1. 26 Jan, 2018 1 commit
    • Ryan Scott's avatar
      Fix #14719 by using the setting the right SrcSpan · 59fa7b32
      Ryan Scott authored
      Currently, error messages that germane to GADT constructors
      put the source span at only the first character in the constructor,
      leading to insufficient caret diagnostics. This can be easily fixed
      by using a source span that spans the entire constructor, instead of
      just the first character.
      
      Test Plan: make test TEST=T14719
      
      Reviewers: alanz, bgamari, simonpj
      
      Reviewed By: alanz, simonpj
      
      Subscribers: simonpj, goldfire, rwbarton, thomie, carter
      
      GHC Trac Issues: #14719
      
      Differential Revision: https://phabricator.haskell.org/D4344
      59fa7b32
  2. 10 Jan, 2018 1 commit
    • niteria's avatar
      Lift constructor tag allocation out of a loop · dbdf77d9
      niteria authored
      Before this change, for each constructor that we want
      to allocate a tag for we would traverse a list of all
      the constructors in a datatype to determine which tag
      a constructor should get.
      
      This is obviously quadratic and for datatypes with 10k
      constructors it actually makes a big difference.
      
      This change implements the plan outlined by @simonpj in
      https://mail.haskell.org/pipermail/ghc-devs/2017-October/014974.html
      which is basically about using a map and constructing it outside the
      loop.
      
      One place where things got a bit awkward was TysWiredIn.hs,
      it would have been possible to just assign the tags by hand, but
      that seemed error-prone to me, so I decided to go through a map
      there as well.
      
      Test Plan:
      ./validate
      On a file with 10k constructors
      Before:
         8,130,522,344 bytes allocated in the heap
        Total   time    3.682s  (  3.920s elapsed)
      After:
         4,133,478,744 bytes allocated in the heap
        Total   time    2.509s  (  2.750s elapsed)
      
      Reviewers: simonpj, bgamari
      
      Reviewed By: simonpj
      
      Subscribers: goldfire, rwbarton, thomie, simonmar, carter, simonpj
      
      GHC Trac Issues: #14657
      
      Differential Revision: https://phabricator.haskell.org/D4289
      dbdf77d9
  3. 28 Dec, 2017 1 commit
  4. 15 Dec, 2017 1 commit
    • Simon Peyton Jones's avatar
      Fix tcDataKindSig · 68149452
      Simon Peyton Jones authored
      This patch fixes an outright bug in tcDataKindSig, shown up in Trac
      of a data type declaration.  See Note [TyConBinders for the result kind
      signature of a data type]
      
      I also took the opportunity to elminate the DataKindCheck argument
      and data type from tcDataKindSig, instead moving the check to the
      call site, which is easier to understand.
      68149452
  5. 14 Dec, 2017 1 commit
  6. 13 Dec, 2017 1 commit
    • Simon Peyton Jones's avatar
      Further improvements to well-kinded types · 0a12d92a
      Simon Peyton Jones authored
      The typechecker has the invariant that every type should be well-kinded
      as it stands, without zonking.  See Note [The well-kinded type invariant]
      in TcType.
      
      That invariant was not being upheld, which led to Trac #14174.  I fixed
      part of it, but T14174a showed that there was more.  This patch finishes
      the job.
      
      * See Note [The tcType invariant] in TcHsType, which articulates an
        invariant that was very nearly, but not quite, true.  One place that
        falisified it was the HsWildCardTy case of tc_hs_type, so I fixed that.
      
      * mkNakedCastTy now makes no attempt to eliminate casts; indeed it cannot
        lest it break Note [The well-kinded type invariant].  The prior comment
        suggested that it was crucial for performance but happily it seems not
        to be. The extra Refls are eliminated by the zonker.
      
      * I found I could tidy up TcHsType.instantiateTyN and instantiateTyUntilN
        by eliminating one of its parameters.  That led to a cascade of minor
        improvements in TcTyClsDecls. Hooray.
      0a12d92a
  7. 11 Dec, 2017 1 commit
    • Simon Peyton Jones's avatar
      Fix SigTvs at the kind level · 8361b2c5
      Simon Peyton Jones authored
      This patch fixes two bugs in the treatment of SigTvs at the
      kind level:
      
      - We should always generalise them, never default them
        (Trac #14555, #14563)
      
      - We should check if they get unified with each other
        (Trac #11203)
      
      Both are described in TcHsType
         Note [Kind generalisation and SigTvs]
      8361b2c5
  8. 08 Dec, 2017 1 commit
    • Simon Peyton Jones's avatar
      Refactor kcHsTyVarBndrs · de204409
      Simon Peyton Jones authored
      This refactoring
      
      * Renames kcHsTyVarBndrs to kcLHsQTyVars,
        which is more truthful. It is only used in getInitialKind.
      
      * Pulls out bind_telescope from that function, and calls it
        kcLHsTyVarBndrs, again to reflect its argument
      
      * Uses the new kcLHsTyVarBndrs in kcConDecl, where the old
        function was wild overkill.
      
      There should not be any change in behaviour
      de204409
  9. 07 Dec, 2017 1 commit
    • Simon Peyton Jones's avatar
      Refactor ConDecl: Trac #14529 · fa29df02
      Simon Peyton Jones authored
      This patch refactors HsDecls.ConDecl.  Specifically
      
      * ConDeclGADT was horrible, with all the information hidden
        inside con_res_ty.  Now it's kept separate, as it should be.
      
      * ConDeclH98: use [LHsTyVarBndr] instead of LHsQTyVars for the
        existentials. There is no implicit binding here.
      
      * Add a field con_forall to both ConDeclGADT and ConDeclH98
        which says if there is an explicit user-written forall.
      
      * Field renamings in ConDecl
           con_cxt     to con_mb_cxt
           con_details to con_args
      
      There is an accompanying submodule update to Haddock.
      
      Also the following change turned out to remove a lot of clutter:
      
      * add a smart constructor for HsAppsTy, namely mkHsAppsTy,
        and use it consistently. This avoids a lot of painful pattern
        matching for the common singleton case.
      
      Two api-annotation tests (T10278, and T10399) are broken, hence marking
      them as expect_broken(14529).  Alan is going to fix them, probably by
      changing the con_forall field to
         con_forall :: Maybe SrcSpan
      instead of Bool
      fa29df02
  10. 01 Dec, 2017 1 commit
    • Edward Z. Yang's avatar
      Make use of boot TyThings during typechecking. · 69987720
      Edward Z. Yang authored
      
      
      Summary:
      Suppose that you are typechecking A.hs, which transitively imports,
      via B.hs, A.hs-boot.  When we poke on B.hs and discover that it
      has a reference to a type from A, what TyThing should we wire
      it up with?  Clearly, if we have already typechecked A, we
      should use the most up-to-date TyThing: the one we freshly
      generated when we typechecked A.  But what if we haven't typechecked
      it yet?
      
      For the longest time, GHC adopted the policy that this was
      *an error condition*; that you MUST NEVER poke on B.hs's reference
      to a thing defined in A.hs until A.hs has gotten around to checking
      this.  However, actually ensuring this is the case has proven
      to be a bug farm.  The problem was especially poignant with
      type family consistency checks, which eagerly happen before
      any typechecking takes place.
      
      This patch takes a different strategy: if we ever try to access
      an entity from A which doesn't exist, we just fall back on the
      definition of A from the hs-boot file.  This means that you may
      end up with a mix of A.hs and A.hs-boot TyThings during the
      course of typechecking.
      Signed-off-by: Edward Z. Yang's avatarEdward Z. Yang <ezyang@fb.com>
      
      Test Plan: validate
      
      Reviewers: simonpj, bgamari, austin, goldfire
      
      Subscribers: thomie, rwbarton
      
      GHC Trac Issues: #14396
      
      Differential Revision: https://phabricator.haskell.org/D4154
      69987720
  11. 27 Nov, 2017 1 commit
  12. 21 Nov, 2017 1 commit
    • Ben Gamari's avatar
      Revert "trees that grow" work · 314bc314
      Ben Gamari authored
      As documented in #14490, the Data instances currently blow up
      compilation time by too much to stomach. Alan will continue working on
      this in a branch and we will perhaps merge to 8.2 before 8.2.1 to avoid
      having to perform painful cherry-picks in 8.2 minor releases.
      
      Reverts haddock submodule.
      
      This reverts commit 47ad6578.
      This reverts commit e3ec2e7a.
      This reverts commit 438dd1cb.
      This reverts commit 0ff152c9.
      314bc314
  13. 08 Nov, 2017 1 commit
  14. 07 Nov, 2017 2 commits
  15. 30 Oct, 2017 1 commit
  16. 25 Oct, 2017 2 commits
  17. 16 Oct, 2017 1 commit
  18. 03 Oct, 2017 2 commits
    • Ryan Scott's avatar
      Track the order of user-written tyvars in DataCon · ef26182e
      Ryan Scott authored
      After typechecking a data constructor's type signature, its type
      variables are partitioned into two distinct groups: the universally
      quantified type variables and the existentially quantified type
      variables. Then, when prompted for the type of the data constructor,
      GHC gives this:
      
      ```lang=haskell
      MkT :: forall <univs> <exis>. (...)
      ```
      
      For H98-style datatypes, this is a fine thing to do. But for GADTs,
      this can sometimes produce undesired results with respect to
      `TypeApplications`. For instance, consider this datatype:
      
      ```lang=haskell
      data T a where
        MkT :: forall b a. b -> T a
      ```
      
      Here, the user clearly intended to have `b` be available for visible
      type application before `a`. That is, the user would expect
      `MkT @Int @Char` to be of type `Int -> T Char`, //not//
      `Char -> T Int`. But alas, up until now that was not how GHC
      operated—regardless of the order in which the user actually wrote
      the tyvars, GHC would give `MkT` the type:
      
      ```lang=haskell
      MkT :: forall a b. b -> T a
      ```
      
      Since `a` is universal and `b` is existential. This makes predicting
      what order to use for `TypeApplications` quite annoying, as
      demonstrated in #11721 and #13848.
      
      This patch cures the problem by tracking more carefully the order in
      which a user writes type variables in data constructor type
      signatures, either explicitly (with a `forall`) or implicitly
      (without a `forall`, in which case the order is inferred). This is
      accomplished by adding a new field `dcUserTyVars` to `DataCon`, which
      is a subset of `dcUnivTyVars` and `dcExTyVars` that is permuted to
      the order in which the user wrote them. For more details, refer to
      `Note [DataCon user type variables]` in `DataCon.hs`.
      
      An interesting consequence of this design is that more data
      constructors require wrappers. This is because the workers always
      expect the first arguments to be the universal tyvars followed by the
      existential tyvars, so when the user writes the tyvars in a different
      order, a wrapper type is needed to swizzle the tyvars around to match
      the order that the worker expects. For more details, refer to
      `Note [Data con wrappers and GADT syntax]` in `MkId.hs`.
      
      Test Plan: ./validate
      
      Reviewers: austin, goldfire, bgamari, simonpj
      
      Reviewed By: goldfire, simonpj
      
      Subscribers: ezyang, goldfire, rwbarton, thomie
      
      GHC Trac Issues: #11721, #13848
      
      Differential Revision: https://phabricator.haskell.org/D3687
      ef26182e
    • Simon Peyton Jones's avatar
      Comments only · a1fc7ce3
      Simon Peyton Jones authored
      a1fc7ce3
  19. 29 Sep, 2017 1 commit
  20. 26 Sep, 2017 1 commit
  21. 19 Sep, 2017 1 commit
    • Herbert Valerio Riedel's avatar
      compiler: introduce custom "GhcPrelude" Prelude · f63bc730
      Herbert Valerio Riedel authored
      This switches the compiler/ component to get compiled with
      -XNoImplicitPrelude and a `import GhcPrelude` is inserted in all
      modules.
      
      This is motivated by the upcoming "Prelude" re-export of
      `Semigroup((<>))` which would cause lots of name clashes in every
      modulewhich imports also `Outputable`
      
      Reviewers: austin, goldfire, bgamari, alanz, simonmar
      
      Reviewed By: bgamari
      
      Subscribers: goldfire, rwbarton, thomie, mpickering, bgamari
      
      Differential Revision: https://phabricator.haskell.org/D3989
      f63bc730
  22. 14 Sep, 2017 2 commits
    • Simon Peyton Jones's avatar
      Refactor to eliminate FamTyConShape · 0390e4a0
      Simon Peyton Jones authored
      Consider this note (TcTyClsDecls)
      
        Note [Type-checking type patterns]
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
        When typechecking the patterns of a family instance declaration, we can't
        rely on using the family TyCon itself, because this is sometimes called
        from within a type-checking knot. (Specifically for closed type families.)
        The FamTyConShape gives just enough information to do the job.
      
      I realised that this exact purpose can be served by TcTyCons, and
      in fact rather better.  So this patch
      
      * Refactors FamTyConShape out of existence, replacing it with TcTyCOn
      
      * I also got rid Type.filterOutInvisibleTyVars, which was a very
        complex way to do something quite simple.  I replaced the calls
        with TyCon.tyConVisibleTyVars.
      
      No change in behaviour.
      0390e4a0
    • Simon Peyton Jones's avatar
      Fix subtle bug in TcTyClsDecls.mkGADTVars · 3a27e34f
      Simon Peyton Jones authored
      This bug was revealed by Trac #14162.  In a GADT-style data-family
      instance we ended up a data constructor whose type mentioned
      an out-of-scope variable.  (This variable was in the kind of
      a variable in the kind of a variable.)
      
      Only Lint complained about this (actually only when the
      data constructor was injected into the bindings by CorePrep).
      So it doesn't matter much -- but it's a solid bug and might
      bite us some day.
      
      It took me quite a while to unravel because the test case was itself
      quite tricky.  But the fix is easy; just add a missing binding to the
      substitution we are building up.  It's in the regrettably-subtle
      mkGADTVars function.
      3a27e34f
  23. 05 Sep, 2017 1 commit
    • Ryan Scott's avatar
      Implicitly bind kind variables in type family instance RHSes when it's sensible · 0829821a
      Ryan Scott authored
      Summary:
      Before, there was a discrepancy in how GHC renamed type synonyms as
      opposed to type family instances. That is, GHC would accept definitions like
      this one:
      
      ```lang=haskell
      type T = (Nothing :: Maybe a)
      ```
      
      However, it would not accept a very similar type family instance:
      
      ```lang=haskell
      type family   T :: Maybe a
      type instance T = (Nothing :: Maybe a)
      ```
      
      The primary goal of this patch is to bring the renaming of type family
      instances up to par with that of type synonyms, causing the latter definition
      to be accepted, and fixing #14131.
      
      In particular, we now allow kind variables on the right-hand sides of type
      (and data) family instances to be //implicitly// bound by LHS type (or kind)
      patterns (as opposed to type variables, which must always be explicitly
      bound by LHS type patterns only). As a consequence, this allows programs
      reported in #7938 and #9574 to typecheck, whereas before they would
      have been rejected.
      
      Implementation-wise, there isn't much trickery involved in making this happen.
      We simply need to bind additional kind variables from the RHS of a type family
      in the right place (in particular, see `RnSource.rnFamInstEqn`, which has
      undergone a minor facelift).
      
      While doing this has the upside of fixing #14131, it also made it easier to
      trigger #13985, so I decided to fix that while I was in town. This was
      accomplished by a careful blast of `reportFloatingKvs` in `tcFamTyPats`.
      
      Test Plan: ./validate
      
      Reviewers: simonpj, goldfire, austin, bgamari
      
      Reviewed By: simonpj
      
      Subscribers: rwbarton, thomie
      
      GHC Trac Issues: #13985, #14131
      
      Differential Revision: https://phabricator.haskell.org/D3872
      0829821a
  24. 31 Aug, 2017 2 commits
    • Simon Peyton Jones's avatar
      Small changes to ddump-tc tracing · 3790ea90
      Simon Peyton Jones authored
      3790ea90
    • Simon Peyton Jones's avatar
      Add debugPprType · 805b29bb
      Simon Peyton Jones authored
      We pretty-print a type by converting it to an IfaceType and
      pretty-printing that.  But
       (a) that's a bit indirect, and
       (b) delibrately loses information about (e.g.) the kind
            on the /occurrences/ of a type variable
      
      So this patch implements debugPprType, which pretty prints
      the type directly, with no fancy formatting.  It's just used
      for debugging.
      
      I took the opportunity to refactor the debug-pretty-printing
      machinery a little.  In particular, define these functions
      and use them:
      
        ifPprDeubug :: SDoc -> SDOc -> SDoc
          -- Says what to do with and without -dppr-debug
        whenPprDebug :: SDoc -> SDoc
          -- Says what to do with  -dppr-debug; without is empty
        getPprDebug :: (Bool -> SDoc) -> SDoc
      
      getPprDebug used to be called sdocPprDebugWith
      whenPprDebug used to be called ifPprDebug
      
      So a lot of files get touched in a very mechanical way
      805b29bb
  25. 29 Aug, 2017 2 commits
  26. 17 Aug, 2017 1 commit
  27. 12 Aug, 2017 2 commits
    • Ryan Scott's avatar
      Expand type synonyms during role inference · 0bb1e840
      Ryan Scott authored
      Summary:
      During role inference, we need to expand type synonyms, since
      oversaturated applications of type synonym tycons would otherwise have overly
      conservative roles inferred for its arguments.
      
      Fixes #14101.
      
      Test Plan: ./validate
      
      Reviewers: goldfire, austin, bgamari
      
      Reviewed By: goldfire
      
      Subscribers: rwbarton, thomie
      
      GHC Trac Issues: #14101
      
      Differential Revision: https://phabricator.haskell.org/D3838
      0bb1e840
    • Ryan Scott's avatar
      Use NonEmpty lists to represent lists of duplicate elements · 7d699782
      Ryan Scott authored
      Summary:
      Three functions in `ListSetOps` which compute duplicate elements
      represent lists of duplicates of `[a]`. This is a really bad way to go about
      things, because these lists are guaranteed to always have at least one element
      (the "representative" of the duplicates), and several places in the GHC API
      call `head` (a partial function) on these lists of duplicates to retrieve the
      representative.
      
      This changes the representation of duplicates to `NonEmpty` lists instead,
      which allow for many partial uses of `head` to be made total.
      
      Fixes #13823.
      
      Test Plan: ./validate
      
      Reviewers: bgamari, austin, goldfire
      
      Reviewed By: bgamari
      
      Subscribers: goldfire, rwbarton, thomie
      
      GHC Trac Issues: #13823
      
      Differential Revision: https://phabricator.haskell.org/D3823
      7d699782
  28. 29 Jul, 2017 1 commit
    • Richard Eisenberg's avatar
      Fix #14045 by omitting an unnecessary check · d1ef223c
      Richard Eisenberg authored
      Previously, we checked the number of patterns in a data instances
      for all data families whose kind did not end in a kind variable.
      But, of course, undersaturating instances can happen even without
      the kind ending in a kind variable. So I've omitted the arity check.
      Data families aren't as particular about their arity as type families
      are (because data families can be undersaturated). Still, this change
      degrades error messages when instances don't have the right arity;
      now, instead of reporting a simple mismatch in the number of patterns,
      GHC reports kind errors. The new errors are fully accurate, but perhaps
      not as easy to work with. Still, with the new flexibility of allowing
      data family instances with varying numbers of patterns, I don't see
      a better way.
      
      This commit also improves source fidelity in some error messages,
      requiring more changes than really are necessary. But without these
      changes, error messages around mismatched associated instance heads
      were poor.
      
      test cases: indexed-types/should_compile/T14045,
                  indexed-types/should_fail/T14045a
      d1ef223c
  29. 27 Jul, 2017 2 commits
    • Richard Eisenberg's avatar
      Fix #12369 by being more flexible with data insts · 42392383
      Richard Eisenberg authored
      Previously, a data family's kind had to end in `Type`,
      and data instances had to list all the type patterns for the
      family. However, both of these restrictions were unnecessary:
      
      - A data family's kind can usefully end in a kind variable `k`.
        See examples on #12369.
      
      - A data instance need not list all patterns, much like how a
        GADT-style data declaration need not list all type parameters,
        when a kind signature is in place. This is useful, for example,
        here:
      
          data family Sing (a :: k)
          data instance Sing :: Bool -> Type where ...
      
      This patch also improved a few error messages, as some error
      plumbing had to be moved around.
      
      See new Note [Arity of data families] in FamInstEnv for more
      info.
      
      test case: indexed-types/should_compile/T12369
      42392383
    • Richard Eisenberg's avatar
      Fix #13819 by refactoring TypeEqOrigin.uo_thing · c2417b87
      Richard Eisenberg authored
      The uo_thing field of TypeEqOrigin is used to track the
      "thing" (either term or type) that has the type (kind) stored
      in the TypeEqOrigin fields. Previously, this was sometimes a
      proper Core Type, which needed zonking and tidying. Now, it
      is only HsSyn: much simpler, and the error messages now use
      the user-written syntax.
      
      But this aspect of uo_thing didn't cause #13819; it was the
      sibling field uo_arity that did. uo_arity stored the number
      of arguments of uo_thing, useful when reporting something
      like "should have written 2 fewer arguments". We wouldn't want
      to say that if the thing didn't have two arguments. However,
      in practice, GHC was getting this wrong, and this message
      didn't seem all that helpful. Furthermore, the calculation
      of the number of arguments is what caused #13819 to fall over.
      This patch just removes uo_arity. In my opinion, the change
      to error messages is a nudge in the right direction.
      
      Test case: typecheck/should_fail/T13819
      c2417b87
  30. 26 Jul, 2017 2 commits
    • Gabor Greif's avatar
      Fix note references and some typos · 362339dd
      Gabor Greif authored
      362339dd
    • Simon Peyton Jones's avatar
      Fix binder visiblity for default methods · 75bf11c0
      Simon Peyton Jones authored
      Trac #13998 showed that default methods were getting bogus tyvar
      binder visiblity info; and that it matters in the code genreated
      by the default-method fill-in mechanism
      
      * The actual fix: in TcTyDecls.mkDefaultMethodType, make TyVarBinders
        with the right visibility info by getting TyConBinders from the
        class TyCon.  (Previously we made up visiblity info, but that
        caused #13998.)
      
      * Define TyCon.tyConTyVarBinders :: [TyConBinder] -> [TyVarBinder]
        which can build correct forall binders for
          a) default methods (Trac #13998)
          b) data constructors
        This was originally BuildTyCl.mkDataConUnivTyVarBinders
      
      * Move mkTyVarBinder, mkTyVarBinders from Type to Var
      75bf11c0
  31. 19 Jul, 2017 1 commit
    • Ryan Scott's avatar
      Fix #13983 by creating a TyConFlavour type, and using it · 6e3c901d
      Ryan Scott authored
      An error message was referring to a type synonym as a datatype.
      Annoyingly, learning that the TyCon over which the error message is
      operating is actually a type synonym was previously impossible, since
      that code only had access to a TcTyCon, which doesn't retain any
      information about what sort of TyCon it is.
      
      To rectify this, I created a new TyConFlavour datatype, intended to
      capture roughly what sort of TyCon we're dealing with. I then performing
      the necessary plumbing to ensure all TcTyCons have a TyConFlavour, and
      propagated this information through to the relevant error message.
      
      Test Plan: ./validate
      
      Reviewers: goldfire, austin, bgamari, simonpj
      
      Reviewed By: simonpj
      
      Subscribers: simonpj, rwbarton, thomie
      
      GHC Trac Issues: #13983
      
      Differential Revision: https://phabricator.haskell.org/D3747
      6e3c901d