[Git][ghc/ghc][wip/forall-vis-coercions] Equality of forall-types is visiblity aware

[Simon Peyton Jones (@simonpj)]

Simon Peyton Jones pushed to branch wip/forall-vis-coercions at Glasgow Haskell Compiler / GHC


Commits:
b782e184 by Matthew Craven at 2023-07-11T16:43:26+01:00
Equality of forall-types is visiblity 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/b782e1842a84d0a6689a2573ce8631a2abc12de4

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View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/b782e1842a84d0a6689a2573ce8631a2abc12de4
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