1. 09 May, 2017 1 commit
    • Ben Gamari's avatar
      Treat banged bindings as FunBinds · 37299536
      Ben Gamari authored
      This reworks the HsSyn representation to make banged variable patterns
      (e.g. !x = e) be represented as FunBinds instead of PatBinds, adding a flag to
      FunRhs to record the bang.
      
      Fixes #13594.
      
      Reviewers: austin, goldfire, alanz, simonpj
      
      Reviewed By: simonpj
      
      Subscribers: simonpj, rwbarton, thomie, mpickering
      
      Differential Revision: https://phabricator.haskell.org/D3525
      37299536
  2. 12 Apr, 2017 1 commit
  3. 10 Mar, 2017 1 commit
  4. 07 Mar, 2017 1 commit
  5. 01 Mar, 2017 1 commit
    • David Feuer's avatar
      Upgrade UniqSet to a newtype · cbe569a5
      David Feuer authored
      The fundamental problem with `type UniqSet = UniqFM` is that `UniqSet`
      has a key invariant `UniqFM` does not. For example, `fmap` over
      `UniqSet` will generally produce nonsense.
      
      * Upgrade `UniqSet` from a type synonym to a newtype.
      
      * Remove unused and shady `extendVarSet_C` and `addOneToUniqSet_C`.
      
      * Use cached unique in `tyConsOfType` by replacing
        `unitNameEnv (tyConName tc) tc` with `unitUniqSet tc`.
      
      Reviewers: austin, hvr, goldfire, simonmar, niteria, bgamari
      
      Reviewed By: niteria
      
      Subscribers: thomie
      
      Differential Revision: https://phabricator.haskell.org/D3146
      cbe569a5
  6. 27 Feb, 2017 1 commit
    • Edward Z. Yang's avatar
      Subtyping for roles in signatures. · 923d7ca2
      Edward Z. Yang authored
      Summary:
      This commit implements the plan in #13140:
      
      * Today, roles in signature files default to representational. Let's change the
        default to nominal, as this is the most flexible implementation side. If a
        client of the signature needs to coerce with a type, the signature can be
        adjusted to have more stringent requirements.
      
      * If a parameter is declared as nominal in a signature, it can be implemented
        by a data type which is actually representational.
      
      * When merging abstract data declarations, we take the smallest role for every
        parameter. The roles are considered fix once we specify the structure of an
        ADT.
      
      * Critically, abstract types are NOT injective, so we aren't allowed to
        make inferences like "if T a ~R T b, then a ~N b" based on the nominal
        role of a parameter in an abstract type (this would be unsound if the
        parameter ended up being phantom.)  This restriction is similar to the
        restriction we have on newtypes.
      Signed-off-by: default avatarEdward Z. Yang <ezyang@cs.stanford.edu>
      
      Test Plan: validate
      
      Reviewers: simonpj, bgamari, austin, goldfire
      
      Subscribers: goldfire, thomie
      
      Differential Revision: https://phabricator.haskell.org/D3123
      923d7ca2
  7. 18 Feb, 2017 1 commit
    • Ben Gamari's avatar
      Generalize kind of the (->) tycon · b207b536
      Ben Gamari authored
      This is generalizes the kind of `(->)`, as discussed in #11714.
      
      This involves a few things,
      
       * Generalizing the kind of `funTyCon`, adding two new `RuntimeRep`
      binders,
        ```lang=haskell
      (->) :: forall (r1 :: RuntimeRep) (r2 :: RuntimeRep)
                     (a :: TYPE r1) (b :: TYPE r2).
              a -> b -> *
        ```
      
       * Unsaturated applications of `(->)` are expressed as explicit
      `TyConApp`s
      
       * Saturated applications of `(->)` are expressed as `FunTy` as they are
      currently
      
       * Saturated applications of `(->)` are expressed by a new `FunCo`
      constructor in coercions
      
       * `splitTyConApp` needs to ensure that `FunTy`s are split to a
      `TyConApp`
         of `(->)` with the appropriate `RuntimeRep` arguments
      
       * Teach CoreLint to check that all saturated applications of `(->)` are
      represented with `FunTy`
      
      At the moment I assume that `Constraint ~ *`, which is an annoying
      source of complexity. This will
      be simplified once D3023 is resolved.
      
      Also, this introduces two known regressions,
      
      `tcfail181`, `T10403`
      =====================
      Only shows the instance,
      
          instance Monad ((->) r) -- Defined in ‘GHC.Base’
      
      in its error message when -fprint-potential-instances is used. This is
      because its instance head now mentions 'LiftedRep which is not in scope.
      I'm not entirely sure of the right way to fix this so I'm just accepting
      the new output for now.
      
      T5963 (Typeable)
      ================
      
      T5963 is now broken since Data.Typeable.Internals.mkFunTy computes its
      fingerprint without the RuntimeRep variables that (->) expects. This
      will be fixed with the merge of D2010.
      
      Haddock performance
      ===================
      
      The `haddock.base` and `haddock.Cabal` tests regress in allocations by
      about 20%. This certainly hurts, but it's also not entirely unexpected:
      the size of every function type grows with this patch and Haddock has a
      lot of functions in its heap.
      b207b536
  8. 18 Jan, 2017 1 commit
  9. 17 Dec, 2016 1 commit
  10. 07 Dec, 2016 1 commit
    • Alan Zimmerman's avatar
      Add HsSyn prettyprinter tests · 499e4382
      Alan Zimmerman authored
      Summary:
      Add prettyprinter tests, which take a file, parse it, pretty print it,
      re-parse the pretty printed version and then compare the original and
      new ASTs (ignoring locations)
      
      Updates haddock submodule to match the AST changes.
      
      There are three issues outstanding
      
      1. Extra parens around a context are not reproduced. This will require an
         AST change and will be done in a separate patch.
      
      2. Currently if an `HsTickPragma` is found, this is not pretty-printed,
         to prevent noise in the output.
      
         I am not sure what the desired behaviour in this case is, so have left
         it as before. Test Ppr047 is marked as expected fail for this.
      
      3. Apart from in a context, the ParsedSource AST keeps all the parens from
         the original source.  Something is happening in the renamer to remove the
         parens around visible type application, causing T12530 to fail, as the
         dumped splice decl is after the renamer.
      
         This needs to be fixed by keeping the parens, but I do not know where they
         are being removed.  I have amended the test to pass, by removing the parens
         in the expected output.
      
      Test Plan: ./validate
      
      Reviewers: goldfire, mpickering, simonpj, bgamari, austin
      
      Reviewed By: simonpj, bgamari
      
      Subscribers: simonpj, goldfire, thomie, mpickering
      
      Differential Revision: https://phabricator.haskell.org/D2752
      
      GHC Trac Issues: #3384
      499e4382
  11. 17 Nov, 2016 1 commit
    • Edward Z. Yang's avatar
      Test for type synonym loops on TyCon. · 31398fbc
      Edward Z. Yang authored
      Summary:
      Previously, we tested for type synonym loops by doing
      a syntactic test on the literal type synonym declarations.
      However, in some cases, loops could go through hs-boot
      files, leading to an infinite loop (#12042); a similar
      situation can occur when signature merging.
      
      This commit replaces the syntactic test with a test on
      TyCon, simply by walking down all type synonyms until
      we bottom out, or find we've looped back.  It's a lot
      simpler.
      Signed-off-by: default avatarEdward Z. Yang <ezyang@cs.stanford.edu>
      
      Test Plan: validate
      
      Reviewers: simonpj, austin, bgamari
      
      Subscribers: goldfire, thomie
      
      Differential Revision: https://phabricator.haskell.org/D2656
      
      GHC Trac Issues: #12042
      31398fbc
  12. 05 Jul, 2016 1 commit
    • Simon Peyton Jones's avatar
      Check generic-default method for ambiguity · 85aa6ef0
      Simon Peyton Jones authored
      Fixes Trac #7497 and #12151.   In some earlier upheaval I introduced
      a bug in the ambiguity check for genreric-default method.
      
      This patch fixes it.  But in fixing it I realised that the
      sourc-location of any such error message was bogus, so I fixed
      that too, which involved a slightly wider change; see the
      comments with TcMethInfo.
      85aa6ef0
  13. 30 Jun, 2016 1 commit
    • Edward Z. Yang's avatar
      Axe RecFlag on TyCons. · b8b3e30a
      Edward Z. Yang authored
      Summary:
      This commit removes the information about whether or not
      a TyCon is "recursive", as well as the code responsible
      for calculating this information.
      
      The original trigger for this change was complexity regarding
      how we computed the RecFlag for hs-boot files.  The problem
      is that in order to determine if a TyCon is recursive or
      not, we need to determine if it was defined in an hs-boot
      file (if so, we conservatively assume that it is recursive.)
      
      It turns that doing this is quite tricky.  The "obvious"
      strategy is to typecheck the hi-boot file (since we are
      eventually going to need the typechecked types to check
      if we properly implemented the hi-boot file) and just extract
      the names of all defined TyCons from the ModDetails, but
      this actually does not work well if Names from the hi-boot
      file are being knot-tied via if_rec_types: the "extraction"
      process will force thunks, which will force the typechecking
      process earlier than we have actually defined the types
      locally.
      
      Rather than work around all this trickiness (it certainly
      can be worked around, either by making interface loading
      MORE lazy, or just reading of the set of defined TyCons
      directly from the ModIface), we instead opted to excise
      the source of the problem, the RecFlag.
      
      For one, it is not clear if the RecFlag even makes sense,
      in the presence of higher-orderness:
      
          data T f a = MkT (f a)
      
      T doesn't look recursive, but if we instantiate f with T,
      then it very well is!  It was all very shaky.
      
      So we just don't bother anymore.  This has two user-visible
      implications:
      
      1. is_too_recursive now assumes that all TyCons are
      recursive and will bail out in a way that is still mysterious
      to me if there are too many TyCons.
      
      2. checkRecTc, which is used when stripping newtypes to
      get to representation, also assumes all TyCons are
      recursive, and will stop running if we hit the limit.
      
      The biggest risk for this patch is that we specialize less
      than we used to; however, the codeGen tests still seem to
      be passing.
      Signed-off-by: default avatarEdward Z. Yang <ezyang@cs.stanford.edu>
      
      Reviewers: simonpj, austin, bgamari
      
      Subscribers: goldfire, thomie
      
      Differential Revision: https://phabricator.haskell.org/D2360
      b8b3e30a
  14. 25 Jun, 2016 1 commit
    • eir@cis.upenn.edu's avatar
      s/Invisible/Inferred/g s/Visible/Required/g · 5fdb854c
      eir@cis.upenn.edu authored
      This renames VisibilityFlag from
      
      > data VisibilityFlag = Visible | Specified | Invisible
      
      to
      
      > data ArgFlag = Required | Specified | Inferred
      
      The old name was quite confusing, because both Specified
      and Invisible were invisible! The new names are hopefully clearer.
      5fdb854c
  15. 23 Jun, 2016 1 commit
    • niteria's avatar
      Provide Uniquable version of SCC · 35d1564c
      niteria authored
      We want to remove the `Ord Unique` instance because there's
      no way to implement it in deterministic way and it's too
      easy to use by accident.
      
      We sometimes compute SCC for datatypes whose Ord instance
      is implemented in terms of Unique. The Ord constraint on
      SCC is just an artifact of some internal data structures.
      We can have an alternative implementation with a data
      structure that uses Uniquable instead.
      
      This does exactly that and I'm pleased that I didn't have
      to introduce any duplication to do that.
      
      Test Plan:
      ./validate
      I looked at performance tests and it's a tiny bit better.
      
      Reviewers: bgamari, simonmar, ezyang, austin, goldfire
      
      Subscribers: thomie
      
      Differential Revision: https://phabricator.haskell.org/D2359
      
      GHC Trac Issues: #4012
      35d1564c
  16. 15 Jun, 2016 2 commits
    • Simon Peyton Jones's avatar
      Major patch to introduce TyConBinder · e368f326
      Simon Peyton Jones authored
      Before this patch, following the TypeInType innovations,
      each TyCon had two lists:
        - tyConBinders :: [TyBinder]
        - tyConTyVars  :: [TyVar]
      
      They were in 1-1 correspondence and contained
      overlapping information.  More broadly, there were many
      places where we had to pass around this pair of lists,
      instead of a single list.
      
      This commit tidies all that up, by having just one list of
      binders in a TyCon:
      
        - tyConBinders :: [TyConBinder]
      
      The new data types look like this:
      
        Var.hs:
           data TyVarBndr tyvar vis = TvBndr tyvar vis
           data VisibilityFlag = Visible | Specified | Invisible
           type TyVarBinder = TyVarBndr TyVar VisibilityFlag
      
        TyCon.hs:
           type TyConBinder = TyVarBndr TyVar TyConBndrVis
      
           data TyConBndrVis
             = NamedTCB VisibilityFlag
             | AnonTCB
      
        TyCoRep.hs:
           data TyBinder
             = Named TyVarBinder
             | Anon Type
      
      Note that Var.TyVarBdr has moved from TyCoRep and has been
      made polymorphic in the tyvar and visiblity fields:
      
           type TyVarBinder = TyVarBndr TyVar VisibilityFlag
              -- Used in ForAllTy
           type TyConBinder = TyVarBndr TyVar TyConBndrVis
              -- Used in TyCon
      
           type IfaceForAllBndr  = TyVarBndr IfaceTvBndr VisibilityFlag
           type IfaceTyConBinder = TyVarBndr IfaceTvBndr TyConBndrVis
               -- Ditto, in interface files
      
      There are a zillion knock-on changes, but everything
      arises from these types.  It was a bit fiddly to get the
      module loops to work out right!
      
      Some smaller points
      ~~~~~~~~~~~~~~~~~~~
      * Nice new functions
          TysPrim.mkTemplateKiTyVars
          TysPrim.mkTemplateTyConBinders
        which help you make the tyvar binders for dependently-typed
        TyCons.  See comments with their definition.
      
      * The change showed up a bug in TcGenGenerics.tc_mkRepTy, where the code
        was making an assumption about the order of the kind variables in the
        kind of GHC.Generics.(:.:).  I fixed this; see TcGenGenerics.mkComp.
      e368f326
    • Simon Peyton Jones's avatar
      Re-add FunTy (big patch) · 77bb0927
      Simon Peyton Jones authored
      With TypeInType Richard combined ForAllTy and FunTy, but that was often
      awkward, and yielded little benefit becuase in practice the two were
      always treated separately.  This patch re-introduces FunTy.  Specfically
      
      * New type
          data TyVarBinder = TvBndr TyVar VisibilityFlag
        This /always/ has a TyVar it.  In many places that's just what
        what we want, so there are /lots/ of TyBinder -> TyVarBinder changes
      
      * TyBinder still exists:
          data TyBinder = Named TyVarBinder | Anon Type
      
      * data Type = ForAllTy TyVarBinder Type
                  | FunTy Type Type
                  |  ....
      
      There are a LOT of knock-on changes, but they are all routine.
      
      The Haddock submodule needs to be updated too
      77bb0927
  17. 06 Jun, 2016 1 commit
    • Alan Zimmerman's avatar
      Merge MatchFixity and HsMatchContext · a13cb279
      Alan Zimmerman authored
      Summary:
      MatchFixity was introduced to facilitate use of API Annotations.
      
      HsMatchContext does the same thing with more detail, but is chased
      through all over the place to provide context when processing a Match.
      
      Since we already have MatchFixity in the Match, it may as well provide
      the full context.
      
      updates submodule haddock
      
      Test Plan: ./validate
      
      Reviewers: austin, goldfire, bgamari
      
      Subscribers: thomie, mpickering
      
      Differential Revision: https://phabricator.haskell.org/D2271
      
      GHC Trac Issues: #12105
      
      (cherry picked from commit 306ecad5)
      a13cb279
  18. 27 May, 2016 1 commit
  19. 11 May, 2016 1 commit
    • niteria's avatar
      Document SCC determinism · 3edbd091
      niteria authored
      I've documented the guarantees that stronglyConnCompFromEdgedVertices
      provides and commented on the call sites to explain why they are
      OK from determinism standpoint. I've changed the functions to
      nonDetUFM versions, so that it's explicit they could introduce
      nondeterminism.  I haven't defined container (VarSet, NameSet)
      specific versions, so that we have less functions to worry about.
      
      Test Plan: this is mostly just documentation,
      it should have no runtime effect
      
      Reviewers: bgamari, simonmar, austin, simonpj
      
      Reviewed By: simonpj
      
      Subscribers: thomie
      
      Differential Revision: https://phabricator.haskell.org/D2194
      
      GHC Trac Issues: #4012
      3edbd091
  20. 28 Apr, 2016 1 commit
    • Simon Peyton Jones's avatar
      Refactor RecordPatSynField, FieldLabel · 3dce4f2d
      Simon Peyton Jones authored
      This patch uses the named fields of
       * FieldLabel
       * RecordPatSynField
      in construction and pattern matching. The fields
      existed before, but we were often using positional notation.
      
      Also a minor refactor of the API of mkPatSynRecSelBinds
      
      No change in functionality
      3dce4f2d
  21. 26 Apr, 2016 1 commit
    • niteria's avatar
      Kill varSetElems in markNominal · f13a8d21
      niteria authored
      varSetElems introduces unnecessary nondeterminism and it was
      straighforward to just get a deterministic list.
      
      Test Plan: ./validate
      
      Reviewers: austin, goldfire, bgamari, simonmar, simonpj
      
      Reviewed By: simonpj
      
      Subscribers: thomie
      
      Differential Revision: https://phabricator.haskell.org/D2145
      
      GHC Trac Issues: #4012
      f13a8d21
  22. 20 Apr, 2016 1 commit
    • Simon Peyton Jones's avatar
      SCC analysis for instances as well as types/classes · 353d8ae6
      Simon Peyton Jones authored
      This big patch is in pursuit of Trac #11348.
      
      It is largely the work of Alex Veith (thank you!), with some
      follow-up simplification and refactoring from Simon PJ.
      
      The main payload is described in RnSource
        Note [Dependency analysis of type, class, and instance decls]
      which is pretty detailed.
      
      * There is a new data type HsDecls.TyClGroup, for a strongly
        connected component of type/class/instance/role decls.
      
        The hs_instds field of HsGroup disappears, in consequence
      
        This forces some knock-on changes, including a minor
        haddock submodule update
      
      Smaller, weakly-related things
      
      * I found that both the renamer and typechecker were building an
        identical env for RoleAnnots, so I put common code for
        RoleAnnotEnv in RnEnv.
      
      * I found that tcInstDecls1 had very clumsy error handling, so I
        put it together into TcInstDcls.doClsInstErrorChecks
      353d8ae6
  23. 15 Apr, 2016 1 commit
    • niteria's avatar
      Kill some unnecessary varSetElems · 928d7473
      niteria authored
      When you do `varSetElems (tyCoVarsOfType x)` it's equivalent to
      `tyCoVarsOfTypeList x`.
      
      Why? If you look at the implementation:
      ```
      tyCoVarsOfTypeList ty = runFVList $ tyCoVarsOfTypeAcc ty
      tyCoVarsOfType ty = runFVSet $ tyCoVarsOfTypeAcc ty
      ```
      they use the same helper function. The helper function returns a
      deterministically ordered list and a set. The only difference
      between the two is which part of the result they take. It is redundant
      to take the set and then immediately convert it to a list.
      
      This helps with determinism and we eventually want to replace the uses
      of `varSetElems` with functions that don't leak the values of uniques.
      This change gets rid of some instances that are easy to kill.
      
      I chose not to annotate every place where I got rid of `varSetElems`
      with a comment about non-determinism, because once we get rid of
      `varSetElems` it will not be possible to do the wrong thing.
      
      Test Plan: ./validate
      
      Reviewers: goldfire, austin, simonmar, bgamari, simonpj
      
      Reviewed By: simonpj
      
      Subscribers: thomie
      
      Differential Revision: https://phabricator.haskell.org/D2115
      
      GHC Trac Issues: #4012
      928d7473
  24. 18 Feb, 2016 1 commit
    • Ben Gamari's avatar
      Unwire Typeable representation types · 206a8bf4
      Ben Gamari authored
      In order to make this work I needed to shuffle around typechecking a bit
      such that `TyCon` and friends are available during compilation of
      GHC.Types.  I also did a bit of refactoring of `TcTypeable`.
      
      Test Plan: Validate
      
      Reviewers: simonpj, austin
      
      Subscribers: simonpj, thomie
      
      Differential Revision: https://phabricator.haskell.org/D1906
      
      GHC Trac Issues: #11120
      206a8bf4
  25. 27 Jan, 2016 1 commit
    • niteria's avatar
      Rename "open" subst functions · 5dcae88b
      niteria authored
      This is the renaming that @simonpj requested:
      ```
      · zipOpenTCvSubst  -> zipTvSubst   (It only deals with tyvars)
      
      · zipOpenTCvSubstCoVars -> zipCvSubst   (it only deals with
      covars)
      
      · zipOpenTCvSubstBinders ->  zipTyBinderSubst  (it only deals
      with TyBinders, not covars)
      ```
      plus the `mk` variant.
      
      Test Plan: ./validate
      
      Reviewers: simonpj, goldfire, austin, bgamari
      
      Subscribers: thomie, simonpj
      
      Differential Revision: https://phabricator.haskell.org/D1853
      
      GHC Trac Issues: #11371
      5dcae88b
  26. 18 Jan, 2016 2 commits
    • Jan Stolarek's avatar
      Replace calls to `ptext . sLit` with `text` · b8abd852
      Jan Stolarek authored
      Summary:
      In the past the canonical way for constructing an SDoc string literal was the
      composition `ptext . sLit`.  But for some time now we have function `text` that
      does the same.  Plus it has some rules that optimize its runtime behaviour.
      This patch takes all uses of `ptext . sLit` in the compiler and replaces them
      with calls to `text`.  The main benefits of this patch are clener (shorter) code
      and less dependencies between module, because many modules now do not need to
      import `FastString`.  I don't expect any performance benefits - we mostly use
      SDocs to report errors and it seems there is little to be gained here.
      
      Test Plan: ./validate
      
      Reviewers: bgamari, austin, goldfire, hvr, alanz
      
      Subscribers: goldfire, thomie, mpickering
      
      Differential Revision: https://phabricator.haskell.org/D1784
      b8abd852
    • Simon Peyton Jones's avatar
      Refactoring on IdInfo and system derived names · ec8a188a
      Simon Peyton Jones authored
      Some modest refactoring, triggered in part by Trac #11051
      
      * Kill off PatSynId, ReflectionId in IdDetails
        They were barely used, and only for pretty-printing
      
      * Add helper function Id.mkExportedVanillaId, and use it
      
      * Polish up OccName.isDerivedOccName, as a predicate for
        definitions generated internally by GHC, which we
        might not want to show to the user.
      
      * Kill off unused OccName.mkDerivedTyConOcc
      
      * Shorten the derived OccNames for newtype and data
        instance axioms
      
      * A bit of related refactoring around newFamInstAxiomName
      ec8a188a
  27. 31 Dec, 2015 1 commit
  28. 24 Dec, 2015 1 commit
    • eir@cis.upenn.edu's avatar
      Visible type application · 2db18b81
      eir@cis.upenn.edu authored
      This re-working of the typechecker algorithm is based on
      the paper "Visible type application", by Richard Eisenberg,
      Stephanie Weirich, and Hamidhasan Ahmed, to be published at
      ESOP'16.
      
      This patch introduces -XTypeApplications, which allows users
      to say, for example `id @Int`, which has type `Int -> Int`. See
      the changes to the user manual for details.
      
      This patch addresses tickets #10619, #5296, #10589.
      2db18b81
  29. 23 Dec, 2015 1 commit
  30. 21 Dec, 2015 1 commit
    • Alan Zimmerman's avatar
      Add Location to RdrName in FieldOcc · d8ed20c8
      Alan Zimmerman authored
      Summary:
      Post #11019, there have been some new instances of RdrName that are not
      located, in particular
      
      ```#!hs
      data FieldOcc name = FieldOcc { rdrNameFieldOcc  :: RdrName
                                    , selectorFieldOcc :: PostRn name name
                                    }
      
      data AmbiguousFieldOcc name
        = Unambiguous RdrName (PostRn name name)
        | Ambiguous   RdrName (PostTc name name)
        deriving (Typeable)
      ```
      Add locations to them
      
      Updates haddock submodule to match
      
      Test Plan: ./validate
      
      Reviewers: goldfire, hvr, bgamari, austin
      
      Reviewed By: hvr
      
      Subscribers: hvr, thomie, mpickering
      
      Differential Revision: https://phabricator.haskell.org/D1670
      
      GHC Trac Issues: #11258
      d8ed20c8
  31. 15 Dec, 2015 1 commit
    • Simon Peyton Jones's avatar
      Allow recursive (undecidable) superclasses · 6eabb6dd
      Simon Peyton Jones authored
      This patch fulfils the request in Trac #11067, #10318, and #10592,
      by lifting the conservative restrictions on superclass constraints.
      
      These restrictions are there (and have been since Haskell was born) to
      ensure that the transitive superclasses of a class constraint is a finite
      set.  However (a) this restriction is conservative, and can be annoying
      when there really is no recursion, and (b) sometimes genuinely recursive
      superclasses are useful (see the tickets).
      
      Dimitrios and I worked out that there is actually a relatively simple way
      to do the job. It’s described in some detail in
      
         Note [The superclass story] in TcCanonical
         Note [Expanding superclasses] in TcType
      
      In brief, the idea is to expand superclasses only finitely, but to
      iterate (using a loop that already existed) if there are more
      superclasses to explore.
      
      Other small things
      
      - I improved grouping of error messages a bit in TcErrors
      
      - I re-centred the haddock.compiler test, which was at 9.8%
        above the norm, and which this patch pushed slightly over
      6eabb6dd
  32. 11 Dec, 2015 1 commit
    • eir@cis.upenn.edu's avatar
      Add kind equalities to GHC. · 67465497
      eir@cis.upenn.edu authored
      This implements the ideas originally put forward in
      "System FC with Explicit Kind Equality" (ICFP'13).
      
      There are several noteworthy changes with this patch:
       * We now have casts in types. These change the kind
         of a type. See new constructor `CastTy`.
      
       * All types and all constructors can be promoted.
         This includes GADT constructors. GADT pattern matches
         take place in type family equations. In Core,
         types can now be applied to coercions via the
         `CoercionTy` constructor.
      
       * Coercions can now be heterogeneous, relating types
         of different kinds. A coercion proving `t1 :: k1 ~ t2 :: k2`
         proves both that `t1` and `t2` are the same and also that
         `k1` and `k2` are the same.
      
       * The `Coercion` type has been significantly enhanced.
         The documentation in `docs/core-spec/core-spec.pdf` reflects
         the new reality.
      
       * The type of `*` is now `*`. No more `BOX`.
      
       * Users can write explicit kind variables in their code,
         anywhere they can write type variables. For backward compatibility,
         automatic inference of kind-variable binding is still permitted.
      
       * The new extension `TypeInType` turns on the new user-facing
         features.
      
       * Type families and synonyms are now promoted to kinds. This causes
         trouble with parsing `*`, leading to the somewhat awkward new
         `HsAppsTy` constructor for `HsType`. This is dispatched with in
         the renamer, where the kind `*` can be told apart from a
         type-level multiplication operator. Without `-XTypeInType` the
         old behavior persists. With `-XTypeInType`, you need to import
         `Data.Kind` to get `*`, also known as `Type`.
      
       * The kind-checking algorithms in TcHsType have been significantly
         rewritten to allow for enhanced kinds.
      
       * The new features are still quite experimental and may be in flux.
      
       * TODO: Several open tickets: #11195, #11196, #11197, #11198, #11203.
      
       * TODO: Update user manual.
      
      Tickets addressed: #9017, #9173, #7961, #10524, #8566, #11142.
      Updates Haddock submodule.
      67465497
  33. 01 Dec, 2015 2 commits
    • Simon Peyton Jones's avatar
      Refactor treatment of wildcards · 1e041b73
      Simon Peyton Jones authored
      This patch began as a modest refactoring of HsType and friends, to
      clarify and tidy up exactly where quantification takes place in types.
      Although initially driven by making the implementation of wildcards more
      tidy (and fixing a number of bugs), I gradually got drawn into a pretty
      big process, which I've been doing on and off for quite a long time.
      
      There is one compiler performance regression as a result of all
      this, in perf/compiler/T3064.  I still need to look into that.
      
      * The principal driving change is described in Note [HsType binders]
        in HsType.  Well worth reading!
      
      * Those data type changes drive almost everything else.  In particular
        we now statically know where
      
             (a) implicit quantification only (LHsSigType),
                 e.g. in instance declaratios and SPECIALISE signatures
      
             (b) implicit quantification and wildcards (LHsSigWcType)
                 can appear, e.g. in function type signatures
      
      * As part of this change, HsForAllTy is (a) simplified (no wildcards)
        and (b) split into HsForAllTy and HsQualTy.  The two contructors
        appear when and only when the correponding user-level construct
        appears.  Again see Note [HsType binders].
      
        HsExplicitFlag disappears altogether.
      
      * Other simplifications
      
           - ExprWithTySig no longer needs an ExprWithTySigOut variant
      
           - TypeSig no longer needs a PostRn name [name] field
             for wildcards
      
           - PatSynSig records a LHsSigType rather than the decomposed
             pieces
      
           - The mysterious 'GenericSig' is now 'ClassOpSig'
      
      * Renamed LHsTyVarBndrs to LHsQTyVars
      
      * There are some uninteresting knock-on changes in Haddock,
        because of the HsSyn changes
      
      I also did a bunch of loosely-related changes:
      
      * We already had type synonyms CoercionN/CoercionR for nominal and
        representational coercions.  I've added similar treatment for
      
            TcCoercionN/TcCoercionR
      
            mkWpCastN/mkWpCastN
      
        All just type synonyms but jolly useful.
      
      * I record-ised ForeignImport and ForeignExport
      
      * I improved the (poor) fix to Trac #10896, by making
        TcTyClsDecls.checkValidTyCl recover from errors, but adding a
        harmless, abstract TyCon to the envt if so.
      
      * I did some significant refactoring in RnEnv.lookupSubBndrOcc,
        for reasons that I have (embarrassingly) now totally forgotten.
        It had to do with something to do with import and export
      
      Updates haddock submodule.
      1e041b73
    • Bartosz Nitka's avatar
      Fix grammar and typo in TcTyDecls · 6dce643d
      Bartosz Nitka authored
      Summary: It's just a docufix.
      
      Test Plan: just a docufix
      
      Reviewers: austin, bgamari
      
      Reviewed By: bgamari
      
      Subscribers: thomie
      
      Differential Revision: https://phabricator.haskell.org/D1550
      6dce643d
  34. 25 Nov, 2015 1 commit
    • Simon Peyton Jones's avatar
      Refactor default methods (Trac #11105) · 924f8517
      Simon Peyton Jones authored
      This patch does some signficant refactoring to the treatment
      of default methods in class declarations, and more generally
      to the type checking of type/class decls.
      
      Highlights:
      
      * When the class has a generic-default method, such as
           class C a where
             op :: a -> a -> Bool
             default op :: Ord a => a -> a -> a
        the ClassOpItem records the type of the generic-default,
        in this case the type (Ord a => a -> a -> a)
      
      * I killed off Class.DefMeth in favour of the very-similar
        BasicTypes.DefMethSpec.  However it turned out to be better
        to use a Maybe, thus
            Maybe (DefMethSpec Type)
        with Nothing meaning "no default method".
      
      * In TcTyClsDecls.tcTyClGroup, we used to accumulate a [TyThing],
        but I found a way to make it much simpler, accumulating only
        a [TyCon].  Much less wrapping and unwrapping.
      
      * On the way I also fixed Trac #10896 in a better way. Instead
        of killing off all ambiguity checks whenever there are any type
        errors (the fix in commit 8e8b9ed9), I instead recover in
        TcTyClsDecls.checkValidTyCl.
      
      There was a lot of associated simplification all round
      924f8517
  35. 22 Nov, 2015 1 commit
    • Alan Zimmerman's avatar
      ApiAnnotations: Make all RdrName occurences Located · 3df9563e
      Alan Zimmerman authored
      At the moment the API Annotations can only be used on the ParsedSource,
      as there are changes made to the RenamedSource that prevent it from
      being used to round trip source code.
      
      It is possible to build a map from every Located Name in the
      RenamedSource from its location to the Name, which can then be used when
      resolved names are required when changing the ParsedSource.
      
      However, there are instances where the identifier is not located,
      specifically
      
        (GHC.VarPat name)
        (GHC.HsVar name)
        (GHC.UserTyVar name)
        (GHC.HsTyVar name)
      
      Replace each of the name types above with (Located name)
      
      Updates the haddock submodule.
      
      Test Plan: ./validate
      
      Reviewers: austin, goldfire, bgamari
      
      Reviewed By: bgamari
      
      Subscribers: goldfire, thomie, mpickering
      
      Differential Revision: https://phabricator.haskell.org/D1512
      
      GHC Trac Issues: #11019
      3df9563e
  36. 30 Oct, 2015 1 commit
    • Ben Gamari's avatar
      Generate Typeable info at definition sites · 91c6b1f5
      Ben Gamari authored
      This is the second attempt at merging D757.
      
      This patch implements the idea floated in Trac #9858, namely that we
      should generate type-representation information at the data type
      declaration site, rather than when solving a Typeable constraint.
      
      However, this turned out quite a bit harder than I expected. I still
      think it's the right thing to do, and it's done now, but it was quite
      a struggle.
      
      See particularly
      
       * Note [Grand plan for Typeable] in TcTypeable (which is a new module)
       * Note [The overall promotion story] in DataCon (clarifies existing
      stuff)
      
      The most painful bit was that to generate Typeable instances (ie
      TyConRepName bindings) for every TyCon is tricky for types in ghc-prim
      etc:
      
       * We need to have enough data types around to *define* a TyCon
       * Many of these types are wired-in
      
      Also, to minimise the code generated for each data type, I wanted to
      generate pure data, not CAFs with unpackCString# stuff floating about.
      
      Performance
      ~~~~~~~~~~~
      Three perf/compiler tests start to allocate quite a bit more. This isn't
      surprising, because they all allocate zillions of data types, with
      practically no other code, esp. T1969
      
       * T1969:    GHC allocates 19% more
       * T4801:    GHC allocates 13% more
       * T5321FD:  GHC allocates 13% more
       * T9675:    GHC allocates 11% more
       * T783:     GHC allocates 11% more
       * T5642:    GHC allocates 10% more
      
      I'm treating this as acceptable. The payoff comes in Typeable-heavy
      code.
      
      Remaining to do
      ~~~~~~~~~~~~~~~
      
       * I think that "TyCon" and "Module" are over-generic names to use for
         the runtime type representations used in GHC.Typeable. Better might
      be
         "TrTyCon" and "TrModule". But I have not yet done this
      
       * Add more info the the "TyCon" e.g. source location where it was
         defined
      
       * Use the new "Module" type to help with Trac Trac #10068
      
       * It would be possible to generate TyConRepName (ie Typeable
         instances) selectively rather than all the time. We'd need to persist
         the information in interface files. Lacking a motivating reason I
      have
         not done this, but it would not be difficult.
      
      Refactoring
      ~~~~~~~~~~~
      As is so often the case, I ended up refactoring more than I intended.
      In particular
      
       * In TyCon, a type *family* (whether type or data) is repesented by a
         FamilyTyCon
           * a algebraic data type (including data/newtype instances) is
             represented by AlgTyCon This wasn't true before; a data family
             was represented as an AlgTyCon. There are some corresponding
             changes in IfaceSyn.
      
           * Also get rid of the (unhelpfully named) tyConParent.
      
       * In TyCon define 'Promoted', isomorphic to Maybe, used when things are
         optionally promoted; and use it elsewhere in GHC.
      
       * Cleanup handling of knownKeyNames
      
       * Each TyCon, including promoted TyCons, contains its TyConRepName, if
         it has one. This is, in effect, the name of its Typeable instance.
      
      Updates haddock submodule
      
      Test Plan: Let Harbormaster validate
      
      Reviewers: austin, hvr, goldfire
      
      Subscribers: goldfire, thomie
      
      Differential Revision: https://phabricator.haskell.org/D1404
      
      GHC Trac Issues: #9858
      91c6b1f5
  37. 29 Oct, 2015 1 commit