[Git][ghc/ghc][wip/int-index/decl-invis-binders] Invisible binders in type declarations (#22560)

[Vladislav Zavialov (@int-index)]

Vladislav Zavialov pushed to branch wip/int-index/decl-invis-binders at Glasgow Haskell Compiler / GHC


Commits:
9b2f2bfb by Vladislav Zavialov at 2023-01-24T18:03:58+03:00
Invisible binders in type declarations (#22560)

This patch implements @k-binders introduced in GHC Proposal #425
and guarded behind the TypeAbstractions extension:

	data D @k @j (a :: k) (b :: j) = ...
	       ^^ ^^

To represent the new syntax, we modify LHsQTyVars as follows:

	-  hsq_explicit :: [LHsTyVarBndr () pass]
	+  hsq_explicit :: [LHsTyVarBndr (HsBndrVis pass) pass]

HsBndrVis is a new data type that records the distinction between
type variable binders written with and without the @ sign:

	data HsBndrVis pass
	  = HsBndrRequired
	  | HsBndrInvisible (LHsToken "@" pass)

The rest of the patch updates GHC, template-haskell, and haddock
to handle the new syntax.

Parser:
  The PsErrUnexpectedTypeAppInDecl error message is removed.
  The syntax it used to reject is now permitted.

Renamer:
  The @ sign does not affect the scope of a binder, so the changes to
  the renamer are minimal.  See rnLHsTyVarBndrVisFlag.

Type checker:
  There are three code paths that were updated to deal with the newly
  introduced invisible type variable binders:

    1. checking SAKS: see kcCheckDeclHeader_sig, matchUpSigWithDecl
    2. checking CUSK: see kcCheckDeclHeader_cusk
    3. inference: see kcInferDeclHeader, generaliseTcTyCon

  Helper functions bindExplicitTKBndrs_Q_Skol and bindExplicitTKBndrs_Q_Tv
  are generalized to work with HsBndrVis.

Updates the haddock submodule.

- - - - -


30 changed files:

- compiler/GHC/Builtin/Names/TH.hs
- compiler/GHC/Core/TyCon.hs
- compiler/GHC/Hs/Instances.hs
- compiler/GHC/Hs/Type.hs
- compiler/GHC/HsToCore/Quote.hs
- compiler/GHC/Parser/Errors/Ppr.hs
- compiler/GHC/Parser/Errors/Types.hs
- compiler/GHC/Parser/PostProcess.hs
- compiler/GHC/Rename/HsType.hs
- compiler/GHC/Tc/Errors/Ppr.hs
- compiler/GHC/Tc/Errors/Types.hs
- compiler/GHC/Tc/Gen/HsType.hs
- compiler/GHC/Tc/Gen/Splice.hs
- compiler/GHC/Tc/TyCl.hs
- compiler/GHC/Tc/Utils/TcMType.hs
- compiler/GHC/ThToHs.hs
- compiler/GHC/Types/Error/Codes.hs
- compiler/Language/Haskell/Syntax/Type.hs
- docs/users_guide/9.8.1-notes.rst
- docs/users_guide/exts/type_abstractions.rst
- libraries/ghci/GHCi/TH/Binary.hs
- libraries/template-haskell/Language/Haskell/TH.hs
- libraries/template-haskell/Language/Haskell/TH/Lib.hs
- libraries/template-haskell/Language/Haskell/TH/Lib/Internal.hs
- libraries/template-haskell/Language/Haskell/TH/Ppr.hs
- libraries/template-haskell/Language/Haskell/TH/Syntax.hs
- libraries/template-haskell/changelog.md
- testsuite/tests/haddock/should_compile_flag_haddock/T17544.stderr
- testsuite/tests/haddock/should_compile_flag_haddock/T17544_kw.stderr
- testsuite/tests/indexed-types/should_fail/T9160.hs


The diff was not included because it is too large.


View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/9b2f2bfb6d2f3fbfa4c9728598bb3d64a051fef9

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View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/9b2f2bfb6d2f3fbfa4c9728598bb3d64a051fef9
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