1. 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
  2. 18 Jan, 2016 1 commit
    • 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
  3. 31 Dec, 2015 1 commit
  4. 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
  5. 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
  6. 23 Nov, 2015 1 commit
  7. 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
  8. 29 Oct, 2015 3 commits
    • Ben Gamari's avatar
      Revert "Generate Typeable info at definition sites" · bbaf76f9
      Ben Gamari authored
      This reverts commit bef2f03e.
      
      This merge was botched
      
      Also reverts haddock submodule.
      bbaf76f9
    • Ben Gamari's avatar
      Generate Typeable info at definition sites · bef2f03e
      Ben Gamari authored
      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
      
       * T3294:   GHC allocates 110% more (filed #11030 to track this)
       * T1969:   GHC allocates 30% more
       * T4801:   GHC allocates 14% more
       * T5321FD: GHC allocates 13% more
       * T783:    GHC allocates 12% more
       * T9675:   GHC allocates 12% more
       * T5642:   GHC allocates 10% more
       * T9961:   GHC allocates 6% more
      
       * T9203:   Program allocates 54% less
      
      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.
      
      Requires update of the haddock submodule.
      
      Differential Revision: https://phabricator.haskell.org/D757
      bef2f03e
    • Matthew Pickering's avatar
      Record pattern synonyms · 2a74a64e
      Matthew Pickering authored
      This patch implements an extension to pattern synonyms which allows user
      to specify pattern synonyms using record syntax. Doing so generates
      appropriate selectors and update functions.
      
      === Interaction with Duplicate Record Fields ===
      
      The implementation given here isn't quite as general as it could be with
      respect to the recently-introduced `DuplicateRecordFields` extension.
      
      Consider the following module:
      
          {-# LANGUAGE DuplicateRecordFields #-}
          {-# LANGUAGE PatternSynonyms #-}
      
          module Main where
      
          pattern S{a, b} = (a, b)
          pattern T{a}    = Just a
      
          main = do
            print S{ a = "fst", b = "snd" }
            print T{ a = "a" }
      
      In principle, this ought to work, because there is no ambiguity. But at
      the moment it leads to a "multiple declarations of a" error. The problem
      is that pattern synonym record selectors don't do the same name mangling
      as normal datatypes when DuplicateRecordFields is enabled. They could,
      but this would require some work to track the field label and selector
      name separately.
      
      In particular, we currently represent datatype selectors in the third
      component of AvailTC, but pattern synonym selectors are just represented
      as Avails (because they don't have a corresponding type constructor).
      Moreover, the GlobalRdrElt for a selector currently requires it to have
      a parent tycon.
      
      (example due to Adam Gundry)
      
      === Updating Explicitly Bidirectional Pattern Synonyms ===
      
      Consider the following
      
      ```
      pattern Silly{a} <- [a] where
        Silly a = [a, a]
      
      f1 = a [5] -- 5
      
      f2 = [5] {a = 6} -- currently [6,6]
      ```
      
      === Fixing Polymorphic Updates ===
      
      They were fixed by adding these two lines in `dsExpr`. This might break
      record updates but will be easy to fix.
      
      ```
      + ; let req_wrap = mkWpTyApps (mkTyVarTys univ_tvs)
      
      - , pat_wrap = idHsWrapper }
      +, pat_wrap = req_wrap }
      ```
      
      === Mixed selectors error ===
      
      Note [Mixed Record Field Updates]
      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      
      Consider the following pattern synonym.
      
          data MyRec = MyRec { foo :: Int, qux :: String }
      
          pattern HisRec{f1, f2} = MyRec{foo = f1, qux=f2}
      
      This allows updates such as the following
      
          updater :: MyRec -> MyRec
          updater a = a {f1 = 1 }
      
      It would also make sense to allow the following update (which we
      reject).
      
          updater a = a {f1 = 1, qux = "two" } ==? MyRec 1 "two"
      
      This leads to confusing behaviour when the selectors in fact refer the
      same field.
      
          updater a = a {f1 = 1, foo = 2} ==? ???
      
      For this reason, we reject a mixture of pattern synonym and normal
      record selectors in the same update block. Although of course we still
      allow the following.
      
          updater a = (a {f1 = 1}) {foo = 2}
      
          > updater (MyRec 0 "str")
          MyRec 2 "str"
      2a74a64e
  9. 16 Oct, 2015 1 commit
    • Adam Gundry's avatar
      Implement DuplicateRecordFields · b1884b0e
      Adam Gundry authored
      This implements DuplicateRecordFields, the first part of the
      OverloadedRecordFields extension, as described at
      https://ghc.haskell.org/trac/ghc/wiki/Records/OverloadedRecordFields/DuplicateRecordFields
      
      This includes fairly wide-ranging changes in order to allow multiple
      records within the same module to use the same field names.  Note that
      it does *not* allow record selector functions to be used if they are
      ambiguous, and it does not have any form of type-based disambiguation
      for selectors (but it does for updates). Subsequent parts will make
      overloading selectors possible using orthogonal extensions, as
      described on the wiki pages.  This part touches quite a lot of the
      codebase, and requires changes to several GHC API datatypes in order
      to distinguish between field labels (which may be overloaded) and
      selector function names (which are always unique).
      
      The Haddock submodule has been adapted to compile with the GHC API
      changes, but it will need further work to properly support modules
      that use the DuplicateRecordFields extension.
      
      Test Plan: New tests added in testsuite/tests/overloadedrecflds; these
      will be extended once the other parts are implemented.
      
      Reviewers: goldfire, bgamari, simonpj, austin
      
      Subscribers: sjcjoosten, haggholm, mpickering, bgamari, tibbe, thomie,
      goldfire
      
      Differential Revision: https://phabricator.haskell.org/D761
      b1884b0e
  10. 21 Sep, 2015 2 commits
    • eir@cis.upenn.edu's avatar
      Refactor BranchLists. · cd2840a7
      eir@cis.upenn.edu authored
      Now we use Array to store branches. This makes sense because we often
      have to do random access (once inference is done). This also vastly
      simplifies the awkward BranchList type.
      
      This fixes #10837 and updates submodule utils/haddock.
      cd2840a7
    • eir@cis.upenn.edu's avatar
      Perform a validity check on assoc type defaults. · e27b267f
      eir@cis.upenn.edu authored
      This fixes #10817 and #10899. A knock-on effect is that we must
      now remember locations of associated type defaults for error
      messages during validity checking. This isn't too bad, but it
      increases the size of the diff somewhat.
      
      Test cases: indexed-types/should_fail/T108{17,99}
      e27b267f
  11. 11 Sep, 2015 1 commit
  12. 03 Sep, 2015 1 commit
  13. 10 Aug, 2015 1 commit
  14. 27 Jul, 2015 2 commits
    • Simon Peyton Jones's avatar
      Improve warnings for rules that might not fire · 2d88a531
      Simon Peyton Jones authored
      Two main things here
      
      * Previously we only warned about the "head" function of the rule,
        but actually the warning applies to any free variable on the LHS.
      
      * We now warn not only when one of these free vars can inline, but
        also if it has an active RULE (c.f. Trac #10528)
      
      See Note [Rules and inlining/other rules] in Desugar
      
      This actually shows up quite a few warnings in the libraries, notably
      in Control.Arrow, where it correctly points out that rules like
          "compose/arr"   forall f g .
                          (arr f) . (arr g) = arr (f . g)
      might never fire, because the rule for 'arr' (dictionary selection)
      might fire first.  I'm not really sure what to do here; there is some
      discussion in Trac #10595.
      
      A minor change is adding BasicTypes.pprRuleName to pretty-print RuleName.
      2d88a531
    • Adam Sandberg Eriksson's avatar
      Implementation of StrictData language extension · f842ad6c
      Adam Sandberg Eriksson authored
      This implements the `StrictData` language extension, which lets the
      programmer default to strict data fields in datatype declarations on a
      per-module basis.
      
      Specification and motivation can be found at
      https://ghc.haskell.org/trac/ghc/wiki/StrictPragma
      
      This includes a tricky parser change due to conflicts regarding `~` in
      the type level syntax: all ~'s are parsed as strictness annotations (see
      `strict_mark` in Parser.y) and then turned into equality constraints at
      the appropriate places using `RdrHsSyn.splitTilde`.
      
      Updates haddock submodule.
      
      Test Plan: Validate through Harbormaster.
      
      Reviewers: goldfire, austin, hvr, simonpj, tibbe, bgamari
      
      Reviewed By: simonpj, tibbe, bgamari
      
      Subscribers: lelf, simonpj, alanz, goldfire, thomie, bgamari, mpickering
      
      Differential Revision: https://phabricator.haskell.org/D1033
      
      GHC Trac Issues: #8347
      f842ad6c
  15. 22 Jul, 2015 1 commit
  16. 21 Jul, 2015 1 commit
    • Simon Peyton Jones's avatar
      Refactor self-boot info · 3c44a46b
      Simon Peyton Jones authored
      This patch is a simple refactoring that prepares for a later one,
      related to Trac #10083.
      
      * Add a field tcg_self_boot :: SelfBootInfo to TcGblEnv,
        where SelfBootInfo is a new data type, describing the
        hi-boot file, if any, for the module being compiled.
      
      * Make tcHiBootIface return SelfBootInfo, a new data type
      
      * Make other functions get SelfBootInfo from the monad.
      
      * Remove tcg_mod_name from TcGblEnv; it was barely used and
        simpler to pass around explicitly.
      3c44a46b
  17. 20 Jun, 2015 1 commit
    • Edward Z. Yang's avatar
      Filter orphan rules based on imports, fixes #10294 and #10420. · 0cb1f5cf
      Edward Z. Yang authored
      Summary:
      If we have an orphan rule in our database, don't apply it
      unless the defining module is transitively imported by the
      module we are processing.  We do this by defining a new RuleEnv
      data type which includes both the RuleBase as well as the set
      of visible orphan modules, and threading this through the
      relevant environments (CoreReader, RuleCheckEnv and ScEnv).
      
      This is analogous to the instances fix we applied in #2182
      4c834fdd, but done for RULES.
      An important knock-on effect is that we can remove some buggy
      code in LoadInterface which tried to avoid loading interfaces
      that were loaded by plugins (which sometimes caused instances
      and rules to NEVER become visible).
      
      One note about tests: I renamed the old plugins07 test to T10420
      and replaced plugins07 with a test to ensure that a plugin
      import did not cause new rules to be loaded in.
      Signed-off-by: default avatarEdward Z. Yang <ezyang@cs.stanford.edu>
      
      Test Plan: validate
      
      Reviewers: simonpj, austin, goldfire
      
      Subscribers: bgamari, thomie
      
      Differential Revision: https://phabricator.haskell.org/D950
      
      GHC Trac Issues: #10420
      0cb1f5cf
  18. 19 Jun, 2015 1 commit
  19. 18 May, 2015 1 commit
    • Simon Peyton Jones's avatar
      Refactor tuple constraints · ffc21506
      Simon Peyton Jones authored
      Make tuple constraints be handled by a perfectly ordinary
      type class, with the component constraints being the
      superclasses:
          class (c1, c2) => (c2, c2)
      
      This change was provoked by
      
        #10359  inability to re-use a given tuple
                constraint as a whole
      
        #9858   confusion between term tuples
                and constraint tuples
      
      but it's generally a very nice simplification. We get rid of
       -  In Type, the TuplePred constructor of PredTree,
          and all the code that dealt with TuplePreds
       -  In TcEvidence, the constructors EvTupleMk, EvTupleSel
      
      See Note [How tuples work] in TysWiredIn.
      
      Of course, nothing is ever entirely simple. This one
      proved quite fiddly.
      
      - I did quite a bit of renaming, which makes this patch
        touch a lot of modules. In partiuclar tupleCon -> tupleDataCon.
      
      - I made constraint tuples known-key rather than wired-in.
        This is different to boxed/unboxed tuples, but it proved
        awkward to have all the superclass selectors wired-in.
        Easier just to use the standard mechanims.
      
      - While I was fiddling with known-key names, I split the TH Name
        definitions out of DsMeta into a new module THNames.  That meant
        that the known-key names can all be gathered in PrelInfo, without
        causing module loops.
      
      - I found that the parser was parsing an import item like
            T( .. )
        as a *data constructor* T, and then using setRdrNameSpace to
        fix it.  Stupid!  So I changed the parser to parse a *type
        constructor* T, which means less use of setRdrNameSpace.
      
        I also improved setRdrNameSpace to behave better on Exact Names.
        Largely on priciple; I don't think it matters a lot.
      
      - When compiling a data type declaration for a wired-in thing like
        tuples (,), or lists, we don't really need to look at the
        declaration.  We have the wired-in thing!  And not doing so avoids
        having to line up the uniques for data constructor workers etc.
        See Note [Declarations for wired-in things]
      
      - I found that FunDeps.oclose wasn't taking superclasses into
        account; easily fixed.
      
      - Some error message refactoring for invalid constraints in TcValidity
      
      - Haddock needs to absorb the change too; so there is a submodule update
      ffc21506
  20. 14 May, 2015 1 commit
    • Austin Seipp's avatar
      Revert multiple commits · 3cf8ecdc
      Austin Seipp authored
      This reverts multiple commits from Simon:
      
        - 04a484ea Test Trac #10359
        - a9ccd37a Test Trac #10403
        - c0aae6f6 Test Trac #10248
        - eb6ca851 Make the "matchable-given" check happen first
        - ca173aa3 Add a case to checkValidTyCon
        - 51cbad15 Update haddock submodule
        - 6e1174da Separate transCloVarSet from fixVarSet
        - a8493e03 Fix imports in HscMain (stage2)
        - a154944b Two wibbles to fix the build
        - 5910a1bc Change in capitalisation of error msg
        - 130e93aa Refactor tuple constraints
        - 8da785d5 Delete commented-out line
      
      These break the build by causing Haddock to fail mysteriously when
      trying to examine GHC.Prim it seems.
      3cf8ecdc
  21. 13 May, 2015 1 commit
    • Simon Peyton Jones's avatar
      Refactor tuple constraints · 130e93aa
      Simon Peyton Jones authored
      Make tuple constraints be handled by a perfectly ordinary
      type class, with the component constraints being the
      superclasses:
          class (c1, c2) => (c2, c2)
      
      This change was provoked by
      
        #10359  inability to re-use a given tuple
                constraint as a whole
      
        #9858   confusion between term tuples
                and constraint tuples
      
      but it's generally a very nice simplification. We get rid of
       -  In Type, the TuplePred constructor of PredTree,
          and all the code that dealt with TuplePreds
       -  In TcEvidence, the constructors EvTupleMk, EvTupleSel
      
      See Note [How tuples work] in TysWiredIn.
      
      Of course, nothing is ever entirely simple. This one
      proved quite fiddly.
      
      - I did quite a bit of renaming, which makes this patch
        touch a lot of modules. In partiuclar tupleCon -> tupleDataCon.
      
      - I made constraint tuples known-key rather than wired-in.
        This is different to boxed/unboxed tuples, but it proved
        awkward to have all the superclass selectors wired-in.
        Easier just to use the standard mechanims.
      
      - While I was fiddling with known-key names, I split the TH Name
        definitions out of DsMeta into a new module THNames.  That meant
        that the known-key names can all be gathered in PrelInfo, without
        causing module loops.
      
      - I found that the parser was parsing an import item like
            T( .. )
        as a *data constructor* T, and then using setRdrNameSpace to
        fix it.  Stupid!  So I changed the parser to parse a *type
        constructor* T, which means less use of setRdrNameSpace.
      
        I also improved setRdrNameSpace to behave better on Exact Names.
        Largely on priciple; I don't think it matters a lot.
      
      - When compiling a data type declaration for a wired-in thing like
        tuples (,), or lists, we don't really need to look at the
        declaration.  We have the wired-in thing!  And not doing so avoids
        having to line up the uniques for data constructor workers etc.
        See Note [Declarations for wired-in things]
      
      - I found that FunDeps.oclose wasn't taking superclasses into
        account; easily fixed.
      
      - Some error message refactoring for invalid constraints in TcValidity
      130e93aa
  22. 04 May, 2015 1 commit
    • Adam Gundry's avatar
      Permit empty closed type families · 4efa4213
      Adam Gundry authored
      Fixes #9840 and #10306, and includes an alternative resolution to #8028.
      This permits empty closed type families, and documents them in the user
      guide. It updates the Haddock submodule to support the API change.
      
      Test Plan: Added `indexed-types/should_compile/T9840` and updated
      `indexed-types/should_fail/ClosedFam4` and `th/T8028`.
      
      Reviewers: austin, simonpj, goldfire
      
      Reviewed By: goldfire
      
      Subscribers: bgamari, jstolarek, thomie, goldfire
      
      Differential Revision: https://phabricator.haskell.org/D841
      
      GHC Trac Issues: #9840, #10306
      4efa4213
  23. 07 Mar, 2015 1 commit
  24. 11 Jan, 2015 1 commit
  25. 23 Dec, 2014 1 commit
    • Simon Peyton Jones's avatar
      Eliminate so-called "silent superclass parameters" · a6f0f5ab
      Simon Peyton Jones authored
      The purpose of silent superclass parameters was to solve the
      awkward problem of superclass dictinaries being bound to bottom.
      See THE PROBLEM in Note [Recursive superclasses] in TcInstDcls
      
      Although the silent-superclass idea worked,
      
        * It had non-local consequences, and had effects even in Haddock,
          where we had to discard silent parameters before displaying
          instance declarations
      
        * It had unexpected peformance costs, shown up by Trac #3064 and its
          test case.  In monad-transformer code, when constructing a Monad
          dictionary you had to pass an Applicative dictionary; and to
          construct that you neede a Functor dictionary. Yet these extra
          dictionaries were often never used.  (All this got much worse when
          we added Applicative as a superclass of Monad.) Test T3064
          compiled *far* faster after silent superclasses were eliminated.
      
        * It introduced new bugs.  For example SilentParametersOverlapping,
          T5051, and T7862, all failed to compile because of instance overlap
          directly because of the silent-superclass trick.
      
      So this patch takes a new approach, which I worked out with Dimitrios
      in the closing hours before Christmas.  It is described in detail
      in THE PROBLEM in Note [Recursive superclasses] in TcInstDcls.
      
      Seems to work great!
      
      Quite a bit of knock-on effect
      
       * The main implementation work is in tcSuperClasses in TcInstDcls
         Everything else is fall-out
      
       * IdInfo.DFunId no longer needs its n-silent argument
         * Ditto IDFunId in IfaceSyn
         * Hence interface file format changes
      
       * Now that DFunIds do not have silent superclass parameters, printing
         out instance declarations is simpler. There is tiny knock-on effect
         in Haddock, so that submodule is updated
      
       * I realised that when computing the "size of a dictionary type"
         in TcValidity.sizePred, we should be rather conservative about
         type functions, which can arbitrarily increase the size of a type.
         Hence the new datatype TypeSize, which has a TSBig constructor for
         "arbitrarily big".
      
       * instDFunType moves from TcSMonad to Inst
      
       * Interestingly, CmmNode and CmmExpr both now need a non-silent
         (Ord r) in a couple of instance declarations. These were previously
         silent but must now be explicit.
      
       * Quite a bit of wibbling in error messages
      a6f0f5ab
  26. 18 Dec, 2014 1 commit
    • Iavor S. Diatchki's avatar
      Add a provenance field to universal coercions. · 1d4e94d1
      Iavor S. Diatchki authored
      Universal coercions allow casting between arbitrary types, so it is a
      good idea to keep track where they came from, which now we can do by
      using the provenance field in `UnivCo`.
      
      This is also handy for type-checker plugins that provide functionality
      beyond what's expressible by GHC's standard coercions:  such plugins
      can generate universal coercions, but they should still tag them,
      so that if something goes wrong we can link the casts to the plugin.
      1d4e94d1
  27. 16 Dec, 2014 2 commits
    • Peter Wortmann's avatar
      Strip source ticks from iface code if DWARF is disabled · a0895fcb
      Peter Wortmann authored
      They would be unneeded at minimum. Not completely sure this is the right
      place to do this.
      
      (From Phabricator D169)
      a0895fcb
    • Peter Wortmann's avatar
      Source notes (Core support) · 993975d3
      Peter Wortmann authored
      This patch introduces "SourceNote" tickishs that link Core to the
      source code that generated it. The idea is to retain these source code
      links throughout code transformations so we can eventually relate
      object code all the way back to the original source (which we can,
      say, encode as DWARF information to allow debugging).  We generate
      these SourceNotes like other tickshs in the desugaring phase. The
      activating command line flag is "-g", consistent with the flag other
      compilers use to decide DWARF generation.
      
      Keeping ticks from getting into the way of Core transformations is
      tricky, but doable. The changes in this patch produce identical Core
      in all cases I tested -- which at this point is GHC, all libraries and
      nofib. Also note that this pass creates *lots* of tick nodes, which we
      reduce somewhat by removing duplicated and overlapping source
      ticks. This will still cause significant Tick "clumps" - a possible
      future optimization could be to make Tick carry a list of Tickishs
      instead of one at a time.
      
      (From Phabricator D169)
      993975d3
  28. 15 Dec, 2014 1 commit
    • Simon Peyton Jones's avatar
      Make Core Lint check for locally-bound GlobalIds · d59c59f4
      Simon Peyton Jones authored
      There should be no bindings in this module for a GlobalId;
      except after CoreTidy, when top-level bindings are globalised.
      
      To check for this, I had to make the CoreToDo pass part of the
      environment that Core Lint caries.  But CoreToDo is defined in
      CoreMonad, which (before this patch) called CoreLint.
      
      So I had to do quite a bit of refactoring, moving some
      lint-invoking code into CoreLint itself.  Crucially, I also
      more tcLookupImported_maybe, importDecl, and checkwiredInTyCon
      from TcIface (which use CoreLint) to LoadIface (which doesn't).
      This is probably better structure anyway.
      
      So most of this patch is refactoring. The actual check for
      GlobalIds is in CoreLint.lintAndScopeId
      d59c59f4
  29. 03 Dec, 2014 1 commit
  30. 30 Nov, 2014 1 commit
    • Edward Z. Yang's avatar
      Filter instance visibility based on set of visible orphans, fixes #2182. · 4c834fdd
      Edward Z. Yang authored
      Summary:
      Amazingly, the fix for this very old bug is quite simple: when type-checking,
      maintain a set of "visible orphan modules" based on the orphans list of
      modules which we explicitly imported.  When we import an instance and it
      is an orphan, we check if it is in the visible modules set, and if not,
      ignore it.  A little bit of refactoring for when orphan-hood is calculated
      happens so that we always know if an instance is an orphan or not.
      
      For GHCi, we preinitialize the visible modules set based on the list of
      interactive imports which are active.
      
      Future work: Cache the visible orphan modules set for GHCi, rather than
      recomputing it every type-checking round.  (But it's tricky what to do when you
      /remove/ a module: you need a data structure a little more complicated than
      just a set of modules.)
      Signed-off-by: default avatarEdward Z. Yang <ezyang@cs.stanford.edu>
      
      Test Plan: new tests and validate
      
      Reviewers: simonpj, austin
      
      Subscribers: thomie, carter
      
      Differential Revision: https://phabricator.haskell.org/D488
      
      GHC Trac Issues: #2182
      4c834fdd
  31. 21 Nov, 2014 1 commit
    • Simon Peyton Jones's avatar
      Rejig builders for pattern synonyms, especially unlifted ones · e8762081
      Simon Peyton Jones authored
      When a pattern synonym is for an unlifted pattern, its "builder" would
      naturally be a top-level unlifted binding, which isn't allowed.  So we
      give it an extra Void# argument.
      
      Our Plan A involved then making *two* Ids for these builders, with
      some consequential fuss in the desugarer.  This was more pain than I
      liked, so I've re-jigged it.
      
       * There is just one builder for a pattern synonym.
      
       * It may have an extra Void# arg, but this decision is signalled
         by the Bool in the psBuilder field.
      
         I did the same for the psMatcher field.
      
         Both Bools are serialised into interface files, so there is
         absolutely no doubt whether that extra Void# argument is required.
      
       * I renamed "wrapper" to "builder".  We have too may "wrappers"
      
       * In order to deal with typecchecking occurrences of P in expressions,
         I refactored the tcInferId code in TcExpr.
      
      All of this allowed me to revert 5fe872
         "Apply compulsory unfoldings during desugaring, except for `seq` which is special."
      which turned out to be a rather messy hack in DsBinds
      e8762081
  32. 20 Nov, 2014 1 commit
    • Jan Stolarek's avatar
      Split SynTyCon to SynonymTyCon and FamilyTyCon · 696fc4ba
      Jan Stolarek authored
      This patch refactors internal representation of type synonyms and type families by splitting them into two separate data constructors of TyCon data type. The main motivation is is that some fields make sense only for type synonyms and some make sense only for type families. This will be even more true with the upcoming injective type families.
      
      There is also some refactoring of names to keep the naming constistent. And thus tc_kind field has become tyConKind and tc_roles has become tcRoles. Both changes are not visible from the outside of TyCon module.
      
      Updates haddock submodule
      
      Reviewers: simonpj
      
      Differential Revision: https://phabricator.haskell.org/D508
      
      GHC Trac Issues: #9812
      696fc4ba
  33. 18 Nov, 2014 1 commit
  34. 13 Nov, 2014 1 commit
  35. 08 Nov, 2014 1 commit