[Git][ghc/ghc][wip/az/exactprint] 13 commits: [linker] Adds void printLoadedObjects(void);

Alan Zimmerman gitlab at gitlab.haskell.org
Wed Jun 10 21:25:39 UTC 2020 


Alan Zimmerman pushed to branch wip/az/exactprint at Glasgow Haskell Compiler / GHC


Commits:
6a4098a4 by Moritz Angermann at 2020-06-04T04:55:51-04:00
[linker] Adds void printLoadedObjects(void);

This allows us to dump in-memory object code locations for debugging.

Fixup printLoadedObjects prototype

- - - - -
af5e3a88 by Artem Pelenitsyn at 2020-06-05T03:18:49-04:00
base: fix sign confusion in log1mexp implementation (fix #17125)

author: claude (https://gitlab.haskell.org/trac-claude)

The correct threshold for log1mexp is -(log 2) with the current specification
of log1mexp. This change improves accuracy for large negative inputs.

To avoid code duplication, a small helper function is added;
it isn't the default implementation in Floating because it needs Ord.

This patch does nothing to address that the Haskell specification is
different from that in common use in other languages.

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2b792fac by Simon Peyton Jones at 2020-06-05T09:27:50-04:00
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

Updates Cabal and haddock submodules.

Metric Increase:
  T12150
  T12234
  T5837
  haddock.base
Metric Decrease:
  haddock.compiler
  haddock.Cabal
  haddock.base

Merge note: This appears to break the
`UnliftedNewtypesDifficultUnification` test. It has been marked as
broken in the interest of merging.

(cherry picked from commit 66b7b195cb3dce93ed5078b80bf568efae904cc5)

- - - - -
2dff8141 by Ryan Scott at 2020-06-05T14:21:24-04:00
Simplify bindLHsTyVarBndrs and bindHsQTyVars

Both `bindLHsTyVarBndrs` and `bindHsQTyVars` take two separate
`Maybe` arguments, which I find terribly confusing. Thankfully, it's
possible to remove one `Maybe` argument from each of these functions,
which this patch accomplishes:

* `bindHsQTyVars` takes a `Maybe SDoc` argument, which is `Just` if
  GHC should warn about any of the quantified type variables going
  unused. However, every call site uses `Nothing` in practice. This
  makes sense, since it doesn't really make sense to warn about
  unused type variables bound by an `LHsQTyVars`. For instance, you
  wouldn't warn about the `a` in `data Proxy a = Proxy` going unused.

  As a result, I simply remove this `Maybe SDoc` argument altogether.
* `bindLHsTyVarBndrs` also takes a `Maybe SDoc` argument for the same
  reasons that `bindHsQTyVars` took one. To make things more
  confusing, however, `bindLHsTyVarBndrs` also takes a separate
  `HsDocContext` argument, which is pretty-printed (to an `SDoc`) in
  warnings and error messages.

  In practice, the `Maybe SDoc` and the `HsDocContext` often contain
  the same text. See the call sites for `bindLHsTyVarBndrs` in
  `rnFamInstEqn` and `rnConDecl`, for instance. There are only a
  handful of call sites where the text differs between the
  `Maybe SDoc` and `HsDocContext` arguments:

  * In `rnHsRuleDecl`, where the `Maybe SDoc` says "`In the rule`"
    and the `HsDocContext` says "`In the transformation rule`".
  * In `rnHsTyKi`/`rn_ty`, where the `Maybe SDoc` says
    "`In the type`" but the `HsDocContext` is inhereted from the
    surrounding context (e.g., if `rnHsTyKi` were called on a
    top-level type signature, the `HsDocContext` would be
    "`In the type signature`" instead)

  In both cases, warnings/error messages arguably _improve_ by
  unifying making the `Maybe SDoc`'s text match that of the
  `HsDocContext`. As a result, I decided to remove the `Maybe SDoc`
  argument to `bindLHsTyVarBndrs` entirely and simply reuse the text
  from the `HsDocContext`. (I decided to change the phrase
  "transformation rule" to "rewrite rule" while I was in the area.)

  The `Maybe SDoc` argument has one other purpose: signaling when to
  emit "`Unused quantified type variable`" warnings. To recover this
  functionality, I replaced the `Maybe SDoc` argument with a
  boolean-like `WarnUnusedForalls` argument. The only
  `bindLHsTyVarBndrs` call site that chooses _not_ to emit these
  warnings in `bindHsQTyVars`.

- - - - -
e372331b by Ben Gamari at 2020-06-07T08:46:41-04:00
hadrian: Add missing deriveConstants dependency on ghcplatform.h

deriveConstants wants to compile C sources which #include PosixSource.h,
which itself #includes ghcplatform.h. Make sure that Hadrian knows
about this dependency.

Fixes #18290.

- - - - -
b022051a by Moritz Angermann at 2020-06-07T08:46:42-04:00
ghc-prim needs to depend on libc and libm

libm is just an empty shell on musl, and all the math functions are contained in
libc.

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6dae6548 by Moritz Angermann at 2020-06-07T08:46:42-04:00
Disable DLL loading if without system linker

Some platforms (musl, aarch64) do not have a working dynamic linker
implemented in the libc, even though we might see dlopen.  It will
ultimately just return that this is not supported.  Hence we'll add
a flag to the compiler to flat our disable loading dlls.  This is
needed as we will otherwise try to load the shared library even
if this will subsequently fail.  At that point we have given up
looking for static options though.

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4a158ffc by Moritz Angermann at 2020-06-07T08:46:43-04:00
Range is actually +/-2^32, not +/-2^31

See also: https://static.docs.arm.com/ihi0056/g/aaelf64.pdf

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f1bfb806 by Ben Gamari at 2020-06-07T10:49:30-04:00
OccurAnal: Avoid exponential behavior due to where clauses

Previously the `Var` case of `occAnalApp` could in some cases (namely
in the case of `runRW#` applications) call `occAnalRhs` two. In the case
of nested `runRW#`s this results in exponential complexity. In some
cases the compilation time that resulted would be very long indeed
(see #18296).

Fixes #18296.

Metric Decrease:
    T9961
    T12150
    T12234

- - - - -
9b607671 by Takenobu Tani at 2020-06-09T08:05:46-04:00
Add link to GHC's wiki in the GHC API header

This adds a URL to point to GHC's wiki in the GHC API header.
Newcomers could easily find more information from the GHC API's
web like [1].

[1]: Current version, https://ghc.gitlab.haskell.org/ghc/doc/libraries/ghc-8.11.0.20200604/index.html

[skip ci]

- - - - -
72c7fe9a by Ryan Scott at 2020-06-09T08:06:24-04:00
Make GADT constructors adhere to the forall-or-nothing rule properly

Issue #18191 revealed that the types of GADT constructors don't quite
adhere to the `forall`-or-nothing rule. This patch serves to clean up
this sad state of affairs somewhat. The main change is not in the
code itself, but in the documentation, as this patch introduces two
sections to the GHC User's Guide:

* A "Formal syntax for GADTs" section that presents a BNF-style
  grammar for what is and isn't allowed in GADT constructor types.
  This mostly exists to codify GHC's existing behavior, but it also
  imposes a new restriction that addresses #18191: the outermost
  `forall` and/or context in a GADT constructor is not allowed to be
  surrounded by parentheses. Doing so would make these
  `forall`s/contexts nested, and GADTs do not support nested
  `forall`s/contexts at present.

* A "`forall`-or-nothing rule" section that describes exactly what
  the `forall`-or-nothing rule is all about. Surprisingly, there was
  no mention of this anywhere in the User's Guide up until now!

To adhere the new specification in the "Formal syntax for GADTs"
section of the User's Guide, the following code changes were made:

* A new function, `GHC.Hs.Type.splitLHsGADTPrefixTy`, was introduced.
  This is very much like `splitLHsSigmaTy`, except that it avoids
  splitting apart any parentheses, which can be syntactically
  significant for GADT types. See
  `Note [No nested foralls or contexts in GADT constructors]` in
  `GHC.Hs.Type`.

* `ConDeclGADTPrefixPs`, an extension constructor for `XConDecl`, was
  introduced so that `GHC.Parser.PostProcess.mkGadtDecl` can return
  it when given a prefix GADT constructor. Unlike `ConDeclGADT`,
  `ConDeclGADTPrefixPs` does not split the GADT type into its argument
  and result types, as this cannot be done until after the type is
  renamed (see `Note [GADT abstract syntax]` in `GHC.Hs.Decls` for why
  this is the case).

* `GHC.Renamer.Module.rnConDecl` now has an additional case for
  `ConDeclGADTPrefixPs` that (1) splits apart the full `LHsType` into
  its `forall`s, context, argument types, and result type, and
  (2) checks for nested `forall`s/contexts. Step (2) used to be
  performed the typechecker (in `GHC.Tc.TyCl.badDataConTyCon`) rather
  than the renamer, but now the relevant code from the typechecker
  can simply be deleted.

  One nice side effect of this change is that we are able to give a
  more accurate error message for GADT constructors that use visible
  dependent quantification (e.g., `MkFoo :: forall a -> a -> Foo a`),
  which improves the stderr in the `T16326_Fail6` test case.

Fixes #18191. Bumps the Haddock submodule.

- - - - -
46c97999 by Alan Zimmerman at 2020-06-09T19:14:19+01:00
Proof of Concept implementation of in-tree API Annotations

This MR introduces a possible machinery to introduce API Annotations
into the TTG extension points.

It is intended to be a concrete example for discussion.

It still needs to process comments.

----

Work in progress, adding more TTG extensions for annotations.

And fixing ppr round-trip tests by being able to blank out in-tree
annotations, as done with SrcSpans.

This is needed for the case of

  class Foo a where

for which current ppr does not print the "where".

Rename AA to AddApiAnn and AA to AddAnn

Add XConPatIn and XConPatOut

Rebase

----

First pass at bringing in LocatedA for API anns in locations

Treatment of ECP in parsing is provisional at this stage, leads to some
horribly stuff in Parser.y and RdrHsSyn.

It is an extensive but not invasive change. I think (AZ).

Locally it reports some parsing tests using less memory.

Add ApiAnns to the HsExpr data structure.

rebase.

Change HsMatchContext and HsStmtContext to use an id, not a GhcPass
parameter.

Add ApiAnns to Hs/Types

Rebase

Rebased 2020-03-25

WIP on in-tree annotations

Includes updating HsModule

Imports

LocateA ImportDecl so we can hang AnnSemi off it

A whole bunch of stuff more

InjectivityAnn and FamEqn now have annotations in them

Add annotations to context srcspan

----

In-tree annotations: LHsDecl and LHsBind LocatedA

----

WIP on in-tree annotations

----

in-tree annotations: LHsType is now LocatedA

----

FunDeps is now also a HS data type

----

WIP.  Added LocatedA to Pat, Expr, Decl

And worked some more through Parser.y

----

LStmt now Located

----

Finished working through Parser.y, tests seem ok

failures relate to annotations.

Adding test infrastructure for check-exact

Like check-ppr, but checking for an exact reproduction of the parsed
source file.

Starting to work on actual exact printer

Bring in ApiAnnName

As an alternative for LocatedA, to be used for names only.

Carrying extra name adornments, such as locations of backticks,
parens, etc.

Working on changing ApiAnnName to accurately reflect actual usage

- - - - -
c26de3c7 by Alan Zimmerman at 2020-06-10T21:56:51+01:00
Get rid of AnnApiName in favour of LocatedN

- - - - -


27 changed files:

- compiler/GHC/Builtin/Names.hs
- compiler/GHC/Builtin/Types.hs
- compiler/GHC/Core.hs
- compiler/GHC/Core/Coercion.hs
- compiler/GHC/Core/Lint.hs
- compiler/GHC/Core/Opt/OccurAnal.hs
- compiler/GHC/Core/Opt/Simplify.hs
- compiler/GHC/Core/Rules.hs
- compiler/GHC/Core/Type.hs
- compiler/GHC/Data/BooleanFormula.hs
- compiler/GHC/Data/OrdList.hs
- compiler/GHC/Driver/Backpack.hs
- compiler/GHC/Driver/Main.hs
- compiler/GHC/Driver/Types.hs
- compiler/GHC/Hs.hs
- compiler/GHC/Hs/Binds.hs
- compiler/GHC/Hs/Decls.hs
- compiler/GHC/Hs/Dump.hs
- + compiler/GHC/Hs/Exact.hs
- compiler/GHC/Hs/Expr.hs
- compiler/GHC/Hs/Expr.hs-boot
- compiler/GHC/Hs/Extension.hs
- compiler/GHC/Hs/ImpExp.hs
- compiler/GHC/Hs/Instances.hs
- compiler/GHC/Hs/Pat.hs
- compiler/GHC/Hs/Stats.hs
- compiler/GHC/Hs/Type.hs


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View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/90b936ed8b54ca58d20ec0d1ffb1610777822676...c26de3c7b8344c2baeb1faa4ff60464a39fa9250

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