1. 23 Jun, 2016 1 commit
    • Simon Peyton Jones's avatar
      Give lookupGRE_Name a better API · 3e0af469
      Simon Peyton Jones authored
      lookupGRE_Name should return either zero or one GREs, never
      several. This is a consequence of INVARIANT 1 on GlobalRdrEnv.
      
      So it's better if it returns a Maybe; the panic on multiple results
      is put in one place, instead of being scattered or ignored.
      
      Just refactoring, no change in behaviour
      3e0af469
  2. 22 Jun, 2016 1 commit
  3. 10 Jun, 2016 1 commit
  4. 24 May, 2016 1 commit
    • niteria's avatar
      Document some benign nondeterminism · 4c6e69d5
      niteria authored
      I've changed the functions to their nonDet equivalents and explained
      why they're OK there. This allowed me to remove foldNameSet,
      foldVarEnv, foldVarEnv_Directly, foldVarSet and foldUFM_Directly.
      
      Test Plan: ./validate, there should be no change in behavior
      
      Reviewers: simonpj, simonmar, austin, goldfire, bgamari
      
      Reviewed By: bgamari
      
      Subscribers: thomie
      
      Differential Revision: https://phabricator.haskell.org/D2244
      
      GHC Trac Issues: #4012
      4c6e69d5
  5. 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
  6. 28 Apr, 2016 2 commits
    • niteria's avatar
      Add uniqSetAny and uniqSetAll and use them · 3c426b05
      niteria authored
      There are couple of places where we do `foldUniqSet` just to
      compute `any` or `all`. `foldUniqSet` is non-deterministic in the
      general case and `any` and `all` also read nicer.
      
      Test Plan: ./validate
      
      Reviewers: simonmar, goldfire, simonpj, bgamari, austin
      
      Reviewed By: simonpj
      
      Subscribers: thomie
      
      Differential Revision: https://phabricator.haskell.org/D2156
      
      GHC Trac Issues: #4012
      3c426b05
    • 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
  7. 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
  8. 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
  9. 12 Apr, 2016 1 commit
    • eir@cis.upenn.edu's avatar
      Fix #11811. · b1084fd7
      eir@cis.upenn.edu authored
      Previously, I had forgotten to omit variables already in scope
      from the TypeInType CUSK check. Simple enough to fix.
      
      Test case: typecheck/should_compile/T11811
      b1084fd7
  10. 10 Apr, 2016 1 commit
    • Jason Eisenberg's avatar
      Fix suggestions for unbound variables (#11680) · 470d4d5b
      Jason Eisenberg authored
      When the typechecker generates the error message for an out-of-scope
      variable, it now uses the GlobalRdrEnv with respect to which the
      variable is unbound, not the GlobalRdrEnv which is available at the time
      the error is reported.  Doing so ensures we do not provide suggestions
      which themselves are out-of-scope (because they are bound in a later
      inter-splice group).
      
      Nonetheless, we do note in the error message if an unambiguous, exact
      match to the out-of-scope variable is found in a later inter-splice
      group, and we specify where that match is not in scope.
      
      Test Plan: ./validate
      
      Reviewers: goldfire, austin, bgamari
      
      Reviewed By: goldfire
      
      Subscribers: thomie
      
      Differential Revision: https://phabricator.haskell.org/D2000
      
      GHC Trac Issues: #11680
      470d4d5b
  11. 15 Mar, 2016 2 commits
    • 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
    • eir@cis.upenn.edu's avatar
      Refactor visible type application. · 972730cc
      eir@cis.upenn.edu authored
      This replaces the old HsType and HsTypeOut constructors
      with HsAppType and HsAppTypeOut, leading to some simplification.
      (This refactoring addresses #11329.)
      
      This also fixes #11456, which stumbled over HsType (which is
      not an expression).
      
      test case: ghci/scripts/T11456
      
      [skip ci]
      972730cc
  12. 11 Mar, 2016 1 commit
  13. 26 Feb, 2016 1 commit
  14. 25 Feb, 2016 1 commit
    • barrucadu's avatar
      Print which warning-flag controls an emitted warning · bb5afd3c
      barrucadu authored
      Both gcc and clang tell which warning flag a reported warning can be
      controlled with, this patch makes ghc do the same. More generally, this
      allows for annotated compiler output, where an optional annotation is
      displayed in brackets after the severity.
      
      This also adds a new flag `-f(no-)show-warning-groups` to control
      whether to show which warning-group (such as `-Wall` or `-Wcompat`)
      a warning belongs to. This flag is on by default.
      
      This implements #10752
      
      Reviewed By: quchen, bgamari, hvr
      
      Differential Revision: https://phabricator.haskell.org/D1943
      bb5afd3c
  15. 08 Feb, 2016 1 commit
    • Simon Peyton Jones's avatar
      Allow foralls in instance decls · 2cf3cac6
      Simon Peyton Jones authored
      This patch finally makes it possible to have explicit
      foralls in an instance decl
         instance forall (a :: *). Eq a => Eq [a] where ...
      
      This is useful to allow kind signatures or indeed
      explicicit kind for-alls; see Trac #11519
      
      I thought it would be really easy, because an instance
      declaration already contains an actual HsSigType, so all
      the syntactic baggage is there.  But in fact it turned
      out that instance declarations were kind-checked a
      little differently, because the body kind of the forall
      is 'Constraint' rather than '*'.
      
      So I fixed that.  There a slight kludge
      (see Note [Body kind of a HsQualTy], but it's still a
      significant improvement.
      
      I also did the usual other round of refactoring,
      improved a few error messages, tidied up comments etc.
      The only significant aspect of all that was
      
        * Kill mkNakedSpecSigmaTy, mkNakedPhiTy, mkNakedFunTy
          These function names suggest that they do something
          complicated, but acutally they do nothing. So I
          killed them.
      
        * Swap the arg order of mkNamedBinder, just so that it is
          convenient to say 'map (mkNamedBinder Invisible) tvs'
      
        * I had to improve isPredTy, to deal with (illegal)
          types like
             (Eq a => Eq [a]) => blah
          See Note [isPeredTy complications] in Type.hs
      
      Still to come: user manual documentation for the
      instance-decl change.
      2cf3cac6
  16. 26 Jan, 2016 1 commit
    • Ryan Scott's avatar
      Split off -Wunused-type-variables from -Wunused-matches · 6817703b
      Ryan Scott authored
      Summary:
      Previously, `-Wunused-matches` would fire whenever it detected unused type
      variables in a type family or data family instance. This can be annoying for
      users who wish to use type variable names as documentation, as being
      `-Wall`-compliant would mean that they'd have to prefix many of their type
      variable names with underscores, making the documentation harder to read.
      
      To avoid this, a new warning `-Wunused-type-variables` was created that only
      encompasses unused variables in family instances. `-Wunused-matches` reverts
      back to its role of only warning on unused term-level pattern names. Unlike
      `-Wunused-matches`, `-Wunused-type-variables` is not implied by `-Wall`.
      
      Fixes #11451.
      
      Test Plan: ./validate
      
      Reviewers: goldfire, ekmett, austin, hvr, simonpj, bgamari
      
      Reviewed By: simonpj, bgamari
      
      Subscribers: thomie
      
      Differential Revision: https://phabricator.haskell.org/D1825
      
      GHC Trac Issues: #11451
      6817703b
  17. 24 Jan, 2016 1 commit
    • Herbert Valerio Riedel's avatar
      Implement `-Wnoncanonical-monadfail-instances` warning · fd6dd41c
      Herbert Valerio Riedel authored
      The MonadFail proposal implemented so far via #10751 only warns about
      missing `MonadFail` instances based on existence of failible pattern
      matches in `do`-blocks.
      
      However, based on the noncanonical Monad warnings implemented via #11150
      we can provide a different mechanism for detecting missing `MonadFail`
      instances quite cheaply. That is, by checking for canonical `fail` definitions.
      
      In the case of `Monad`/`MonadFail`, we define the canonical implementation of
      `fail` to be such that the soft-deprecated method shall (iff overridden) be
      defined in terms of the non-deprecated method. Consequently, in case of
      `MonadFail`, the `Monad(fail)` method shall be defined as alias of
      the `MonadFail(fail)` method.
      
      This allows us at some distant point in the future to remove `fail` from
      the `Monad` class, while having GHC ignore/tolerate such literal canonical
      method definitions.
      
      Reviewed By: bgamari, RyanGlScott
      
      Differential Revision: https://phabricator.haskell.org/D1838
      fd6dd41c
  18. 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
  19. 15 Jan, 2016 1 commit
    • eir@cis.upenn.edu's avatar
      Fix #11404 · 072191fe
      eir@cis.upenn.edu authored
      We now check for unused variables one at a time, instead of
      all at the top.
      
      Test: dependent/should_compile/T11405
      072191fe
  20. 07 Jan, 2016 1 commit
  21. 31 Dec, 2015 1 commit
  22. 23 Dec, 2015 1 commit
  23. 22 Dec, 2015 1 commit
    • Simon Peyton Jones's avatar
      Refactor named wildcards (again) · 575a98e4
      Simon Peyton Jones authored
      Michal's work on #10982, #11098, refactored the handling of named
      wildcards by making them more like ordinary type variables.
      
      This patch takes the same idea to its logical conclusion, resulting
      in a much tidier, tighter implementation.
      
      Read Note [The wildcard story for types] in HsTypes.
      
      Changes:
      
       * Named wildcards are ordinary type variables, throughout
      
       * HsType no longer has a data constructor for named wildcards
         (was NamedWildCard in HsWildCardInfo).  Named wildcards are
         simply HsTyVars
      
       * Similarly named wildcards disappear from Template Haskell
      
       * I refactored RnTypes to avoid polluting LocalRdrEnv with something
         as narrow as named wildcards.  Instead the named wildcard set is
         carried in RnTyKiEnv.
      
      There is a submodule update for Haddock.
      575a98e4
  24. 21 Dec, 2015 2 commits
    • msosn's avatar
      Warn about unused type variables in type families · eb7796f1
      msosn authored
      The warnings are enabled with the flag -fwarn-unused-matches, the same
      one that enables warnings on the term level.
      
      Identifiers starting with an underscore are now always parsed as type
      variables.  When the NamedWildCards extension is enabled, the renamer
      replaces those variables with named wildcards.
      
      An additional NameSet nwcs is added to LocalRdrEnv. It's used to keep
      names of the type variables that should be replaced with wildcards.
      
      While renaming HsForAllTy, when a name is explicitly bound it is removed
      from the nwcs NameSet. As a result, the renamer doesn't replace them in
      the quantifier body. (Trac #11098)
      
      Fixes #10982, #11098
      
      Reviewers: alanz, bgamari, hvr, austin, jstolarek
      
      Reviewed By: jstolarek
      
      Subscribers: goldfire, mpickering, RyanGlScott, thomie
      
      Differential Revision: https://phabricator.haskell.org/D1576
      
      GHC Trac Issues: #10982
      eb7796f1
    • 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
  25. 15 Dec, 2015 1 commit
    • Ben Gamari's avatar
      Expose enabled language extensions to TH · c1e25536
      Ben Gamari authored
      This exposes `template-haskell` functions for querying the language
      extensions which are enabled when compiling a module,
      
      - an `isExtEnabled` function to check whether an extension is enabled
      - an `extsEnabled` function to obtain a full list of enabled extensions
      
      To avoid code duplication this adds a `GHC.LanguageExtensions` module to
      `ghc-boot` and moves `DynFlags.ExtensionFlag` into it. A happy
      consequence of this is that the ungainly `DynFlags` lost around 500
      lines. Moreover, flags corresponding to language extensions are now
      clearly distinguished from other flags due to the `LangExt.*` prefix.
      
      Updates haddock submodule.
      
      This fixes #10820.
      
      Test Plan: validate
      
      Reviewers: austin, spinda, hvr, goldfire, alanz
      
      Reviewed By: goldfire
      
      Subscribers: mpickering, RyanGlScott, hvr, simonpj, thomie
      
      Differential Revision: https://phabricator.haskell.org/D1200
      
      GHC Trac Issues: #10820
      c1e25536
  26. 11 Dec, 2015 2 commits
    • 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
    • Adam Gundry's avatar
      Fix infix record field fixity (#11167 and #11173). · 6e56ac58
      Adam Gundry authored
      This extends D1585 with proper support for infix duplicate record
      fields.  In particular, it is now possible to declare record fields as
      infix in a module for which `DuplicateRecordFields` is enabled, fixity
      is looked up correctly and a readable (although unpleasant) error
      message is generated if multiple fields with different fixities are in
      scope.
      
      As a bonus, `DEPRECATED` and `WARNING` pragmas now work for
      duplicate record fields. The pragma applies to all fields with the
      given label.
      
      In addition, a couple of minor `DuplicateRecordFields` bugs, which were
      pinpointed by the `T11167_ambig` test case, are fixed by this patch:
      
        - Ambiguous infix fields can now be disambiguated by putting a type
          signature on the first argument
      
        - Polymorphic type constructor signatures (such as `ContT () IO a` in
          `T11167_ambig`) now work for disambiguation
      
      Parts of this patch are from D1585 authored by @KaneTW.
      
      Test Plan: New tests added.
      
      Reviewers: KaneTW, bgamari, austin
      
      Reviewed By: bgamari
      
      Subscribers: thomie, hvr
      
      Differential Revision: https://phabricator.haskell.org/D1600
      
      GHC Trac Issues: #11167, #11173
      6e56ac58
  27. 07 Dec, 2015 1 commit
    • Alan Zimmerman's avatar
      Refactor ConDecl · 51a5e68d
      Alan Zimmerman authored
      The ConDecl type in HsDecls is an uneasy compromise. For the most part,
      HsSyn directly reflects the syntax written by the programmer; and that
      gives just the right "pegs" on which to hang Alan's API annotations. But
      ConDecl doesn't properly reflect the syntax of Haskell-98 and GADT-style
      data type declarations.
      
      To be concrete, here's a draft new data type
      
      ```lang=hs
      data ConDecl name
        | ConDeclGADT
            { con_names   :: [Located name]
            , con_type    :: LHsSigType name  -- The type after the ‘::’
            , con_doc     :: Maybe LHsDocString }
      
        | ConDeclH98
            { con_name    :: Located name
      
            , con_qvars     :: Maybe (LHsQTyVars name)
              -- User-written forall (if any), and its implicit
              -- kind variables
              -- Non-Nothing needs -XExistentialQuantification
      
            , con_cxt       :: Maybe (LHsContext name)
              -- ^ User-written context (if any)
      
            , con_details   :: HsConDeclDetails name
                -- ^ Arguments
      
            , con_doc       :: Maybe LHsDocString
                -- ^ A possible Haddock comment.
            } deriving (Typeable)
      ```
      
      Note that
      
          For GADTs, just keep a type. That's what the user writes.
          NB:HsType can represent records on the LHS of an arrow:
      
            { x:Int,y:Bool} -> T
      
          con_qvars and con_cxt are both Maybe because they are both
          optional (the forall and the context of an existential data type
      
          For ConDeclGADT the type variables of the data type do not scope
          over the con_type; whereas for ConDeclH98 they do scope over con_cxt
          and con_details.
      
      Updates haddock submodule.
      
      Test Plan: ./validate
      
      Reviewers: simonpj, erikd, hvr, goldfire, austin, bgamari
      
      Subscribers: erikd, goldfire, thomie, mpickering
      
      Differential Revision: https://phabricator.haskell.org/D1558
      
      GHC Trac Issues: #11028
      51a5e68d
  28. 06 Dec, 2015 1 commit
    • Herbert Valerio Riedel's avatar
      Implement new `-fwarn-noncanonical-monoid-instances` · 986ceb16
      Herbert Valerio Riedel authored
      This is similiar to the `-fwarn-noncanonical-monad-instances` warning
      implemented via #11128, but applies to `Semigroup`/`Monoid` instead
      and the `(<>)`/`mappend` methods (of which `mappend` is planned to move
      out of `Monoid` at some point in the future being redundant and thus
      error-prone).
      
      This warning is contained in `-Wcompat` but not in `-Wall`.
      
      This addresses #11150
      
      Reviewed By: quchen
      
      Differential Revision: https://phabricator.haskell.org/D1553
      986ceb16
  29. 01 Dec, 2015 1 commit
    • 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
  30. 24 Nov, 2015 1 commit
    • Herbert Valerio Riedel's avatar
      Implement new `-fwarn-noncanonical-monad-instances` · f09f2470
      Herbert Valerio Riedel authored
      Warn about incoherent/non-canonical 'Applicative'/'Monad' instance
      declarations. Specifically the following invariants are checked:
      
      In 'Monad' instances declarations warn if the any of the following
      conditions does not hold:
      
       * If `return` is overridden it must be canonical (i.e. `return = pure`).
       * If `(>>)` is overridden it must be canonical (i.e. `(>>) = (*>)`).
      
      In 'Applicative' instance declarations:
      
       * Warn if 'pure' is defined backwards (i.e. `pure = return`).
       * Warn if '(*>)' is defined backwards (i.e. `(*>) = (>>)`).
      
      NB, this warning flag is not enabled via `-Wall` nor `-Wcompat`.
      
      This addresses #11128
      
      Reviewers: quchen, austin, bgamari
      
      Reviewed By: bgamari
      
      Differential Revision: https://phabricator.haskell.org/D1516
      f09f2470
  31. 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
  32. 11 Nov, 2015 2 commits
  33. 29 Oct, 2015 1 commit
    • 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
  34. 16 Oct, 2015 2 commits
    • Jan Stolarek's avatar
      Add typed holes support in Template Haskell. · 75492e74
      Jan Stolarek authored
      Fixes #10267. Typed holes in typed Template Haskell currently don't work.
      See #10945 and #10946.
      75492e74
    • 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