1. 27 Feb, 2017 1 commit
  2. 21 Feb, 2017 2 commits
    • Simon Peyton Jones's avatar
      A bit more tc-tracing in TcTyClsDecls · e3e218e2
      Simon Peyton Jones authored
      e3e218e2
    • Simon Peyton Jones's avatar
      Remove panics for TcTyCon · 0c9d9dec
      Simon Peyton Jones authored
      Previously TcTyCons were used only for knot-tying, but now they
      are also used after an error, to add a benign TyCon to the envt
      so we can carry on; see TyCon.makeRecoveryTyCon.  But since it
      is used in this way, subsequent declarations may see a TcTyCon
      (e.g. during injectivity checks) and should not have a heart attack
      as a result.
      
      See Note [TcTyCon] in TyCon.
      
      This fixes Trac #13271
      0c9d9dec
  3. 20 Feb, 2017 1 commit
  4. 30 Jan, 2017 1 commit
    • Ryan Scott's avatar
      Check that a default type signature aligns with the non-default signature · 7363d538
      Ryan Scott authored
      Before, GHC was extremely permissive about the form a default type
      signature could take on in a class declaration. Notably, it would accept
      garbage like this:
      
        class Monad m => MonadSupply m where
          fresh :: m Integer
          default fresh :: MonadTrans t => t m Integer
          fresh = lift fresh
      
      And then give an extremely confusing error message when you actually
      tried to declare an empty instance of MonadSupply. We now do extra
      validity checking of default type signatures to ensure that they align
      with their non-default type signature counterparts. That is, a default
      type signature is allowed to differ from the non-default one only in its
      context - they must otherwise be alpha-equivalent.
      
      Fixes #12918.
      
      Test Plan: ./validate
      
      Reviewers: goldfire, simonpj, austin, bgamari
      
      Reviewed By: bgamari
      
      Subscribers: mpickering, dfeuer, thomie
      
      Differential Revision: https://phabricator.haskell.org/D2983
      
      GHC Trac Issues: #12918
      7363d538
  5. 26 Jan, 2017 1 commit
  6. 19 Jan, 2017 1 commit
    • Richard Eisenberg's avatar
      Update levity polymorphism · e7985ed2
      Richard Eisenberg authored
      This commit implements the proposal in
      https://github.com/ghc-proposals/ghc-proposals/pull/29 and
      https://github.com/ghc-proposals/ghc-proposals/pull/35.
      
      Here are some of the pieces of that proposal:
      
      * Some of RuntimeRep's constructors have been shortened.
      
      * TupleRep and SumRep are now parameterized over a list of RuntimeReps.
      * This
      means that two types with the same kind surely have the same
      representation.
      Previously, all unboxed tuples had the same kind, and thus the fact
      above was
      false.
      
      * RepType.typePrimRep and friends now return a *list* of PrimReps. These
      functions can now work successfully on unboxed tuples. This change is
      necessary because we allow abstraction over unboxed tuple types and so
      cannot
      always handle unboxed tuples specially as we did before.
      
      * We sometimes have to create an Id from a PrimRep. I thus split PtrRep
      * into
      LiftedRep and UnliftedRep, so that the created Ids have the right
      strictness.
      
      * The RepType.RepType type was removed, as it didn't seem to help with
      * much.
      
      * The RepType.repType function is also removed, in favor of typePrimRep.
      
      * I have waffled a good deal on whether or not to keep VoidRep in
      TyCon.PrimRep. In the end, I decided to keep it there. PrimRep is *not*
      represented in RuntimeRep, and typePrimRep will never return a list
      including
      VoidRep. But it's handy to have in, e.g., ByteCodeGen and friends. I can
      imagine another design choice where we have a PrimRepV type that is
      PrimRep
      with an extra constructor. That seemed to be a heavier design, though,
      and I'm
      not sure what the benefit would be.
      
      * The last, unused vestiges of # (unliftedTypeKind) have been removed.
      
      * There were several pretty-printing bugs that this change exposed;
      * these are fixed.
      
      * We previously checked for levity polymorphism in the types of binders.
      * But we
      also must exclude levity polymorphism in function arguments. This is
      hard to check
      for, requiring a good deal of care in the desugarer. See Note [Levity
      polymorphism
      checking] in DsMonad.
      
      * In order to efficiently check for levity polymorphism in functions, it
      * was necessary
      to add a new bit of IdInfo. See Note [Levity info] in IdInfo.
      
      * It is now safe for unlifted types to be unsaturated in Core. Core Lint
      * is updated
      accordingly.
      
      * We can only know strictness after zonking, so several checks around
      * strictness
      in the type-checker (checkStrictBinds, the check for unlifted variables
      under a ~
      pattern) have been moved to the desugarer.
      
      * Along the way, I improved the treatment of unlifted vs. banged
      * bindings. See
      Note [Strict binds checks] in DsBinds and #13075.
      
      * Now that we print type-checked source, we must be careful to print
      * ConLikes correctly.
      This is facilitated by a new HsConLikeOut constructor to HsExpr.
      Particularly troublesome
      are unlifted pattern synonyms that get an extra void# argument.
      
      * Includes a submodule update for haddock, getting rid of #.
      
      * New testcases:
        typecheck/should_fail/StrictBinds
        typecheck/should_fail/T12973
        typecheck/should_run/StrictPats
        typecheck/should_run/T12809
        typecheck/should_fail/T13105
        patsyn/should_fail/UnliftedPSBind
        typecheck/should_fail/LevPolyBounded
        typecheck/should_compile/T12987
        typecheck/should_compile/T11736
      
      * Fixed tickets:
        #12809
        #12973
        #11736
        #13075
        #12987
      
      * This also adds a test case for #13105. This test case is
      * "compile_fail" and
      succeeds, because I want the testsuite to monitor the error message.
      When #13105 is fixed, the test case will compile cleanly.
      e7985ed2
  7. 18 Dec, 2016 1 commit
  8. 17 Dec, 2016 1 commit
    • eir@cis.upenn.edu's avatar
      Reshuffle levity polymorphism checks. · 8906e7b7
      eir@cis.upenn.edu authored
      Previously, GHC checked for bad levity polymorphism to the left of all
      arrows in data constructors. This was wrong, as reported in #12911
      (where an example is also shown). The solution is to check each
      individual argument for bad levity polymorphism.  Thus the check has
      been moved from TcValidity to TcTyClsDecls.
      
      A similar situation exists with pattern synonyms, also fixed here.
      
      This patch also nabs #12819 while I was in town.
      
      Test cases: typecheck/should_compile/T12911, patsyn/should_fail/T12819
      
      Test Plan: ./validate
      
      Reviewers: simonpj, austin, bgamari
      
      Reviewed By: bgamari
      
      Subscribers: thomie
      
      Differential Revision: https://phabricator.haskell.org/D2783
      
      GHC Trac Issues: #12819, #12911
      8906e7b7
  9. 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
  10. 25 Nov, 2016 1 commit
    • Simon Peyton Jones's avatar
      Use TyVars in PatSyns · 12eff239
      Simon Peyton Jones authored
      I found that some TcTyVars were lurking in a PatSyn, because
      tc_patsyn_finish was using the TcType -> TcType zonker rather
      than the TcType -> Type zonker.  Eeek.
      
      I fixing this I also tided up function naming a bit (still not
      terrific), and removed the unused TcTyBinder type entirely.
      12eff239
  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. 13 Nov, 2016 1 commit
    • Ben Gamari's avatar
      Kill Type pretty-printer · 6c0f10fa
      Ben Gamari authored
      Here we consolidate the pretty-printing logic for types in IfaceType. We
      need IfaceType regardless and the printer for Type can be implemented in
      terms of that for IfaceType. See #11660.
      
      Note that this is very much a work-in-progress. Namely I still have yet
      to ponder how to ease the hs-boot file situation, still need to rip out
      more dead code, need to move some of the special cases for, e.g., `*` to
      the IfaceType printer, and need to get it to validate. That being said,
      it comes close to validating as-is.
      
      Test Plan: Validate
      
      Reviewers: goldfire, austin
      
      Subscribers: goldfire, thomie, simonpj
      
      Differential Revision: https://phabricator.haskell.org/D2528
      
      GHC Trac Issues: #11660
      6c0f10fa
  13. 02 Nov, 2016 2 commits
    • Simon Peyton Jones's avatar
      Simplify the API for TcHsType.kcHsTyVarBndrs · 7a509660
      Simon Peyton Jones authored
      Pass in a Bool rather than return a funcion!
      
      No change in behaviour.
      7a509660
    • Simon Peyton Jones's avatar
      Get rid of TcTyVars more assiduously · 99689492
      Simon Peyton Jones authored
      * I found a bug in 'generalize' in TcTyClsDecls.kcTyClGroup, where
        the kind variables weren't being turned into proper TyVars, so
        we got (skolem) TcTyVars in TyCons, which shouldn't happen.  Fix
        was easy.
      
      * Similarly TcHsType.kindGeneralizeType wasn't turning the forall'd
        TcTyVars into TyVars.  To achieve this I defined TcHsTyn.zonkSigType.
      
      * All this allowed me to remove awkward and ill-explained bit of
        footwork on DFunIds in Inst.newClsInst
      
      This is just refactoring, but it does make the printout from
      -ddump-deriv make a bit more sense by not grautuitiously cloning
      type variables.  In the display I was seeing
      
         instance C [a_df4] where
            f x = ...a_dx5...
      
      where actually the d_df4 and a_dx5 were the same.
      99689492
  14. 31 Oct, 2016 1 commit
  15. 27 Oct, 2016 1 commit
  16. 21 Oct, 2016 1 commit
    • Simon Peyton Jones's avatar
      Refactor occurrence-check logic · 9417e579
      Simon Peyton Jones authored
      This patch does two related things
      
      * Combines the occurrence-check logic in the on-the-fly unifier with
        that in the constraint solver.  They are both doing the same job,
        after all.  The resulting code is now in TcUnify:
           metaTyVarUpdateOK
           occCheckExpand
           occCheckForErrors (called in TcErrors)
      
      * In doing this I disovered checking for family-free-ness and foralls
        can be unnecessarily inefficient, because it expands type synonyms.
        It's easy just to cache this info in the type syononym TyCon, which
        I am now doing.
      9417e579
  17. 20 Oct, 2016 1 commit
    • Edward Z. Yang's avatar
      New story for abstract data types in hsig files. · 518f2895
      Edward Z. Yang authored
      
      
      Summary:
      In the old implementation of hsig files, we directly
      reused the implementation of abstract data types from
      hs-boot files.  However, this was WRONG.  Consider the
      following program (an abridged version of bkpfail24):
      
          {-# LANGUAGE GADTs #-}
          unit p where
              signature H1 where
                  data T
              signature H2 where
                  data T
              module M where
                  import qualified H1
                  import qualified H2
      
                  f :: H1.T ~ H2.T => a -> b
                  f x = x
      
      Prior to this patch, M was accepted, because the type
      inference engine concluded that H1.T ~ H2.T does not
      hold (indeed, *presently*, it does not).  However, if
      we subsequently instantiate p with the same module for
      H1 and H2, H1.T ~ H2.T does hold!  Unsound.
      
      The key is that abstract types from signatures need to
      be treated like *skolem variables*, since you can interpret
      a Backpack unit as a record which is universally quantified
      over all of its abstract types, as such (with some fake
      syntax for structural records):
      
          p :: forall t1 t2. { f :: t1 ~ t2 => a -> b }
          p = { f = \x -> x } -- ill-typed
      
      Clearly t1 ~ t2 is not solvable inside p, and also clearly
      it could be true at some point in the future, so we better
      not treat the lambda expression after f as inaccessible.
      
      The fix seems to be simple: do NOT eagerly fail when trying
      to simplify the given constraints.  Instead, treat H1.T ~ H2.T
      as an irreducible constraint (rather than an insoluble
      one); this causes GHC to treat f as accessible--now we will
      typecheck the rest of the function (and correctly fail).
      Per the OutsideIn(X) paper, it's always sound to fail less
      when simplifying givens.
      
      We do NOT apply this fix to hs-boot files, where abstract
      data is also guaranteed to be nominally distinct (since
      it can't be implemented via a reexport or a type synonym.)
      This is a somewhat unnatural state of affairs (there's
      no way to really interpret this in Haskell land) but
      no reason to change behavior.
      
      I deleted "representationally distinct abstract data",
      which is never used anywhere in GHC.
      
      In the process of constructing this fix, I also realized
      our implementation of type synonym matching against abstract
      data was not sufficiently restrictive.  In order for
      a type synonym T to be well-formed type, it must be a
      nullary synonym (i.e., type T :: * -> *, not type T a = ...).
      Furthermore, since we use abstract data when defining
      instances, they must not have any type family applications.
      
      More details in #12680.  This probably deserves some sort
      of short paper report.
      Signed-off-by: default avatarEdward Z. Yang <ezyang@cs.stanford.edu>
      
      Test Plan: validate
      
      Reviewers: goldfire, simonpj, austin, bgamari
      
      Subscribers: thomie
      
      Differential Revision: https://phabricator.haskell.org/D2594
      518f2895
  18. 19 Oct, 2016 1 commit
    • Simon Peyton Jones's avatar
      Test for newtype with unboxed argument · 1f09c16c
      Simon Peyton Jones authored
      Newtypes cannot (currently) have an unboxed argument type.
      But Trac #12729 showed that this was only being checked for
      newtypes in H98 syntax; in GADT snytax they were let through.
      
      This patch moves the test to checkValidDataCon, where it properly
      belongs.
      1f09c16c
  19. 10 Oct, 2016 1 commit
    • Simon Peyton Jones's avatar
      Move zonking out of tcFamTyPats · 76a5477b
      Simon Peyton Jones authored
      In tcFamTyPats we were zonking from the TcType world to the
      Type world, ready to build the results into a CoAxiom (which
      should have no TcType stuff.  But the 'thing_inside' for
      tcFamTyPats also must be zonked, and that zonking must have
      the ZonkEnv from the binders zonked tcFamTyPats.
      
      Ugh.  This caused an assertion failure (with DEBUG on) in
      RaeBlobPost and TypeLevelVec, both in tests/dependent, as
      shown in Trac #12682.  Why it hasn't shown up before now
      is obscure to me.
      
      So I moved the zonking stuff out of tcFamTyPats to its
      three call sites, where we can do it all together. Very
      slightly longer, but much more robust.
      76a5477b
  20. 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
  21. 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
  22. 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
  23. 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
  24. 13 Jun, 2016 1 commit
    • Simon Peyton Jones's avatar
      Move the constraint-kind validity check · 35c9de7c
      Simon Peyton Jones authored
      For type synonyms, we need to check that if the RHS has
      kind Constraint, then we have -XConstraintKinds.  For
      some reason this was done in checkValidType, but it makes
      more sense to do it in checkValidTyCon.
      
      I can't remember quite why I made this change; maybe it fixes
      a Trac ticket, but if so I forget which.  But it's a modest
      improvement anyway.
      35c9de7c
  25. 19 May, 2016 1 commit
  26. 29 Apr, 2016 1 commit
    • eir@cis.upenn.edu's avatar
      Remove the incredibly hairy splitTelescopeTvs. · c5919f75
      eir@cis.upenn.edu authored
      This patch removes splitTelescopeTvs by adding information about
      scoped type variables to TcTyCon. Vast simplification!
      
      This also fixes #11821 by bringing only unzonked vars into scope.
      
      Test case: polykinds/T11821
      c5919f75
  27. 20 Apr, 2016 2 commits
    • Simon Peyton Jones's avatar
      Tighten up imports on TcTyClsDecls · cdcf014d
      Simon Peyton Jones authored
      cdcf014d
    • 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
  28. 19 Apr, 2016 1 commit
    • Simon Peyton Jones's avatar
      Tighten checking for associated type instances · 8136a5cb
      Simon Peyton Jones authored
      This patch finishes off Trac #11450.  Following debate on that ticket,
      the patch tightens up the rules for what the instances of an
      associated type can look like.  Now they must match the instance
      header exactly. Eg
      
         class C a b where
          type T a x b
      
      With this class decl, if we have an instance decl
        instance C ty1 ty2 where ...
      then the type instance must look like
           type T ty1 v ty2 = ...
      with exactly
        - 'ty1' for 'a'
        -  'ty2' for 'b', and
        - a variable for 'x'
      
      For example:
      
        instance C [p] Int
          type T [p] y Int = (p,y,y)
      
      Previously we allowed multiple instance equations and now, in effect,
      we don't since they would all overlap.  If you want multiple cases,
      use an auxiliary type family.
      
      This is consistent with the treatment of generic-default instances,
      and the user manual always said "WARNING: this facility (multiple
      instance equations may be withdrawn in the future".
      
      I also improved error messages, and did other minor refactoring.
      8136a5cb
  29. 15 Apr, 2016 1 commit
  30. 11 Apr, 2016 1 commit
    • Rik Steenkamp's avatar
      Fix a closed type family error message · 46e8f199
      Rik Steenkamp authored
      Now we check whether a closed type family's equation is headed with
      the correct type before we kind-check the equation.
      
      Also, instead of "expected only no parameters" we now generate the
      message "expected no parameters".
      
      Fixes #11623.
      
      Reviewers: simonpj, austin, bgamari
      
      Reviewed By: simonpj, bgamari
      
      Subscribers: simonpj, goldfire, thomie
      
      Differential Revision: https://phabricator.haskell.org/D2089
      
      GHC Trac Issues: #11623
      46e8f199
  31. 25 Mar, 2016 1 commit
    • Simon Peyton Jones's avatar
      A raft of comments about TyBinders · 067335a6
      Simon Peyton Jones authored
      I had a conversation with Richard about TyBinders
      and VisibilityFlags.  This patch adds a lot of comments
      to explain what is going on.  I feel much more secure now.
      
      Richard please check.
      067335a6
  32. 21 Mar, 2016 2 commits
    • eir@cis.upenn.edu's avatar
      Zonk before calling splitDepVarsOfType. · 5c0c751a
      eir@cis.upenn.edu authored
      It was Utterly Wrong before.
      
      Note to self: Never, ever take the free vars of an unzonked type.
      5c0c751a
    • eir@cis.upenn.edu's avatar
      Track specified/invisible more carefully. · 35e93797
      eir@cis.upenn.edu authored
      In particular, this allows correct tracking of specified/invisible
      for variables in Haskell98 data constructors and in pattern synonyms.
      GADT-syntax constructors are harder, and are left until #11721.
      
      This was all inspired by Simon's comments to my fix for #11512,
      which this subsumes.
      
      Test case: ghci/scripts/TypeAppData
      
      [skip ci]  (The test case fails because of an unrelated problem
      fixed in the next commit.)
      35e93797
  33. 17 Mar, 2016 1 commit
    • eir@cis.upenn.edu's avatar
      Fix #11716. · 3fe87aa0
      eir@cis.upenn.edu authored
      There were several smallish bugs here:
       - We had too small an InScopeSet when rejigging GADT return types.
       - When adding the extra_tvs with a datatype kind signature, we
         were sometimes changing Uniques of an explicitly bound kind var.
       - Using coercionKind in the flattener got the wrong visibility
         for a binder. Now we just zonk to get what we need.
      
      Test case: dependent/should_compile/RaeJobTalk
      3fe87aa0
  34. 15 Mar, 2016 2 commits
    • eir@cis.upenn.edu's avatar
      Remove redundant anonymiseTyBinders (#11648) · 19be5385
      eir@cis.upenn.edu authored
      This was necessary in an earlier version of the patch for #11648,
      but not in the final version. I forgot to remove it.
      19be5385
    • eir@cis.upenn.edu's avatar
      Fix #11648. · 55577a91
      eir@cis.upenn.edu authored
      We now check that a CUSK is really a CUSK and issue an error if
      it isn't. This also involves more solving and zonking in
      kcHsTyVarBndrs, which was the outright bug reported in #11648.
      
      Test cases: polykinds/T11648{,b}
      
      This updates the haddock submodule.
      
      [skip ci]
      55577a91