[Git][ghc/ghc][wip/T18126] 19 commits: Remove custom ExceptionMonad class (#18075) (updating haddock submodule accordingly)

Simon Peyton Jones gitlab at gitlab.haskell.org
Wed May 6 23:19:18 UTC 2020



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


Commits:
30272412 by Artem Pelenitsyn at 2020-05-04T13:19:59-04:00
Remove custom ExceptionMonad class (#18075) (updating haddock submodule accordingly)

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b9f7c08f by jneira at 2020-05-04T13:20:37-04:00
Remove unused hs-boot file

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1d8f80cd by Sylvain Henry at 2020-05-05T03:22:46-04:00
Remove references to -package-key

* remove references to `-package-key` which has been removed in 2016
  (240ddd7c39536776e955e881d709bbb039b48513)

* remove support for `-this-package-key` which has been deprecated at the
  same time

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7bc3a65b by Sylvain Henry at 2020-05-05T03:23:31-04:00
Remove SpecConstrAnnotation (#13681)

This has been deprecated since 2013. Use GHC.Types.SPEC instead.

Make GHC.Exts "not-home" for haddock

Metric Decrease:
   haddock.base

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3c862f63 by DenisFrezzato at 2020-05-05T03:24:15-04:00
Fix Haskell98 short description in documentation

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2420c555 by Ryan Scott at 2020-05-05T03:24:53-04:00
Add regression tests for #16244, #16245, #16758

Commit e3c374cc5bd7eb49649b9f507f9f7740697e3f70 ended up
fixing quite a few bugs:

* This commit fixes #16244 completely. A regression test has been
  added.
* This commit fixes one program from #16245. (The program in
  https://gitlab.haskell.org/ghc/ghc/issues/16245#note_211369 still
  panics, and the program in
  https://gitlab.haskell.org/ghc/ghc/issues/16245#note_211400 still
  loops infinitely.) A regression test has been added for this
  program.
* This commit fixes #16758. Accordingly, this patch removes the
  `expect_broken` label from the `T16758` test case, moves it from
  `should_compile` to `should_fail` (as it should produce an error
  message), and checks in the expected stderr.

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40c71c2c by Sylvain Henry at 2020-05-05T03:25:31-04:00
Fix colorized error messages (#18128)

In b3df9e780fb2f5658412c644849cd0f1e6f50331 I broke colorized messages
by using "dump" style instead of "user" style. This commits fixes it.

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7ab6ab09 by Richard Eisenberg at 2020-05-06T04:39:32-04:00
Refactor hole constraints.

Previously, holes (both expression holes / out of scope variables and
partial-type-signature wildcards) were emitted as *constraints* via
the CHoleCan constructor. While this worked fine for error reporting,
there was a fair amount of faff in keeping these constraints in line.
In particular, and unlike other constraints, we could never change
a CHoleCan to become CNonCanonical. In addition:
 * the "predicate" of a CHoleCan constraint was really the type
   of the hole, which is not a predicate at all
 * type-level holes (partial type signature wildcards) carried
   evidence, which was never used
 * tcNormalise (used in the pattern-match checker) had to create
   a hole constraint just to extract it again; it was quite messy

The new approach is to record holes directly in WantedConstraints.
It flows much more nicely now.

Along the way, I did some cleaning up of commentary in
GHC.Tc.Errors.Hole, which I had a hard time understanding.

This was instigated by a future patch that will refactor
the way predicates are handled. The fact that CHoleCan's
"predicate" wasn't really a predicate is incompatible with
that future patch.

No test case, because this is meant to be purely internal.

It turns out that this change improves the performance of
the pattern-match checker, likely because fewer constraints
are sloshing about in tcNormalise. I have not investigated
deeply, but an improvement is not a surprise here:

-------------------------
Metric Decrease:
    PmSeriesG
-------------------------

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420b957d by Ben Gamari at 2020-05-06T04:40:08-04:00
rts: Zero block flags with -DZ

Block flags are very useful for determining the state of a block.
However, some block allocator users don't touch them, leading to
misleading values. Ensure that we zero then when zero-on-gc is set. This
is safe and makes the flags more useful during debugging.

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740b3b8d by Ben Gamari at 2020-05-06T04:40:08-04:00
nonmoving: Fix incorrect failed_to_evac value during deadlock gc

Previously we would incorrectly set the failed_to_evac flag if we
evacuated a value due to a deadlock GC. This would cause us to mark more
things as dirty than strictly necessary. It also turned up a nasty but
which I will fix next.

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b2d72c75 by Ben Gamari at 2020-05-06T04:40:08-04:00
nonmoving: Fix handling of dirty objects

Previously we (incorrectly) relied on failed_to_evac to be "precise".
That is, we expected it to only be true if *all* of an object's fields
lived outside of the non-moving heap. However, does not match the
behavior of failed_to_evac, which is true if *any* of the object's
fields weren't promoted (meaning that some others *may* live in the
non-moving heap).

This is problematic as we skip the non-moving write barrier for dirty
objects (which we can only safely do if *all* fields point outside of
the non-moving heap).

Clearly this arises due to a fundamental difference in the behavior
expected of failed_to_evac in the moving and non-moving collector.
e.g., in the moving collector it is always safe to conservatively say
failed_to_evac=true whereas in the non-moving collector the safe value
is false.

This issue went unnoticed as I never wrote down the dirtiness
invariant enforced by the non-moving collector. We now define this
invariant as

    An object being marked as dirty implies that all of its fields are
    on the mark queue (or, equivalently, update remembered set).

To maintain this invariant we teach nonmovingScavengeOne to push the
fields of objects which we fail to evacuate to the update remembered
set. This is a simple and reasonably cheap solution and avoids the
complexity and fragility that other, more strict alternative invariants
would require.

All of this is described in a new Note, Note [Dirty flags in the
non-moving collector] in NonMoving.c.

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9f3e6884 by Zubin Duggal at 2020-05-06T04:41:08-04:00
Allow atomic update of NameCache in readHieFile

The situation arises in ghcide where multiple different threads may need to
update the name cache, therefore with the older interface it could happen
that you start reading a hie file with name cache A and produce name cache
A + B, but another thread in the meantime updated the namecache to A +
C. Therefore if you write the new namecache you will lose the A' updates
from the second thread.

Updates haddock submodule

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edec6a6c by Ryan Scott at 2020-05-06T04:41:57-04:00
Make isTauTy detect higher-rank contexts

Previously, `isTauTy` would only detect higher-rank `forall`s, not
higher-rank contexts, which led to some minor bugs observed
in #18127. Easily fixed by adding a case for
`(FunTy InvisArg _ _)`.

Fixes #18127.

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a95e7fe0 by Ömer Sinan Ağacan at 2020-05-06T04:42:39-04:00
ELF linker: increment curSymbol after filling in fields of current entry

The bug was introduced in a8b7cef4d45 which added a field to the
`symbols` array elements and then updated this code incorrectly:

    - oc->symbols[curSymbol++] = nm;
    + oc->symbols[curSymbol++].name = nm;
    + oc->symbols[curSymbol].addr = symbol->addr;

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cab1871a by Sylvain Henry at 2020-05-06T04:43:21-04:00
Move LeadingUnderscore into Platform (#17957)

Avoid direct use of DynFlags to know if symbols must be prefixed by an
underscore.

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94e7c563 by Sylvain Henry at 2020-05-06T04:43:21-04:00
Don't use DynFlags in showLinkerState (#17957)

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9afd9251 by Ryan Scott at 2020-05-06T04:43:58-04:00
Refactoring: Use bindSigTyVarsFV in rnMethodBinds

`rnMethodBinds` was explicitly using `xoptM` to determine if
`ScopedTypeVariables` is enabled before bringing type variables
bound by the class/instance header into scope. However, this `xoptM`
logic is already performed by the `bindSigTyVarsFV` function. This
patch uses `bindSigTyVarsFV` in `rnMethodBinds` to reduce the number
of places where we need to consult if `ScopedTypeVariables` is on.

This is purely refactoring, and there should be no user-visible
change in behavior.

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2a57ffcd by Simon Peyton Jones at 2020-05-07T00:12:33+01:00
Simple subsumption

This patch simplifies GHC to use simple subsumption.
  Ticket #17775

Implements GHC proposal #287
   https://github.com/ghc-proposals/ghc-proposals/blob/master/
   proposals/0287-simplify-subsumption.rst

All the motivation is described there; I will not repeat it here.
The implementation payload:
 * tcSubType and friends become noticably simpler, because it no
   longer uses eta-expansion when checking subsumption.
 * No deeplyInstantiate or deeplySkolemise

That in turn means that some tests fail, by design; they can all
be fixed by eta expansion.  There is a list of such changes below.

Implementing the patch led me into a variety of sticky corners, so
the patch includes several othe changes, some quite significant:

* I made String wired-in, so that
    "foo" :: String   rather than
    "foo" :: [Char]
  This improves error messages, and fixes #15679

* The pattern match checker relies on knowing about in-scope equality
  constraints, andd adds them to the desugarer's environment using
  addTyCsDs.  But the co_fn in a FunBind was missed, and for some reason
  simple-subsumption ends up with dictionaries there. So I added a
  call to addTyCsDs.  This is really part of #18049.

* I moved the ic_telescope field out of Implication and into
  ForAllSkol instead.  This is a nice win; just expresses the code
  much better.

* There was a bug in GHC.Tc.TyCl.Instance.tcDataFamInstHeader.
  We called checkDataKindSig inside tc_kind_sig, /before/
  solveEqualities and zonking.  Obviously wrong, easily fixed.

* solveLocalEqualitiesX: there was a whole mess in here, around
  failing fast enough.  I discovered a bad latent bug where we
  could successfully kind-check a type signature, and use it,
  but have unsolved constraints that could fill in coercion
  holes in that signature --  aargh.

  It's all explained in Note [Failure in local type signatures]
  in GHC.Tc.Solver. Much better now.

* I fixed a serious bug in anonymous type holes. IN
    f :: Int -> (forall a. a -> _) -> Int
  that "_" should be a unification variable at the /outer/
  level; it cannot be instantiated to 'a'.  This was plain
  wrong.  New fields mode_lvl and mode_holes in TcTyMode,
  and auxiliary data type GHC.Tc.Gen.HsType.HoleMode.

  This fixes #16292, but makes no progress towards the more
  ambitious #16082

* I got sucked into an enormous refactoring of the reporting of
  equality errors in GHC.Tc.Errors, especially in
      mkEqErr1
      mkTyVarEqErr
      misMatchMsg
      misMatchMsgOrCND
  In particular, the very tricky mkExpectedActualMsg function
  is gone.

  It took me a full day.  But the result is far easier to understand.
  (Still not easy!)  This led to various minor improvements in error
  output, and an enormous number of test-case error wibbles.

  One particular point: for occurs-check errors I now just say
     Can't match 'a' against '[a]'
  rather than using the intimidating language of "occurs check".

* Pretty-printing AbsBinds

Tests review

* Eta expansions
   T11305: one eta expansion
   T12082: one eta expansion (undefined)
   T13585a: one eta expansion
   T3102:  one eta expansion
   T3692:  two eta expansions (tricky)
   T2239:  two eta expansions
   T16473: one eta
   determ004: two eta expansions (undefined)
   annfail06: two eta (undefined)
   T17923: four eta expansions (a strange program indeed!)
   tcrun035: one eta expansion

* Ambiguity check at higher rank.  Now that we have simple
  subsumption, a type like
     f :: (forall a. Eq a => Int) -> Int
  is no longer ambiguous, because we could write
     g :: (forall a. Eq a => Int) -> Int
     g = f
  and it'd typecheck just fine.  But f's type is a bit
  suspicious, and we might want to consider making the
  ambiguity check do a check on each sub-term.  Meanwhile,
  these tests are accepted, whereas they were previously
  rejected as ambiguous:
     T7220a
     T15438
     T10503
     T9222

* Some more interesting error message wibbles
   T13381: Fine: one error (Int ~ Exp Int)
           rather than two (Int ~ Exp Int, Exp Int ~ Int)
   T9834:  Small change in error (improvement)
   T10619: Improved
   T2414:  Small change, due to order of unification, fine
   T2534:  A very simple case in which a change of unification order
           means we get tow unsolved constraints instead of one
   tc211: bizarre impredicative tests; just accept this for now

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81ef202e by Simon Peyton Jones at 2020-05-07T00:19:07+01:00
First draft of Quick Look impredicativity

This patch implements Quick Look impredicativity
(see #18126).

The main action in is in the new module GHC.Tc.Gen.App, which
deals with typechecking function applications.  Much code has
moved from Tc.Gen.Expr into Tc.Gen.App, but Tc.Gen.App also
includes the new Quick Look code: see the function quickLook.

Not properly tested yet -- this is just so you can see what
I'm up to.

- - - - -


30 changed files:

- compiler/GHC.hs
- compiler/GHC/Builtin/Names.hs
- compiler/GHC/Builtin/Types.hs
- compiler/GHC/Cmm/CLabel.hs
- compiler/GHC/Core/Coercion.hs
- compiler/GHC/Core/FamInstEnv.hs
- compiler/GHC/Core/Opt/SpecConstr.hs
- compiler/GHC/Core/Type.hs
- compiler/GHC/Data/IOEnv.hs
- compiler/GHC/Driver/Finder.hs
- compiler/GHC/Driver/Main.hs
- compiler/GHC/Driver/Make.hs
- compiler/GHC/Driver/Monad.hs
- compiler/GHC/Driver/Pipeline.hs
- compiler/GHC/Driver/Session.hs
- compiler/GHC/Driver/Types.hs
- compiler/GHC/Hs/Binds.hs
- compiler/GHC/Hs/Types.hs
- compiler/GHC/HsToCore/Binds.hs
- compiler/GHC/HsToCore/PmCheck.hs
- compiler/GHC/HsToCore/PmCheck/Oracle.hs
- compiler/GHC/Iface/Ext/Binary.hs
- compiler/GHC/Iface/Load.hs
- compiler/GHC/Iface/Recomp.hs
- compiler/GHC/Plugins.hs
- compiler/GHC/Rename/Bind.hs
- compiler/GHC/Rename/HsType.hs
- compiler/GHC/Rename/Splice.hs
- compiler/GHC/Runtime/Debugger.hs
- compiler/GHC/Runtime/Eval.hs


The diff was not included because it is too large.


View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/87760b048b7dc59b4f6d275672bb7bac0a4f0e25...81ef202e7467b9ebdd52adde7af7c3dd390b77c5

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View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/87760b048b7dc59b4f6d275672bb7bac0a4f0e25...81ef202e7467b9ebdd52adde7af7c3dd390b77c5
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