1. 02 May, 2016 1 commit
    • Facundo Domínguez's avatar
      StaticPointers: Allow closed vars in the static form. · 36d29f7c
      Facundo Domínguez authored
      Summary:
      With this patch closed variables are allowed regardless of whether
      they are bound at the top level or not.
      
      The FloatOut pass is always performed. When optimizations are
      disabled, only expressions that go to the top level are floated.
      Thus, the applications of the StaticPtr data constructor are always
      floated.
      
      The CoreTidy pass makes sure the floated applications appear in the
      symbol table of object files. It also collects the floated bindings
      and inserts them in the static pointer table.
      
      The renamer does not check anymore if free variables appearing in the
      static form are top-level. Instead, the typechecker looks at the
      tct_closed flag to decide if the free variables are closed.
      
      The linter checks that applications of StaticPtr only occur at the
      top of top-level bindings after the FloatOut pass.
      
      The field spInfoName of StaticPtrInfo has been removed. It used to
      contain the name of the top-level binding that contains the StaticPtr
      application. However, this information is no longer available when the
      StaticPtr is constructed, as the binding name is determined now by the
      FloatOut pass.
      
      Test Plan: ./validate
      
      Reviewers: goldfire, simonpj, austin, hvr, bgamari
      
      Reviewed By: simonpj
      
      Subscribers: thomie, mpickering, mboes
      
      Differential Revision: https://phabricator.haskell.org/D2104
      
      GHC Trac Issues: #11656
      36d29f7c
  2. 28 Apr, 2016 1 commit
  3. 15 Apr, 2016 1 commit
    • niteria's avatar
      Kill some unnecessary varSetElems · 928d7473
      niteria authored
      When you do `varSetElems (tyCoVarsOfType x)` it's equivalent to
      `tyCoVarsOfTypeList x`.
      
      Why? If you look at the implementation:
      ```
      tyCoVarsOfTypeList ty = runFVList $ tyCoVarsOfTypeAcc ty
      tyCoVarsOfType ty = runFVSet $ tyCoVarsOfTypeAcc ty
      ```
      they use the same helper function. The helper function returns a
      deterministically ordered list and a set. The only difference
      between the two is which part of the result they take. It is redundant
      to take the set and then immediately convert it to a list.
      
      This helps with determinism and we eventually want to replace the uses
      of `varSetElems` with functions that don't leak the values of uniques.
      This change gets rid of some instances that are easy to kill.
      
      I chose not to annotate every place where I got rid of `varSetElems`
      with a comment about non-determinism, because once we get rid of
      `varSetElems` it will not be possible to do the wrong thing.
      
      Test Plan: ./validate
      
      Reviewers: goldfire, austin, simonmar, bgamari, simonpj
      
      Reviewed By: simonpj
      
      Subscribers: thomie
      
      Differential Revision: https://phabricator.haskell.org/D2115
      
      GHC Trac Issues: #4012
      928d7473
  4. 30 Mar, 2016 1 commit
    • niteria's avatar
      Don't recompute some free vars in lintCoercion · 1757dd8e
      niteria authored
      As pointed out by @simonpj on D2044 we don't need
      to compute the free vars of the range of the substitution
      as most of them are already carried by the monad.
      This should be a tiny performance improvement over the version
      from before D2044.
      
      Also removes an extra function that is now unnecessary.
      
      Test Plan: ./validate && ./validate --slow
      
      Reviewers: goldfire, simonpj, austin, bgamari
      
      Reviewed By: simonpj
      
      Subscribers: thomie, simonmar, simonpj
      
      Differential Revision: https://phabricator.haskell.org/D2060
      
      GHC Trac Issues: #11371
      1757dd8e
  5. 29 Mar, 2016 1 commit
  6. 24 Mar, 2016 2 commits
    • Simon Peyton Jones's avatar
      Tidy up handling of coercion variables · cb08f8da
      Simon Peyton Jones authored
      * Comments to explain that a CoVar, whose IdInfo is CoVarId,
        is always unlifted (but may be nominal or representational role)
      
        And TyCoRep.isCoercionType picks out only those unlifted
        types, NOT the lifted versions
      
      * Introduce Var.NcId for non-co-var Ids
        with predicate isNonCoVarId
      
      * Add assertions in CoreSubst that the Id env is only
        used for NcIds
      
      * Fix lurking bug in CSE which extended the
        CoreSubst Id env with a CoVar
      
      * Fix two bugs in Specialise.spec_call, which wrongly treated
        CoVars like NcIds
          - needed a varToCoreExpr in one place
          - needed extendSubst not extendIdSubst in another
        This was the root cause of Trac #11644
      
      Minor refactoring
      
      * Eliminate unused mkDerivedLocalCoVarM, mkUserLocalCoVar
      * Small refactor in mkSysLocalOrCoVar
      cb08f8da
    • Ben Gamari's avatar
      ErrUtils: Add timings to compiler phases · 8048d51b
      Ben Gamari authored and Ben Gamari's avatar Ben Gamari committed
      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
  7. 01 Mar, 2016 1 commit
  8. 26 Feb, 2016 1 commit
    • Simon Peyton Jones's avatar
      Fix and refactor strict pattern bindings · e3f341f3
      Simon Peyton Jones authored
      This patch was triggered by Trac #11601, where I discovered that
      -XStrict was really not doing the right thing. In particular,
      
        f y = let !(Just x) = blah[y] in body[y,x]
      
      This was evaluating 'blah' but not pattern matching it
      against Just until x was demanded.  This is wrong.
      
      The patch implements a new semantics which ensures that strict
      patterns (i.e. ones with an explicit bang, or with -XStrict)
      are evaluated fully when bound.
      
      * There are extensive notes in DsUtils:
        Note [mkSelectorBinds]
      
      * To do this I found I need one-tuples;
        see Note [One-tuples] in TysWiredIn
      
      I updated the user manual to give the new semantics
      e3f341f3
  9. 25 Feb, 2016 1 commit
    • 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
  10. 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
  11. 18 Feb, 2016 2 commits
    • Simon Peyton Jones's avatar
      Improve piResultTys and friends · 4d031cf9
      Simon Peyton Jones authored
      Several things here:
      
      * Re-implement piResultTys so that its substitution has
        the correct in-scope set
      
        That means paying close attention to performance, since as we
        discovered in Trac #11371, it's a heavily used function and
        is often used on ordinary function types, with no foralls to
        worry about substituting.
      
      * Kill off applyTys, which was just the same as piResultTys.
      
      * Re-engineer MkCore.mkCoreApps so that it calls piResultTys,
        rather than repeatedly calling piResultTy.
      4d031cf9
    • Simon Peyton Jones's avatar
      (Another) minor refactoring of substitutions · b5292557
      Simon Peyton Jones authored
      No change in functionality here, but greater clarity:
      
      * In FamInstEnv.FlattenEnv, kill off the fi_in_scope field
        We are already maintaining an in-scope set in the fe_subst field,
        so it's silly do to it twice.
      
        (This isn't strictly connected to the rest of this patch, but
        the nomenclature changes below affect the same code, so I put
        them together.)
      
      * TyCoRep.extendTCVSubst used to take a TyVar or a CoVar and work
        out what to do, but in fact we almost always know which of the
        two we are doing.  So:
          - define extendTvSubst, extendCvSubst
          - and use them
      
      * Similar renamings in TyCoRep:
         - extendTCvSubstList        -->   extendTvSubstList
         - extendTCvSubstBinder      -->   extendTvSubstBinder
         - extendTCvSubstAndInScope  --> extendTvSubstAndInScope
      
      * Add Type.extendTvSubstWithClone, extendCvSubstWithClone
      
      * Similar nomenclature changes in Subst, SimplEnv, Specialise
      
      * Kill off TyCoRep.substTelescope (never used)
      b5292557
  12. 15 Feb, 2016 1 commit
  13. 30 Jan, 2016 1 commit
    • niteria's avatar
      Add asserts to other substitution functions · bb956eb8
      niteria authored
      This adds asserts to `substTys`, `substCo` and `substCos` in
      the same spirit as already existing asserts on `substTy`, protecting
      every possible entry point to `subst_ty` and `subst_co`.
      
      I've replaced the violators with unchecked versions.
      
      Test Plan: ./validate --slow
      
      Reviewers: simonpj, goldfire, austin, bgamari
      
      Subscribers: thomie
      
      Differential Revision: https://phabricator.haskell.org/D1862
      
      GHC Trac Issues: #11371
      bb956eb8
  14. 28 Jan, 2016 1 commit
    • niteria's avatar
      Use the in_scope set in lint_app · 63700a19
      niteria authored
      This makes the call to `substTy` satisfy the invariant from
      Note [The substitution invariant] in TyCoRep.
      
      Test Plan: ./validate --slow
      
      Reviewers: goldfire, austin, bgamari, simonpj
      
      Reviewed By: simonpj
      
      Subscribers: thomie
      
      Differential Revision: https://phabricator.haskell.org/D1861
      
      GHC Trac Issues: #11371
      63700a19
  15. 27 Jan, 2016 2 commits
  16. 26 Jan, 2016 1 commit
    • niteria's avatar
      Pass InScopeSet to substTy in lintTyApp · 01809bcd
      niteria authored
      This is the fix proposed in #11371:
      ```
      In other cases, we already have the in-scope set in hand. Example: in
      CoreLint.lintTyApp we find a call to substTyWith. But Lint carries an
      in-scope set, so it would be easy to pass it to substTyWith.
      ```
      
      Test Plan: ./validate --slow (only pre-existing problems)
      
      Reviewers: simonpj, goldfire, austin, nomeata, bgamari
      
      Subscribers: thomie
      
      Differential Revision: https://phabricator.haskell.org/D1820
      
      GHC Trac Issues: #11371
      01809bcd
  17. 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
  18. 31 Dec, 2015 1 commit
  19. 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. ...
      67465497
  20. 23 Nov, 2015 1 commit
  21. 18 Nov, 2015 1 commit
    • msosn's avatar
      Fix inconsistent pretty-printing of type families · c61759d5
      msosn authored and Ben Gamari's avatar Ben Gamari committed
      After the changes, the three functions used to print type families
      were identical, so they are refactored into one.
      
      Original RHSs of data instance declarations are recreated and
      printed in user error messages.
      
      RHSs containing representation TyCons are printed in the
      Coercion Axioms section in a typechecker dump.
      
      Add vbar to the list of SDocs exported by Outputable.
      Replace all text "|" docs with it.
      
      Fixes #10839
      
      Reviewers: goldfire, jstolarek, austin, bgamari
      
      Reviewed By: jstolarek
      
      Subscribers: jstolarek, thomie
      
      Differential Revision: https://phabricator.haskell.org/D1441
      
      GHC Trac Issues: #10839
      c61759d5
  22. 17 Nov, 2015 1 commit
    • quchen's avatar
      MonadFail proposal, phase 1 · 233d1312
      quchen authored
      This implements phase 1 of the MonadFail proposal (MFP, #10751).
      
      - MonadFail warnings are all issued as desired, tunable with two new flags
      - GHC was *not* made warning-free with `-fwarn-missing-monadfail-warnings`
        (but it's disabled by default right now)
      
      Credits/thanks to
      - Franz Thoma, whose help was crucial to implementing this
      - My employer TNG Technology Consulting GmbH for partially funding us
        for this work
      
      Reviewers: goldfire, austin, #core_libraries_committee, hvr, bgamari, fmthoma
      
      Reviewed By: hvr, bgamari, fmthoma
      
      Subscribers: thomie
      
      Projects: #ghc
      
      Differential Revision: https://phabricator.haskell.org/D1248
      
      GHC Trac Issues: #10751
      233d1312
  23. 17 Oct, 2015 1 commit
    • Herbert Valerio Riedel's avatar
      Make Monad/Applicative instances MRP-friendly · e8ed2136
      Herbert Valerio Riedel authored and Ben Gamari's avatar Ben Gamari committed
      This patch refactors pure/(*>) and return/(>>) in MRP-friendly way, i.e.
      such that the explicit definitions for `return` and `(>>)` match the
      MRP-style default-implementation, i.e.
      
        return = pure
      
      and
      
        (>>) = (*>)
      
      This way, e.g. all `return = pure` definitions can easily be grepped and
      removed in GHC 8.1;
      
      Test Plan: Harbormaster
      
      Reviewers: goldfire, alanz, bgamari, quchen, austin
      
      Reviewed By: quchen, austin
      
      Subscribers: thomie
      
      Differential Revision: https://phabricator.haskell.org/D1312
      e8ed2136
  24. 02 Oct, 2015 1 commit
    • Ben Gamari's avatar
      Fix treatment of -0.0 · eb975d2e
      Ben Gamari authored and Ben Gamari's avatar Ben Gamari committed
      Here we fix a few mis-optimizations that could occur in code with
      floating point comparisons with -0.0. These issues arose from our
      insistence on rewriting equalities into case analyses and the
      simplifier's ignorance of floating-point semantics.
      
      For instance, in Trac #10215 (and the similar issue Trac #9238) we
      turned `ds == 0.0` into a case analysis,
      
      ```
      case ds of
          __DEFAULT -> ...
          0.0 -> ...
      ```
      
      Where the second alternative matches where `ds` is +0.0 and *also* -0.0.
      However, the simplifier doesn't realize this and will introduce a local
      inlining of `ds = -- +0.0` as it believes this is the only
      value that matches this pattern.
      
      Instead of teaching the simplifier about floating-point semantics
      we simply prohibit case analysis on floating-point scrutinees and keep
      this logic in the comparison primops, where it belongs.
      
      We do several things here,
      
       - Add test cases from relevant tickets
       - Clean up a bit of documentation
       - Desugar literal matches against floats into applications of the
         appropriate equality primitive instead of case analysis
       - Add a CoreLint to ensure we don't pattern match on floats in Core
      
      Test Plan: validate with included testcases
      
      Reviewers: goldfire, simonpj, austin
      
      Subscribers: thomie
      
      Differential Revision: https://phabricator.haskell.org/D1061
      
      GHC Trac Issues: #10215, #9238
      eb975d2e
  25. 21 Sep, 2015 1 commit
    • eir@cis.upenn.edu's avatar
      Refactor BranchLists. · cd2840a7
      eir@cis.upenn.edu authored
      Now we use Array to store branches. This makes sense because we often
      have to do random access (once inference is done). This also vastly
      simplifies the awkward BranchList type.
      
      This fixes #10837 and updates submodule utils/haddock.
      cd2840a7
  26. 05 Aug, 2015 1 commit
    • Simon Peyton Jones's avatar
      Allow proper errors/warnings in core2core passes · e2b57381
      Simon Peyton Jones authored
      This patch makes it possible for core-to-core passes to emit
      proper error messages and warnings.
      
        * New function CoreMonad.warnMsg
      
        * CoreMonad.warnMsg and errorMsg now print a proper warning/error
          message heading.
      
        * CoreMonad carries a SrcSpan, which is used in warning/error
          messages.  It is initialised to be the source file name, but
          a core-to-core pass could set it more specifically if it had
          better location information.
      
      There was a bit of plumbing needed to get the filename to the
      right place.
      e2b57381
  27. 03 Aug, 2015 1 commit
  28. 16 Jul, 2015 2 commits
  29. 13 Jul, 2015 2 commits
  30. 20 Jun, 2015 1 commit
    • Edward Z. Yang's avatar
      Filter orphan rules based on imports, fixes #10294 and #10420. · 0cb1f5cf
      Edward Z. Yang authored
      Summary:
      If we have an orphan rule in our database, don't apply it
      unless the defining module is transitively imported by the
      module we are processing.  We do this by defining a new RuleEnv
      data type which includes both the RuleBase as well as the set
      of visible orphan modules, and threading this through the
      relevant environments (CoreReader, RuleCheckEnv and ScEnv).
      
      This is analogous to the instances fix we applied in #2182
      4c834fdd
      
      , but done for RULES.
      An important knock-on effect is that we can remove some buggy
      code in LoadInterface which tried to avoid loading interfaces
      that were loaded by plugins (which sometimes caused instances
      and rules to NEVER become visible).
      
      One note about tests: I renamed the old plugins07 test to T10420
      and replaced plugins07 with a test to ensure that a plugin
      import did not cause new rules to be loaded in.
      Signed-off-by: default avatarEdward Z. Yang <ezyang@cs.stanford.edu>
      
      Test Plan: validate
      
      Reviewers: simonpj, austin, goldfire
      
      Subscribers: bgamari, thomie
      
      Differential Revision: https://phabricator.haskell.org/D950
      
      GHC Trac Issues: #10420
      0cb1f5cf
  31. 16 Jun, 2015 1 commit
    • eir@cis.upenn.edu's avatar
      Refactor handling of decomposition. · 7eceffb3
      eir@cis.upenn.edu authored
      This adds the significant Note [Decomposing equalities] to
      TcCanonical, trying to sort out the various cases involved.
      
      The only functional change this commit should make is a different
      treatment of data families, which were wrong before (they could
      be decomposed at role R, which is wrong).
      7eceffb3
  32. 18 May, 2015 1 commit
    • Simon Peyton Jones's avatar
      Refactor tuple constraints · ffc21506
      Simon Peyton Jones authored
      Make tuple constraints be handled by a perfectly ordinary
      type class, with the component constraints being the
      superclasses:
          class (c1, c2) => (c2, c2)
      
      This change was provoked by
      
        #10359  inability to re-use a given tuple
                constraint as a whole
      
        #9858   confusion between term tuples
                and constraint tuples
      
      but it's generally a very nice simplification. We get rid of
       -  In Type, the TuplePred constructor of PredTree,
          and all the code that dealt with TuplePreds
       -  In TcEvidence, the constructors EvTupleMk, EvTupleSel
      
      See Note [How tuples work] in TysWiredIn.
      
      Of course, nothing is ever entirely simple. This one
      proved quite fiddly.
      
      - I did quite a bit of renaming, which makes this patch
        touch a lot of modules. In partiuclar tupleCon -> tupleDataCon.
      
      - I made constraint tuples known-key rather than wired-in.
        This is different to boxed/unboxed tuples, but it proved
        awkward to have all the superclass selectors wired-in.
        Easier just to use the standard mechanims.
      
      - While I was fiddling with known-key names, I split the TH Name
        definitions out of DsMeta into a new module THNames.  That meant
        that the known-key names can all be gathered in PrelInfo, without
        causing module loops.
      
      - I found that the parser was parsing an import item like
            T( .. )
        as a *data constructor* T, and then using setRdrNameSpace to
        fix it.  Stupid!  So I changed the parser to parse a *type
        constructor* T, which means less use of setRdrNameSpace.
      
        I also improved setRdrNameSpace to behave better on Exact Names.
        Largely on priciple; I don't think it matters a lot.
      
      - When compiling a data type declaration for a wired-in thing like
        tuples (,), or lists, we don't really need to look at the
        declaration.  We have the wired-in thing!  And not doing so avoids
        having to line up the uniques for data constructor workers etc.
        See Note [Declarations for wired-in things]
      
      - I found that FunDeps.oclose wasn't taking superclasses into
        account; easily fixed.
      
      - Some error message refactoring for invalid constraints in TcValidity
      
      - Haddock needs to absorb the change too; so there is a submodule update
      ffc21506
  33. 14 May, 2015 1 commit
    • Austin Seipp's avatar
      Revert multiple commits · 3cf8ecdc
      Austin Seipp authored
      This reverts multiple commits from Simon:
      
        - 04a484ea Test Trac #10359
        - a9ccd37a Test Trac #10403
        - c0aae6f6 Test Trac #10248
        - eb6ca851 Make the "matchable-given" check happen first
        - ca173aa3 Add a case to checkValidTyCon
        - 51cbad15 Update haddock submodule
        - 6e1174da Separate transCloVarSet from fixVarSet
        - a8493e03 Fix imports in HscMain (stage2)
        - a154944b Two wibbles to fix the build
        - 5910a1bc Change in capitalisation of error msg
        - 130e93aa Refactor tuple constraints
        - 8da785d5 Delete commented-out line
      
      These break the build by causing Haddock to fail mysteriously when
      trying to examine GHC.Prim it seems.
      3cf8ecdc
  34. 13 May, 2015 1 commit
    • Simon Peyton Jones's avatar
      Refactor tuple constraints · 130e93aa
      Simon Peyton Jones authored
      Make tuple constraints be handled by a perfectly ordinary
      type class, with the component constraints being the
      superclasses:
          class (c1, c2) => (c2, c2)
      
      This change was provoked by
      
        #10359  inability to re-use a given tuple
                constraint as a whole
      
        #9858   confusion between term tuples
                and constraint tuples
      
      but it's generally a very nice simplification. We get rid of
       -  In Type, the TuplePred constructor of PredTree,
          and all the code that dealt with TuplePreds
       -  In TcEvidence, the constructors EvTupleMk, EvTupleSel
      
      See Note [How tuples work] in TysWiredIn.
      
      Of course, nothing is ever entirely simple. This one
      proved quite fiddly.
      
      - I did quite a bit of renaming, which makes this patch
        touch a lot of modules. In partiuclar tupleCon -> tupleDataCon.
      
      - I made constraint tuples known-key rather than wired-in.
        This is different to boxed/unboxed tuples, but it proved
        awkward to have all the superclass selectors wired-in.
        Easier just to use the standard mechanims.
      
      - While I was fiddling with known-key names, I split the TH Name
        definitions out of DsMeta into a new module THNames.  That meant
        that the known-key names can all be gathered in PrelInfo, without
        causing module loops.
      
      - I found that the parser was parsing an import item like
            T( .. )
        as a *data constructor* T, and then using setRdrNameSpace to
        fix it.  Stupid!  So I changed the parser to parse a *type
        constructor* T, which means less use of setRdrNameSpace.
      
        I also improved setRdrNameSpace to behave better on Exact Names.
        Largely on priciple; I don't think it matters a lot.
      
      - When compiling a data type declaration for a wired-in thing like
        tuples (,), or lists, we don't really need to look at the
        declaration.  We have the wired-in thing!  And not doing so avoids
        having to line up the uniques for data constructor workers etc.
        See Note [Declarations for wired-in things]
      
      - I found that FunDeps.oclose wasn't taking superclasses into
        account; easily fixed.
      
      - Some error message refactoring for invalid constraints in TcValidity
      130e93aa
  35. 24 Apr, 2015 1 commit