Simon Peyton Jones pushed to branch wip/spj-reinstallable-base at Glasgow Haskell Compiler / GHC

Commits:

• 18513365
  by Matthew Pickering at 2026-03-21T04:43:26-04:00

  Add support for custom external interpreter commands
  
  It can be useful for GHC API clients to implement their own external
  interpreter commands.
  
  For example, the debugger may want an efficient way to inspect the
  stacks of the running threads in the external interpreter.
  

• 4636d906
  by mangoiv at 2026-03-21T04:44:10-04:00

  ci: remove obsolete fallback for old debian and ubuntu versions
  

• 2e3a2805
  by mangoiv at 2026-03-21T04:44:10-04:00

  ci: drop ubuntu 18 and 20
  
  Ubuntu 18 EOL: May 2023
  Ubuntu 20 EOL: May 2025
  
  We should probably not make another major release supporting these platforms.
  
  Also updates the generator script.
  
  Resolves #25876
  

• de54e264
  by Cheng Shao at 2026-03-21T17:52:08+01:00

  rts: fix -Wcompare-distinct-pointer-types errors
  
  This commit fixes `-Wcompare-distinct-pointer-types` errors in the RTS
  which should have been caught by the `validate` flavour but was
  warnings in CI due to the recent `+werror` regression.
  

• b9bd73de
  by Cheng Shao at 2026-03-21T17:52:08+01:00

  ghc-internal: fix unused imports
  
  This commit fixes unused imports in `ghc-internal` which should have
  been caught by the `validate` flavour but was warnings in CI due to
  the recent `+werror` regression. Fixes #26987 #27059.
  

• da946a16
  by Cheng Shao at 2026-03-21T17:03:51+00:00

  ghci: fix unused imports
  
  This commit fixes unused imports in `ghci` which should have been
  caught by the `validate` flavour but was warnings in CI due to the
  recent `+werror` regression. Fixes #26987 #27059.
  

• 955b1cf8
  by Cheng Shao at 2026-03-21T17:03:51+00:00

  compiler: fix unused imports in GHC.Tc.Types.Origin
  
  This commit fixes unused imports in `GHC.Tc.Types.Origin` which should
  have been caught by the `validate` flavour but was warnings in CI due
  to the recent `+werror` regression. Fixes #27059.
  

• 3b1aeb50
  by Cheng Shao at 2026-03-21T17:03:51+00:00

  hadrian: fix missing +werror in validate flavour
  
  This patch fixes missing `+werror` in validate flavour, which was an
  oversight in bb3a2ba1eefadf0b2ef4f39b31337a23eec67f29. Fixes #27066.
  

• 44f118f0
  by Cheng Shao at 2026-03-22T04:54:01-04:00

  ci: bump CACHE_REV and add the missing reminder
  
  This patch bumps `CACHE_REV` to address recent `[Cabal-7159]` CI
  errors due to stale cabal cache on some runners, and also adds a
  reminder to remind future maintainers. Fixes #27075.
  

• 8e22047b
  by Simon Peyton Jones at 2026-03-23T11:35:12+00:00

  Major patch to re-engineer known-key names
  
  This big patch implements the New Plan for known-key names,
  described in #27013.
  
  Read the big Note [Overview of known-key names] in GHC.Types.Name
  

• 82387824
  by Simon Peyton Jones at 2026-03-23T17:46:38+00:00

  Moving more into the new mechanism [skip ci]
  
  DOES NOT COMPILE, just work in progress
  

124 changed files:

• .gitlab-ci.yml
• .gitlab/generate-ci/flake.lock
• .gitlab/generate-ci/gen_ci.hs
• .gitlab/jobs.yaml
• .gitlab/rel_eng/fetch-gitlab-artifacts/fetch_gitlab.py
• .gitlab/rel_eng/mk-ghcup-metadata/mk_ghcup_metadata.py
• compiler/GHC/Builtin/Names.hs
• compiler/GHC/Builtin/Names/TH.hs
• compiler/GHC/Builtin/Types.hs
• compiler/GHC/Builtin/Utils.hs
• compiler/GHC/Driver/Backpack.hs
• compiler/GHC/Driver/Downsweep.hs
• compiler/GHC/Driver/Env/KnotVars.hs
• compiler/GHC/Driver/Flags.hs
• compiler/GHC/Driver/Main.hs
• compiler/GHC/Driver/Pipeline/Execute.hs
• compiler/GHC/Driver/Session.hs
• compiler/GHC/Hs/Expr.hs
• compiler/GHC/Hs/Type.hs
• compiler/GHC/HsToCore/Arrows.hs
• compiler/GHC/HsToCore/Monad.hs
• compiler/GHC/HsToCore/Pmc/Desugar.hs
• compiler/GHC/HsToCore/Quote.hs
• compiler/GHC/HsToCore/Types.hs
• compiler/GHC/Iface/Binary.hs
• compiler/GHC/Iface/Env.hs
• − compiler/GHC/Iface/Env.hs-boot
• compiler/GHC/Iface/Errors/Ppr.hs
• compiler/GHC/Iface/Load.hs
• compiler/GHC/Iface/Tidy.hs
• compiler/GHC/Iface/Type.hs
• compiler/GHC/IfaceToCore.hs
• compiler/GHC/Parser/Header.hs
• compiler/GHC/Rename/Env.hs
• compiler/GHC/Rename/Expr.hs
• compiler/GHC/Rename/HsType.hs
• compiler/GHC/Rename/Module.hs
• compiler/GHC/Rename/Names.hs
• compiler/GHC/Rename/Pat.hs
• compiler/GHC/Tc/Deriv/Generate.hs
• compiler/GHC/Tc/Deriv/Generics.hs
• compiler/GHC/Tc/Deriv/Infer.hs
• compiler/GHC/Tc/Deriv/Utils.hs
• compiler/GHC/Tc/Errors/Hole.hs
• compiler/GHC/Tc/Gen/Arrow.hs
• compiler/GHC/Tc/Gen/Default.hs
• compiler/GHC/Tc/Gen/Export.hs
• compiler/GHC/Tc/Gen/Pat.hs
• compiler/GHC/Tc/Gen/Splice.hs
• compiler/GHC/Tc/Instance/Class.hs
• compiler/GHC/Tc/Instance/Typeable.hs
• compiler/GHC/Tc/Module.hs
• compiler/GHC/Tc/TyCl/Build.hs
• compiler/GHC/Tc/Types.hs
• compiler/GHC/Tc/Types/Constraint.hs
• compiler/GHC/Tc/Types/Origin.hs
• compiler/GHC/Tc/Utils/Env.hs
• compiler/GHC/Tc/Utils/Instantiate.hs
• compiler/GHC/Tc/Utils/Monad.hs
• compiler/GHC/Tc/Utils/TcType.hs
• compiler/GHC/Tc/Zonk/Type.hs
• compiler/GHC/Types/DefaultEnv.hs
• compiler/GHC/Types/Name.hs
• compiler/GHC/Types/Name/Cache.hs
• compiler/GHC/Unit/External.hs
• compiler/GHC/Unit/Module/ModSummary.hs
• docs/users_guide/exts/rebindable_syntax.rst
• docs/users_guide/separate_compilation.rst
• docs/users_guide/utils.py
• hadrian/cabal.project
• hadrian/src/Settings/Flavours/Validate.hs
• libraries/base/base.cabal.in
• libraries/base/src/Control/Applicative.hs
• libraries/base/src/Data/Bifoldable1.hs
• libraries/base/src/Data/Bool.hs
• libraries/base/src/Data/Enum.hs
• libraries/base/src/Data/Foldable1.hs
• libraries/base/src/Data/List.hs
• libraries/base/src/Data/List/NubOrdSet.hs
• + libraries/base/src/GHC/KnownKeyNames.hs
• libraries/base/src/GHC/RTS/Flags.hs
• libraries/base/src/GHC/Stats.hs
• libraries/base/src/GHC/Weak/Finalize.hs
• libraries/base/src/System/Exit.hs
• libraries/base/src/System/IO/OS.hs
• libraries/base/src/System/IO/Unsafe.hs
• libraries/ghc-internal/ghc-internal.cabal.in
• libraries/ghc-internal/src/GHC/Internal/Base.hs
• libraries/ghc-internal/src/GHC/Internal/Classes.hs
• libraries/ghc-internal/src/GHC/Internal/Conc/IO.hs
• libraries/ghc-internal/src/GHC/Internal/Data/Foldable.hs
• libraries/ghc-internal/src/GHC/Internal/Data/String.hs
• libraries/ghc-internal/src/GHC/Internal/Data/Traversable.hs
• libraries/ghc-internal/src/GHC/Internal/Enum.hs
• libraries/ghc-internal/src/GHC/Internal/Enum.hs-boot
• libraries/ghc-internal/src/GHC/Internal/Event/Control.hs
• libraries/ghc-internal/src/GHC/Internal/Event/KQueue.hsc
• libraries/ghc-internal/src/GHC/Internal/Float.hs
• libraries/ghc-internal/src/GHC/Internal/Float/RealFracMethods.hs
• libraries/ghc-internal/src/GHC/Internal/IO/FD.hs
• libraries/ghc-internal/src/GHC/Internal/Int.hs
• libraries/ghc-internal/src/GHC/Internal/Num.hs
• libraries/ghc-internal/src/GHC/Internal/Num.hs-boot
• libraries/ghc-internal/src/GHC/Internal/RTS/Flags.hsc
• libraries/ghc-internal/src/GHC/Internal/RTS/Flags/Test.hsc
• libraries/ghc-internal/src/GHC/Internal/Real.hs
• libraries/ghc-internal/src/GHC/Internal/Real.hs-boot
• libraries/ghc-internal/src/GHC/Internal/Show.hs
• libraries/ghc-internal/src/GHC/Internal/System/Environment.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/Internals.hs
• libraries/ghc-internal/src/GHC/Internal/TH/Lift.hs
• libraries/ghc-internal/src/GHC/Internal/TopHandler.hs
• libraries/ghc-prim/ghc-prim.cabal
• libraries/ghci/GHCi/Message.hs
• libraries/ghci/GHCi/Run.hs
• libraries/ghci/GHCi/Server.hs
• rts/Interpreter.c
• testsuite/tests/ghc-api/downsweep/PartialDownsweep.hs
• + testsuite/tests/ghci/custom-external-interpreter-commands/Main.hs
• + testsuite/tests/ghci/custom-external-interpreter-commands/all.T
• + testsuite/tests/ghci/custom-external-interpreter-commands/custom-external-interpreter-commands.stdout
• testsuite/tests/parser/should_fail/T16270h.hs

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