sphinx (in RST) format, using the tool. New hadrian `changelog` target to generate changelogs CI job to validate changelog entries for MRs unless skipped with ~"no-changelog" label Teach sphinx about ghc-mr: extlink to link to MRs Remove `ghc-package-list` from sphinx, and implement it in changelog-d instead (Fixes #26476). (cherry picked from commit 989c07249978f418dfde1353abfad453f024d61a) - - - - - 59 changed files: - .gitlab-ci.yml - .gitlab/issue_templates/release_tracking.md - .gitlab/merge_request_templates/Default.md - + changelog.d/changelog-entries - + changelog.d/config - compiler/ghc.cabal.in - configure.ac - − docs/users_guide/10.0.1-notes.rst - + docs/users_guide/10.2.1-notes.rst - docs/users_guide/conf.py - docs/users_guide/ghc_config.py.in - − docs/users_guide/ghc_packages.py - docs/users_guide/release-notes.rst - hadrian/hadrian.cabal - hadrian/src/CommandLine.hs - hadrian/src/Main.hs - hadrian/src/Packages.hs - + hadrian/src/Rules/Changelog.hs - hadrian/src/Rules/Documentation.hs - hadrian/src/Rules/Test.hs - hadrian/src/Settings/Default.hs - libraries/array - libraries/base/base.cabal.in - libraries/deepseq - libraries/directory - libraries/filepath - libraries/ghc-boot-th/ghc-boot-th.cabal.in - libraries/ghc-boot/ghc-boot.cabal.in - libraries/ghc-compact/ghc-compact.cabal - libraries/ghc-experimental/ghc-experimental.cabal.in - libraries/ghci/ghci.cabal.in - libraries/haskeline - libraries/hpc - libraries/os-string - libraries/parsec - libraries/process - libraries/semaphore-compat - libraries/stm - libraries/template-haskell-lift - libraries/template-haskell-quasiquoter - libraries/template-haskell/template-haskell.cabal.in - libraries/terminfo - libraries/unix - m4/fp_setup_project_version.m4 - m4/fptools_ghc_version.m4 - testsuite/mk/boilerplate.mk - testsuite/tests/linters/Makefile - testsuite/tests/linters/all.T - + testsuite/tests/linters/changelog-d.stdout - + utils/changelog-d/ChangelogD.hs - + utils/changelog-d/LICENSE - + utils/changelog-d/README.md - + utils/changelog-d/changelog-d.cabal - utils/haddock/haddock-api/haddock-api.cabal - utils/haddock/haddock-api/src/Haddock/InterfaceFile.hs - utils/haddock/haddock-library/haddock-library.cabal - utils/haddock/haddock-test/haddock-test.cabal - utils/haddock/haddock.cabal - utils/hsc2hs The diff was not included because it is too large. View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/05d661d5a4e860f84ce11c82a85885… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/05d661d5a4e860f84ce11c82a85885… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/spj-reinstallable-base] More [skip ci]
by Simon Peyton Jones (＠simonpj) 10 Apr '26

10 Apr '26

Simon Peyton Jones pushed to branch wip/spj-reinstallable-base at Glasgow Haskell Compiler / GHC Commits: e57ac81f by Simon Peyton Jones at 2026-04-10T00:39:52+01:00 More [skip ci] - - - - - 50 changed files: - compiler/GHC/Iface/Load.hs - libraries/base/src/GHC/KnownKeyNames.hs - libraries/ghc-internal/ghc-internal.cabal.in - libraries/ghc-internal/src/GHC/Internal/Conc/Bound.hs - libraries/ghc-internal/src/GHC/Internal/Conc/IO.hs - libraries/ghc-internal/src/GHC/Internal/Control/Exception/Base.hs - libraries/ghc-internal/src/GHC/Internal/Control/Monad/Fix.hs - libraries/ghc-internal/src/GHC/Internal/Control/Monad/ST.hs - libraries/ghc-internal/src/GHC/Internal/Control/Monad/ST/Lazy.hs - libraries/ghc-internal/src/GHC/Internal/Data/Data.hs - libraries/ghc-internal/src/GHC/Internal/Data/Dynamic.hs - libraries/ghc-internal/src/GHC/Internal/Data/List/NonEmpty.hs - libraries/ghc-internal/src/GHC/Internal/Data/STRef/Strict.hs - libraries/ghc-internal/src/GHC/Internal/Data/Typeable/Internal.hs - libraries/ghc-internal/src/GHC/Internal/Debug/Trace.hs - libraries/ghc-internal/src/GHC/Internal/Desugar.hs - libraries/ghc-internal/src/GHC/Internal/Event.hs - libraries/ghc-internal/src/GHC/Internal/Event/Thread.hs - libraries/ghc-internal/src/GHC/Internal/Event/TimeOut.hs - libraries/ghc-internal/src/GHC/Internal/Exception/Backtrace.hs - libraries/ghc-internal/src/GHC/Internal/Exts.hs - libraries/ghc-internal/src/GHC/Internal/Foreign/Concurrent.hs - libraries/ghc-internal/src/GHC/Internal/Foreign/ForeignPtr.hs - libraries/ghc-internal/src/GHC/Internal/Foreign/ForeignPtr/Unsafe.hs - libraries/ghc-internal/src/GHC/Internal/Foreign/Marshal/Safe.hs - libraries/ghc-internal/src/GHC/Internal/Foreign/Marshal/Unsafe.hs - libraries/ghc-internal/src/GHC/Internal/Foreign/StablePtr.hs - libraries/ghc-internal/src/GHC/Internal/GHCi/Helpers.hs - libraries/ghc-internal/src/GHC/Internal/IO/Exception.hs - libraries/ghc-internal/src/GHC/Internal/IO/FD.hs - libraries/ghc-internal/src/GHC/Internal/IO/Handle.hs - libraries/ghc-internal/src/GHC/Internal/IO/Handle/FD.hs - libraries/ghc-internal/src/GHC/Internal/IO/Handle/Lock.hs - libraries/ghc-internal/src/GHC/Internal/IO/Handle/Lock/Common.hs - libraries/ghc-internal/src/GHC/Internal/IO/Handle/Lock/Flock.hsc - libraries/ghc-internal/src/GHC/Internal/IO/Handle/Lock/LinuxOFD.hsc - libraries/ghc-internal/src/GHC/Internal/IO/Handle/Text.hs - libraries/ghc-internal/src/GHC/Internal/IO/StdHandles.hs - libraries/ghc-internal/src/GHC/Internal/InfoProv.hs - libraries/ghc-internal/src/GHC/Internal/IsList.hs - libraries/ghc-internal/src/GHC/Internal/STM.hs - libraries/ghc-internal/src/GHC/Internal/System/Environment/Blank.hsc - libraries/ghc-internal/src/GHC/Internal/System/IO.hs - libraries/ghc-internal/src/GHC/Internal/System/Posix/Types.hs - libraries/ghc-internal/src/GHC/Internal/TH/Lib.hs - libraries/ghc-internal/src/GHC/Internal/TH/Lift.hs - libraries/ghc-internal/src/GHC/Internal/TH/Monad.hs - libraries/ghc-internal/src/GHC/Internal/TH/Syntax.hs - libraries/ghc-internal/src/GHC/Internal/TopHandler.hs - libraries/ghc-internal/src/GHC/Internal/Type/Reflection.hs The diff was not included because it is too large. View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/e57ac81fac2952505c0056669ae0d7c… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/e57ac81fac2952505c0056669ae0d7c… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/ani/T27156] move Record dot syntax expansion from renamer to Expand
by Apoorv Ingle (＠ani) 10 Apr '26

10 Apr '26

Apoorv Ingle pushed to branch wip/ani/T27156 at Glasgow Haskell Compiler / GHC Commits: 3bd74519 by Apoorv Ingle at 2026-04-09T18:15:00-05:00 move Record dot syntax expansion from renamer to Expand - - - - - 7 changed files: - compiler/GHC/Hs/Expr.hs - compiler/GHC/Rename/Expr.hs - compiler/GHC/Rename/Utils.hs - compiler/GHC/Tc/Gen/Expand.hs - compiler/GHC/Tc/Types/Origin.hs - testsuite/tests/parser/should_fail/RecordDotSyntaxFail8.stderr - testsuite/tests/parser/should_fail/RecordDotSyntaxFail9.stderr Changes: ===================================== compiler/GHC/Hs/Expr.hs ===================================== @@ -340,13 +340,13 @@ type instance XLHsRecUpdLabels GhcTc = DataConCantHappen type instance XLHsOLRecUpdLabels p = NoExtField type instance XGetField GhcPs = NoExtField -type instance XGetField GhcRn = NoExtField +type instance XGetField GhcRn = Name type instance XGetField GhcTc = DataConCantHappen -- HsGetField is eliminated by the renamer. See [Handling overloaded -- and rebindable constructs]. type instance XProjection GhcPs = AnnProjection -type instance XProjection GhcRn = NoExtField +type instance XProjection GhcRn = (Name, Name) type instance XProjection GhcTc = DataConCantHappen -- HsProjection is eliminated by the renamer. See [Handling overloaded -- and rebindable constructs]. ===================================== compiler/GHC/Rename/Expr.hs ===================================== @@ -72,7 +72,7 @@ import qualified GHC.LanguageExtensions as LangExt import Control.Monad import qualified Data.Foldable as Partial (maximum) import Data.List (unzip4) -import Data.List.NonEmpty ( NonEmpty(..), head, init, last, nonEmpty, scanl, tail ) +import Data.List.NonEmpty ( NonEmpty(..), head, nonEmpty, scanl, tail ) import Control.Arrow (first) import Data.Ord import Data.Array @@ -419,19 +419,13 @@ rnExpr (HsGetField _ e f) = do { (getField, fv_getField) <- lookupSyntaxName getFieldName ; (e, fv_e) <- rnLExpr e ; let f' = rnDotFieldOcc <$> f - ; return ( mkExpandedExpr - (HsGetField noExtField e f') - (mkGetField getField e (fmap (unLoc . dfoLabel) f')) - , fv_e `plusFN` fv_getField ) } + ; return (HsGetField getField e f', fv_e `plusFN` fv_getField) } rnExpr (HsProjection _ fs) = do { (getField, fv_getField) <- lookupSyntaxName getFieldName ; circ <- lookupOccRn WL_TermVariable compose_RDR ; let fs' = NE.map rnDotFieldOcc fs - ; return ( mkExpandedExpr - (HsProjection noExtField fs') - (mkProjection getField circ $ NE.map (unLoc . dfoLabel) fs') - , unitFN circ `plusFN` fv_getField) } + ; return (HsProjection (getField , circ) fs', unitFN circ `plusFN` fv_getField) } ------------------------------------------ -- Template Haskell extensions @@ -717,14 +711,12 @@ rnSection :: HsExpr GhcPs -> RnM (HsExpr GhcRn, FreeNames) -- Also see Note [Handling overloaded and rebindable constructs] rnSection section@(SectionR x op expr) - -- See Note [Left and right sections] = do { (op', fvs_op) <- rnLExpr op ; (expr', fvs_expr) <- rnLExpr expr ; checkSectionPrec InfixR section op' expr' ; return $ (SectionR x op' expr' , fvs_op `plusFN` fvs_expr) } rnSection section@(SectionL x expr op) - -- See Note [Left and right sections] = do { (expr', fvs_expr) <- rnLExpr expr ; (op', fvs_op) <- rnLExpr op ; checkSectionPrec InfixL section op' expr' @@ -732,129 +724,7 @@ rnSection section@(SectionL x expr op) rnSection other = pprPanic "rnSection" (ppr other) -{- Note [Left and right sections] -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -Dealing with left sections (x *) and right sections (* x) is -surprisingly fiddly. We expand like this - (`op` e) ==> rightSection op e - (e `op`) ==> leftSection (op e) - -Using an auxiliary function in this way avoids the awkwardness of -generating a lambda, esp if `e` is a redex, so we *don't* want -to generate `(\x -> op x e)`. See Historical -Note [Desugaring operator sections] - -Here are their definitions: - leftSection :: forall r1 r2 n (a::TYPE r1) (b::TYPE r2). - (a %n-> b) -> a %n-> b - leftSection f x = f x - - rightSection :: forall r1 r2 r3 n1 n2 (a::TYPE r1) (b::TYPE r2) (c::TYPE r3). - (a %n1 -> b %n2-> c) -> b %n2-> a %n1-> c - rightSection f y x = f x y - -Note the wrinkles: - -* We do /not/ use lookupSyntaxName, which would make left and right - section fall under RebindableSyntax. Reason: it would be a user- - facing change, and there are some tricky design choices (#19354). - Plus, infix operator applications would be trickier to make - rebindable, so it'd be inconsistent to do so for sections. - - TL;DR: we still use the renamer-expansion mechanism for operator - sections, but only to eliminate special-purpose code paths in the - renamer and desugarer. - -* leftSection and rightSection must be representation-polymorphic, to allow - (+# 4#) and (4# +#) to work. See - Note [Wired-in Ids for rebindable syntax] in GHC.Types.Id.Make. - -* leftSection and rightSection must be multiplicity-polymorphic. - (Test linear/should_compile/OldList showed this up.) - -* Because they are representation-polymorphic, we have to define them - as wired-in Ids, with compulsory inlining. See - GHC.Types.Id.Make.leftSectionId, rightSectionId. - -* leftSection is just ($) really; but unlike ($) it is - representation-polymorphic in the result type, so we can write - `(x +#)`, say. - -* The type of leftSection must have an arrow in its first argument, - because (x `ord`) should be rejected, because ord does not take two - arguments - -* It's important that we define leftSection in an eta-expanded way, - (i.e. not leftSection f = f), so that - (True `undefined`) `seq` () - = (leftSection (undefined True) `seq` ()) - evaluates to () and not undefined - -* If PostfixOperators is ON, then we expand a left section like this: - (e `op`) ==> op e - with no auxiliary function at all. Simple! - -* leftSection and rightSection switch on ImpredicativeTypes locally, - during Quick Look; see GHC.Tc.Gen.App.wantQuickLook. Consider - test DeepSubsumption08: - type Setter st t a b = forall f. Identical f => blah - (.~) :: Setter s t a b -> b -> s -> t - clear :: Setter a a' b (Maybe b') -> a -> a' - clear = (.~ Nothing) - The expansion look like (rightSection (.~) Nothing). So we must - instantiate `rightSection` first type argument to a polytype! - Hence the special magic in App.wantQuickLook. - -Historical Note [Desugaring operator sections] -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -This Note explains some historical trickiness in desugaring left and -right sections. That trickiness has completely disappeared now that -we desugar to calls to 'leftSection` and `rightSection`, but I'm -leaving it here to remind us how nice the new story is. - -Desugaring left sections with -XPostfixOperators is straightforward: convert -(expr `op`) to (op expr). - -Without -XPostfixOperators it's a bit more tricky. At first it looks as if we -can convert - - (expr `op`) - -naively to - - \x -> op expr x - -But no! expr might be a redex, and we can lose laziness badly this -way. Consider - - map (expr `op`) xs - -for example. If expr were a redex then eta-expanding naively would -result in multiple evaluations where the user might only have expected one. - -So we convert instead to - - let y = expr in \x -> op y x - -Also, note that we must do this for both right and (perhaps surprisingly) left -sections. Why are left sections necessary? Consider the program (found in #18151), - - seq (True `undefined`) () - -according to the Haskell Report this should reduce to () (as it specifies -desugaring via eta expansion). However, if we fail to eta expand we will rather -bottom. Consequently, we must eta expand even in the case of a left section. - -If `expr` is actually just a variable, say, then the simplifier -will inline `y`, eliminating the redundant `let`. - -Note that this works even in the case that `expr` is unlifted. In this case -bindNonRec will automatically do the right thing, giving us: - - case expr of y -> (\x -> op y x) - -See #18151. - +{- Note [Reporting unbound names] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Faced with an out-of-scope `RdrName` there are two courses of action @@ -2841,64 +2711,6 @@ rnHsIf p b1 b2 fvs = plusFNs [fvs_if, unitFN ite_name] ; return (mkExpandedExpr rn_if ds_if, fvs) } } ------------------------------------------ --- Bits and pieces for RecordDotSyntax. --- --- See Note [Overview of record dot syntax] in GHC.Hs.Expr. - --- mkGetField arg field calculates a get_field @field arg expression. --- e.g. z.x = mkGetField z x = get_field @x z -mkGetField :: Name -> LHsExpr GhcRn -> LocatedAn NoEpAnns FieldLabelString -> HsExpr GhcRn -mkGetField get_field arg field = unLoc (head $ mkGet get_field (arg :| []) field) - --- mkSetField a field b calculates a set_field @field expression. --- e.g mkSetSetField a field b = set_field @"field" a b (read as "set field 'field' to a on b"). --- NB: the order of aruments is specified by GHC Proposal 583: HasField redesign. -mkSetField :: Name -> LHsExpr GhcRn -> LocatedAn NoEpAnns FieldLabelString -> LHsExpr GhcRn -> HsExpr GhcRn -mkSetField set_field a (L _ (FieldLabelString field)) b = - genHsApp (genHsApp (genHsVar set_field `genAppType` genHsTyLit field) b) a - -mkGet :: Name -> NonEmpty (LHsExpr GhcRn) -> LocatedAn NoEpAnns FieldLabelString -> NonEmpty (LHsExpr GhcRn) -mkGet get_field l@(r :| _) (L _ (FieldLabelString field)) = - wrapGenSpan (genHsApp (genHsVar get_field `genAppType` genHsTyLit field) r) NE.<| l - -mkSet :: Name -> LHsExpr GhcRn -> (LocatedAn NoEpAnns FieldLabelString, LHsExpr GhcRn) -> LHsExpr GhcRn -mkSet set_field acc (field, g) = wrapGenSpan (mkSetField set_field g field acc) - --- mkProjection fields calculates a projection. --- e.g. .x = mkProjection [x] = getField @"x" --- .x.y = mkProjection [.x, .y] = (.y) . (.x) = getField @"y" . getField @"x" -mkProjection :: Name -> Name -> NonEmpty FieldLabelString -> HsExpr GhcRn -mkProjection getFieldName circName (field :| fields) = foldl' f (proj field) fields - where - f :: HsExpr GhcRn -> FieldLabelString -> HsExpr GhcRn - f acc field = genHsApps circName $ map wrapGenSpan [proj field, acc] - - proj :: FieldLabelString -> HsExpr GhcRn - proj (FieldLabelString f) = genHsVar getFieldName `genAppType` genHsTyLit f - --- mkProjUpdateSetField calculates functions representing dot notation record updates. --- e.g. Suppose an update like foo.bar = 1. --- We calculate the function \a -> setField @"foo" a (setField @"bar" (getField @"foo" a) 1). -mkProjUpdateSetField :: Name -> Name -> LHsRecProj GhcRn (LHsExpr GhcRn) -> (LHsExpr GhcRn -> LHsExpr GhcRn) -mkProjUpdateSetField get_field set_field (L _ (HsFieldBind { hfbLHS = (L _ (FieldLabelStrings flds')), hfbRHS = arg } )) - = let { - ; flds = NE.map (fmap (unLoc . dfoLabel)) flds' - ; final = last flds -- quux - ; fields = init flds -- [foo, bar, baz] - ; getters = \a -> foldl' (mkGet get_field) (a :| []) fields -- Ordered from deep to shallow. - -- [getField@"baz"(getField@"bar"(getField@"foo" a), getField@"bar"(getField@"foo" a), getField@"foo" a, a] - ; zips = \a -> (final, head (getters a)) : zip (reverse fields) (tail (getters a)) -- Ordered from deep to shallow. - -- [("quux", getField@"baz"(getField@"bar"(getField@"foo" a)), ("baz", getField@"bar"(getField@"foo" a)), ("bar", getField@"foo" a), ("foo", a)] - } - in (\a -> foldl' (mkSet set_field) arg (zips a)) - -- setField@"foo" (a) (setField@"bar" (getField @"foo" (a))(setField@"baz" (getField @"bar" (getField @"foo" (a)))(setField@"quux" (getField @"baz" (getField @"bar" (getField @"foo" (a))))(quux)))) - -mkRecordDotUpd :: Name -> Name -> LHsExpr GhcRn -> [LHsRecUpdProj GhcRn] -> HsExpr GhcRn -mkRecordDotUpd get_field set_field exp updates = foldl' fieldUpdate (unLoc exp) updates - where - fieldUpdate :: HsExpr GhcRn -> LHsRecUpdProj GhcRn -> HsExpr GhcRn - fieldUpdate acc lpu = unLoc $ (mkProjUpdateSetField get_field set_field lpu) (wrapGenSpan acc) rnHsUpdProjs :: [LHsRecUpdProj GhcPs] -> RnM ([LHsRecUpdProj GhcRn], FreeNames) rnHsUpdProjs us = do ===================================== compiler/GHC/Rename/Utils.hs ===================================== @@ -24,6 +24,8 @@ module GHC.Rename.Utils ( genSimpleFunBind, genFunBind, genHsLamDoExp, genHsCaseAltDoExp, genSimpleMatch, genHsLet, + mkGetField, mkSetField, mkProjection, mkRecordDotUpd, + mkExpandedRn, mkExpandedExpr, mkExpandedStmt, mkExpandedLExpr, mkExpandedTc, mkExpandedExprTc, mkRnSyntaxExpr, @@ -41,7 +43,7 @@ module GHC.Rename.Utils ( where -import GHC.Prelude +import GHC.Prelude hiding (init, last, scanl, tail) import GHC.Core.Type import GHC.Hs @@ -71,6 +73,7 @@ import GHC.Iface.Load import qualified GHC.LanguageExtensions as LangExt import qualified Data.List.NonEmpty as NE +import Data.List.NonEmpty ( NonEmpty(..), init, last, tail ) import Data.Foldable (for_) import Data.Maybe @@ -867,3 +870,63 @@ mkExpandedTc -> LHsExpr GhcTc -- ^ expanded typechecked expression -> HsExpr GhcTc -- ^ suitably wrapped 'XXExprGhcTc' mkExpandedTc o e = XExpr (ExpandedThingTc (HSE o e)) + + +----------------------------------------- +-- Bits and pieces for RecordDotSyntax. +-- +-- See Note [Overview of record dot syntax] in GHC.Hs.Expr. + +-- mkGetField arg field calculates a get_field @field arg expression. +-- e.g. z.x = mkGetField z x = get_field @x z +mkGetField :: Name -> LHsExpr GhcRn -> LocatedAn NoEpAnns FieldLabelString -> HsExpr GhcRn +mkGetField get_field arg field = unLoc (NE.head $ mkGet get_field (arg :| []) field) + +-- mkSetField a field b calculates a set_field @field expression. +-- e.g mkSetSetField a field b = set_field @"field" a b (read as "set field 'field' to a on b"). +-- NB: the order of aruments is specified by GHC Proposal 583: HasField redesign. +mkSetField :: Name -> LHsExpr GhcRn -> LocatedAn NoEpAnns FieldLabelString -> LHsExpr GhcRn -> HsExpr GhcRn +mkSetField set_field a (L _ (FieldLabelString field)) b = + genHsApp (genHsApp (genHsVar set_field `genAppType` genHsTyLit field) b) a + +mkGet :: Name -> NonEmpty (LHsExpr GhcRn) -> LocatedAn NoEpAnns FieldLabelString -> NonEmpty (LHsExpr GhcRn) +mkGet get_field l@(r :| _) (L _ (FieldLabelString field)) = + wrapGenSpan (genHsApp (genHsVar get_field `genAppType` genHsTyLit field) r) NE.<| l + +mkSet :: Name -> LHsExpr GhcRn -> (LocatedAn NoEpAnns FieldLabelString, LHsExpr GhcRn) -> LHsExpr GhcRn +mkSet set_field acc (field, g) = wrapGenSpan (mkSetField set_field g field acc) + +-- mkProjection fields calculates a projection. +-- e.g. .x = mkProjection [x] = getField @"x" +-- .x.y = mkProjection [.x, .y] = (.y) . (.x) = getField @"y" . getField @"x" +mkProjection :: Name -> Name -> NonEmpty FieldLabelString -> HsExpr GhcRn +mkProjection getFieldName circName (field :| fields) = foldl' f (proj field) fields + where + f :: HsExpr GhcRn -> FieldLabelString -> HsExpr GhcRn + f acc field = genHsApps circName $ map wrapGenSpan [proj field, acc] + + proj :: FieldLabelString -> HsExpr GhcRn + proj (FieldLabelString f) = genHsVar getFieldName `genAppType` genHsTyLit f + +-- mkProjUpdateSetField calculates functions representing dot notation record updates. +-- e.g. Suppose an update like foo.bar = 1. +-- We calculate the function \a -> setField @"foo" a (setField @"bar" (getField @"foo" a) 1). +mkProjUpdateSetField :: Name -> Name -> LHsRecProj GhcRn (LHsExpr GhcRn) -> (LHsExpr GhcRn -> LHsExpr GhcRn) +mkProjUpdateSetField get_field set_field (L _ (HsFieldBind { hfbLHS = (L _ (FieldLabelStrings flds')), hfbRHS = arg } )) + = let { + ; flds = NE.map (fmap (unLoc . dfoLabel)) flds' + ; final = last flds -- quux + ; fields = init flds -- [foo, bar, baz] + ; getters = \a -> foldl' (mkGet get_field) (a :| []) fields -- Ordered from deep to shallow. + -- [getField@"baz"(getField@"bar"(getField@"foo" a), getField@"bar"(getField@"foo" a), getField@"foo" a, a] + ; zips = \a -> (final, NE.head (getters a)) : zip (reverse fields) (tail (getters a)) -- Ordered from deep to shallow. + -- [("quux", getField@"baz"(getField@"bar"(getField@"foo" a)), ("baz", getField@"bar"(getField@"foo" a)), ("bar", getField@"foo" a), ("foo", a)] + } + in (\a -> foldl' (mkSet set_field) arg (zips a)) + -- setField@"foo" (a) (setField@"bar" (getField @"foo" (a))(setField@"baz" (getField @"bar" (getField @"foo" (a)))(setField@"quux" (getField @"baz" (getField @"bar" (getField @"foo" (a))))(quux)))) + +mkRecordDotUpd :: Name -> Name -> LHsExpr GhcRn -> [LHsRecUpdProj GhcRn] -> HsExpr GhcRn +mkRecordDotUpd get_field set_field exp updates = foldl' fieldUpdate (unLoc exp) updates + where + fieldUpdate :: HsExpr GhcRn -> LHsRecUpdProj GhcRn -> HsExpr GhcRn + fieldUpdate acc lpu = unLoc $ (mkProjUpdateSetField get_field set_field lpu) (wrapGenSpan acc) ===================================== compiler/GHC/Tc/Gen/Expand.hs ===================================== @@ -17,8 +17,10 @@ import GHC.Tc.Utils.Monad import GHC.Tc.Types.ErrCtxt import GHC.Types.Id.Make +import GHC.Types.SrcLoc import GHC.Rename.Utils +import qualified Data.List.NonEmpty as NE (map) import qualified GHC.LanguageExtensions as LangExt @@ -105,7 +107,8 @@ Wrinkle (TBE1) -} ---------------- +------------------------------------------ +-- Operator Applications tcExpand :: HsExpr GhcRn -> TcM (Maybe (HsExpansion GhcRn)) tcExpand e@(OpApp _ arg1 op arg2) = return $ Just $ @@ -114,14 +117,18 @@ tcExpand e@(OpApp _ arg1 op arg2) where ap f a = wrapGenSpan (HsApp noExtField f a) +------------------------------------------ +-- Left and Right Sections + tcExpand e@(SectionR _ op expr) + -- See Note [Left and right sections] = return $ Just $ HSE { hse_ctxt = ExprCtxt e , hse_exp = wrapGenSpan $ genHsApps rightSectionName [op, expr] } tcExpand e@(SectionL _ expr op) + -- Note [Left and right sections] = do { postfix_ops <- xoptM LangExt.PostfixOperators - -- Note [Left and right sections] ; let ds_section | postfix_ops = HsApp noExtField op expr | otherwise = genHsApps leftSectionName @@ -130,10 +137,26 @@ tcExpand e@(SectionL _ expr op) HSE { hse_ctxt = ExprCtxt e , hse_exp = wrapGenSpan ds_section } } +------------------------------------------ +-- Record dot syntax + +tcExpand e@(HsGetField getFieldName expr f) + = return $ Just $ + HSE { hse_ctxt = ExprCtxt e + , hse_exp = wrapGenSpan $ (mkGetField getFieldName expr (fmap (unLoc . dfoLabel) f)) } + +tcExpand e@(HsProjection (getFieldName, circName) fs) + = return$ Just $ + HSE { hse_ctxt = ExprCtxt e + , hse_exp = wrapGenSpan $ (mkProjection getFieldName circName $ NE.map (unLoc . dfoLabel) fs) } +--------- tcExpand (XExpr (ExpandedThingRn hse)) = return (Just hse) +------------------------------------------ +-- Template Haskell Splices + tcExpand e@(HsUntypedSplice splice_res _) -- See Note [Looking through Template Haskell splices in splitHsApps] = do { fun <- getUntypedSpliceBody splice_res @@ -142,3 +165,132 @@ tcExpand e@(HsUntypedSplice splice_res _) , hse_exp = wrapGenSpan fun } } tcExpand _ = return Nothing + + + + + + +{- Note [Left and right sections] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +Dealing with left sections (x *) and right sections (* x) is +surprisingly fiddly. We expand like this + (`op` e) ==> rightSection op e + (e `op`) ==> leftSection (op e) + +Using an auxiliary function in this way avoids the awkwardness of +generating a lambda, esp if `e` is a redex, so we *don't* want +to generate `(\x -> op x e)`. See Historical +Note [Desugaring operator sections] + +Here are their definitions: + leftSection :: forall r1 r2 n (a::TYPE r1) (b::TYPE r2). + (a %n-> b) -> a %n-> b + leftSection f x = f x + + rightSection :: forall r1 r2 r3 n1 n2 (a::TYPE r1) (b::TYPE r2) (c::TYPE r3). + (a %n1 -> b %n2-> c) -> b %n2-> a %n1-> c + rightSection f y x = f x y + +Note the wrinkles: + +* We do /not/ use lookupSyntaxName, which would make left and right + section fall under RebindableSyntax. Reason: it would be a user- + facing change, and there are some tricky design choices (#19354). + Plus, infix operator applications would be trickier to make + rebindable, so it'd be inconsistent to do so for sections. + + TL;DR: we still use the renamer-expansion mechanism for operator + sections, but only to eliminate special-purpose code paths in the + renamer and desugarer. + +* leftSection and rightSection must be representation-polymorphic, to allow + (+# 4#) and (4# +#) to work. See + Note [Wired-in Ids for rebindable syntax] in GHC.Types.Id.Make. + +* leftSection and rightSection must be multiplicity-polymorphic. + (Test linear/should_compile/OldList showed this up.) + +* Because they are representation-polymorphic, we have to define them + as wired-in Ids, with compulsory inlining. See + GHC.Types.Id.Make.leftSectionId, rightSectionId. + +* leftSection is just ($) really; but unlike ($) it is + representation-polymorphic in the result type, so we can write + `(x +#)`, say. + +* The type of leftSection must have an arrow in its first argument, + because (x `ord`) should be rejected, because ord does not take two + arguments + +* It's important that we define leftSection in an eta-expanded way, + (i.e. not leftSection f = f), so that + (True `undefined`) `seq` () + = (leftSection (undefined True) `seq` ()) + evaluates to () and not undefined + +* If PostfixOperators is ON, then we expand a left section like this: + (e `op`) ==> op e + with no auxiliary function at all. Simple! + +* leftSection and rightSection switch on ImpredicativeTypes locally, + during Quick Look; see GHC.Tc.Gen.App.wantQuickLook. Consider + test DeepSubsumption08: + type Setter st t a b = forall f. Identical f => blah + (.~) :: Setter s t a b -> b -> s -> t + clear :: Setter a a' b (Maybe b') -> a -> a' + clear = (.~ Nothing) + The expansion look like (rightSection (.~) Nothing). So we must + instantiate `rightSection` first type argument to a polytype! + Hence the special magic in App.wantQuickLook. + +Historical Note [Desugaring operator sections] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +This Note explains some historical trickiness in desugaring left and +right sections. That trickiness has completely disappeared now that +we desugar to calls to 'leftSection` and `rightSection`, but I'm +leaving it here to remind us how nice the new story is. + +Desugaring left sections with -XPostfixOperators is straightforward: convert +(expr `op`) to (op expr). + +Without -XPostfixOperators it's a bit more tricky. At first it looks as if we +can convert + + (expr `op`) + +naively to + + \x -> op expr x + +But no! expr might be a redex, and we can lose laziness badly this +way. Consider + + map (expr `op`) xs + +for example. If expr were a redex then eta-expanding naively would +result in multiple evaluations where the user might only have expected one. + +So we convert instead to + + let y = expr in \x -> op y x + +Also, note that we must do this for both right and (perhaps surprisingly) left +sections. Why are left sections necessary? Consider the program (found in #18151), + + seq (True `undefined`) () + +according to the Haskell Report this should reduce to () (as it specifies +desugaring via eta expansion). However, if we fail to eta expand we will rather +bottom. Consequently, we must eta expand even in the case of a left section. + +If `expr` is actually just a variable, say, then the simplifier +will inline `y`, eliminating the redundant `let`. + +Note that this works even in the case that `expr` is unlifted. In this case +bindNonRec will automatically do the right thing, giving us: + + case expr of y -> (\x -> op y x) + +See #18151. +-} ===================================== compiler/GHC/Tc/Types/Origin.hs ===================================== @@ -634,6 +634,7 @@ exprCtOrigin (XExpr (ExpandedThingRn (HSE o _))) = hsCtxtCtOrigin o exprCtOrigin (XExpr (HsRecSelRn f)) = OccurrenceOfRecSel $ L (getLoc $ foLabel f) (foExt f) hsCtxtCtOrigin :: HsCtxt -> CtOrigin +hsCtxtCtOrigin (ExprCtxt (ExprWithTySig _ (L _ e) _)) = exprCtOrigin e hsCtxtCtOrigin (ExprCtxt e) = exprCtOrigin e hsCtxtCtOrigin (FunAppCtxt (FunAppCtxtExpr _ e) _) = exprCtOrigin e hsCtxtCtOrigin (StmtErrCtxt{}) = DoStmtOrigin ===================================== testsuite/tests/parser/should_fail/RecordDotSyntaxFail8.stderr ===================================== @@ -2,11 +2,11 @@ RecordDotSyntaxFail8.hs:47:17: error: [GHC-39999] • No instance for ‘HasField "quux1" Quux Quux’ arising from selecting the field ‘quux1’ NB: ‘HasField’ is not the built-in ‘GHC.Internal.Records.HasField’ class. - • In the second argument of ‘($)’, namely ‘....bar.baz.quux1’ - In a stmt of a 'do' block: print @Quux $ ....baz.quux1 + • In the second argument of ‘($)’, namely ‘a.foo.bar.baz.quux1’ + In a stmt of a 'do' block: print @Quux $ a.foo.bar.baz.quux1 In the expression: do let a = Foo {foo = ...} - print @Quux $ ....quux1 + print @Quux $ ....bar.baz.quux1 let b = myQuux print @Quux $ b.quux2 let c = Foo {foo = ...} @@ -20,7 +20,7 @@ RecordDotSyntaxFail8.hs:50:17: error: [GHC-39999] In a stmt of a 'do' block: print @Quux $ b.quux2 In the expression: do let a = Foo {foo = ...} - print @Quux $ ....quux1 + print @Quux $ ....bar.baz.quux1 let b = myQuux print @Quux $ b.quux2 let c = Foo {foo = ...} @@ -30,11 +30,11 @@ RecordDotSyntaxFail8.hs:53:17: error: [GHC-39999] • No instance for ‘HasField "quux3" Quux r0’ arising from selecting the field ‘quux3’ NB: ‘HasField’ is not the built-in ‘GHC.Internal.Records.HasField’ class. - • In the second argument of ‘($)’, namely ‘....baz.quux3.wob’ - In a stmt of a 'do' block: print @Bool $ ....quux3.wob + • In the second argument of ‘($)’, namely ‘a.foo.bar.baz.quux3.wob’ + In a stmt of a 'do' block: print @Bool $ a.foo.bar.baz.quux3.wob In the expression: do let a = Foo {foo = ...} - print @Quux $ ....quux1 + print @Quux $ ....bar.baz.quux1 let b = myQuux print @Quux $ b.quux2 let c = Foo {foo = ...} ===================================== testsuite/tests/parser/should_fail/RecordDotSyntaxFail9.stderr ===================================== @@ -1,7 +1,7 @@ RecordDotSyntaxFail9.hs:7:11: error: [GHC-18872] • Couldn't match type ‘Int’ with ‘[Char]’ arising from selecting the field ‘foo’ - • In the expression: a.foo + • In the expression: a.foo :: String In a pattern binding: _ = a.foo :: String In a stmt of a 'do' block: let _ = a.foo :: String View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/3bd7451922702c7402fc0b397924500… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/3bd7451922702c7402fc0b397924500… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/ani/T27156] move Record dot syntax expansion from renamer to Expand
by Apoorv Ingle (＠ani) 10 Apr '26

10 Apr '26

Apoorv Ingle pushed to branch wip/ani/T27156 at Glasgow Haskell Compiler / GHC Commits: 106d086f by Apoorv Ingle at 2026-04-09T17:47:35-05:00 move Record dot syntax expansion from renamer to Expand - - - - - 5 changed files: - compiler/GHC/Hs/Expr.hs - compiler/GHC/Rename/Expr.hs - compiler/GHC/Rename/Utils.hs - compiler/GHC/Tc/Gen/Expand.hs - compiler/GHC/Tc/Types/Origin.hs Changes: ===================================== compiler/GHC/Hs/Expr.hs ===================================== @@ -340,13 +340,13 @@ type instance XLHsRecUpdLabels GhcTc = DataConCantHappen type instance XLHsOLRecUpdLabels p = NoExtField type instance XGetField GhcPs = NoExtField -type instance XGetField GhcRn = NoExtField +type instance XGetField GhcRn = Name type instance XGetField GhcTc = DataConCantHappen -- HsGetField is eliminated by the renamer. See [Handling overloaded -- and rebindable constructs]. type instance XProjection GhcPs = AnnProjection -type instance XProjection GhcRn = NoExtField +type instance XProjection GhcRn = (Name, Name) type instance XProjection GhcTc = DataConCantHappen -- HsProjection is eliminated by the renamer. See [Handling overloaded -- and rebindable constructs]. ===================================== compiler/GHC/Rename/Expr.hs ===================================== @@ -72,7 +72,7 @@ import qualified GHC.LanguageExtensions as LangExt import Control.Monad import qualified Data.Foldable as Partial (maximum) import Data.List (unzip4) -import Data.List.NonEmpty ( NonEmpty(..), head, init, last, nonEmpty, scanl, tail ) +import Data.List.NonEmpty ( NonEmpty(..), head, nonEmpty, scanl, tail ) import Control.Arrow (first) import Data.Ord import Data.Array @@ -419,19 +419,13 @@ rnExpr (HsGetField _ e f) = do { (getField, fv_getField) <- lookupSyntaxName getFieldName ; (e, fv_e) <- rnLExpr e ; let f' = rnDotFieldOcc <$> f - ; return ( mkExpandedExpr - (HsGetField noExtField e f') - (mkGetField getField e (fmap (unLoc . dfoLabel) f')) - , fv_e `plusFN` fv_getField ) } + ; return (HsGetField getField e f', fv_e `plusFN` fv_getField) } rnExpr (HsProjection _ fs) = do { (getField, fv_getField) <- lookupSyntaxName getFieldName ; circ <- lookupOccRn WL_TermVariable compose_RDR ; let fs' = NE.map rnDotFieldOcc fs - ; return ( mkExpandedExpr - (HsProjection noExtField fs') - (mkProjection getField circ $ NE.map (unLoc . dfoLabel) fs') - , unitFN circ `plusFN` fv_getField) } + ; return (HsProjection (getField , circ) fs', unitFN circ `plusFN` fv_getField) } ------------------------------------------ -- Template Haskell extensions @@ -717,14 +711,12 @@ rnSection :: HsExpr GhcPs -> RnM (HsExpr GhcRn, FreeNames) -- Also see Note [Handling overloaded and rebindable constructs] rnSection section@(SectionR x op expr) - -- See Note [Left and right sections] = do { (op', fvs_op) <- rnLExpr op ; (expr', fvs_expr) <- rnLExpr expr ; checkSectionPrec InfixR section op' expr' ; return $ (SectionR x op' expr' , fvs_op `plusFN` fvs_expr) } rnSection section@(SectionL x expr op) - -- See Note [Left and right sections] = do { (expr', fvs_expr) <- rnLExpr expr ; (op', fvs_op) <- rnLExpr op ; checkSectionPrec InfixL section op' expr' @@ -732,129 +724,7 @@ rnSection section@(SectionL x expr op) rnSection other = pprPanic "rnSection" (ppr other) -{- Note [Left and right sections] -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -Dealing with left sections (x *) and right sections (* x) is -surprisingly fiddly. We expand like this - (`op` e) ==> rightSection op e - (e `op`) ==> leftSection (op e) - -Using an auxiliary function in this way avoids the awkwardness of -generating a lambda, esp if `e` is a redex, so we *don't* want -to generate `(\x -> op x e)`. See Historical -Note [Desugaring operator sections] - -Here are their definitions: - leftSection :: forall r1 r2 n (a::TYPE r1) (b::TYPE r2). - (a %n-> b) -> a %n-> b - leftSection f x = f x - - rightSection :: forall r1 r2 r3 n1 n2 (a::TYPE r1) (b::TYPE r2) (c::TYPE r3). - (a %n1 -> b %n2-> c) -> b %n2-> a %n1-> c - rightSection f y x = f x y - -Note the wrinkles: - -* We do /not/ use lookupSyntaxName, which would make left and right - section fall under RebindableSyntax. Reason: it would be a user- - facing change, and there are some tricky design choices (#19354). - Plus, infix operator applications would be trickier to make - rebindable, so it'd be inconsistent to do so for sections. - - TL;DR: we still use the renamer-expansion mechanism for operator - sections, but only to eliminate special-purpose code paths in the - renamer and desugarer. - -* leftSection and rightSection must be representation-polymorphic, to allow - (+# 4#) and (4# +#) to work. See - Note [Wired-in Ids for rebindable syntax] in GHC.Types.Id.Make. - -* leftSection and rightSection must be multiplicity-polymorphic. - (Test linear/should_compile/OldList showed this up.) - -* Because they are representation-polymorphic, we have to define them - as wired-in Ids, with compulsory inlining. See - GHC.Types.Id.Make.leftSectionId, rightSectionId. - -* leftSection is just ($) really; but unlike ($) it is - representation-polymorphic in the result type, so we can write - `(x +#)`, say. - -* The type of leftSection must have an arrow in its first argument, - because (x `ord`) should be rejected, because ord does not take two - arguments - -* It's important that we define leftSection in an eta-expanded way, - (i.e. not leftSection f = f), so that - (True `undefined`) `seq` () - = (leftSection (undefined True) `seq` ()) - evaluates to () and not undefined - -* If PostfixOperators is ON, then we expand a left section like this: - (e `op`) ==> op e - with no auxiliary function at all. Simple! - -* leftSection and rightSection switch on ImpredicativeTypes locally, - during Quick Look; see GHC.Tc.Gen.App.wantQuickLook. Consider - test DeepSubsumption08: - type Setter st t a b = forall f. Identical f => blah - (.~) :: Setter s t a b -> b -> s -> t - clear :: Setter a a' b (Maybe b') -> a -> a' - clear = (.~ Nothing) - The expansion look like (rightSection (.~) Nothing). So we must - instantiate `rightSection` first type argument to a polytype! - Hence the special magic in App.wantQuickLook. - -Historical Note [Desugaring operator sections] -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -This Note explains some historical trickiness in desugaring left and -right sections. That trickiness has completely disappeared now that -we desugar to calls to 'leftSection` and `rightSection`, but I'm -leaving it here to remind us how nice the new story is. - -Desugaring left sections with -XPostfixOperators is straightforward: convert -(expr `op`) to (op expr). - -Without -XPostfixOperators it's a bit more tricky. At first it looks as if we -can convert - - (expr `op`) - -naively to - - \x -> op expr x - -But no! expr might be a redex, and we can lose laziness badly this -way. Consider - - map (expr `op`) xs - -for example. If expr were a redex then eta-expanding naively would -result in multiple evaluations where the user might only have expected one. - -So we convert instead to - - let y = expr in \x -> op y x - -Also, note that we must do this for both right and (perhaps surprisingly) left -sections. Why are left sections necessary? Consider the program (found in #18151), - - seq (True `undefined`) () - -according to the Haskell Report this should reduce to () (as it specifies -desugaring via eta expansion). However, if we fail to eta expand we will rather -bottom. Consequently, we must eta expand even in the case of a left section. - -If `expr` is actually just a variable, say, then the simplifier -will inline `y`, eliminating the redundant `let`. - -Note that this works even in the case that `expr` is unlifted. In this case -bindNonRec will automatically do the right thing, giving us: - - case expr of y -> (\x -> op y x) - -See #18151. - +{- Note [Reporting unbound names] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Faced with an out-of-scope `RdrName` there are two courses of action @@ -2841,64 +2711,6 @@ rnHsIf p b1 b2 fvs = plusFNs [fvs_if, unitFN ite_name] ; return (mkExpandedExpr rn_if ds_if, fvs) } } ------------------------------------------ --- Bits and pieces for RecordDotSyntax. --- --- See Note [Overview of record dot syntax] in GHC.Hs.Expr. - --- mkGetField arg field calculates a get_field @field arg expression. --- e.g. z.x = mkGetField z x = get_field @x z -mkGetField :: Name -> LHsExpr GhcRn -> LocatedAn NoEpAnns FieldLabelString -> HsExpr GhcRn -mkGetField get_field arg field = unLoc (head $ mkGet get_field (arg :| []) field) - --- mkSetField a field b calculates a set_field @field expression. --- e.g mkSetSetField a field b = set_field @"field" a b (read as "set field 'field' to a on b"). --- NB: the order of aruments is specified by GHC Proposal 583: HasField redesign. -mkSetField :: Name -> LHsExpr GhcRn -> LocatedAn NoEpAnns FieldLabelString -> LHsExpr GhcRn -> HsExpr GhcRn -mkSetField set_field a (L _ (FieldLabelString field)) b = - genHsApp (genHsApp (genHsVar set_field `genAppType` genHsTyLit field) b) a - -mkGet :: Name -> NonEmpty (LHsExpr GhcRn) -> LocatedAn NoEpAnns FieldLabelString -> NonEmpty (LHsExpr GhcRn) -mkGet get_field l@(r :| _) (L _ (FieldLabelString field)) = - wrapGenSpan (genHsApp (genHsVar get_field `genAppType` genHsTyLit field) r) NE.<| l - -mkSet :: Name -> LHsExpr GhcRn -> (LocatedAn NoEpAnns FieldLabelString, LHsExpr GhcRn) -> LHsExpr GhcRn -mkSet set_field acc (field, g) = wrapGenSpan (mkSetField set_field g field acc) - --- mkProjection fields calculates a projection. --- e.g. .x = mkProjection [x] = getField @"x" --- .x.y = mkProjection [.x, .y] = (.y) . (.x) = getField @"y" . getField @"x" -mkProjection :: Name -> Name -> NonEmpty FieldLabelString -> HsExpr GhcRn -mkProjection getFieldName circName (field :| fields) = foldl' f (proj field) fields - where - f :: HsExpr GhcRn -> FieldLabelString -> HsExpr GhcRn - f acc field = genHsApps circName $ map wrapGenSpan [proj field, acc] - - proj :: FieldLabelString -> HsExpr GhcRn - proj (FieldLabelString f) = genHsVar getFieldName `genAppType` genHsTyLit f - --- mkProjUpdateSetField calculates functions representing dot notation record updates. --- e.g. Suppose an update like foo.bar = 1. --- We calculate the function \a -> setField @"foo" a (setField @"bar" (getField @"foo" a) 1). -mkProjUpdateSetField :: Name -> Name -> LHsRecProj GhcRn (LHsExpr GhcRn) -> (LHsExpr GhcRn -> LHsExpr GhcRn) -mkProjUpdateSetField get_field set_field (L _ (HsFieldBind { hfbLHS = (L _ (FieldLabelStrings flds')), hfbRHS = arg } )) - = let { - ; flds = NE.map (fmap (unLoc . dfoLabel)) flds' - ; final = last flds -- quux - ; fields = init flds -- [foo, bar, baz] - ; getters = \a -> foldl' (mkGet get_field) (a :| []) fields -- Ordered from deep to shallow. - -- [getField@"baz"(getField@"bar"(getField@"foo" a), getField@"bar"(getField@"foo" a), getField@"foo" a, a] - ; zips = \a -> (final, head (getters a)) : zip (reverse fields) (tail (getters a)) -- Ordered from deep to shallow. - -- [("quux", getField@"baz"(getField@"bar"(getField@"foo" a)), ("baz", getField@"bar"(getField@"foo" a)), ("bar", getField@"foo" a), ("foo", a)] - } - in (\a -> foldl' (mkSet set_field) arg (zips a)) - -- setField@"foo" (a) (setField@"bar" (getField @"foo" (a))(setField@"baz" (getField @"bar" (getField @"foo" (a)))(setField@"quux" (getField @"baz" (getField @"bar" (getField @"foo" (a))))(quux)))) - -mkRecordDotUpd :: Name -> Name -> LHsExpr GhcRn -> [LHsRecUpdProj GhcRn] -> HsExpr GhcRn -mkRecordDotUpd get_field set_field exp updates = foldl' fieldUpdate (unLoc exp) updates - where - fieldUpdate :: HsExpr GhcRn -> LHsRecUpdProj GhcRn -> HsExpr GhcRn - fieldUpdate acc lpu = unLoc $ (mkProjUpdateSetField get_field set_field lpu) (wrapGenSpan acc) rnHsUpdProjs :: [LHsRecUpdProj GhcPs] -> RnM ([LHsRecUpdProj GhcRn], FreeNames) rnHsUpdProjs us = do ===================================== compiler/GHC/Rename/Utils.hs ===================================== @@ -24,6 +24,8 @@ module GHC.Rename.Utils ( genSimpleFunBind, genFunBind, genHsLamDoExp, genHsCaseAltDoExp, genSimpleMatch, genHsLet, + mkGetField, mkSetField, mkProjection, mkRecordDotUpd, + mkExpandedRn, mkExpandedExpr, mkExpandedStmt, mkExpandedLExpr, mkExpandedTc, mkExpandedExprTc, mkRnSyntaxExpr, @@ -41,7 +43,7 @@ module GHC.Rename.Utils ( where -import GHC.Prelude +import GHC.Prelude hiding (init, last, scanl, tail) import GHC.Core.Type import GHC.Hs @@ -71,6 +73,7 @@ import GHC.Iface.Load import qualified GHC.LanguageExtensions as LangExt import qualified Data.List.NonEmpty as NE +import Data.List.NonEmpty ( NonEmpty(..), init, last, tail ) import Data.Foldable (for_) import Data.Maybe @@ -867,3 +870,63 @@ mkExpandedTc -> LHsExpr GhcTc -- ^ expanded typechecked expression -> HsExpr GhcTc -- ^ suitably wrapped 'XXExprGhcTc' mkExpandedTc o e = XExpr (ExpandedThingTc (HSE o e)) + + +----------------------------------------- +-- Bits and pieces for RecordDotSyntax. +-- +-- See Note [Overview of record dot syntax] in GHC.Hs.Expr. + +-- mkGetField arg field calculates a get_field @field arg expression. +-- e.g. z.x = mkGetField z x = get_field @x z +mkGetField :: Name -> LHsExpr GhcRn -> LocatedAn NoEpAnns FieldLabelString -> HsExpr GhcRn +mkGetField get_field arg field = unLoc (NE.head $ mkGet get_field (arg :| []) field) + +-- mkSetField a field b calculates a set_field @field expression. +-- e.g mkSetSetField a field b = set_field @"field" a b (read as "set field 'field' to a on b"). +-- NB: the order of aruments is specified by GHC Proposal 583: HasField redesign. +mkSetField :: Name -> LHsExpr GhcRn -> LocatedAn NoEpAnns FieldLabelString -> LHsExpr GhcRn -> HsExpr GhcRn +mkSetField set_field a (L _ (FieldLabelString field)) b = + genHsApp (genHsApp (genHsVar set_field `genAppType` genHsTyLit field) b) a + +mkGet :: Name -> NonEmpty (LHsExpr GhcRn) -> LocatedAn NoEpAnns FieldLabelString -> NonEmpty (LHsExpr GhcRn) +mkGet get_field l@(r :| _) (L _ (FieldLabelString field)) = + wrapGenSpan (genHsApp (genHsVar get_field `genAppType` genHsTyLit field) r) NE.<| l + +mkSet :: Name -> LHsExpr GhcRn -> (LocatedAn NoEpAnns FieldLabelString, LHsExpr GhcRn) -> LHsExpr GhcRn +mkSet set_field acc (field, g) = wrapGenSpan (mkSetField set_field g field acc) + +-- mkProjection fields calculates a projection. +-- e.g. .x = mkProjection [x] = getField @"x" +-- .x.y = mkProjection [.x, .y] = (.y) . (.x) = getField @"y" . getField @"x" +mkProjection :: Name -> Name -> NonEmpty FieldLabelString -> HsExpr GhcRn +mkProjection getFieldName circName (field :| fields) = foldl' f (proj field) fields + where + f :: HsExpr GhcRn -> FieldLabelString -> HsExpr GhcRn + f acc field = genHsApps circName $ map wrapGenSpan [proj field, acc] + + proj :: FieldLabelString -> HsExpr GhcRn + proj (FieldLabelString f) = genHsVar getFieldName `genAppType` genHsTyLit f + +-- mkProjUpdateSetField calculates functions representing dot notation record updates. +-- e.g. Suppose an update like foo.bar = 1. +-- We calculate the function \a -> setField @"foo" a (setField @"bar" (getField @"foo" a) 1). +mkProjUpdateSetField :: Name -> Name -> LHsRecProj GhcRn (LHsExpr GhcRn) -> (LHsExpr GhcRn -> LHsExpr GhcRn) +mkProjUpdateSetField get_field set_field (L _ (HsFieldBind { hfbLHS = (L _ (FieldLabelStrings flds')), hfbRHS = arg } )) + = let { + ; flds = NE.map (fmap (unLoc . dfoLabel)) flds' + ; final = last flds -- quux + ; fields = init flds -- [foo, bar, baz] + ; getters = \a -> foldl' (mkGet get_field) (a :| []) fields -- Ordered from deep to shallow. + -- [getField@"baz"(getField@"bar"(getField@"foo" a), getField@"bar"(getField@"foo" a), getField@"foo" a, a] + ; zips = \a -> (final, NE.head (getters a)) : zip (reverse fields) (tail (getters a)) -- Ordered from deep to shallow. + -- [("quux", getField@"baz"(getField@"bar"(getField@"foo" a)), ("baz", getField@"bar"(getField@"foo" a)), ("bar", getField@"foo" a), ("foo", a)] + } + in (\a -> foldl' (mkSet set_field) arg (zips a)) + -- setField@"foo" (a) (setField@"bar" (getField @"foo" (a))(setField@"baz" (getField @"bar" (getField @"foo" (a)))(setField@"quux" (getField @"baz" (getField @"bar" (getField @"foo" (a))))(quux)))) + +mkRecordDotUpd :: Name -> Name -> LHsExpr GhcRn -> [LHsRecUpdProj GhcRn] -> HsExpr GhcRn +mkRecordDotUpd get_field set_field exp updates = foldl' fieldUpdate (unLoc exp) updates + where + fieldUpdate :: HsExpr GhcRn -> LHsRecUpdProj GhcRn -> HsExpr GhcRn + fieldUpdate acc lpu = unLoc $ (mkProjUpdateSetField get_field set_field lpu) (wrapGenSpan acc) ===================================== compiler/GHC/Tc/Gen/Expand.hs ===================================== @@ -17,8 +17,10 @@ import GHC.Tc.Utils.Monad import GHC.Tc.Types.ErrCtxt import GHC.Types.Id.Make +import GHC.Types.SrcLoc import GHC.Rename.Utils +import qualified Data.List.NonEmpty as NE (map) import qualified GHC.LanguageExtensions as LangExt @@ -114,14 +116,18 @@ tcExpand e@(OpApp _ arg1 op arg2) where ap f a = wrapGenSpan (HsApp noExtField f a) +------------------------------------------ +-- Left and Right Sections + tcExpand e@(SectionR _ op expr) + -- See Note [Left and right sections] = return $ Just $ HSE { hse_ctxt = ExprCtxt e , hse_exp = wrapGenSpan $ genHsApps rightSectionName [op, expr] } tcExpand e@(SectionL _ expr op) + -- Note [Left and right sections] = do { postfix_ops <- xoptM LangExt.PostfixOperators - -- Note [Left and right sections] ; let ds_section | postfix_ops = HsApp noExtField op expr | otherwise = genHsApps leftSectionName @@ -130,10 +136,26 @@ tcExpand e@(SectionL _ expr op) HSE { hse_ctxt = ExprCtxt e , hse_exp = wrapGenSpan ds_section } } +------------------------------------------ +-- Record dot syntax + +tcExpand e@(HsGetField getField expr f) + = return $ Just $ + HSE { hse_ctxt = ExprCtxt e + , hse_exp = wrapGenSpan $ (mkGetField getField expr (fmap (unLoc . dfoLabel) f)) } + +tcExpand e@(HsProjection (getField, circ) fs) + = return$ Just $ + HSE { hse_ctxt = ExprCtxt e + , hse_exp = wrapGenSpan $ (mkProjection getField circ $ NE.map (unLoc . dfoLabel) fs) } +--------- tcExpand (XExpr (ExpandedThingRn hse)) = return (Just hse) +------------------------------------------ +-- Template Haskell Splices + tcExpand e@(HsUntypedSplice splice_res _) -- See Note [Looking through Template Haskell splices in splitHsApps] = do { fun <- getUntypedSpliceBody splice_res @@ -142,3 +164,132 @@ tcExpand e@(HsUntypedSplice splice_res _) , hse_exp = wrapGenSpan fun } } tcExpand _ = return Nothing + + + + + + +{- Note [Left and right sections] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +Dealing with left sections (x *) and right sections (* x) is +surprisingly fiddly. We expand like this + (`op` e) ==> rightSection op e + (e `op`) ==> leftSection (op e) + +Using an auxiliary function in this way avoids the awkwardness of +generating a lambda, esp if `e` is a redex, so we *don't* want +to generate `(\x -> op x e)`. See Historical +Note [Desugaring operator sections] + +Here are their definitions: + leftSection :: forall r1 r2 n (a::TYPE r1) (b::TYPE r2). + (a %n-> b) -> a %n-> b + leftSection f x = f x + + rightSection :: forall r1 r2 r3 n1 n2 (a::TYPE r1) (b::TYPE r2) (c::TYPE r3). + (a %n1 -> b %n2-> c) -> b %n2-> a %n1-> c + rightSection f y x = f x y + +Note the wrinkles: + +* We do /not/ use lookupSyntaxName, which would make left and right + section fall under RebindableSyntax. Reason: it would be a user- + facing change, and there are some tricky design choices (#19354). + Plus, infix operator applications would be trickier to make + rebindable, so it'd be inconsistent to do so for sections. + + TL;DR: we still use the renamer-expansion mechanism for operator + sections, but only to eliminate special-purpose code paths in the + renamer and desugarer. + +* leftSection and rightSection must be representation-polymorphic, to allow + (+# 4#) and (4# +#) to work. See + Note [Wired-in Ids for rebindable syntax] in GHC.Types.Id.Make. + +* leftSection and rightSection must be multiplicity-polymorphic. + (Test linear/should_compile/OldList showed this up.) + +* Because they are representation-polymorphic, we have to define them + as wired-in Ids, with compulsory inlining. See + GHC.Types.Id.Make.leftSectionId, rightSectionId. + +* leftSection is just ($) really; but unlike ($) it is + representation-polymorphic in the result type, so we can write + `(x +#)`, say. + +* The type of leftSection must have an arrow in its first argument, + because (x `ord`) should be rejected, because ord does not take two + arguments + +* It's important that we define leftSection in an eta-expanded way, + (i.e. not leftSection f = f), so that + (True `undefined`) `seq` () + = (leftSection (undefined True) `seq` ()) + evaluates to () and not undefined + +* If PostfixOperators is ON, then we expand a left section like this: + (e `op`) ==> op e + with no auxiliary function at all. Simple! + +* leftSection and rightSection switch on ImpredicativeTypes locally, + during Quick Look; see GHC.Tc.Gen.App.wantQuickLook. Consider + test DeepSubsumption08: + type Setter st t a b = forall f. Identical f => blah + (.~) :: Setter s t a b -> b -> s -> t + clear :: Setter a a' b (Maybe b') -> a -> a' + clear = (.~ Nothing) + The expansion look like (rightSection (.~) Nothing). So we must + instantiate `rightSection` first type argument to a polytype! + Hence the special magic in App.wantQuickLook. + +Historical Note [Desugaring operator sections] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +This Note explains some historical trickiness in desugaring left and +right sections. That trickiness has completely disappeared now that +we desugar to calls to 'leftSection` and `rightSection`, but I'm +leaving it here to remind us how nice the new story is. + +Desugaring left sections with -XPostfixOperators is straightforward: convert +(expr `op`) to (op expr). + +Without -XPostfixOperators it's a bit more tricky. At first it looks as if we +can convert + + (expr `op`) + +naively to + + \x -> op expr x + +But no! expr might be a redex, and we can lose laziness badly this +way. Consider + + map (expr `op`) xs + +for example. If expr were a redex then eta-expanding naively would +result in multiple evaluations where the user might only have expected one. + +So we convert instead to + + let y = expr in \x -> op y x + +Also, note that we must do this for both right and (perhaps surprisingly) left +sections. Why are left sections necessary? Consider the program (found in #18151), + + seq (True `undefined`) () + +according to the Haskell Report this should reduce to () (as it specifies +desugaring via eta expansion). However, if we fail to eta expand we will rather +bottom. Consequently, we must eta expand even in the case of a left section. + +If `expr` is actually just a variable, say, then the simplifier +will inline `y`, eliminating the redundant `let`. + +Note that this works even in the case that `expr` is unlifted. In this case +bindNonRec will automatically do the right thing, giving us: + + case expr of y -> (\x -> op y x) + +See #18151. +-} ===================================== compiler/GHC/Tc/Types/Origin.hs ===================================== @@ -634,6 +634,7 @@ exprCtOrigin (XExpr (ExpandedThingRn (HSE o _))) = hsCtxtCtOrigin o exprCtOrigin (XExpr (HsRecSelRn f)) = OccurrenceOfRecSel $ L (getLoc $ foLabel f) (foExt f) hsCtxtCtOrigin :: HsCtxt -> CtOrigin +hsCtxtCtOrigin (ExprCtxt (ExprWithTySig _ (L _ e) _)) = exprCtOrigin e hsCtxtCtOrigin (ExprCtxt e) = exprCtOrigin e hsCtxtCtOrigin (FunAppCtxt (FunAppCtxtExpr _ e) _) = exprCtOrigin e hsCtxtCtOrigin (StmtErrCtxt{}) = DoStmtOrigin View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/106d086fa2b35f43edea7a77dab037c… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/106d086fa2b35f43edea7a77dab037c… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/10.1] 7 commits: Release notes for GHC 10.0
by Zubin (＠wz1000) 10 Apr '26

10 Apr '26

Zubin pushed to branch wip/10.1 at Glasgow Haskell Compiler / GHC Commits: 813b7f9c by Zubin Duggal at 2026-04-10T01:26:42+05:30 Release notes for GHC 10.0 - - - - - 6de3cd2b by Zubin Duggal at 2026-04-10T01:26:42+05:30 Bump ghc-prim version to 0.14.0 - - - - - 9c3d3895 by Zubin Duggal at 2026-04-10T01:26:42+05:30 Bump template-haskell to 2.25.0.0; update submodule exceptions for TH 2.25 - - - - - 75a0d97f by Zubin Duggal at 2026-04-10T01:26:42+05:30 Bump GHC version to 10.0 - - - - - 28924613 by Zubin Duggal at 2026-04-10T01:30:15+05:30 Bump base to 4.23.0.0; update submodules for base 4.24 upper bound - - - - - 37efea9e by Zubin Duggal at 2026-04-10T01:30:15+05:30 Bump GHC version to 10.1; update submodules template-haskell-lift and template-haskell-quasiquoter for ghc-internal 10.200 - - - - - 05d661d5 by Zubin Duggal at 2026-04-10T01:30:15+05:30 Use changelog.d for release notes (#26002) GHC now uses a fragment-based changelog workflow using a custom script adapted from https://codeberg.org/fgaz/changelog-d. Contributors add a file in changelog.d/ for each user-facing change. At release time, these are assembled into release notes for sphinx (in RST) format, using the tool. New hadrian `changelog` target to generate changelogs CI job to validate changelog entries for MRs unless skipped with ~"no-changelog" label Teach sphinx about ghc-mr: extlink to link to MRs Remove `ghc-package-list` from sphinx, and implement it in changelog-d instead (Fixes #26476). (cherry picked from commit 989c07249978f418dfde1353abfad453f024d61a) - - - - - 63 changed files: - .gitlab-ci.yml - .gitlab/issue_templates/release_tracking.md - .gitlab/merge_request_templates/Default.md - + changelog.d/changelog-entries - + changelog.d/config - compiler/ghc.cabal.in - configure.ac - − docs/users_guide/10.0.1-notes.rst - + docs/users_guide/10.2.1-notes.rst - − docs/users_guide/9.16.1-notes.rst - docs/users_guide/conf.py - docs/users_guide/ghc_config.py.in - − docs/users_guide/ghc_packages.py - docs/users_guide/release-notes.rst - ghc/ghc-bin.cabal.in - hadrian/hadrian.cabal - hadrian/src/CommandLine.hs - hadrian/src/Main.hs - hadrian/src/Packages.hs - + hadrian/src/Rules/Changelog.hs - hadrian/src/Rules/Documentation.hs - hadrian/src/Rules/Test.hs - hadrian/src/Settings/Default.hs - libraries/array - libraries/base/base.cabal.in - libraries/deepseq - libraries/directory - libraries/exceptions - libraries/filepath - libraries/ghc-boot-th/ghc-boot-th.cabal.in - libraries/ghc-boot/ghc-boot.cabal.in - libraries/ghc-compact/ghc-compact.cabal - libraries/ghc-experimental/ghc-experimental.cabal.in - libraries/ghc-prim/changelog.md - libraries/ghc-prim/ghc-prim.cabal - libraries/ghci/ghci.cabal.in - libraries/haskeline - libraries/hpc - libraries/os-string - libraries/parsec - libraries/process - libraries/semaphore-compat - libraries/stm - libraries/template-haskell-lift - libraries/template-haskell-quasiquoter - libraries/template-haskell/template-haskell.cabal.in - libraries/terminfo - libraries/unix - m4/fp_setup_project_version.m4 - testsuite/mk/boilerplate.mk - testsuite/tests/linters/Makefile - testsuite/tests/linters/all.T - + testsuite/tests/linters/changelog-d.stdout - + utils/changelog-d/ChangelogD.hs - + utils/changelog-d/LICENSE - + utils/changelog-d/README.md - + utils/changelog-d/changelog-d.cabal - utils/haddock/haddock-api/haddock-api.cabal - utils/haddock/haddock-api/src/Haddock/InterfaceFile.hs - utils/haddock/haddock-library/haddock-library.cabal - utils/haddock/haddock-test/haddock-test.cabal - utils/haddock/haddock.cabal - utils/hsc2hs The diff was not included because it is too large. View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/8f65b3c3a782b0800285020c0ce1de… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/8f65b3c3a782b0800285020c0ce1de… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/T27135] Fix check for C11 atomic_load
by Peter Trommler (＠trommler) 10 Apr '26

10 Apr '26

Peter Trommler pushed to branch wip/T27135 at Glasgow Haskell Compiler / GHC Commits: 739ddbba by Peter Trommler at 2026-04-09T21:49:18+02:00 Fix check for C11 atomic_load - - - - - 1 changed file: - m4/fp_cc_supports__atomics.m4 Changes: ===================================== m4/fp_cc_supports__atomics.m4 ===================================== @@ -6,7 +6,7 @@ AC_DEFUN([FP_CC_SUPPORTS__ATOMICS], AC_REQUIRE([AC_PROG_CC]) AC_MSG_CHECKING([whether C compiler supports C11 atomics]) AC_COMPILE_IFELSE([AC_LANG_PROGRAM( - [[#include <stdatomic.h>; + [[#include <stdatomic.h> int x;]], [[atomic_load(&x); return x;]])], [ View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/739ddbba35c6ab381b742e55ea3600e… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/739ddbba35c6ab381b742e55ea3600e… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/T27135] Require autoconf 2.70 for C11 test
by Peter Trommler (＠trommler) 10 Apr '26

10 Apr '26

Peter Trommler pushed to branch wip/T27135 at Glasgow Haskell Compiler / GHC Commits: a24c1e68 by Peter Trommler at 2026-04-09T21:15:52+02:00 Require autoconf 2.70 for C11 test - - - - - 1 changed file: - configure.ac Changes: ===================================== configure.ac ===================================== @@ -61,6 +61,7 @@ FP_PROG_FIND dnl ---------------------------------------------------------- FP_SETUP_PROJECT_VERSION +dnl * We need 2.70 for C11 detection dnl * We require autoconf version 2.69 due to dnl https://bugs.ruby-lang.org/issues/8179. Also see #14910. dnl * We need 2.50 due to the use of AC_SYS_LARGEFILE and AC_MSG_NOTICE. @@ -68,7 +69,7 @@ dnl * We need 2.52 due to the use of AS_TR_CPP and AS_TR_SH. dnl * Using autoconf 2.59 started to give nonsense like this dnl #define SIZEOF_CHAR 0 dnl recently. -AC_PREREQ([2.69]) +AC_PREREQ([2.70]) # No, semi-sadly, we don't do `--srcdir'... if test x"$srcdir" != 'x.' ; then View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/a24c1e68d848aa9e5db68fb47a394d7… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/a24c1e68d848aa9e5db68fb47a394d7… You're receiving this email because of your account on gitlab.haskell.org.

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