From 099416669cf8a37f7eb00f9b2c0d78a7c8402af1 Mon Sep 17 00:00:00 2001
From: Adam Gundry <adam@well-typed.com>
Date: Thu, 15 Feb 2024 20:50:17 +0000
Subject: [PATCH] Define GHC2024 language edition (#24320)
See https://github.com/ghc-proposals/ghc-proposals/pull/613. Also
fixes #24343 and improves the documentation of language editions.
Co-authored-by: Joachim Breitner <mail@joachim-breitner.de>
---
compiler/GHC/Driver/DynFlags.hs | 12 +-
compiler/GHC/Driver/Flags.hs | 8 +-
compiler/GHC/Driver/Session.hs | 3 +-
docs/users_guide/9.10.1-notes.rst | 18 +++
docs/users_guide/exts/binary_literals.rst | 2 +-
.../exts/constrained_class_methods.rst | 2 +-
docs/users_guide/exts/constraint_kind.rst | 2 +-
docs/users_guide/exts/control.rst | 153 +++++++++++++++---
docs/users_guide/exts/data_kinds.rst | 2 +
docs/users_guide/exts/deriving_extra.rst | 8 +-
docs/users_guide/exts/deriving_strategies.rst | 2 +
.../exts/disambiguate_record_fields.rst | 1 +
docs/users_guide/exts/empty_case.rst | 2 +-
docs/users_guide/exts/empty_data_deriving.rst | 2 +-
.../exts/existential_quantification.rst | 2 +-
docs/users_guide/exts/explicit_forall.rst | 2 +-
docs/users_guide/exts/explicit_namespaces.rst | 1 +
docs/users_guide/exts/ffi.rst | 2 +-
docs/users_guide/exts/field_selectors.rst | 2 +-
docs/users_guide/exts/flexible_contexts.rst | 2 +-
docs/users_guide/exts/gadt.rst | 1 +
docs/users_guide/exts/gadt_syntax.rst | 2 +-
docs/users_guide/exts/generics.rst | 2 +-
docs/users_guide/exts/hex_float_literals.rst | 2 +-
.../exts/import_qualified_post.rst | 2 +-
docs/users_guide/exts/instances.rst | 6 +-
docs/users_guide/exts/intro.rst | 7 +-
docs/users_guide/exts/kind_signatures.rst | 2 +-
docs/users_guide/exts/lambda_case.rst | 1 +
docs/users_guide/exts/let_generalisation.rst | 1 +
.../exts/multi_param_type_classes.rst | 2 +-
docs/users_guide/exts/newtype_deriving.rst | 2 +-
docs/users_guide/exts/nullary_types.rst | 2 +-
docs/users_guide/exts/numeric_underscores.rst | 2 +-
.../exts/partial_type_signatures.rst | 2 +-
docs/users_guide/exts/poly_kinds.rst | 6 +-
docs/users_guide/exts/rank_polymorphism.rst | 2 +-
docs/users_guide/exts/rebindable_syntax.rst | 2 +-
docs/users_guide/exts/record_puns.rst | 2 +-
docs/users_guide/exts/roles.rst | 1 +
.../exts/scoped_type_variables.rst | 2 +-
docs/users_guide/exts/standalone_deriving.rst | 2 +-
docs/users_guide/exts/strict.rst | 2 +-
docs/users_guide/exts/tuple_sections.rst | 2 +-
docs/users_guide/exts/type_applications.rst | 2 +-
docs/users_guide/exts/type_operators.rst | 2 +-
ghc/GHCi/UI.hs | 4 +-
.../tests/roles/should_compile/Roles1.hs | 2 +-
48 files changed, 222 insertions(+), 73 deletions(-)
diff --git a/compiler/GHC/Driver/DynFlags.hs b/compiler/GHC/Driver/DynFlags.hs
index 83f7e2ab649c..6398f29f9a42 100644
--- a/compiler/GHC/Driver/DynFlags.hs
+++ b/compiler/GHC/Driver/DynFlags.hs
@@ -1339,7 +1339,7 @@ default_PIC platform =
languageExtensions :: Maybe Language -> [LangExt.Extension]
-- Nothing: the default case
-languageExtensions Nothing = languageExtensions (Just GHC2021)
+languageExtensions Nothing = languageExtensions (Just defaultLanguage)
languageExtensions (Just Haskell98)
= [LangExt.ImplicitPrelude,
@@ -1427,6 +1427,16 @@ languageExtensions (Just GHC2021)
LangExt.TypeOperators,
LangExt.TypeSynonymInstances]
+languageExtensions (Just GHC2024)
+ = languageExtensions (Just GHC2021) ++
+ [LangExt.DataKinds,
+ LangExt.DerivingStrategies,
+ LangExt.DisambiguateRecordFields,
+ LangExt.ExplicitNamespaces,
+ LangExt.GADTs,
+ LangExt.MonoLocalBinds,
+ LangExt.LambdaCase,
+ LangExt.RoleAnnotations]
ways :: DynFlags -> Ways
ways dflags
diff --git a/compiler/GHC/Driver/Flags.hs b/compiler/GHC/Driver/Flags.hs
index 3b5cfc1a26e4..59647631f454 100644
--- a/compiler/GHC/Driver/Flags.hs
+++ b/compiler/GHC/Driver/Flags.hs
@@ -4,6 +4,7 @@ module GHC.Driver.Flags
, enabledIfVerbose
, GeneralFlag(..)
, Language(..)
+ , defaultLanguage
, optimisationFlags
, codeGenFlags
@@ -38,9 +39,14 @@ import Control.Monad (guard)
import Data.List.NonEmpty (NonEmpty(..))
import Data.Maybe (fromMaybe,mapMaybe)
-data Language = Haskell98 | Haskell2010 | GHC2021
+data Language = Haskell98 | Haskell2010 | GHC2021 | GHC2024
deriving (Eq, Enum, Show, Bounded)
+-- | The default Language is used if one is not specified explicitly, by both
+-- GHC and GHCi.
+defaultLanguage :: Language
+defaultLanguage = GHC2021
+
instance Outputable Language where
ppr = text . show
diff --git a/compiler/GHC/Driver/Session.hs b/compiler/GHC/Driver/Session.hs
index b36a9a7f1488..72301f947f81 100644
--- a/compiler/GHC/Driver/Session.hs
+++ b/compiler/GHC/Driver/Session.hs
@@ -2603,7 +2603,8 @@ languageFlagsDeps :: [(Deprecation, FlagSpec Language)]
languageFlagsDeps = [
flagSpec "Haskell98" Haskell98,
flagSpec "Haskell2010" Haskell2010,
- flagSpec "GHC2021" GHC2021
+ flagSpec "GHC2021" GHC2021,
+ flagSpec "GHC2024" GHC2024
]
-- | These -X<blah> flags cannot be reversed with -XNo<blah>
diff --git a/docs/users_guide/9.10.1-notes.rst b/docs/users_guide/9.10.1-notes.rst
index 2633529325c6..b8b43fec159f 100644
--- a/docs/users_guide/9.10.1-notes.rst
+++ b/docs/users_guide/9.10.1-notes.rst
@@ -6,6 +6,24 @@ Version 9.10.1
Language
~~~~~~~~
+- The :extension:`GHC2024` language edition is now supported. It builds on top of
+ :extension:`GHC2021`, adding the following extensions:
+
+ * :extension:`DataKinds`
+ * :extension:`DerivingStrategies`
+ * :extension:`DisambiguateRecordFields`
+ * :extension:`ExplicitNamespaces`
+ * :extension:`GADTs`
+ * :extension:`MonoLocalBinds`
+ * :extension:`LambdaCase`
+ * :extension:`RoleAnnotations`
+
+ At the moment, :extension:`GHC2021` remains the default langauge edition that
+ is used when no other language edition is explicitly loaded (e.g. when running
+ ``ghc`` directly). Because language editions are not necessarily backwards
+ compatible, and future releases of GHC may change the default, it is highly
+ recommended to specify the language edition explicitly.
+
- GHC Proposal `#281 <https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0281-visible-forall.rst>`_
"Visible forall in types of terms" has been partially implemented.
The following code is now accepted by GHC::
diff --git a/docs/users_guide/exts/binary_literals.rst b/docs/users_guide/exts/binary_literals.rst
index 29c5ad290fb4..b65f6522f671 100644
--- a/docs/users_guide/exts/binary_literals.rst
+++ b/docs/users_guide/exts/binary_literals.rst
@@ -8,7 +8,7 @@ Binary integer literals
:since: 7.10.1
- :status: Included in :extension:`GHC2021`
+ :status: Included in :extension:`GHC2024`, :extension:`GHC2021`
Allow the use of binary notation in integer literals.
diff --git a/docs/users_guide/exts/constrained_class_methods.rst b/docs/users_guide/exts/constrained_class_methods.rst
index 37ca499c6cea..f28bf0c55dd3 100644
--- a/docs/users_guide/exts/constrained_class_methods.rst
+++ b/docs/users_guide/exts/constrained_class_methods.rst
@@ -9,7 +9,7 @@ Constrained class method types
:since: 6.8.1
- :status: Included in :extension:`GHC2021`
+ :status: Included in :extension:`GHC2024`, :extension:`GHC2021`
:implied by: :extension:`MultiParamTypeClasses`
diff --git a/docs/users_guide/exts/constraint_kind.rst b/docs/users_guide/exts/constraint_kind.rst
index 7cbe132ff827..7915b893884e 100644
--- a/docs/users_guide/exts/constraint_kind.rst
+++ b/docs/users_guide/exts/constraint_kind.rst
@@ -8,7 +8,7 @@ The ``Constraint`` kind
:since: 7.4.1
- :status: Included in :extension:`GHC2021`
+ :status: Included in :extension:`GHC2024`, :extension:`GHC2021`
Allow types of kind ``Constraint`` to be used in contexts.
diff --git a/docs/users_guide/exts/control.rst b/docs/users_guide/exts/control.rst
index 60726e9dbabe..b5b8383a0792 100644
--- a/docs/users_guide/exts/control.rst
+++ b/docs/users_guide/exts/control.rst
@@ -1,49 +1,144 @@
.. _options-language:
-Controlling extensions
-----------------------
+Controlling editions and extensions
+-----------------------------------
.. index::
single: language; option
single: options; language
single: extensions; options controlling
+ single: editions; language
-Language extensions can be controlled (i.e. allowed or not) in two ways:
+GHC supports multiple language editions: :extension:`Haskell98`,
+:extension:`Haskell2010`, :extension:`GHC2021` and :extension:`GHC2024`. Each
+language edition consists of a collection of language extensions, and there are
+many other language extensions not currently part of a language edition but that
+can be enabled explicitly.
-- Every language extension can be switched on by a command-line flag
+Currently, :extension:`GHC2021` is used by default if no other language edition
+is explicitly requested, for backwards compatibility purposes. Since later
+versions of GHC may use a different language edition by default, users are
+advised to declare a language edition explicitly. Using :extension:`GHC2024` is
+recommended for new code.
+
+A language edition can be selected:
+
+- at the package level, e.g. using ``default-language: GHC2024`` in a
+ ``.cabal`` file;
+
+- with a command-line flag prefixed by "``-X...``" (e.g. ``-XGHC2024``); or
+
+- for an individual module using the :pragma:`LANGUAGE` pragma, e.g.
+ ``{-# LANGUAGE GHC2024 #-}``.
+
+Selecting a language edition overrides any previous selection. It is not
+possible to disable a language edition.
+
+Similarly, language extensions can be controlled (either enabled or disabled):
+
+- at the package level, e.g. using ``default-extensions: TemplateHaskell`` in a
+ ``.cabal`` file;
+
+- with command-line flags, switched on by a command-line flag
"``-X...``" (e.g. ``-XTemplateHaskell``), and switched off by the
- flag "``-XNo...``"; (e.g. ``-XNoTemplateHaskell``).
+ flag "``-XNo...``"; (e.g. ``-XNoTemplateHaskell``);
-- Language extensions can also be enabled using the ``LANGUAGE`` pragma, thus
- ``{-# LANGUAGE TemplateHaskell #-}`` (see :ref:`language-pragma`).
+- for an individual module using the :pragma:`LANGUAGE` pragma, e.g.
+ ``{-# LANGUAGE TemplateHaskell #-}`` or ``{-# LANGUAGE NoTemplateHaskell #-}``.
-.. extension:: GHC2021
- :shortdesc: Use GHC’s set of default language extensions from 2021
+.. extension:: GHC2024
+ :shortdesc: Use GHC’s set of default language extensions from 2024
+
+ :since: 9.10.1
GHC blesses a number of extensions, beyond Haskell 2010, to be suitable to
turned on by default. These extensions are considered to be stable and
conservative.
- ``GHC2021`` is used by GHC if neither ``Haskell98`` nor ``Haskell2010`` is
- turned on explicitly. Since later versions of GHC may use a later
- ``GHC20xx`` by default, users are advised to declare the language set
- explicitly with ``-XGHC2021``.
-
- Note that, because GHC2021 includes a number of non-standardized
+ Note that, because GHC2024 includes a number of non-standardized
extensions, the stability guarantees it provides are not quite as strong as
those provided by, e.g., :extension:`Haskell2010`. While GHC does take
pains to avoid changing the semantics of these extensions, changes may
still happen (e.g. the simplified subsumption change introduced in GHC 9.0
which caused GHC to reject some programs using :extension:`RankNTypes`).
+ The ``GHC2024`` language edition includes the following extensions:
+
+ .. hlist::
+
+ * :extension:`BangPatterns`
+ * :extension:`BinaryLiterals`
+ * :extension:`ConstrainedClassMethods`
+ * :extension:`ConstraintKinds`
+ * :extension:`DataKinds`
+ * :extension:`DeriveDataTypeable`
+ * :extension:`DeriveFoldable`
+ * :extension:`DeriveFunctor`
+ * :extension:`DeriveGeneric`
+ * :extension:`DeriveLift`
+ * :extension:`DeriveTraversable`
+ * :extension:`DerivingStrategies`
+ * :extension:`DisambiguateRecordFields`
+ * :extension:`DoAndIfThenElse`
+ * :extension:`EmptyCase`
+ * :extension:`EmptyDataDecls`
+ * :extension:`EmptyDataDeriving`
+ * :extension:`ExistentialQuantification`
+ * :extension:`ExplicitForAll`
+ * :extension:`ExplicitNamespaces`
+ * :extension:`FieldSelectors`
+ * :extension:`FlexibleContexts`
+ * :extension:`FlexibleInstances`
+ * :extension:`ForeignFunctionInterface`
+ * :extension:`GADTs`
+ * :extension:`GADTSyntax`
+ * :extension:`GeneralisedNewtypeDeriving`
+ * :extension:`HexFloatLiterals`
+ * :extension:`ImplicitPrelude`
+ * :extension:`ImportQualifiedPost`
+ * :extension:`InstanceSigs`
+ * :extension:`KindSignatures`
+ * :extension:`LambdaCase`
+ * :extension:`MonoLocalBinds`
+ * :extension:`MonomorphismRestriction`
+ * :extension:`MultiParamTypeClasses`
+ * :extension:`NamedFieldPuns`
+ * :extension:`NamedWildCards`
+ * :extension:`NumericUnderscores`
+ * :extension:`PatternGuards`
+ * :extension:`PolyKinds`
+ * :extension:`PostfixOperators`
+ * :extension:`RankNTypes`
+ * :extension:`RelaxedPolyRec`
+ * :extension:`RoleAnnotations`
+ * :extension:`ScopedTypeVariables`
+ * :extension:`StandaloneDeriving`
+ * :extension:`StandaloneKindSignatures`
+ * :extension:`StarIsType`
+ * :extension:`TraditionalRecordSyntax`
+ * :extension:`TupleSections`
+ * :extension:`TypeApplications`
+ * :extension:`TypeOperators`
+ * :extension:`TypeSynonymInstances`
+
+.. extension:: GHC2021
+ :shortdesc: Use GHC’s set of default language extensions from 2021
+
+ :since: 9.2.1
+
+ See :extension:`GHC2024` for general comments about ``GHC20xx`` language
+ editions.
+
Also note that due to a `minor oversight
- <https://github.com/ghc-proposals/ghc-proposals/issues/551>`_, this
- extension set behaves slightly differently than enabling each of its
+ <https://github.com/ghc-proposals/ghc-proposals/issues/551>`_, enabling
+ this edition behaves slightly differently than enabling each of its
constituent extensions. Specifically, while :extension:`TypeOperators` implies
:extension:`ExplicitNamespaces`, :extension:`ExplicitNamespaces` is not included
- in :extension:`GHC2021`.
+ in :extension:`GHC2021`. Moreover, while :extension:`GADTs` is not part of
+ :extension:`GHC2021`, the combination of :extension:`GADTSyntax` and
+ :extension:`ExistentialQuantification` is enough to define and use GADTs.
- The ``GHC2021`` language set comprises the following extensions:
+ The ``GHC2021`` language edition includes the following extensions:
.. hlist::
@@ -97,10 +192,14 @@ Language extensions can be controlled (i.e. allowed or not) in two ways:
.. extension:: Haskell2010
- :shortdesc: Use the Haskell 2010 language variant.
+ :shortdesc: Use the Haskell 2010 language edition.
- Compile Haskell 2010 language variant. Enables the
- following language extensions:
+ Compile using the Haskell 2010 language edition, as specified by the
+ `Haskell 2010 report <https://www.haskell.org/onlinereport/haskell2010/>`_.
+ GHC aims to behave mostly as a Haskell 2010 compiler, but there are a few
+ known deviations from the standard (see :ref:`vs-Haskell-defn`).
+
+ The ``Haskell2010`` language edition includes the following language extensions:
.. hlist::
@@ -120,10 +219,14 @@ Language extensions can be controlled (i.e. allowed or not) in two ways:
.. extension:: Haskell98
- :shortdesc: Use the Haskell 98 language variant.
+ :shortdesc: Use the Haskell 98 language edition.
+
+ Compile using the Haskell 98 language edition, as specified by the `Haskell
+ 98 report <https://www.haskell.org/onlinereport/>`_. GHC aims to behave
+ mostly as a Haskell 98 compiler, but there are a few known deviations from
+ the standard (see :ref:`vs-Haskell-defn`).
- Compile using Haskell 98 language variant. Enables the
- following language extensions:
+ The ``Haskell98`` language edition includes the following language extensions:
.. hlist::
diff --git a/docs/users_guide/exts/data_kinds.rst b/docs/users_guide/exts/data_kinds.rst
index 2843819bfecc..278e82e6681c 100644
--- a/docs/users_guide/exts/data_kinds.rst
+++ b/docs/users_guide/exts/data_kinds.rst
@@ -8,6 +8,8 @@ Datatype promotion
:since: 7.4.1
+ :status: Included in :extension:`GHC2024`
+
Allow promotion of data types to kind level.
This section describes *data type promotion*, an extension to the kind
diff --git a/docs/users_guide/exts/deriving_extra.rst b/docs/users_guide/exts/deriving_extra.rst
index 42d684f499c9..9f3374e0f146 100644
--- a/docs/users_guide/exts/deriving_extra.rst
+++ b/docs/users_guide/exts/deriving_extra.rst
@@ -55,7 +55,7 @@ Deriving ``Functor`` instances
:implied by: :extension:`DeriveTraversable`
:since: 7.10.1
- :status: Included in :extension:`GHC2021`
+ :status: Included in :extension:`GHC2024`, :extension:`GHC2021`
Allow automatic deriving of instances for the ``Functor`` typeclass.
@@ -251,7 +251,7 @@ Deriving ``Foldable`` instances
:implied by: :extension:`DeriveTraversable`
:since: 7.10.1
- :status: Included in :extension:`GHC2021`
+ :status: Included in :extension:`GHC2024`, :extension:`GHC2021`
Allow automatic deriving of instances for the ``Foldable`` typeclass.
@@ -472,7 +472,7 @@ Deriving ``Data`` instances
:shortdesc: Enable deriving for the ``Data`` class.
:since: 6.8.1
- :status: Included in :extension:`GHC2021`
+ :status: Included in :extension:`GHC2024`, :extension:`GHC2021`
Enable automatic deriving of instances for the ``Data`` typeclass
@@ -526,7 +526,7 @@ Deriving ``Lift`` instances
:shortdesc: Enable deriving for the Lift class
:since: 8.0.1
- :status: Included in :extension:`GHC2021`
+ :status: Included in :extension:`GHC2024`, :extension:`GHC2021`
Enable automatic deriving of instances for the ``Lift`` typeclass for
Template Haskell.
diff --git a/docs/users_guide/exts/deriving_strategies.rst b/docs/users_guide/exts/deriving_strategies.rst
index 77e5aa5ffb16..7a879a9cde3d 100644
--- a/docs/users_guide/exts/deriving_strategies.rst
+++ b/docs/users_guide/exts/deriving_strategies.rst
@@ -8,6 +8,8 @@ Deriving strategies
:since: 8.2.1
+ :status: Included in :extension:`GHC2024`
+
Allow multiple ``deriving``, each optionally qualified with a *strategy*.
In most scenarios, every ``deriving`` statement generates a typeclass instance
diff --git a/docs/users_guide/exts/disambiguate_record_fields.rst b/docs/users_guide/exts/disambiguate_record_fields.rst
index 3c1fbcc4b4b7..6e0653d64113 100644
--- a/docs/users_guide/exts/disambiguate_record_fields.rst
+++ b/docs/users_guide/exts/disambiguate_record_fields.rst
@@ -9,6 +9,7 @@ Record field disambiguation
:since: 6.8.1
:implied by: :extension:`RecordWildCards`, :extension:`DuplicateRecordFields`
+ :status: Included in :extension:`GHC2024`
Allow the compiler to automatically choose between identically-named record
fields (if the choice is unambiguous).
diff --git a/docs/users_guide/exts/empty_case.rst b/docs/users_guide/exts/empty_case.rst
index e69a761bff08..0b4e7ce6deac 100644
--- a/docs/users_guide/exts/empty_case.rst
+++ b/docs/users_guide/exts/empty_case.rst
@@ -7,7 +7,7 @@ Empty case alternatives
:shortdesc: Allow empty case alternatives.
:since: 7.8.1
- :status: Included in :extension:`GHC2021`
+ :status: Included in :extension:`GHC2024`, :extension:`GHC2021`
Allow empty case expressions.
diff --git a/docs/users_guide/exts/empty_data_deriving.rst b/docs/users_guide/exts/empty_data_deriving.rst
index e75d9a8e4171..0f26ee0f7efa 100644
--- a/docs/users_guide/exts/empty_data_deriving.rst
+++ b/docs/users_guide/exts/empty_data_deriving.rst
@@ -8,7 +8,7 @@ Deriving instances for empty data types
empty data types.
:since: 8.4.1
- :status: Included in :extension:`Haskell2010`, :extension:`GHC2021`
+ :status: Included in :extension:`GHC2024`, :extension:`GHC2021`, :extension:`Haskell2010`
Allow deriving instances of standard type classes for empty data types.
diff --git a/docs/users_guide/exts/existential_quantification.rst b/docs/users_guide/exts/existential_quantification.rst
index 568eb63b7b49..b71ccf74175b 100644
--- a/docs/users_guide/exts/existential_quantification.rst
+++ b/docs/users_guide/exts/existential_quantification.rst
@@ -8,7 +8,7 @@ Existentially quantified data constructors
:implies: :extension:`ExplicitForAll`
:since: 6.8.1
- :status: Included in :extension:`GHC2021`
+ :status: Included in :extension:`GHC2024`, :extension:`GHC2021`
Allow existentially quantified type variables in types.
diff --git a/docs/users_guide/exts/explicit_forall.rst b/docs/users_guide/exts/explicit_forall.rst
index 5a6212ee4b3f..ef470cc22da3 100644
--- a/docs/users_guide/exts/explicit_forall.rst
+++ b/docs/users_guide/exts/explicit_forall.rst
@@ -11,7 +11,7 @@ Explicit universal quantification (forall)
:implied by: :extension:`ScopedTypeVariables`, :extension:`LiberalTypeSynonyms`,
:extension:`RankNTypes`, :extension:`ExistentialQuantification`
:since: 6.12.1
- :status: Included in :extension:`GHC2021`
+ :status: Included in :extension:`GHC2024`, :extension:`GHC2021`
Allow use of the ``forall`` keyword in places where universal quantification
is implicit.
diff --git a/docs/users_guide/exts/explicit_namespaces.rst b/docs/users_guide/exts/explicit_namespaces.rst
index 74d3a79124af..0e6509c31bb6 100644
--- a/docs/users_guide/exts/explicit_namespaces.rst
+++ b/docs/users_guide/exts/explicit_namespaces.rst
@@ -10,6 +10,7 @@ Explicit namespaces in import/export
:implied by: :extension:`TypeOperators`, :extension:`TypeFamilies`
:since: 7.6.1
+ :status: Included in :extension:`GHC2024`
Enable use of explicit namespaces in module export lists, patterns, and expressions.
diff --git a/docs/users_guide/exts/ffi.rst b/docs/users_guide/exts/ffi.rst
index 6246ca3b495a..4000c5cd7399 100644
--- a/docs/users_guide/exts/ffi.rst
+++ b/docs/users_guide/exts/ffi.rst
@@ -12,7 +12,7 @@ Foreign function interface (FFI)
:since: 6.8.1
- :status: Included in :extension:`Haskell2010`, :extension:`GHC2021`
+ :status: Included in :extension:`GHC2024`, :extension:`GHC2021`, :extension:`Haskell2010`
Allow use of the Haskell foreign function interface.
diff --git a/docs/users_guide/exts/field_selectors.rst b/docs/users_guide/exts/field_selectors.rst
index 513947fe4f3f..e22f920f9801 100644
--- a/docs/users_guide/exts/field_selectors.rst
+++ b/docs/users_guide/exts/field_selectors.rst
@@ -7,7 +7,7 @@ Field selectors
:shortdesc: Control visibility of field selector functions.
:since: 9.2.1
- :status: Included in :extension:`Haskell98`, :extension:`Haskell2010`, :extension:`GHC2021`
+ :status: Included in :extension:`GHC2024`, :extension:`GHC2021`, :extension:`Haskell2010`, :extension:`Haskell98`
Make `record field selector functions
<https://www.haskell.org/onlinereport/haskell2010/haskellch3.html#x8-500003.15.1>`_
diff --git a/docs/users_guide/exts/flexible_contexts.rst b/docs/users_guide/exts/flexible_contexts.rst
index 532f3f2bb886..0c4222804c92 100644
--- a/docs/users_guide/exts/flexible_contexts.rst
+++ b/docs/users_guide/exts/flexible_contexts.rst
@@ -7,7 +7,7 @@ Loosening restrictions on class contexts
:shortdesc: Remove some restrictions on class contexts
:since: 6.8.1
- :status: Included in :extension:`GHC2021`
+ :status: Included in :extension:`GHC2024`, :extension:`GHC2021`
Remove the type-variable restriction on class contexts.
diff --git a/docs/users_guide/exts/gadt.rst b/docs/users_guide/exts/gadt.rst
index 9190178ec1a1..856322077b31 100644
--- a/docs/users_guide/exts/gadt.rst
+++ b/docs/users_guide/exts/gadt.rst
@@ -9,6 +9,7 @@ Generalised Algebraic Data Types (GADTs)
:implies: :extension:`MonoLocalBinds`, :extension:`GADTSyntax`
:since: 6.8.1
+ :status: Included in :extension:`GHC2024`
Allow use of Generalised Algebraic Data Types (GADTs).
diff --git a/docs/users_guide/exts/gadt_syntax.rst b/docs/users_guide/exts/gadt_syntax.rst
index 40e5086d052a..239dd0326e7c 100644
--- a/docs/users_guide/exts/gadt_syntax.rst
+++ b/docs/users_guide/exts/gadt_syntax.rst
@@ -9,7 +9,7 @@ Declaring data types with explicit constructor signatures
:implied by: :extension:`GADTs`
:since: 7.2.1
- :status: Included in :extension:`GHC2021`
+ :status: Included in :extension:`GHC2024`, :extension:`GHC2021`
Allow the use of GADT syntax in data type definitions (but not GADTs
themselves; for this see :extension:`GADTs`)
diff --git a/docs/users_guide/exts/generics.rst b/docs/users_guide/exts/generics.rst
index 1cd47e277656..f7a21bcb0920 100644
--- a/docs/users_guide/exts/generics.rst
+++ b/docs/users_guide/exts/generics.rst
@@ -96,7 +96,7 @@ enabled, then it can range of types of kind ``k -> Type``, for any kind ``k``.
:since: 7.2.1
- :status: Included in :extension:`GHC2021`
+ :status: Included in :extension:`GHC2024`, :extension:`GHC2021`
Allow automatic deriving of instances for the ``Generic`` typeclass.
diff --git a/docs/users_guide/exts/hex_float_literals.rst b/docs/users_guide/exts/hex_float_literals.rst
index c8f3708c290a..7ebe6551b429 100644
--- a/docs/users_guide/exts/hex_float_literals.rst
+++ b/docs/users_guide/exts/hex_float_literals.rst
@@ -8,7 +8,7 @@ Hexadecimal floating point literals
:since: 8.4.1
- :status: Included in :extension:`GHC2021`
+ :status: Included in :extension:`GHC2024`, :extension:`GHC2021`
Allow writing floating point literals using hexadecimal notation.
diff --git a/docs/users_guide/exts/import_qualified_post.rst b/docs/users_guide/exts/import_qualified_post.rst
index 2719463b5b18..b89a70d986f4 100644
--- a/docs/users_guide/exts/import_qualified_post.rst
+++ b/docs/users_guide/exts/import_qualified_post.rst
@@ -8,7 +8,7 @@ Writing qualified in postpositive position
:since: 8.10.1
- :status: Included in :extension:`GHC2021`
+ :status: Included in :extension:`GHC2024`, :extension:`GHC2021`
``ImportQualifiedPost`` allows the syntax ``import M qualified``, that is, to annotate a module as qualified by writing ``qualified`` after the module name.
diff --git a/docs/users_guide/exts/instances.rst b/docs/users_guide/exts/instances.rst
index ff8f9139fcc9..75f58ef0661c 100644
--- a/docs/users_guide/exts/instances.rst
+++ b/docs/users_guide/exts/instances.rst
@@ -48,7 +48,7 @@ Relaxed rules for the instance head
:implied by: :extension:`FlexibleInstances`
:since: 6.8.1
- :status: Included in :extension:`GHC2021`
+ :status: Included in :extension:`GHC2024`, :extension:`GHC2021`
Allow definition of type class instances for type synonyms.
@@ -60,7 +60,7 @@ Relaxed rules for the instance head
:since: 6.8.1
- :status: Included in :extension:`GHC2021`
+ :status: Included in :extension:`GHC2024`, :extension:`GHC2021`
Allow definition of type class instances with arbitrary nested types in the
instance head.
@@ -671,7 +671,7 @@ Instance signatures: type signatures in instance declarations
:since: 7.6.1
- :status: Included in :extension:`GHC2021`
+ :status: Included in :extension:`GHC2024`, :extension:`GHC2021`
Allow type signatures for members in instance definitions.
diff --git a/docs/users_guide/exts/intro.rst b/docs/users_guide/exts/intro.rst
index 299e756d2e47..1adf5eb4fb03 100644
--- a/docs/users_guide/exts/intro.rst
+++ b/docs/users_guide/exts/intro.rst
@@ -1,10 +1,9 @@
Introduction
============
-As with all known Haskell systems, GHC implements some extensions to the
-standard Haskell language. They can all be enabled or disabled by command line
-flags or language pragmas. By default GHC understands the most recent Haskell
-version it supports, plus a handful of extensions.
+GHC implements several variants of the Haskell language, along with many
+extensions. They can all be enabled or disabled by command line flags or
+:pragma:`LANGUAGE` pragmas.
Some of the extensions serve to give you access to the
underlying facilities with which we implement Haskell. Thus, you can get
diff --git a/docs/users_guide/exts/kind_signatures.rst b/docs/users_guide/exts/kind_signatures.rst
index a953899be207..4b4ced0a37df 100644
--- a/docs/users_guide/exts/kind_signatures.rst
+++ b/docs/users_guide/exts/kind_signatures.rst
@@ -10,7 +10,7 @@ Explicitly-kinded quantification
:implied by: :extension:`TypeFamilies`, :extension:`PolyKinds`
:since: 6.8.1
- :status: Included in :extension:`GHC2021`
+ :status: Included in :extension:`GHC2024`, :extension:`GHC2021`
Allow explicit kind signatures on type variables.
diff --git a/docs/users_guide/exts/lambda_case.rst b/docs/users_guide/exts/lambda_case.rst
index 4712da3d744b..b6866f3beec9 100644
--- a/docs/users_guide/exts/lambda_case.rst
+++ b/docs/users_guide/exts/lambda_case.rst
@@ -7,6 +7,7 @@ Lambda-case
:shortdesc: Enable lambda-case expressions.
:since: 7.6.1
+ :status: Included in :extension:`GHC2024`
Allow the use of lambda-case syntax.
diff --git a/docs/users_guide/exts/let_generalisation.rst b/docs/users_guide/exts/let_generalisation.rst
index bdb0c2ef8644..259e9b9d3e30 100644
--- a/docs/users_guide/exts/let_generalisation.rst
+++ b/docs/users_guide/exts/let_generalisation.rst
@@ -9,6 +9,7 @@ Let-generalisation
:implied by: :extension:`TypeFamilies`, :extension:`GADTs`
:since: 6.12.1
+ :status: Included in :extension:`GHC2024`
Infer less polymorphic types for local bindings by default.
diff --git a/docs/users_guide/exts/multi_param_type_classes.rst b/docs/users_guide/exts/multi_param_type_classes.rst
index cb2ebdc8af36..83a59e5a1995 100644
--- a/docs/users_guide/exts/multi_param_type_classes.rst
+++ b/docs/users_guide/exts/multi_param_type_classes.rst
@@ -12,7 +12,7 @@ Multi-parameter type classes
:implied by: :extension:`FunctionalDependencies`
:since: 6.8.1
- :status: Included in :extension:`GHC2021`
+ :status: Included in :extension:`GHC2024`, :extension:`GHC2021`
Allow the definition of typeclasses with more than one parameter.
diff --git a/docs/users_guide/exts/newtype_deriving.rst b/docs/users_guide/exts/newtype_deriving.rst
index 8856287a9160..94df2a5ad3d7 100644
--- a/docs/users_guide/exts/newtype_deriving.rst
+++ b/docs/users_guide/exts/newtype_deriving.rst
@@ -9,7 +9,7 @@ Generalised derived instances for newtypes
:since: 6.8.1. British spelling since 8.6.1.
- :status: Included in :extension:`GHC2021`
+ :status: Included in :extension:`GHC2024`, :extension:`GHC2021`
Enable GHC's cunning generalised deriving mechanism for ``newtype``\s
diff --git a/docs/users_guide/exts/nullary_types.rst b/docs/users_guide/exts/nullary_types.rst
index 2ce85cb9d95c..f0b70eddc2ef 100644
--- a/docs/users_guide/exts/nullary_types.rst
+++ b/docs/users_guide/exts/nullary_types.rst
@@ -8,7 +8,7 @@ Data types with no constructors
:since: 6.8.1
- :status: Included in :extension:`GHC2021` and :extension:`Haskell2010`
+ :status: Included in :extension:`GHC2024`, :extension:`GHC2021` and :extension:`Haskell2010`
Allow definition of empty ``data`` types.
diff --git a/docs/users_guide/exts/numeric_underscores.rst b/docs/users_guide/exts/numeric_underscores.rst
index 7a96e00d88ac..c8a9d708a7b0 100644
--- a/docs/users_guide/exts/numeric_underscores.rst
+++ b/docs/users_guide/exts/numeric_underscores.rst
@@ -8,7 +8,7 @@ Numeric underscores
:since: 8.6.1
- :status: Included in :extension:`GHC2021`
+ :status: Included in :extension:`GHC2024`, :extension:`GHC2021`
Allow the use of underscores in numeric literals.
diff --git a/docs/users_guide/exts/partial_type_signatures.rst b/docs/users_guide/exts/partial_type_signatures.rst
index 6b3b88a59cf8..c6e1b30952ae 100644
--- a/docs/users_guide/exts/partial_type_signatures.rst
+++ b/docs/users_guide/exts/partial_type_signatures.rst
@@ -125,7 +125,7 @@ Named Wildcards
:since: 7.10.1
- :status: Included in :extension:`GHC2021`
+ :status: Included in :extension:`GHC2024`, :extension:`GHC2021`
Allow naming of wildcards (e.g. ``_x``) in type signatures.
diff --git a/docs/users_guide/exts/poly_kinds.rst b/docs/users_guide/exts/poly_kinds.rst
index 4b5d609b0ef3..06b51d0e1a42 100644
--- a/docs/users_guide/exts/poly_kinds.rst
+++ b/docs/users_guide/exts/poly_kinds.rst
@@ -22,7 +22,7 @@ Kind polymorphism
:implies: :extension:`KindSignatures`
:since: 7.4.1
- :status: Included in :extension:`GHC2021`
+ :status: Included in :extension:`GHC2024`, :extension:`GHC2021`
Allow kind polymorphic types.
@@ -389,7 +389,7 @@ Standalone kind signatures and polymorphic recursion
:implies: :extension:`NoCUSKs`
:since: 8.10.1
- :status: Included in :extension:`GHC2021`
+ :status: Included in :extension:`GHC2024`, :extension:`GHC2021`
Just as in type inference, kind inference for recursive types can only
use *monomorphic* recursion. Consider this (contrived) example: ::
@@ -922,7 +922,7 @@ The kind ``Type``
:shortdesc: Treat ``*`` as ``Data.Kind.Type``.
:since: 8.6.1
- :status: Included in :extension:`Haskell98`, :extension:`Haskell2010`, :extension:`GHC2021`
+ :status: Included in :extension:`GHC2024`, :extension:`GHC2021`, :extension:`Haskell2010`, :extension:`Haskell98`
Treat the unqualified uses of the ``*`` type operator as nullary and desugar
to ``Data.Kind.Type``.
diff --git a/docs/users_guide/exts/rank_polymorphism.rst b/docs/users_guide/exts/rank_polymorphism.rst
index 9c9e40012b7e..1aaab408e3b1 100644
--- a/docs/users_guide/exts/rank_polymorphism.rst
+++ b/docs/users_guide/exts/rank_polymorphism.rst
@@ -9,7 +9,7 @@ Arbitrary-rank polymorphism
:implies: :extension:`ExplicitForAll`
:since: 6.8.1
- :status: Included in :extension:`GHC2021`
+ :status: Included in :extension:`GHC2024`, :extension:`GHC2021`
Allow types of arbitrary rank.
diff --git a/docs/users_guide/exts/rebindable_syntax.rst b/docs/users_guide/exts/rebindable_syntax.rst
index 4955e17c1135..72445374ef85 100644
--- a/docs/users_guide/exts/rebindable_syntax.rst
+++ b/docs/users_guide/exts/rebindable_syntax.rst
@@ -166,7 +166,7 @@ Postfix operators
:shortdesc: Enable postfix operators.
:since: 7.10.1
- :status: Included in :extension:`GHC2021`
+ :status: Included in :extension:`GHC2024`, :extension:`GHC2021`
Allow the use of post-fix operators
diff --git a/docs/users_guide/exts/record_puns.rst b/docs/users_guide/exts/record_puns.rst
index c1bfc6fad8e9..8682d8123867 100644
--- a/docs/users_guide/exts/record_puns.rst
+++ b/docs/users_guide/exts/record_puns.rst
@@ -8,7 +8,7 @@ Record puns
:since: 6.10.1
- :status: Included in :extension:`GHC2021`
+ :status: Included in :extension:`GHC2024`, :extension:`GHC2021`
Allow use of record puns.
diff --git a/docs/users_guide/exts/roles.rst b/docs/users_guide/exts/roles.rst
index 43c0d1f0d132..16cc84772fc4 100644
--- a/docs/users_guide/exts/roles.rst
+++ b/docs/users_guide/exts/roles.rst
@@ -151,6 +151,7 @@ Role annotations
:shortdesc: Enable role annotations.
:since: 7.8.1
+ :status: Included in :extension:`GHC2024`
Allow role annotation syntax.
diff --git a/docs/users_guide/exts/scoped_type_variables.rst b/docs/users_guide/exts/scoped_type_variables.rst
index feeb65ecb7fe..8133e8f81c54 100644
--- a/docs/users_guide/exts/scoped_type_variables.rst
+++ b/docs/users_guide/exts/scoped_type_variables.rst
@@ -12,7 +12,7 @@ Lexically scoped type variables
:since: 6.8.1
- :status: Included in :extension:`GHC2021`
+ :status: Included in :extension:`GHC2024`, :extension:`GHC2021`
Enable lexical scoping of type variables explicitly introduced with
``forall``.
diff --git a/docs/users_guide/exts/standalone_deriving.rst b/docs/users_guide/exts/standalone_deriving.rst
index ef2bd86d2844..f9c06ee691a0 100644
--- a/docs/users_guide/exts/standalone_deriving.rst
+++ b/docs/users_guide/exts/standalone_deriving.rst
@@ -8,7 +8,7 @@ Stand-alone deriving declarations
:since: 6.8.1
- :status: Included in :extension:`GHC2021`
+ :status: Included in :extension:`GHC2024`, :extension:`GHC2021`
Allow the use of stand-alone ``deriving`` declarations.
diff --git a/docs/users_guide/exts/strict.rst b/docs/users_guide/exts/strict.rst
index 1e7bca739bb6..17e1365092f8 100644
--- a/docs/users_guide/exts/strict.rst
+++ b/docs/users_guide/exts/strict.rst
@@ -41,7 +41,7 @@ Bang patterns
:since: 6.8.1
- :status: Included in :extension:`GHC2021`
+ :status: Included in :extension:`GHC2024`, :extension:`GHC2021`
Allow use of bang pattern syntax.
diff --git a/docs/users_guide/exts/tuple_sections.rst b/docs/users_guide/exts/tuple_sections.rst
index d03153583141..156816120de1 100644
--- a/docs/users_guide/exts/tuple_sections.rst
+++ b/docs/users_guide/exts/tuple_sections.rst
@@ -8,7 +8,7 @@ Tuple sections
:since: 6.12
- :status: Included in :extension:`GHC2021`
+ :status: Included in :extension:`GHC2024`, :extension:`GHC2021`
Allow the use of tuple section syntax
diff --git a/docs/users_guide/exts/type_applications.rst b/docs/users_guide/exts/type_applications.rst
index f37325d9cd6b..cee3b8c2bf4f 100644
--- a/docs/users_guide/exts/type_applications.rst
+++ b/docs/users_guide/exts/type_applications.rst
@@ -8,7 +8,7 @@ Visible type application
:since: 8.0.1
- :status: Included in :extension:`GHC2021`
+ :status: Included in :extension:`GHC2024`, :extension:`GHC2021`
Allow the use of type application syntax.
diff --git a/docs/users_guide/exts/type_operators.rst b/docs/users_guide/exts/type_operators.rst
index 30886913d5ad..f3a6abdb02b9 100644
--- a/docs/users_guide/exts/type_operators.rst
+++ b/docs/users_guide/exts/type_operators.rst
@@ -11,7 +11,7 @@ Type operators
:since: 6.8.1
- :status: Included in :extension:`GHC2021`
+ :status: Included in :extension:`GHC2024`, :extension:`GHC2021`
Allow the use and definition of types with operator names.
diff --git a/ghc/GHCi/UI.hs b/ghc/GHCi/UI.hs
index d0e39e2cc78d..3a9dfd92d6a3 100644
--- a/ghc/GHCi/UI.hs
+++ b/ghc/GHCi/UI.hs
@@ -45,6 +45,7 @@ import GHC.ByteCode.Types
import GHC.Core.DataCon
import GHC.Core.ConLike
import GHC.Core.PatSyn
+import GHC.Driver.Flags
import GHC.Driver.Errors
import GHC.Driver.Errors.Types
import GHC.Driver.Phases
@@ -3488,6 +3489,7 @@ showLanguages' show_all dflags =
Haskell98 -> text "Haskell98"
Haskell2010 -> text "Haskell2010"
GHC2021 -> text "GHC2021"
+ GHC2024 -> text "GHC2024"
, (if show_all then text "all active language options:"
else text "with the following modifiers:") $$
nest 2 (vcat (map (setting xopt) DynFlags.xFlags))
@@ -3504,7 +3506,7 @@ showLanguages' show_all dflags =
default_dflags = defaultDynFlags (settings dflags) `lang_set` Just lang
- lang = fromMaybe GHC2021 (language dflags)
+ lang = fromMaybe defaultLanguage (language dflags)
showTargets :: GHC.GhcMonad m => m ()
diff --git a/testsuite/tests/roles/should_compile/Roles1.hs b/testsuite/tests/roles/should_compile/Roles1.hs
index 8488665fc613..036149b7c1a7 100644
--- a/testsuite/tests/roles/should_compile/Roles1.hs
+++ b/testsuite/tests/roles/should_compile/Roles1.hs
@@ -1,4 +1,4 @@
-{-# LANGUAGE RoleAnnotations, PolyKinds #-}
+{-# LANGUAGE GHC2024 #-}
module Roles1 where
--
GitLab