[Git][ghc/ghc][wip/T18126] 6 commits: Revert "AArch32 symbols only on aarch32."

Tue Jul 21 08:15:50 UTC 2020

Simon Peyton Jones pushed to branch wip/T18126 at Glasgow Haskell Compiler / GHC

Commits:
868e4523 by Moritz Angermann at 2020-07-20T04:30:38-04:00
Revert "AArch32 symbols only on aarch32."

This reverts commit cdfeb3f24f76e8fd30452016676e56fbc827789a.

Signed-off-by: Moritz Angermann <moritz.angermann at gmail.com>

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c915ba84 by Moritz Angermann at 2020-07-20T04:30:38-04:00
Revert "Fix (1)"

This reverts commit 7abffced01f5680efafe44f6be2733eab321b039.

Signed-off-by: Moritz Angermann <moritz.angermann at gmail.com>

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777c452a by Moritz Angermann at 2020-07-20T04:30:38-04:00
Revert "better if guards."

This reverts commit 3f60b94de1f460ca3f689152860b108a19ce193e.

Signed-off-by: Moritz Angermann <moritz.angermann at gmail.com>

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0dd40552 by Moritz Angermann at 2020-07-20T04:30:38-04:00
Revert "[linker/rtsSymbols] More linker symbols"

This reverts commit 686e72253aed3880268dd6858eadd8c320f09e97.

Signed-off-by: Moritz Angermann <moritz.angermann at gmail.com>

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c60e4c5a by Simon Peyton Jones at 2020-07-21T09:15:04+01:00
Implement Quick Look impredicativity

This patch implements Quick Look impredicativity (#18126), sticking
very closely to the design in
    A quick look at impredicativity, Serrano et al, ICFP 2020

The main change is that a big chunk of GHC.Tc.Gen.Expr has been
extracted to two new modules
    GHC.Tc.Gen.App
    GHC.Tc.Gen.Head
which deal with typechecking n-ary applications, and the head of
such applications, respectively.  Both contain a good deal of
documentation.

Three other loosely-related changes are in this patch:

* I implemented (partly by accident) point (2) of the accepted GHC
  proposal "Clean up printing of foralls", namely
  https://github.com/ghc-proposals/ghc-proposals/blob/
        master/proposals/0179-printing-foralls.rst

  In particular, see Note [TcRnExprMode] in GHC.Tc.Module
  - :type instantiates /inferred/, but not /specified/, quantifiers
  - :type +d instantiates /all/ quantifiers
  - :type +v is killed off

* HsRecFld (which the renamer introduces for record field selectors),
  is now preserved by the typechecker, rather than being rewritten
  back to HsVar.  This is more uniform, and turned out to be more
  convenient in the new scheme of things.

* The GHCi debugger uses a non-standard unification that allows the
  unification variables to unify with polytypes.  We used to hack
  this by using ImpredicativeTypes, but that doesn't work anymore
  so I introduces RuntimeUnkTv.  See Note [RuntimeUnkTv] in
  GHC.Runtime.Heap.Inspect

WARNING: this patch won't validate on its own.  It was too
hard to fully disentangle it from the following patch, on
type errors and kind generalisation.

Changes to tests

* Fixes #9730 (test added)

* Fixes #7026 (test added)

* Fixes most of #8808, except function `g2'` which uses a
  section (which doesn't play with QL yet -- see #18126)
  Test added

* Fixes #1330. NB Church1.hs subsumes Church2.hs, which is now deleted

* Fixes #17332 (test added)

* Fixes #4295

* This patch makes typecheck/should_run/T7861 fail.
  But that turns out to be a pre-existing bug: #18467.
  So I have just made T7861 into expect_broken(18467)

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29962b14 by Simon Peyton Jones at 2020-07-21T09:15:04+01:00
Improve kind generalisation, error messages

This patch does two things:

* It refactors GHC.Tc.Errors a bit.  In debugging Quick Look I was
  forced to look in detail at error messages, and ended up doing a bit
  of refactoring, esp in mkTyVarEqErr'.  It's still quite a mess, but
  a bit better, I think.

* It makes a significant improvement to the kind checking of type and
  class declarations. Specifically, we now ensure that if kind
  checking fails with an unsolved constraint, all the skolems are in
  scope.  That wasn't the case before, which led to some obscure error
  messages; and occasional failures with "no skolem info" (eg #16245).

Both of these, and the main Quick Look patch itself, affect a /lot/ of
error messages, as you can see from the number of files changed.  I've
checked them all; I think they are as good or better than before.

Smaller things

* I documented the various instances of VarBndr better.
  See Note [The VarBndr tyep and its uses] in GHC.Types.Var

* Renamed GHC.Tc.Solver.simpl_top to simplifyTopWanteds

* A bit of refactoring in bindExplicitTKTele, to avoid the
  footwork with Either.  Simpler now.

* Move promoteTyVar from GHC.Tc.Solver to GHC.Tc.Utils.TcMType

Fixes #16245 (comment 211369), memorialised as
  typeecheck/polykinds/T16245a

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18 changed files:

- compiler/GHC/Core/TyCon.hs
- compiler/GHC/Hs/Expr.hs
- compiler/GHC/Hs/Pat.hs
- compiler/GHC/Hs/Type.hs
- compiler/GHC/HsToCore/Coverage.hs
- compiler/GHC/HsToCore/Expr.hs
- compiler/GHC/Parser/PostProcess.hs
- compiler/GHC/Rename/Pat.hs
- compiler/GHC/Runtime/Eval.hs
- compiler/GHC/Runtime/Heap/Inspect.hs
- compiler/GHC/Tc/Deriv/Generate.hs
- compiler/GHC/Tc/Errors.hs
- compiler/GHC/Tc/Errors/Hole.hs
- + compiler/GHC/Tc/Gen/App.hs
- compiler/GHC/Tc/Gen/Arrow.hs
- compiler/GHC/Tc/Gen/Default.hs
- compiler/GHC/Tc/Gen/Expr.hs
- compiler/GHC/Tc/Gen/Expr.hs-boot

The diff was not included because it is too large.

View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/91c6850416ea62b7685b88c1d1655afcf4aee4e6...29962b14c720698dba888b6d62ad3d80d65eeb29

-- 
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/91c6850416ea62b7685b88c1d1655afcf4aee4e6...29962b14c720698dba888b6d62ad3d80d65eeb29
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