1. 02 Jun, 2016 1 commit
  2. 10 May, 2016 1 commit
    • Matthew Pickering's avatar
      Forbid variables to be parents in import lists. · 53f26f5a
      Matthew Pickering authored and Ben Gamari's avatar Ben Gamari committed
      In the long discussion on #11432, it was decided that when a type
      constructor is parsed as a variable ((--.->) is one example) then in
      order to export the type constructor then the user should be required to
      use the ExplicitNamespaces keyword.
      
      This was implemented in quite an indirect manner in the renamer. It
      is much more direct to enforce this in the parser at the expense of
      slighty worse error messages. Further to this, the check in the
      renamer was actually slightly wrong. If the variable was in scope
      then no error was raised, this was causing panics, see #12026 for an
      example.
      
      Reviewers: austin, bgamari
      
      Subscribers: davean, skvadrik, thomie
      
      Differential Revision: https://phabricator.haskell.org/D2181
      
      GHC Trac Issues: #12026
      53f26f5a
  3. 28 Apr, 2016 1 commit
  4. 22 Apr, 2016 1 commit
    • Simon Peyton Jones's avatar
      Improve the behaviour of warnIf · f02af79e
      Simon Peyton Jones authored
      Now that warnIf takes a "reason", we can test the reason
      in warnIf rather than in the caller.  Less code, and less
      risk of getting the test and the reason out of sync.
      f02af79e
  5. 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
  6. 10 Apr, 2016 1 commit
    • bollmann's avatar
      Fix Template Haskell bug reported in #11809. · 2f82da76
      bollmann authored and Ben Gamari's avatar Ben Gamari committed
      Record selectors of data types spliced in with Template Haskell are not
      renamer-resolved correctly in GHC HEAD. The culprit is
      `newRecordSelector` which violates notes `Note [Binders in Template
      Haskell] in Convert.hs` and `Note [Looking up Exact RdrNames] in
      RnEnv.hs`. This commit fixes `newRecordSelector` accordingly.
      
      Test Plan: ./validate
      
      Reviewers: thomie, mpickering, bgamari, austin, simonpj, goldfire
      
      Reviewed By: goldfire
      
      Differential Revision: https://phabricator.haskell.org/D2091
      
      GHC Trac Issues: #11809
      2f82da76
  7. 02 Apr, 2016 1 commit
    • Rik Steenkamp's avatar
      Improve printing of pattern synonym types · 72bd7f7b
      Rik Steenkamp authored and Matthew Pickering's avatar Matthew Pickering committed
      Add the function `pprPatSynType :: PatSyn -> SDoc` for printing pattern
      synonym types, and remove the ambiguous `patSynType` function. Also,
      the types in a `PatSyn` are now tidy.
      
      Haddock submodule updated to reflect the removal of `patSynType` by
      mpickering.
      
      Fixes: #11213.
      
      Reviewers: goldfire, simonpj, austin, mpickering, bgamari
      
      Reviewed By: simonpj, mpickering
      
      Subscribers: bollmann, simonpj, thomie
      
      Differential Revision: https://phabricator.haskell.org/D1896
      
      GHC Trac Issues: #11213
      72bd7f7b
  8. 29 Feb, 2016 1 commit
  9. 25 Feb, 2016 2 commits
    • barrucadu's avatar
      Print which warning-flag controls an emitted warning · bb5afd3c
      barrucadu authored and Herbert Valerio Riedel's avatar Herbert Valerio Riedel committed
      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
    • manav's avatar
      Make warning names more consistent · 66584914
      manav authored and Ben Gamari's avatar Ben Gamari committed
      - Replace "Sigs" with "Signatures" in WarningFlag data constructors.
      - Replace "PatSyn" with "PatternSynonym" in WarningFlag data
        constructors.
      - Deprecate "missing-local-sigs" in favor of "missing-local-signatures".
      - Deprecate "missing-exported-sigs" in favor of
        "missing-exported-signatures".
      - Deprecate "missing-pat-syn-signatures" in favor of
        "missing-pattern-synonym-signatures".
      - Replace "ddump-strsigs" with "ddump-str-signatures"
      
      These complete the tasks that were explicitly mentioned in #11583
      
      Test Plan:
      Executed `ghc --show-options` and verified that the flags were changed
      as expected.
      
      Reviewers: svenpanne, austin, bgamari
      
      Reviewed By: austin, bgamari
      
      Subscribers: mpickering, thomie
      
      Differential Revision: https://phabricator.haskell.org/D1939
      
      GHC Trac Issues: #11583
      66584914
  10. 16 Feb, 2016 1 commit
    • skvadrik's avatar
      Improved error message about exported type operators. · 693a54ea
      skvadrik authored and Ben Gamari's avatar Ben Gamari committed
      There is ambiguty between (1) type constructors and (2) data
      constructors in export lists, e.g. '%%' can stand for both of them. This
      ambiguity is resolved in favor of (2).
      
      If the exported data constructor is not in scope, but type constructor
      with the same name is in scope, GHC should suggest adding 'type' keyword
      to resolve ambiguity in favor of (1) and enabling 'TypeOperators'
      extension.
      
      The patch only extends the error message.
      
      See Trac #11432.
      
      Test Plan: `make test`
      
      Reviewers: simonpj, bgamari, austin
      
      Reviewed By: simonpj
      
      Subscribers: mpickering, thomie, goldfire, kosmikus
      
      Differential Revision: https://phabricator.haskell.org/D1902
      
      GHC Trac Issues: #11432
      693a54ea
  11. 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
  12. 22 Dec, 2015 1 commit
    • Alan Zimmerman's avatar
      Make HsAppsType contents Located · ff923954
      Alan Zimmerman authored
      An HsAppInfix can carry a qconop/varop preceded by a SIMPLEQUOTE as a
      Located RdrName.
      
      In this case AnnSimpleQuote is attached to the Located HsAppType.
      
          | SIMPLEQUOTE qconop            {% ams (sLL $1 $> $ HsAppInfix $2)
                                                 [mj AnnSimpleQuote $1] }
          | SIMPLEQUOTE varop             {% ams (sLL $1 $> $ HsAppInfix $2)
                                                 [mj AnnSimpleQuote $1] }
      
      This patch changes
      
          data HsType name
            ...
            | HsAppsTy [HsAppType name]
      
      to
      
          data HsType name
            ...
            | HsAppsTy [LHsAppType name]
      
      so that the annotation is not discarded when it reaches the ParsedSource
      ff923954
  13. 21 Dec, 2015 2 commits
    • Jan Stolarek's avatar
      Add proper GADTs support to Template Haskell · eeecb864
      Jan Stolarek authored
      Until now GADTs were supported in Template Haskell by encoding them using
      normal data types.  This patch adds proper support for representing GADTs
      in TH.
      
      Test Plan: T10828
      
      Reviewers: goldfire, austin, bgamari
      
      Subscribers: thomie, mpickering
      
      Differential Revision: https://phabricator.haskell.org/D1465
      
      GHC Trac Issues: #10828
      eeecb864
    • 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
  14. 15 Dec, 2015 1 commit
    • Ben Gamari's avatar
      Expose enabled language extensions to TH · c1e25536
      Ben Gamari authored and Ben Gamari's avatar Ben Gamari committed
      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
  15. 12 Dec, 2015 1 commit
    • Matthew Pickering's avatar
      Implement -fwarn-missing-pat-syn-sigs · 1883afb2
      Matthew Pickering authored
      This adds a warning when a pattern synonym is not accompanied by a
      signature in the style of `-fwarn-missing-sigs`.
      
      It is turned on by -Wall.
      
      If the user specifies, `-fwarn-missing-exported-signatures` with
      `-fwarn-missing-pat-syn-sigs` then it will only warn when the pattern
      synonym is exported.
      
      Test Plan: ./validate
      
      Reviewers: hvr, austin, bgamari
      
      Reviewed By: bgamari
      
      Subscribers: thomie
      
      Differential Revision: https://phabricator.haskell.org/D1596
      
      GHC Trac Issues: #11053
      1883afb2
  16. 11 Dec, 2015 3 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 and Ben Gamari's avatar Ben Gamari committed
      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
    • kanetw's avatar
      Improved data family export documentation · b1382481
      kanetw authored and Ben Gamari's avatar Ben Gamari committed
      Reviewers: simonpj, austin, bgamari
      
      Reviewed By: simonpj
      
      Subscribers: thomie
      
      Differential Revision: https://phabricator.haskell.org/D1587
      
      GHC Trac Issues: #11164
      b1382481
  17. 07 Dec, 2015 3 commits
    • Eric Seidel's avatar
      Move checking for missing signatures to RnNames.reportUnusedNames · 1bd40c86
      Eric Seidel authored and Ben Gamari's avatar Ben Gamari committed
      Checking for missing signatures before renaming the export list is
      prone to errors, so we now perform the check in `reportUnusedNames` at
      which point everything has been renamed.
      
      Test Plan: validate, new test case is T10908
      
      Reviewers: goldfire, simonpj, austin, bgamari
      
      Subscribers: thomie
      
      Projects: #ghc
      
      Differential Revision: https://phabricator.haskell.org/D1561
      
      GHC Trac Issues: #10908
      1bd40c86
    • Alan Zimmerman's avatar
      Refactor ConDecl · 51a5e68d
      Alan Zimmerman authored and Ben Gamari's avatar Ben Gamari committed
      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
    • kanetw's avatar
      Re-export data family when exporting a data instance without an export list · 8cef8af3
      kanetw authored and Ben Gamari's avatar Ben Gamari committed
      Whenever a data instance is exported, the corresponding data family
      is exported, too. This allows one to write
      
      ```
           -- Foo.hs
           module Foo where
      
           data family T a
      
           -- Bar.hs
           module Bar where
      
           import Foo
      
           data instance T Int = MkT
      
           -- Baz.hs
           module Baz where
      
           import Bar (T(MkT))
      ```
      
      In previous versions of GHC, this required a workaround
      explicit export list in `Bar`.
      
      Reviewers: bgamari, goldfire, austin
      
      Reviewed By: bgamari, goldfire
      
      Subscribers: goldfire, thomie
      
      Differential Revision: https://phabricator.haskell.org/D1573
      
      GHC Trac Issues: #11164
      8cef8af3
  18. 01 Dec, 2015 1 commit
    • Simon Peyton Jones's avatar
      Refactor treatment of wildcards · 1e041b73
      Simon Peyton Jones authored and Ben Gamari's avatar Ben Gamari committed
      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
  19. 18 Nov, 2015 1 commit
  20. 13 Nov, 2015 3 commits
  21. 11 Nov, 2015 1 commit
  22. 30 Oct, 2015 2 commits
    • Simon Peyton Jones's avatar
      Record usage information using GlobalRdrElt · 3e94842d
      Simon Peyton Jones authored
      This patch implements an improvment that I've wanted to do for ages, but
      never gotten around to.
      
      Unused imports are computed based on how imported entities occur (qualified,
      unqualified).   This info was accumulated in tcg_used_rdrnames :: Set RdrName.
      But that was a huge pain, and it got worse when we introduced duplicate
      record fields.
      
      The Right Thing is to record tcg_used_gres :: [GlobalRdrElt], which records
      the GRE *after* filtering with pickGREs.  See Note [GRE filtering] in RdrName.
      This is much, much bette.  This patch deletes quite a bit of code, and is
      conceptually much easier to follow.
      
      Hooray.  There should be no change in functionality.
      3e94842d
    • Simon Peyton Jones's avatar
      Fix unused-import stuff in a better way · 9376249b
      Simon Peyton Jones authored
      The fix for Trac #10890 in commit 1818b48e, namely
         Fix incorrect import warnings when methods with identical names are imported
      was wrong, as demonstrated by the new test T10890_2.  It suppressed
      far too many warnings!
      
      This patch fixes the original problem in a different way, by making
      RdrName.greUsedRdrName a bit cleverer.
      
      But this too is not really the Right Thing.  I think the Right Thing is
      to store the /GRE/ in the tcg_used_rdrnames, not the /RdrName/.  That
      would be a lot simpler and more direct.
      
      But one step at a time.
      9376249b
  23. 29 Oct, 2015 1 commit
    • Matthew Pickering's avatar
      Record pattern synonyms · 2a74a64e
      Matthew Pickering authored and Ben Gamari's avatar Ben Gamari committed
      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
  24. 19 Oct, 2015 1 commit
  25. 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
  26. 15 Oct, 2015 1 commit
  27. 13 Oct, 2015 1 commit
    • Ömer Sinan Ağacan's avatar
      Fix incorrect import warnings when methods with identical names are imported · 1818b48e
      Ömer Sinan Ağacan authored
      Currently, GHC's warning generation code is assuming that a name (`RdrName`)
      can be imported at most once. This is a correct assumption, because 1) it's OK
      to import same names as long as we don't use any of them 2) when we use one of
      them, GHC generates an error because it doesn't disambiguate it automatically.
      
      But apparently the story is different with typeclass methods. If I import two
      methods with same names, it's OK to use them in typeclass instance
      declarations, because the context specifies which one to use. For example, this
      is OK (where modules A and B define typeclasses A and B, both with a function
      has),
      
          import A
          import B
      
          data Blah = Blah
      
          instance A Blah where
            has = Blah
      
          instance B Blah where
            has = Blah
      
      But GHC's warning generator is not taking this into account, and so if I change
      import list of this program to:
      
          import A (A (has))
          import B (B (has))
      
      GHC is printing these warnings:
      
          Main.hs:5:1: Warning:
              The import of ‘A.has’ from module ‘A’ is redundant
      
          Main.hs:6:1: Warning:
              The import of ‘B.has’ from module ‘B’ is redundant
      
      Why? Because warning generation code is _silently_ ignoring multiple symbols
      with same names.
      
      With this patch, GHC takes this into account. If there's only one name, then
      this patch reduces to the previous version, that is, it works exactly the same
      as current GHC (thanks goes to @quchen for realizing this).
      
      Reviewed By: austin
      
      Differential Revision: https://phabricator.haskell.org/D1257
      
      GHC Trac Issues: #10890
      1818b48e
  28. 21 Sep, 2015 1 commit
  29. 02 Aug, 2015 1 commit
    • Alan Zimmerman's avatar
      Replace (SourceText,FastString) with StringLiteral data type · 15dd7007
      Alan Zimmerman authored
      Summary:
      Phab:D907 introduced SourceText for a number of data types, by replacing
      FastString with (SourceText,FastString). Since this has an Outputable
      instance, no warnings are generated when ppr is called on it, but
      unexpected output is generated. See Phab:D1096 for an example of this.
      
      Replace the (SourceText,FastString) tuples with a new data type,
      ```lang=hs
      data StringLiteral = StringLiteral SourceText FastString
      ```
      
      Update haddock submodule accordingly
      
      Test Plan: ./validate
      
      Reviewers: hvr, austin, rwbarton, trofi, bgamari
      
      Reviewed By: trofi, bgamari
      
      Subscribers: thomie, trofi, rwbarton, mpickering
      
      Differential Revision: https://phabricator.haskell.org/D1101
      
      GHC Trac Issues: #10692
      15dd7007
  30. 25 Jul, 2015 1 commit
    • Sergei Trofimovich's avatar
      renamer: fix module-level deprecation message · b04bed0a
      Sergei Trofimovich authored
      Noticed today that deprecation warnings are
      slightly broken in -HEAD:
      
        mtl-2.2.1/Control/Monad/Error/Class.hs:46:1: warning:
          Module ‘Control.Monad.Trans.Error’ is deprecated:
            ([", U, s, e,  , C, o, n, t, r, o, l, ., M, o, n, a, d, ., T, r, a,
              n, s, ., E, x, c, e, p, t,  , i, n, s, t, e, a, d, "],
             Use Control.Monad.Trans.Except instead)
      
      Commit e6191d1c
      
      
      slightly changed WarningTxt declaration:
      
      -data WarningTxt = WarningTxt (Located SourceText) [Located FastString]
      -                | DeprecatedTxt (Located SourceText) [Located FastString]
      +data WarningTxt = WarningTxt (Located SourceText)
      +                             [Located (SourceText,FastString)]
      +                | DeprecatedTxt (Located SourceText)
      +                                [Located (SourceText,FastString)]
      
      But 'moduleWarn' function was not updated to do the stripping.
      Signed-off-by: default avatarSergei Trofimovich <siarheit@google.com>
      
      Reviewers: austin, bgamari, hvr, goldfire, rwbarton, alanz
      
      Reviewed By: rwbarton, alanz
      
      Subscribers: thomie
      
      Differential Revision: https://phabricator.haskell.org/D1096
      
      GHC Trac Issues: #10313
      b04bed0a
  31. 23 Jul, 2015 1 commit
    • thomasw's avatar
      Parenthesise TypeOperator in import hints · b5c94262
      thomasw authored and Ben Gamari's avatar Ben Gamari committed
      When a constructor was mistakenly imported directly instead of as a
      constructor of a data type, a hint will be shown on how to correctly
      import
      it. Just like the constructor, the data type should be surrounded in
      parentheses if it is an operator (TypeOperator in this case).
      
      Instead of:
      
          error:
              In module ‘Data.Type.Equality’:
                ‘Refl’ is a data constructor of ‘:~:’
              To import it use
                ‘import’ Data.Type.Equality( :~:( Refl ) )
              or
                ‘import’ Data.Type.Equality( :~:(..) )
      
      Print:
      
          error:
              In module ‘Data.Type.Equality’:
                ‘Refl’ is a data constructor of ‘(:~:)’
              To import it use
                ‘import’ Data.Type.Equality( (:~:)( Refl ) )
              or
                ‘import’ Data.Type.Equality( (:~:)(..) )
      
      Test Plan: pass new test
      
      Reviewers: austin, bgamari, simonpj
      
      Reviewed By: simonpj
      
      Subscribers: simonpj, thomie
      
      Differential Revision: https://phabricator.haskell.org/D1093
      
      GHC Trac Issues: #10668
      b5c94262