1. 02 Oct, 2016 1 commit
  2. 01 Oct, 2016 1 commit
    • Ryan Scott's avatar
      Implement deriving strategies · 9e862765
      Ryan Scott authored
      Allows users to explicitly request which approach to `deriving` to use
      via keywords, e.g.,
      
      ```
      newtype Foo = Foo Bar
        deriving Eq
        deriving stock    Ord
        deriving newtype Show
      ```
      
      Fixes #10598. Updates haddock submodule.
      
      Test Plan: ./validate
      
      Reviewers: hvr, kosmikus, goldfire, alanz, bgamari, simonpj, austin,
      erikd, simonmar
      
      Reviewed By: alanz, bgamari, simonpj
      
      Subscribers: thomie, mpickering, oerjan
      
      Differential Revision: https://phabricator.haskell.org/D2280
      
      GHC Trac Issues: #10598
      9e862765
  3. 30 Sep, 2016 1 commit
    • Simon Peyton Jones's avatar
      Fix impredicativity (again) · b612da66
      Simon Peyton Jones authored
      This patch fixes Trac #12616.
      
      Dignosis.  In TcUnify.tc_sub_type_ds we were going to some trouble to
      support co- and contra-variance even for impredicative types.  With
      -XImpredicativeTYpes, this allowed a unification variable to be
      unified with a polytype (probably wrongly) and that caused later
      trouble in the constraint solver, where -XImpredicativeTypes was /not/
      on.  In effect, -XImpredicativeTypes can't be switched on locally.
      
      Why did we want ImpredicativeTypes locally?  Because the program
      generated by GND for a higher-rank method involved impredicative
      instantation of 'coerce':
            op = coerce op   -- where op has a higher rank type
      See Note [Newtype-deriving instances] in TcGenDeriv.
      
      Cure.
      
      1.  It is ghastly to rely on ImpredicativeTypes (a 100% flaky
          feature) to instantiate coerce polymorphically.  Happily we
          now have Visible Type Application, so I've used that instead
          which should be solid and reliable.
      
      2.  I deleted the code in tc_sub_type_ds that allows the constraint
          solver to "look through" a unification variable to find a
          polytype.  That used to be essential in the days of ReturnTv,
          but it's utterly unreliable and should be consigned to the dustbin
          of history.  (We have ExpType now for the essential uses.)
      
      Tests involving ImpredicativeTypes are affected, but I'm not worried
      about them... it's advertised as a feature you can't rely on, and
      I want to reform it outright.
      b612da66
  4. 05 Sep, 2016 1 commit
  5. 22 Jun, 2016 1 commit
  6. 20 Jun, 2016 2 commits
  7. 13 Jun, 2016 1 commit
    • Simon Peyton Jones's avatar
      Improve typechecking of let-bindings · 15b9bf4b
      Simon Peyton Jones authored
      This major commit was initially triggered by #11339, but it spiraled
      into a major review of the way in which type signatures for bindings
      are handled, especially partial type signatures.  On the way I fixed a
      number of other bugs, namely
         #12069
         #12033
         #11700
         #11339
         #11670
      
      The main change is that I completely reorganised the way in which type
      signatures in bindings are handled. The new story is in TcSigs
      Note [Overview of type signatures].  Some specific:
      
      * Changes in the data types for signatures in TcRnTypes:
        TcIdSigInfo and new TcIdSigInst
      
      * New module TcSigs deals with typechecking type signatures
        and pragmas. It contains code mostly moved from TcBinds,
        which is already too big
      
      * HsTypes: I swapped the nesting of HsWildCardBndrs
        and HsImplicitBndsrs, so that the wildcards are on the
        oustide not the insidde in a LHsSigWcType.  This is just
        a matter of convenient, nothing deep.
      
      There are a host of other changes as knock-on effects, and
      it all took FAR longer than I anticipated :-).  But it is
      a significant improvement, I think.
      
      Lots of error messages changed slightly, some just variants but
      some modest improvements.
      
      New tests
      
      * typecheck/should_compile
          * SigTyVars: a scoped-tyvar test
          * ExPat, ExPatFail: existential pattern bindings
          * T12069
          * T11700
          * T11339
      
      * partial-sigs/should_compile
          * T12033
          * T11339a
          * T11670
      
      One thing to check:
      
      * Small change to output from ghc-api/landmines.
        Need to check with Alan Zimmerman
      15b9bf4b
  8. 24 May, 2016 1 commit
  9. 28 Apr, 2016 1 commit
  10. 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
  11. 23 Feb, 2016 3 commits
  12. 07 Jan, 2016 2 commits
    • Simon Peyton Jones's avatar
      Use an Implication in 'deriving' error · 02c1c573
      Simon Peyton Jones authored
      Trac #11437 showed that erroneous constraints from a 'deriving'
      clause need to be wrapped in an Implication to properly scope
      their skolems.
      
      The main change is in TcDeriv.simplifyDeriv; the call to
      buildImplicationFor is new.
      02c1c573
    • Simon Peyton Jones's avatar
      Tidy up tidySkolemInfo · 290a553e
      Simon Peyton Jones authored
      Previously tidySkolemInfo used tidyOpenType, and returned a new
      TidyEnv.  But that's not needed any more, because all the skolems
      should be in scope in the constraint tree.
      
      I also removed a (now-unnecessary) field of UnifyForAllSkol
      290a553e
  13. 17 Dec, 2015 1 commit
  14. 15 Dec, 2015 1 commit
    • Ben Gamari's avatar
      Narrow scope of special-case for unqualified printing of names in core libraries · e2c91738
      Ben Gamari authored
      Commit 547c5971 modifies the
      pretty-printer to render names from a set of core packages (`base`,
      `ghc-prim`, `template-haskell`) as unqualified. The idea here was that
      many of these names typically are not in scope but are well-known by the
      user and therefore qualification merely introduces noise.
      
      This, however, is a very large hammer and potentially breaks any
      consumer who relies on parsing GHC output (hence #11208). This commit
      partially reverts this change, now only printing `Constraint` (which
      appears quite often in errors) as unqualified.
      
      Fixes #11208.
      
      Updates tests in `array` submodule.
      
      Test Plan: validate
      
      Reviewers: hvr, thomie, austin
      
      Subscribers: thomie
      
      Differential Revision: https://phabricator.haskell.org/D1619
      
      GHC Trac Issues: #11208
      e2c91738
  15. 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
  16. 09 Dec, 2015 1 commit
    • Simon Peyton Jones's avatar
      Fix DeriveAnyClass (Trac #9968) · af77089b
      Simon Peyton Jones authored
      The main issue concerned things like
      
         data T a = MkT a deriving( C Int )
      
      which is supposed to generate
      
         instance C Int (T a) where {}
      
      But the 'Int' argument (called cls_tys in the code) wasn't
      even being passed to inferConstraints and mk_data_eqn, so it
      really had no chance.   DeriveAnyClass came along after this
      code was written!
      
      Anyway I did quite a bit of tidying up in inferConstraints.
      
      Also I discovered that this case was not covered at all
      
         data T a b = MkT a b deriving( Bifunctor )
      
      What constraints should we generate for the instance context?
      We can deal with classes whose last arg has kind *, like Eq, Ord;
      or (* -> *), like Functor, Traversable.  But we really don't have
      a story for classes whose last arg has kind (* -> * -> *).
      
      So I augmented checkSideConditions to check for that and give
      a sensible error message.
      
      ToDo: update the user manual.
      af77089b
  17. 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
  18. 30 Oct, 2015 1 commit
    • Ben Gamari's avatar
      Generate Typeable info at definition sites · 91c6b1f5
      Ben Gamari authored
      This is the second attempt at merging D757.
      
      This patch implements the idea floated in Trac #9858, namely that we
      should generate type-representation information at the data type
      declaration site, rather than when solving a Typeable constraint.
      
      However, this turned out quite a bit harder than I expected. I still
      think it's the right thing to do, and it's done now, but it was quite
      a struggle.
      
      See particularly
      
       * Note [Grand plan for Typeable] in TcTypeable (which is a new module)
       * Note [The overall promotion story] in DataCon (clarifies existing
      stuff)
      
      The most painful bit was that to generate Typeable instances (ie
      TyConRepName bindings) for every TyCon is tricky for types in ghc-prim
      etc:
      
       * We need to have enough data types around to *define* a TyCon
       * Many of these types are wired-in
      
      Also, to minimise the code generated for each data type, I wanted to
      generate pure data, not CAFs with unpackCString# stuff floating about.
      
      Performance
      ~~~~~~~~~~~
      Three perf/compiler tests start to allocate quite a bit more. This isn't
      surprising, because they all allocate zillions of data types, with
      practically no other code, esp. T1969
      
       * T1969:    GHC allocates 19% more
       * T4801:    GHC allocates 13% more
       * T5321FD:  GHC allocates 13% more
       * T9675:    GHC allocates 11% more
       * T783:     GHC allocates 11% more
       * T5642:    GHC allocates 10% more
      
      I'm treating this as acceptable. The payoff comes in Typeable-heavy
      code.
      
      Remaining to do
      ~~~~~~~~~~~~~~~
      
       * I think that "TyCon" and "Module" are over-generic names to use for
         the runtime type representations used in GHC.Typeable. Better might
      be
         "TrTyCon" and "TrModule". But I have not yet done this
      
       * Add more info the the "TyCon" e.g. source location where it was
         defined
      
       * Use the new "Module" type to help with Trac Trac #10068
      
       * It would be possible to generate TyConRepName (ie Typeable
         instances) selectively rather than all the time. We'd need to persist
         the information in interface files. Lacking a motivating reason I
      have
         not done this, but it would not be difficult.
      
      Refactoring
      ~~~~~~~~~~~
      As is so often the case, I ended up refactoring more than I intended.
      In particular
      
       * In TyCon, a type *family* (whether type or data) is repesented by a
         FamilyTyCon
           * a algebraic data type (including data/newtype instances) is
             represented by AlgTyCon This wasn't true before; a data family
             was represented as an AlgTyCon. There are some corresponding
             changes in IfaceSyn.
      
           * Also get rid of the (unhelpfully named) tyConParent.
      
       * In TyCon define 'Promoted', isomorphic to Maybe, used when things are
         optionally promoted; and use it elsewhere in GHC.
      
       * Cleanup handling of knownKeyNames
      
       * Each TyCon, including promoted TyCons, contains its TyConRepName, if
         it has one. This is, in effect, the name of its Typeable instance.
      
      Updates haddock submodule
      
      Test Plan: Let Harbormaster validate
      
      Reviewers: austin, hvr, goldfire
      
      Subscribers: goldfire, thomie
      
      Differential Revision: https://phabricator.haskell.org/D1404
      
      GHC Trac Issues: #9858
      91c6b1f5
  19. 29 Oct, 2015 2 commits
    • Ben Gamari's avatar
      Revert "Generate Typeable info at definition sites" · bbaf76f9
      Ben Gamari authored
      This reverts commit bef2f03e.
      
      This merge was botched
      
      Also reverts haddock submodule.
      bbaf76f9
    • Ben Gamari's avatar
      Generate Typeable info at definition sites · bef2f03e
      Ben Gamari authored
      This patch implements the idea floated in Trac #9858, namely that we
      should generate type-representation information at the data type
      declaration site, rather than when solving a Typeable constraint.
      
      However, this turned out quite a bit harder than I expected. I still
      think it's the right thing to do, and it's done now, but it was quite
      a struggle.
      
      See particularly
      
       * Note [Grand plan for Typeable] in TcTypeable (which is a new module)
       * Note [The overall promotion story] in DataCon (clarifies existing stuff)
      
      The most painful bit was that to generate Typeable instances (ie
      TyConRepName bindings) for every TyCon is tricky for types in ghc-prim
      etc:
      
       * We need to have enough data types around to *define* a TyCon
       * Many of these types are wired-in
      
      Also, to minimise the code generated for each data type, I wanted to
      generate pure data, not CAFs with unpackCString# stuff floating about.
      
      Performance
      ~~~~~~~~~~~
      Three perf/compiler tests start to allocate quite a bit more. This isn't
      surprising, because they all allocate zillions of data types, with
      practically no other code, esp. T1969
      
       * T3294:   GHC allocates 110% more (filed #11030 to track this)
       * T1969:   GHC allocates 30% more
       * T4801:   GHC allocates 14% more
       * T5321FD: GHC allocates 13% more
       * T783:    GHC allocates 12% more
       * T9675:   GHC allocates 12% more
       * T5642:   GHC allocates 10% more
       * T9961:   GHC allocates 6% more
      
       * T9203:   Program allocates 54% less
      
      I'm treating this as acceptable. The payoff comes in Typeable-heavy
      code.
      
      Remaining to do
      ~~~~~~~~~~~~~~~
      
       * I think that "TyCon" and "Module" are over-generic names to use for
         the runtime type representations used in GHC.Typeable. Better might be
         "TrTyCon" and "TrModule". But I have not yet done this
      
       * Add more info the the "TyCon" e.g. source location where it was
         defined
      
       * Use the new "Module" type to help with Trac Trac #10068
      
       * It would be possible to generate TyConRepName (ie Typeable
         instances) selectively rather than all the time. We'd need to persist
         the information in interface files. Lacking a motivating reason I have
         not done this, but it would not be difficult.
      
      Refactoring
      ~~~~~~~~~~~
      As is so often the case, I ended up refactoring more than I intended.
      In particular
      
       * In TyCon, a type *family* (whether type or data) is repesented by a
         FamilyTyCon
           * a algebraic data type (including data/newtype instances) is
             represented by AlgTyCon This wasn't true before; a data family
             was represented as an AlgTyCon. There are some corresponding
             changes in IfaceSyn.
      
           * Also get rid of the (unhelpfully named) tyConParent.
      
       * In TyCon define 'Promoted', isomorphic to Maybe, used when things are
         optionally promoted; and use it elsewhere in GHC.
      
       * Cleanup handling of knownKeyNames
      
       * Each TyCon, including promoted TyCons, contains its TyConRepName, if
         it has one. This is, in effect, the name of its Typeable instance.
      
      Requires update of the haddock submodule.
      
      Differential Revision: https://phabricator.haskell.org/D757
      bef2f03e
  20. 23 Sep, 2015 1 commit
  21. 22 Sep, 2015 1 commit
  22. 30 Jul, 2015 1 commit
    • JohnWiegley's avatar
      Improve error message for newtypes and deriving clauses · 4f80ec0e
      JohnWiegley authored
      Summary:
      Change the error message generated when a deriving clause related to a newtype
      fails to always suggested trying GeneralizedNewtypeDeriving, even in
      situations where it may not work. Fixes #9600.
      
      Test Plan: testsuite/deriving/should_fail/9600.hs
      
      Reviewers: austin, bgamari, simonpj
      
      Rebased-by: bgamari
      
      Reviewed By: simonpj
      
      Subscribers: bgamari, hvr, simonmar, carter
      
      Differential Revision: https://phabricator.haskell.org/D216
      
      GHC Trac Issues: #9600
      4f80ec0e
  23. 05 Jul, 2015 1 commit
  24. 26 Jun, 2015 2 commits
  25. 25 Jun, 2015 1 commit
  26. 18 Jun, 2015 1 commit
    • Simon Peyton Jones's avatar
      Remove some horrible munging of origins for Coercible · 02bac025
      Simon Peyton Jones authored
      I just didn't think it was buying enough for all the cruft it caused.
      We can put some back if people start complaining about poor error
      messages. I forget quite how I tripped over this but I got sucked in.
      
      * Lots of tidying up in TcErrors
      
      * Rename pprArisingAt to pprCtLoc, by analogy with pprCtOrigin
      
      * Remove CoercibleOrigin data constructor from CtOrigin
      
      * Make relevantBindings return a Ct with a zonked
        and tidied CtOrigin
      
      * Add to TcRnTypes
            ctOrigin   :: Ct -> CtOrigin
            ctEvOrigin :: CtEvidence -> CtOrigin
            setCtLoc   :: Ct -> CtLoc -> Ct
      02bac025
  27. 22 Apr, 2015 1 commit
  28. 07 Apr, 2015 1 commit
  29. 23 Mar, 2015 1 commit
    • eir@cis.upenn.edu's avatar
      Do proper depth checking in the flattener to avoid looping. · c1edbdfd
      eir@cis.upenn.edu authored
      This implements (roughly) the plan put forward in comment:14:ticket:7788,
      fixing #7788, #8550, #9554, #10139, and addressing concerns raised in #10079.
      There are some regressions w.r.t. GHC 7.8, but only with pathological type
      families (like F a = F a). This also (hopefully -- don't have a test case)
      fixes #10158. Unsolved problems include #10184 and #10185, which are both
      known deficiencies of the approach used here.
      
      As part of this change, the plumbing around detecting infinite loops has
      changed. Instead of -fcontext-stack and -ftype-function-depth, we now have
      one combined -freduction-depth parameter. Setting it to 0 disbales the
      check, which is now the recommended way to get (terminating) code to
      typecheck in releases. (The number of reduction steps may well change between
      minor GHC releases!)
      
      This commit also introduces a new IntWithInf type in BasicTypes
      that represents an integer+infinity. This type is used in a few
      places throughout the code.
      
      Tests in
        indexed-types/should_fail/T7788
        indexed-types/should_fail/T8550
        indexed-types/should_fail/T9554
        indexed-types/should_compile/T10079
        indexed-types/should_compile/T10139
        typecheck/should_compile/T10184  (expected broken)
        typecheck/should_compile/T10185  (expected broken)
      
      This commit also changes performance testsuite numbers, for the better.
      c1edbdfd
  30. 07 Mar, 2015 1 commit
    • Iavor S. Diatchki's avatar
      Custom `Typeable` solver, that keeps track of kinds. · b359c886
      Iavor S. Diatchki authored
      Summary:
      This implements the new `Typeable` solver: when GHC sees `Typeable` constraints
      it solves them on the spot.
      
      The current implementation creates `TyCon` representations on the spot.
      
      Pro: No overhead at all in code that does not use `Typeable`
      Cons: Code that uses `Typeable` may create multipe `TyCon` represntations.
      
      We have discussed an implementation where representations of `TyCons` are
      computed once, in the module, where a datatype is declared.  This would
      lead to more code being generated:  for a promotable datatype we need to
      generate `2 + number_of_data_cons` type-constructro representations,
      and we have to do that for all programs, even ones that do not intend to
      use typeable.
      
      I added code to emit warning whenevar `deriving Typeable` is encountered---
      the idea being that this is not needed anymore, and shold be fixed.
      
      Also, we allow `instance Typeable T` in .hs-boot files, but they result
      in a warning, and are ignored.  This last one was to avoid breaking exisitng
      code, and should become an error, eventually.
      
      Test Plan:
      1. GHC can compile itself.
      2. I compiled a number of large libraries, including `lens`.
          - I had to make some small changes:
            `unordered-containers` uses internals of `TypeReps`, so I had to do a 1 line fix
          - `lens` needed one instance changed, due to a poly-kinded `Typeble` instance
      
      3. I also run some code that uses `syb` to traverse a largish datastrucutre.
      I didn't notice any signifiant performance difference between the 7.8.3 version,
      and this implementation.
      
      Reviewers: simonpj, simonmar, austin, hvr
      
      Reviewed By: austin, hvr
      
      Subscribers: thomie
      
      Differential Revision: https://phabricator.haskell.org/D652
      
      GHC Trac Issues: #9858
      b359c886
  31. 04 Mar, 2015 1 commit
  32. 23 Feb, 2015 1 commit
    • thomie's avatar
      Error out on `Main` without `main` in GHCi (#7765) · 0fa20726
      thomie authored
      Summary:
      GHC does 2 validation checks for module `Main`:
      * does `main` exist
      * is `main` exported (#414)
      
      The second check is done in ghc as well as in ghci (and runghc and ghc -e).
      The first check however is currently not done in ghci, to prevent "'main' is
      not in scope" errors when loading simple scripts. See commit d28ba8c8 for
      more information.
      
      This commit tightens the special case for ghci. When the file does not contain
      a main function, but does contain an explicit module header (i.e. "module Main
      where"), then /do/ raise an error in ghci (and runghc and ghc -e) as well
      
      Test Plan:
      module/T7765: a module Main with an explicit module header but without a
      main function should be an error for all Ways.
      
      Additionaly: delete test module/mod174. It was added in commit 5a54c38e, but it
      is a duplicate of module/T414.
      
      Reviewers: austin
      
      Reviewed By: austin
      
      Subscribers: thomie
      
      Differential Revision: https://phabricator.haskell.org/D649
      
      GHC Trac Issues: #7765
      0fa20726
  33. 06 Jan, 2015 2 commits
    • Simon Peyton Jones's avatar
      Print singleton consraints without parens · da9b2ec3
      Simon Peyton Jones authored
      The main change is in TypeRep.pprTheta, so we print
             Eq a
      for a singleton, but
            (Eq a, Show a)
      for multiple constraints.
      
      There are lots of trivial knock-on changes to error messages
      da9b2ec3
    • Simon Peyton Jones's avatar
      Modify a couple of error messages slightly · 00e1fc1b
      Simon Peyton Jones authored
      In particular
        In the type signature for:
           f :: Int -> Int
      I added the colon
      
      Also reword the "maybe you haven't applied a function to enough arguments?"
      suggestion to make grammatical sense.
      
      These tiny changes affect a lot of error messages.
      00e1fc1b