[Git][ghc/ghc][master] Equality of forall-types is visibility aware

[Marge Bot (@marge-bot)]

Marge Bot pushed to branch master at Glasgow Haskell Compiler / GHC


Commits:
cf86f3ec by Matthew Craven at 2023-07-16T01:42:09+02:00
Equality of forall-types is visibility aware

This patch finally (I hope) nails the question of whether
   (forall a. ty) and (forall a -> ty)
are `eqType`: they aren't!

There is a long discussion in #22762, plus useful Notes:

* Note [ForAllTy and type equality] in GHC.Core.TyCo.Compare
* Note [Comparing visiblities] in GHC.Core.TyCo.Compare
* Note [ForAllCo] in GHC.Core.TyCo.Rep

It also establishes a helpful new invariant for ForAllCo,
and ForAllTy, when the bound variable is a CoVar:in that
case the visibility must be coreTyLamForAllTyFlag.

All this is well documented in revised Notes.

- - - - -


30 changed files:

- compiler/GHC/Core/Coercion.hs
- compiler/GHC/Core/Coercion.hs-boot
- compiler/GHC/Core/Coercion/Opt.hs
- compiler/GHC/Core/FVs.hs
- compiler/GHC/Core/Lint.hs
- compiler/GHC/Core/Opt/Arity.hs
- compiler/GHC/Core/Reduction.hs
- compiler/GHC/Core/TyCo/Compare.hs
- compiler/GHC/Core/TyCo/FVs.hs
- compiler/GHC/Core/TyCo/FVs.hs-boot
- compiler/GHC/Core/TyCo/Rep.hs
- compiler/GHC/Core/TyCo/Subst.hs
- compiler/GHC/Core/TyCo/Tidy.hs
- compiler/GHC/Core/Type.hs
- compiler/GHC/Core/Unify.hs
- compiler/GHC/Core/Utils.hs
- compiler/GHC/CoreToIface.hs
- compiler/GHC/Iface/Rename.hs
- compiler/GHC/Iface/Syntax.hs
- compiler/GHC/Iface/Type.hs
- compiler/GHC/IfaceToCore.hs
- compiler/GHC/Tc/Solver/Equality.hs
- compiler/GHC/Tc/Solver/Monad.hs
- compiler/GHC/Tc/TyCl/Utils.hs
- compiler/GHC/Tc/Utils/TcMType.hs
- compiler/GHC/Types/Var.hs
- docs/core-spec/core-spec.mng
- testsuite/tests/cpranal/should_compile/T18174.stderr
- testsuite/tests/cpranal/should_compile/T18401.stderr
- testsuite/tests/pmcheck/should_compile/T11195.hs


The diff was not included because it is too large.


View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/cf86f3ece835ecb389d73760c1d757622c084f0f

-- 
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/cf86f3ece835ecb389d73760c1d757622c084f0f
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