1. 28 Apr, 2016 2 commits
    • niteria's avatar
      Kill mapUniqSet · 73129231
      niteria authored
      Note [Unsound mapUniqSet] explains why it got removed.
      
      Test Plan: build ghc
      
      Reviewers: simonpj, austin, bgamari
      
      Reviewed By: bgamari
      
      Subscribers: thomie, simonmar
      
      Differential Revision: https://phabricator.haskell.org/D2152
      73129231
    • 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
  2. 26 Apr, 2016 1 commit
    • niteria's avatar
      Kill varSetElemsWellScoped in quantifyTyVars · c9bcaf31
      niteria authored
      varSetElemsWellScoped introduces unnecessary non-determinism in
      inferred type signatures.
      Removing this instance required changing the representation of
      TcDepVars to use deterministic sets.
      This is the last occurence of varSetElemsWellScoped, allowing me to
      finally remove it.
      
      Test Plan:
      ./validate
      I will update the expected outputs when commiting, some reordering
      of type variables in types is expected.
      
      Reviewers: goldfire, simonpj, austin, bgamari
      
      Reviewed By: simonpj
      
      Subscribers: thomie, simonmar
      
      Differential Revision: https://phabricator.haskell.org/D2135
      
      GHC Trac Issues: #4012
      c9bcaf31
  3. 22 Apr, 2016 1 commit
    • niteria's avatar
      Make benign non-determinism in pretty-printing more obvious · 0f96686b
      niteria authored
      This change takes us one step closer to being able to remove
      `varSetElemsWellScoped`. The end goal is to make every source
      of non-determinism obvious at the source level, so that when
      we achieve determinism it doesn't get broken accidentally.
      
      Test Plan: compile GHC
      
      Reviewers: simonmar, goldfire, simonpj, austin, bgamari
      
      Reviewed By: simonpj
      
      Subscribers: thomie
      
      Differential Revision: https://phabricator.haskell.org/D2123
      
      GHC Trac Issues: #4012
      0f96686b
  4. 20 Apr, 2016 1 commit
    • niteria's avatar
      Rename FV related functions · 2e33320a
      niteria authored
      This is from Simon's suggestion:
      
      * `tyCoVarsOfTypesAcc` is a terrible name for a function with a
        perfectly decent type `[Type] -> FV`. Maybe `tyCoFVsOfTypes`?
        Similarly others
      
      * `runFVList` is also terrible, but also has a decent type.
        Maybe just `fvVarList` (and `fvVarSet` for `runFVSet`).
      
      * `someVars` could be `mkFVs :: [Var] -> FV`.
      2e33320a
  5. 15 Apr, 2016 1 commit
  6. 06 Apr, 2016 1 commit
  7. 28 Mar, 2016 1 commit
    • Herbert Valerio Riedel's avatar
      Scrap DEC OSF/1 support · f911358b
      Herbert Valerio Riedel authored
      DEC OSF/1 (aka Tru64 UNIX) has been discontinued a few years ago already[1].
      
      This removes the undoubtedly bitrotten support for `OSOsf3 :: OS` from GHC's
      code-base.
      
      Support for `ArchAlpha :: Arch` may be removed at some later point, as there
      may still be users out there running a more or less recent Linux/alpha
      distribution on their more-than-a-decade old Alpha hardware...
      
       [1]: https://en.wikipedia.org/wiki/Tru64_UNIX
      f911358b
  8. 25 Mar, 2016 1 commit
  9. 24 Mar, 2016 1 commit
    • Ben Gamari's avatar
      ErrUtils: Add timings to compiler phases · 8048d51b
      Ben Gamari authored
      This adds timings and allocation figures to the compiler's output when
      run with `-v2` in an effort to ease performance analysis.
      
      Todo:
        * Documentation
        * Where else should we add these?
        * Perhaps we should remove some of the now-arguably-redundant
          `showPass` occurrences where they are
        * Must we force more?
        * Perhaps we should place this behind a `-ftimings` instead of `-v2`
      
      Test Plan: `ghc -v2 Test.hs`, look at the output
      
      Reviewers: hvr, goldfire, simonmar, austin
      
      Reviewed By: simonmar
      
      Subscribers: angerman, michalt, niteria, ezyang, thomie
      
      Differential Revision: https://phabricator.haskell.org/D1959
      8048d51b
  10. 11 Mar, 2016 1 commit
  11. 04 Mar, 2016 1 commit
  12. 24 Feb, 2016 1 commit
    • eir@cis.upenn.edu's avatar
      Address #11471 by putting RuntimeRep in kinds. · d8c64e86
      eir@cis.upenn.edu authored
      See Note [TYPE] in TysPrim. There are still some outstanding
      pieces in #11471 though, so this doesn't actually nail the bug.
      
      This commit also contains a few performance improvements:
      
      * Short-cut equality checking of nullary type syns
      
      * Compare types before kinds in eqType
      
      * INLINE coreViewOneStarKind
      
      * Store tycon binders separately from kinds.
      
      This resulted in a ~10% performance improvement in compiling
      the Cabal package. No change in functionality other than
      performance. (This affects the interface file format, though.)
      
      This commit updates the haddock submodule.
      d8c64e86
  13. 17 Feb, 2016 1 commit
    • Ryan Scott's avatar
      Remove superfluous code when deriving Foldable/Traversable · a82956df
      Ryan Scott authored
      Currently, `-XDeriveFoldable` and `-XDeriveTraversable` generate
      unnecessary `mempty` and `pure` expressions when it traverses of an
      argument of a constructor whose type does not mention the last type
      parameter. Not only is this inefficient, but it prevents `Traversable`
      from being derivable for datatypes with unlifted arguments (see
      Trac #11174).
      
      The solution to this problem is to adopt a slight change to the
      algorithms for `-XDeriveFoldable` and `-XDeriveTraversable`, which is
      described in [this wiki
      page](https://ghc.haskell.org/trac/ghc/wiki/Commentary/Compiler/DeriveFu
      nctor#Proposal:alternativestrategyforderivingFoldableandTraversable).
      The wiki page also describes why we don't apply the same changes to the
      algorithm for `-XDeriveFunctor`.
      
      This is techincally a breaking change for users of `-XDeriveFoldable`
      and `-XDeriveTraversable`, since if someone was using a law-breaking
      `Monoid` instance with a derived `Foldable` instance (i.e., one where `x
      <> mempty` does not equal `x`) or a law-breaking `Applicative` instance
      with a derived `Traversable` instance, then the new generated code could
      result in different behavior. I suspect the number of scenarios like
      this is very small, and the onus really should be on those users to fix
      up their `Monoid`/`Applicative` instances.
      
      Fixes #11174.
      
      Test Plan: ./validate
      
      Reviewers: hvr, simonpj, austin, bgamari
      
      Reviewed By: simonpj, bgamari
      
      Subscribers: thomie
      
      Differential Revision: https://phabricator.haskell.org/D1908
      
      GHC Trac Issues: #11174
      a82956df
  14. 09 Feb, 2016 1 commit
  15. 02 Feb, 2016 1 commit
    • Simon Marlow's avatar
      Remote GHCi: parallelise BCO serialization · c996db5b
      Simon Marlow authored
      Summary:
      Serialization of BCOs is slow, but we can parallelise it when using
      ghci -j<n>.  It parallelises nicely, saving multiple seconds off the
      link time in a large example I have.
      
      Test Plan:
      * validate
      * `ghci -fexternal-interpreter` in `nofib/real/anna`
      
      Reviewers: niteria, bgamari, ezyang, austin, hvr, erikd
      
      Subscribers: thomie
      
      Differential Revision: https://phabricator.haskell.org/D1877
      
      GHC Trac Issues: #11100
      c996db5b
  16. 01 Feb, 2016 1 commit
  17. 27 Jan, 2016 1 commit
    • eir@cis.upenn.edu's avatar
      Refactor the typechecker to use ExpTypes. · 00cbbab3
      eir@cis.upenn.edu authored
      The idea here is described in [wiki:Typechecker]. Briefly,
      this refactor keeps solid track of "synthesis" mode vs
      "checking" in GHC's bidirectional type-checking algorithm.
      When in synthesis mode, the expected type is just an IORef
      to write to.
      
      In addition, this patch does a significant reworking of
      RebindableSyntax, allowing much more freedom in the types
      of the rebindable operators. For example, we can now have
      `negate :: Int -> Bool` and
      `(>>=) :: m a -> (forall x. a x -> m b) -> m b`. The magic
      is in tcSyntaxOp.
      
      This addresses tickets #11397, #11452, and #11458.
      
      Tests:
        typecheck/should_compile/{RebindHR,RebindNegate,T11397,T11458}
        th/T11452
      00cbbab3
  18. 19 Jan, 2016 1 commit
    • niteria's avatar
      Check InScopeSet in substTy and provide substTyUnchecked · 9d33adb6
      niteria authored
      This adds sanity checks to `substTy` that implement:
      
      > when calling substTy subst ty it should be the case that the in-scope
      > set in the substitution is a superset of
      > * The free vars of the range of the substitution
      > * The free vars of ty minus the domain of the substitution
      
      and replaces violators with unchecked version. The violators were found
      by running the GHC test suite.
      
      This ensures that I can work on this incrementally and that what I fix won't
      be undone by some other change.
      
      It also includes a couple of fixes that I've already done.
      
      Test Plan: ./validate
      
      Reviewers: simonmar, goldfire, simonpj, austin, bgamari
      
      Reviewed By: simonpj, bgamari
      
      Subscribers: thomie
      
      Differential Revision: https://phabricator.haskell.org/D1792
      
      GHC Trac Issues: #11371
      9d33adb6
  19. 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
  20. 16 Jan, 2016 1 commit
    • Alan Zimmerman's avatar
      Work SourceText in for all integer literals · 3a1babd6
      Alan Zimmerman authored
      Summary:
      Certain syntactic elements have integers in them, such as fixity
      specifications, SPECIALISE pragmas and so on.
      
      The lexer will accept mult-radix literals, with arbitrary leading zeros
      in these.
      
      Bring in a SourceText field to each affected AST element to capture the
      original literal text for use with API Annotations.
      
      Affected hsSyn elements are
      
      ```
           -- See note [Pragma source text]
           data Activation = NeverActive
                           | AlwaysActive
                           | ActiveBefore SourceText PhaseNum
                                -- Active only *strictly before* this phase
                           | ActiveAfter SourceText PhaseNum
                                 -- Active in this phase and later
                           deriving( Eq, Data, Typeable )
                                     -- Eq used in comparing rules in HsDecls
      
           data Fixity = Fixity SourceText Int FixityDirection
             -- Note [Pragma source text]
             deriving (Data, Typeable)
       ```
      
      and
      
      ```
            | HsTickPragma         -- A pragma introduced tick
               SourceText           -- Note [Pragma source text] in BasicTypes
               (StringLiteral,(Int,Int),(Int,Int))
                                                -- external span for this tick
               ((SourceText,SourceText),(SourceText,SourceText))
                  -- Source text for the four integers used in the span.
                  -- See note [Pragma source text] in BasicTypes
               (LHsExpr id)
      ```
      
      Updates haddock submodule
      
      Test Plan: ./validate
      
      Reviewers: goldfire, bgamari, austin
      
      Reviewed By: bgamari
      
      Subscribers: thomie, mpickering
      
      Differential Revision: https://phabricator.haskell.org/D1781
      
      GHC Trac Issues: #11430
      3a1babd6
  21. 13 Jan, 2016 1 commit
    • niteria's avatar
      Use implicit CallStacks for ASSERT when available · 88d6d5aa
      niteria authored
      This aids with debugging, since all you have to do to get more
      stack frames is add a constraint `(?callStack :: CallStack) =>`.
      
      Old output:
      ```
      ghc-stage2: panic! (the 'impossible' happened)
        (GHC version 8.1.20160107 for x86_64-unknown-linux):
              ASSERT failed!
        file compiler/types/TyCoRep.hs line 1800
        InScope []
        [Xuv :-> n_av5[sk]]
        []
      ```
      
      New output:
      ```
      ghc-stage2: panic! (the 'impossible' happened)
        (GHC version 8.1.20160107 for x86_64-unknown-linux):
              ASSERT failed!
        CallStack (from ImplicitParams):
        assertPprPanic, called at compiler/types/TyCoRep.hs:1800:95 in
      ghc:TyCoRep
        InScope []
        [Xuv :-> n_av5[sk]]
        []
      ```
      
      Test Plan:
      harbormaster
      manual testing
      
      Reviewers: austin, gridaphobe, bgamari
      
      Reviewed By: gridaphobe, bgamari
      
      Subscribers: thomie
      
      Differential Revision: https://phabricator.haskell.org/D1751
      88d6d5aa
  22. 01 Jan, 2016 1 commit
    • Herbert Valerio Riedel's avatar
      Canonicalise `MonadPlus` instances · dafeb51f
      Herbert Valerio Riedel authored
      This refactoring exploits the fact that since AMP, in most cases,
      `instance MonadPlus` can be automatically derived from the respective
      `Alternative` instance.  This is because `MonadPlus`'s default method
      implementations are fully defined in terms of `Alternative(empty, (<>))`.
      dafeb51f
  23. 31 Dec, 2015 2 commits
  24. 19 Dec, 2015 1 commit
  25. 17 Dec, 2015 1 commit
    • Simon Marlow's avatar
      Remote GHCi, -fexternal-interpreter · 4905b83a
      Simon Marlow authored
      Summary:
      (Apologies for the size of this patch, I couldn't make a smaller one
      that was validate-clean and also made sense independently)
      
      (Some of this code is derived from GHCJS.)
      
      This commit adds support for running interpreted code (for GHCi and
      TemplateHaskell) in a separate process.  The functionality is
      experimental, so for now it is off by default and enabled by the flag
      -fexternal-interpreter.
      
      Reaosns we want this:
      
      * compiling Template Haskell code with -prof does not require
        building the code without -prof first
      
      * when GHC itself is profiled, it can interpret unprofiled code, and
        the same applies to dynamic linking.  We would no longer need to
        force -dynamic-too with TemplateHaskell, and we can load ordinary
        objects into a dynamically-linked GHCi (and vice versa).
      
      * An unprofiled GHCi can load and run profiled code, which means it
        can use the stack-trace functionality provided by profiling without
        taking the performance hit on the compiler that...
      4905b83a
  26. 15 Dec, 2015 1 commit
    • Simon Peyton Jones's avatar
      Allow recursive (undecidable) superclasses · 6eabb6dd
      Simon Peyton Jones authored
      This patch fulfils the request in Trac #11067, #10318, and #10592,
      by lifting the conservative restrictions on superclass constraints.
      
      These restrictions are there (and have been since Haskell was born) to
      ensure that the transitive superclasses of a class constraint is a finite
      set.  However (a) this restriction is conservative, and can be annoying
      when there really is no recursion, and (b) sometimes genuinely recursive
      superclasses are useful (see the tickets).
      
      Dimitrios and I worked out that there is actually a relatively simple way
      to do the job. It’s described in some detail in
      
         Note [The superclass story] in TcCanonical
         Note [Expanding superclasses] in TcType
      
      In brief, the idea is to expand superclasses only finitely, but to
      iterate (using a loop that already existed) if there are more
      superclasses to explore.
      
      Other small things
      
      - I improved grouping of error messages a bit in TcErrors
      
      - I re-centred the haddock.compiler test, which was at 9.8...
      6eabb6dd
  27. 14 Dec, 2015 1 commit
  28. 12 Dec, 2015 1 commit
    • Eric Seidel's avatar
      Rework the Implicit CallStack solver to handle local lets. · 3ec8288a
      Eric Seidel authored
      We can't just solve CallStack constraints indiscriminately when they
      occur in the RHS of a let-binder. The top-level given CallStack (if
      any) will not be in scope, so I've re-worked the CallStack solver as
      follows:
      
      1. CallStacks are treated like regular IPs unless one of the following
         two rules apply.
      
      2. In a function call, we push the call-site onto a NEW wanted
         CallStack, which GHC will solve as a regular IP (either directly from a
         given, or by quantifying over it in a local let).
      
      3. If, after the constraint solver is done, any wanted CallStacks
         remain, we default them to the empty CallStack. This rule exists mainly
         to clean up after rule 2 in a top-level binder with no given CallStack.
      
      In rule (2) we have to be careful to emit the new wanted with an
      IPOccOrigin instead of an OccurrenceOf origin, so rule (2) doesn't fire
      again. This is a bit shady but I've updated the Note to explain the
      trick.
      
      Test Plan: validate
      
      Reviewers: simonpj, austin, bgamari, hvr
      
      Reviewed By: simonpj, bgamari
      
      Subscribers: thomie
      
      Differential Revision: https://phabricator.haskell.org/D1422
      
      GHC Trac Issues: #10845
      3ec8288a
  29. 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
  30. 08 Dec, 2015 1 commit
  31. 07 Dec, 2015 1 commit
  32. 03 Dec, 2015 1 commit
    • Georgios Karachalias's avatar
      Major Overhaul of Pattern Match Checking (Fixes #595) · 8a506104
      Georgios Karachalias authored
      This patch adresses several problems concerned with exhaustiveness and
      redundancy checking of pattern matching. The list of improvements includes:
      
      * Making the check type-aware (handles GADTs, Type Families, DataKinds, etc.).
        This fixes #4139, #3927, #8970 and other related tickets.
      
      * Making the check laziness-aware. Cases that are overlapped but affect
        evaluation are issued now with "Patterns have inaccessible right hand side".
        Additionally, "Patterns are overlapped" is now replaced by "Patterns are
        redundant".
      
      * Improved messages for literals. This addresses tickets #5724, #2204, etc.
      
      * Improved reasoning concerning cases where simple and overloaded
        patterns are matched (See #322).
      
      * Substantially improved reasoning for pattern guards. Addresses #3078.
      
      * OverloadedLists extension does not break exhaustiveness checking anymore
        (addresses #9951). Note that in general this cannot be handled but if we know
        that an argument has type '[a]', we treat it as a list since, the instance of
        'IsList' gives the identity for both 'fromList' and 'toList'. If the type is
        not clear or is not the list type, then the check cannot do much still. I am
        a bit concerned about OverlappingInstances though, since one may override the
        '[a]' instance with e.g. an '[Int]' instance that is not the identity.
      
      * Improved reasoning for nested pattern matching (partial solution). Now we
        propagate type and (some) term constraints deeper when checking, so we can
        detect more inconsistencies. For example, this is needed for #4139.
      
      I am still not satisfied with several things but I would like to address at
      least the following before the next release:
          Term constraints are too many and not printed for non-exhaustive matches
      (with the exception of literals). This sometimes results in two identical (in
      appearance) uncovered warnings. Unless we actually show their difference, I
      would like to have a single warning.
      8a506104
  33. 02 Dec, 2015 1 commit
  34. 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
  35. 29 Nov, 2015 1 commit
    • quchen's avatar
      Implement warnings for Semigroups as parent of Monoid · 290def72
      quchen authored
      This patch is similar to the AMP patch (#8004), which offered two
      functions:
      
        1. Warn when an instance of a class has been given, but the type does
           not have a certain superclass instance
        2. Warn when top-level definitions conflict with future Prelude names
      
      These warnings are issued as part of the new `-Wcompat` warning group.
      
      Reviewers: hvr, ekmett, austin, bgamari
      
      Reviewed By: hvr, ekmett, bgamari
      
      Subscribers: ekmett, thomie
      
      Differential Revision: https://phabricator.haskell.org/D1539
      
      GHC Trac Issues: #11139
      290def72
  36. 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
  37. 24 Nov, 2015 1 commit
    • elaforge's avatar
      Rearrange error msgs and add section markers (Trac #11014). · c05fddde
      elaforge authored
      This puts the "Relevant bindings" section at the end.
      
      It uses a TcErrors.Report Monoid to divide messages by importance and
      then mappends them together.  This is not the most efficient way since
      there are various intermediate Reports and list appends, but it probably
      doesn't matter since error messages shouldn't get that large, and are
      usually prepended.  In practice, everything is `important` except
      `relevantBindings`, which is `supplementary`.
      
      ErrMsg's errMsgShortDoc and errMsgExtraInfo were extracted into ErrDoc,
      which has important, context, and suppelementary fields.  Each of those
      three sections is marked with a bullet character, '•' on unicode
      terminals and '*' on ascii terminals.  Since this breaks tons of tests,
      I also modified testlib.normalise_errmsg to strip out '•'s.
      
      --- Additional notes:
      
      To avoid prepending * to an empty doc, I needed to filter empty docs.
      This seemed less error-prone than trying to modify everyone who produces
      SDoc to instead produce Maybe SDoc.  So I added `Outputable.isEmpty`.
      Unfortunately it needs a DynFlags, which is kind of bogus, but otherwise
      I think I'd need another Empty case for SDoc, and then it couldn't be a
      newtype any more.
      
      ErrMsg's errMsgShortString is only used by the Show instance, which is
      in turn only used by Show HscTypes.SourceError, which is in turn only
      needed for the Exception instance.  So it's probably possible to get rid
      of errMsgShortString, but that would a be an unrelated cleanup.
      
      Fixes #11014.
      
      Test Plan: see above
      
      Reviewers: austin, simonpj, thomie, bgamari
      
      Reviewed By: thomie, bgamari
      
      Subscribers: simonpj, nomeata, thomie
      
      Differential Revision: https://phabricator.haskell.org/D1427
      
      GHC Trac Issues: #11014
      c05fddde
  38. 21 Nov, 2015 1 commit
    • niteria's avatar
      Create a deterministic version of tyVarsOfType · 2325bd4e
      niteria authored
      I've run into situations where I need deterministic `tyVarsOfType` and
      this implementation achieves that and also brings an algorithmic
      improvement.  Union of two `VarSet`s takes linear time the size of the
      sets and in the worst case we can have `n` unions of sets of sizes
      `(n-1, 1), (n-2, 1)...` making it quadratic.
      
      One reason why we need deterministic `tyVarsOfType` is in `abstractVars`
      in `SetLevels`. When we abstract type variables when floating we want
      them to be abstracted in deterministic order.
      
      Test Plan: harbormaster
      
      Reviewers: simonpj, goldfire, austin, hvr, simonmar, bgamari
      
      Reviewed By: simonmar
      
      Subscribers: thomie
      
      Differential Revision: https://phabricator.haskell.org/D1468
      
      GHC Trac Issues: #4012
      2325bd4e