1. 12 Jan, 2017 1 commit
  2. 09 Jan, 2017 2 commits
  3. 08 Jan, 2017 1 commit
    • Ömer Sinan Ağacan's avatar
      Parse holes as infix operators · 6c869f90
      Ömer Sinan Ağacan authored
      Reported as #13050. Since holes are expressions but not identifiers,
      holes were not allowed in infix operator position. This patch introduces
      a new production in infix operator parser to allow this.
      
      Reviewers: simonpj, austin, bgamari
      
      Reviewed By: simonpj
      
      Subscribers: simonpj, RyanGlScott, thomie, mpickering
      
      Differential Revision: https://phabricator.haskell.org/D2910
      
      GHC Trac Issues: #13050
      6c869f90
  4. 02 Jan, 2017 1 commit
  5. 18 Dec, 2016 2 commits
  6. 17 Dec, 2016 1 commit
    • eir@cis.upenn.edu's avatar
      Reshuffle levity polymorphism checks. · 8906e7b7
      eir@cis.upenn.edu authored
      Previously, GHC checked for bad levity polymorphism to the left of all
      arrows in data constructors. This was wrong, as reported in #12911
      (where an example is also shown). The solution is to check each
      individual argument for bad levity polymorphism.  Thus the check has
      been moved from TcValidity to TcTyClsDecls.
      
      A similar situation exists with pattern synonyms, also fixed here.
      
      This patch also nabs #12819 while I was in town.
      
      Test cases: typecheck/should_compile/T12911, patsyn/should_fail/T12819
      
      Test Plan: ./validate
      
      Reviewers: simonpj, austin, bgamari
      
      Reviewed By: bgamari
      
      Subscribers: thomie
      
      Differential Revision: https://phabricator.haskell.org/D2783
      
      GHC Trac Issues: #12819, #12911
      8906e7b7
  7. 15 Dec, 2016 3 commits
  8. 12 Dec, 2016 1 commit
  9. 07 Dec, 2016 1 commit
    • Alan Zimmerman's avatar
      Add HsSyn prettyprinter tests · 499e4382
      Alan Zimmerman authored
      Summary:
      Add prettyprinter tests, which take a file, parse it, pretty print it,
      re-parse the pretty printed version and then compare the original and
      new ASTs (ignoring locations)
      
      Updates haddock submodule to match the AST changes.
      
      There are three issues outstanding
      
      1. Extra parens around a context are not reproduced. This will require an
         AST change and will be done in a separate patch.
      
      2. Currently if an `HsTickPragma` is found, this is not pretty-printed,
         to prevent noise in the output.
      
         I am not sure what the desired behaviour in this case is, so have left
         it as before. Test Ppr047 is marked as expected fail for this.
      
      3. Apart from in a context, the ParsedSource AST keeps all the parens from
         the original source.  Something is happening in the renamer to remove the
         parens around visible type application, causing T12530 to fail, as the
         dumped splice decl is after the renamer.
      
         This needs to be fixed by keeping the parens, but I do not know where they
         are being removed.  I have amended the test to pass, by removing the parens
         in the expected output.
      
      Test Plan: ./validate
      
      Reviewers: goldfire, mpickering, simonpj, bgamari, austin
      
      Reviewed By: simonpj, bgamari
      
      Subscribers: simonpj, goldfire, thomie, mpickering
      
      Differential Revision: https://phabricator.haskell.org/D2752
      
      GHC Trac Issues: #3384
      499e4382
  10. 06 Dec, 2016 1 commit
  11. 05 Dec, 2016 2 commits
    • Simon Peyton Jones's avatar
      Test Trac #12925 · 3e3f7c21
      Simon Peyton Jones authored
      3e3f7c21
    • Simon Peyton Jones's avatar
      Fix an asymptotic bug in the occurrence analyser · 517d03e4
      Simon Peyton Jones authored
      Trac #12425 and #12234 showed up a major and long-standing
      bug in the occurrence analyser, whereby it could generate
      explonentially large program!
      
      There's a lot of commentary on #12425; and it's all described
      in Note [Loop breakers, node scoring, and stability]
      
      I did quite a lot of refactoring to make the code comprehensibe
      again (its structure had bit-rotted rather), so the patch
      looks bigger than it really is.
      
      Hurrah!
      
      I did a nofib run to check that I hadn't inadertently ruined
      anything:
      
      --------------------------------------------------------------------------------
              Program           Size    Allocs   Runtime   Elapsed  TotalMem
      --------------------------------------------------------------------------------
                fluid          -0.3%     -1.5%      0.01      0.01     +0.0%
               parser          -0.9%     +0.6%      0.04      0.04     +0.0%
               prolog          -0.1%     +1.2%      0.00      0.00     +0.0%
      
      --------------------------------------------------------------------------------
                  Min          -0.9%     -1.5%     -8.6%     -8.7%     +0.0%
                  Max          +0.1%     +1.2%     +7.7%     +7.8%     +2.4%
       Geometric Mean          -0.2%     -0.0%     -0.2%     -0.3%     +0.0%
      
      I checked what happened in 'prolog'.  It seems that we have a
      recursive data structure something like this
      
         f :: [blah]
         f x = build (\cn.  ...g...  )
      
         g :: [blah2]
         g y = ....(foldr k z (f y))....
      
      If we inline 'f' into 'g' we get better fusion than the other
      way round, but we don't have any way to spot that at the moment.
      (I wonder if we could do worker/wrapper for functions returning
      a 'build'?)  It was happening before by a fluke.
      
      Anyway I decided to accept this; it's relatively rare I think.
      517d03e4
  12. 01 Dec, 2016 1 commit
  13. 29 Nov, 2016 1 commit
  14. 25 Nov, 2016 1 commit
    • Simon Peyton Jones's avatar
      Another major constraint-solver refactoring · 1eec1f21
      Simon Peyton Jones authored
      This patch takes further my refactoring of the constraint
      solver, which I've been doing over the last couple of months
      in consultation with Richard.
      
      It fixes a number of tricky bugs that made the constraint
      solver actually go into a loop, including
      
        Trac #12526
        Trac #12444
        Trac #12538
      
      The main changes are these
      
      * Flatten unification variables (fmvs/fuvs) appear on the LHS
        of a tvar/tyvar equality; thus
                 fmv ~ alpha
        and not
                 alpha ~ fmv
      
        See Note [Put flatten unification variables on the left]
        in TcUnify.  This is implemented by TcUnify.swapOverTyVars.
      
      * Don't reduce a "loopy" CFunEqCan where the fsk appears on
        the LHS:
            F t1 .. tn ~ fsk
        where 'fsk' is free in t1..tn.
        See Note [FunEq occurs-check principle] in TcInteract
      
        This neatly stops some infinite loops that people reported;
        and it allows us to delete some crufty code in reduce_top_fun_eq.
        And it appears to be no loss whatsoever.
      
        As well as fixing loops, ContextStack2 and T5837 both terminate
        when they didn't before.
      
      * Previously we generated "derived shadow" constraints from
        Wanteds, but we could (and sometimes did; Trac #xxxx) repeatedly
        generate a derived shadow from the same Wanted.
      
        A big change in this patch is to have two kinds of Wanteds:
           [WD] behaves like a pair of a Wanted and a Derived
           [W]  behaves like a Wanted only
        See CtFlavour and ShadowInfo in TcRnTypes, and the ctev_nosh
        field of a Wanted.
      
        This turned out to be a lot simpler.  A [WD] gets split into a
        [W] and a [D] in TcSMonad.maybeEmitShaodow.
      
        See TcSMonad Note [The improvement story and derived shadows]
      
      * Rather than have a separate inert_model in the InertCans, I've
        put the derived equalities back into inert_eqs.  We weren't
        gaining anything from a separate field.
      
      * Previously we had a mode for the constraint solver in which it
        would more aggressively solve Derived constraints; it was used
        for simplifying the context of a 'deriving' clause, or a 'default'
        delcaration, for example.
      
        But the complexity wasn't worth it; now I just make proper Wanted
        constraints.  See TcMType.cloneWC
      
      * Don't generate injectivity improvement for Givens; see
        Note [No FunEq improvement for Givens] in TcInteract
      
      * solveSimpleWanteds leaves the insolubles in-place rather than
        returning them.  Simpler.
      
      I also did lots of work on comments, including fixing Trac #12821.
      1eec1f21
  15. 21 Nov, 2016 1 commit
  16. 17 Nov, 2016 1 commit
    • Edward Z. Yang's avatar
      Test for type synonym loops on TyCon. · 31398fbc
      Edward Z. Yang authored
      
      
      Summary:
      Previously, we tested for type synonym loops by doing
      a syntactic test on the literal type synonym declarations.
      However, in some cases, loops could go through hs-boot
      files, leading to an infinite loop (#12042); a similar
      situation can occur when signature merging.
      
      This commit replaces the syntactic test with a test on
      TyCon, simply by walking down all type synonyms until
      we bottom out, or find we've looped back.  It's a lot
      simpler.
      Signed-off-by: default avatarEdward Z. Yang <ezyang@cs.stanford.edu>
      
      Test Plan: validate
      
      Reviewers: simonpj, austin, bgamari
      
      Subscribers: goldfire, thomie
      
      Differential Revision: https://phabricator.haskell.org/D2656
      
      GHC Trac Issues: #12042
      31398fbc
  17. 15 Nov, 2016 1 commit
  18. 13 Nov, 2016 1 commit
    • Ben Gamari's avatar
      Kill Type pretty-printer · 6c0f10fa
      Ben Gamari authored
      Here we consolidate the pretty-printing logic for types in IfaceType. We
      need IfaceType regardless and the printer for Type can be implemented in
      terms of that for IfaceType. See #11660.
      
      Note that this is very much a work-in-progress. Namely I still have yet
      to ponder how to ease the hs-boot file situation, still need to rip out
      more dead code, need to move some of the special cases for, e.g., `*` to
      the IfaceType printer, and need to get it to validate. That being said,
      it comes close to validating as-is.
      
      Test Plan: Validate
      
      Reviewers: goldfire, austin
      
      Subscribers: goldfire, thomie, simonpj
      
      Differential Revision: https://phabricator.haskell.org/D2528
      
      GHC Trac Issues: #11660
      6c0f10fa
  19. 12 Nov, 2016 1 commit
  20. 04 Nov, 2016 1 commit
  21. 02 Nov, 2016 1 commit
  22. 31 Oct, 2016 1 commit
  23. 26 Oct, 2016 1 commit
    • Simon Peyton Jones's avatar
      Fundeps work even for unary type classes · 801c2637
      Simon Peyton Jones authored
      The functional-dependency improvement functions,
         improveFromAnother
         improveFromInstEnv
      had a side-condition that said the type class has to have at
      least two arguments.  But not so, as Trac #12763 shows:
      
         class C a | -> a where ...
      
      is perfectly legal, albeit a bit of a corner case.
      801c2637
  24. 24 Oct, 2016 1 commit
    • Simon Peyton Jones's avatar
      Prioritise class-level equality costraints · 1c4a39d3
      Simon Peyton Jones authored
      This patch fixes Trac #12734 by prioritising the class-level
      variants of equality constraints, namely (a~b) and (a~~b).
      
      See comment:10 of Trac #12734 for a description of what
      went wrong, and Note [Prioritise class equalities] in TcSMonad.
      
      The fix is still not great, but it's a definite step forward, and
      cures the particular problem.
      
      Worth merging to 8.0.
      1c4a39d3
  25. 21 Oct, 2016 3 commits
    • Simon Peyton Jones's avatar
      A collection of type-inference refactorings. · 3f5673f3
      Simon Peyton Jones authored
      This patch does a raft of useful tidy-ups in the type checker.
      I've been meaning to do this for some time, and finally made
      time to do it en route to ICFP.
      
      1. Modify TcType.ExpType to make a distinct data type,
         InferResult for the Infer case, and consequential
         refactoring.
      
      2. Define a new function TcUnify.fillInferResult, to fill in
         an InferResult. It uses TcMType.promoteTcType to promote
         the type to the level of the InferResult.
         See TcMType Note [Promoting a type]
         This refactoring is in preparation for an improvement
         to typechecking pattern bindings, coming next.
      
         I flirted with an elaborate scheme to give better
         higher rank inference, but it was just too complicated.
         See TcMType Note [Promotion and higher rank types]
      
      3. Add to InferResult a new field ir_inst :: Bool to say
         whether or not the type used to fill in the
         InferResult should be deeply instantiated.  See
         TcUnify Note [Deep instantiation of InferResult].
      
      4. Add a TcLevel to SkolemTvs. This will be useful generally
      
          - it's a fast way to see if the type
            variable escapes when floating (not used yet)
      
          - it provides a good consistency check when updating a
            unification variable (TcMType.writeMetaTyVarRef, the
            level_check_ok check)
      
         I originally had another reason (related to the flirting
         in (2), but I left it in because it seems like a step in
         the right direction.
      
      5. Reduce and simplify the plethora of uExpType,
         tcSubType and related functions in TcUnify.  It was
         such an opaque mess and it's still not great, but it's
         better.
      
      6. Simplify the uo_expected field of TypeEqOrigin.  Richard
         had generatlised it to a ExpType, but it was almost always
         a Check type.  Now it's back to being a plain TcType which
         is much, much easier.
      
      7. Improve error messages by refraining from skolemisation when
         it's clear that there's an error: see
         TcUnify Note [Don't skolemise unnecessarily]
      
      8. Type.isPiTy and isForAllTy seem to be missing a coreView check,
         so I added it
      
      9. Kill off tcs_used_tcvs.  Its purpose is to track the
         givens used by wanted constraints.  For dictionaries etc
         we do that via the free vars of the /bindings/ in the
         implication constraint ic_binds.  But for coercions we
         just do update-in-place in the type, rather than
         generating a binding.  So we need something analogous to
         bindings, to track what coercions we have added.
      
         That was the purpose of tcs_used_tcvs.  But it only
         worked for a /single/ iteration, whereas we may have
         multiple iterations of solving an implication.  Look
         at (the old) 'setImplicationStatus'.  If the constraint
         is unsolved, it just drops the used_tvs on the floor.
         If it becomes solved next time round, we'll pick up
         coercions used in that round, but ignore ones used in
         the first round.
      
         There was an outright bug.  Result = (potentialy) bogus
         unused-constraint errors.  Constructing a case where this
         actually happens seems quite trick so I did not do so.
      
         Solution: expand EvBindsVar to include the (free vars of
         the) coercions, so that the coercions are tracked in
         essentially the same way as the bindings.
      
         This turned out to be much simpler.  Less code, more
         correct.
      
      10. Make the ic_binds field in an implication have type
            ic_binds :: EvBindsVar
          instead of (as previously)
             ic_binds :: Maybe EvBindsVar
          This is notably simpler, and faster to use -- less
          testing of the Maybe.  But in the occaional situation
          where we don't have anywhere to put the bindings, the
          belt-and-braces error check is lost.  So I put it back
          as an ASSERT in 'setImplicationStatus' (see the use of
          'termEvidenceAllowed')
      
      All these changes led to quite bit of error message wibbling
      3f5673f3
    • Simon Peyton Jones's avatar
      Test Trac #12507 · cdbc73ae
      Simon Peyton Jones authored
      This is now working apparently.  It relates to when a
      polymorphic function gets instantiated, under some
      implicit paramter bindings.
      cdbc73ae
    • Simon Peyton Jones's avatar
      Refactor typechecking of pattern bindings · 45bfd1a6
      Simon Peyton Jones authored
      This patch fixes a regression introduced, post 8.0.1, by
      this major commit:
      
           commit 15b9bf4b
           Author: Simon Peyton Jones <simonpj@microsoft.com>
           Date:   Sat Jun 11 23:49:27 2016 +0100
      
               Improve typechecking of let-bindings
      
               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.
      
      I didn't get the typechecking of pattern bindings right, leading
      to Trac #12427.
      
      In fixing this I found that this program doesn't work:
      
        data T where
          T :: a -> ((forall b. [b]->[b]) -> Int) -> T
      
        h1 y = case y of T _ v -> v
      
      Works in 7.10, but not in 8.0.1.
      
      There's a happy ending. I found a way to fix this, and improve
      pattern bindings too.  Not only does this fix #12427, but it also
      allows
      
      In particular,we now can accept
      
        data T where MkT :: a -> Int -> T
      
        ... let { MkT _ q = t } in ...
      
      Previously this elicited "my head exploded" but it's really
      fine since q::Int.
      
      The approach is described in detail in TcBinds
         Note [Typechecking pattern bindings]
      Super cool.  And not even a big patch!
      45bfd1a6
  26. 19 Oct, 2016 1 commit
    • Simon Peyton Jones's avatar
      Test for newtype with unboxed argument · 1f09c16c
      Simon Peyton Jones authored
      Newtypes cannot (currently) have an unboxed argument type.
      But Trac #12729 showed that this was only being checked for
      newtypes in H98 syntax; in GADT snytax they were let through.
      
      This patch moves the test to checkValidDataCon, where it properly
      belongs.
      1f09c16c
  27. 17 Oct, 2016 1 commit
  28. 14 Oct, 2016 1 commit
    • Ben Gamari's avatar
      Clean up handling of known-key Names in interface files · 34d933d6
      Ben Gamari authored
      Previously BinIface had some dedicated logic for handling tuple names in
      the symbol table. As it turns out, this logic was essentially dead code
      as it was superceded by the special handling of known-key things. Here
      we cull the tuple code-path and use the known-key codepath for all
      tuple-ish things.
      
      This had a surprising number of knock-on effects,
      
       * constraint tuple datacons had to be made known-key (previously they
         were not)
      
       * IfaceTopBndr was changed from being a synonym of OccName to a
         synonym of Name (since we now need to be able to deserialize Names
         directly from interface files)
      
       * the change to IfaceTopBndr complicated fingerprinting, since we need
         to ensure that we don't go looking for the fingerprint of the thing
         we are currently fingerprinting in the fingerprint environment (see
         notes in MkIface). Handling this required distinguishing between
         binding and non-binding Name occurrences in the Binary serializers.
      
       * the original name cache logic which previously lived in IfaceEnv has
         been moved to a new NameCache module
      
       * I ripped tuples and sums out of knownKeyNames since they introduce a
         very large number of entries. During interface file deserialization
         we use static functions (defined in the new KnownUniques module) to
         map from a Unique to a known-key Name (the Unique better correspond
         to a known-key name!) When we need to do an original name cache
         lookup we rely on the parser implemented in isBuiltInOcc_maybe.
      
       * HscMain.allKnownKeyNames was folded into PrelInfo.knownKeyNames.
      
       * Lots of comments were sprinkled about describing the new scheme.
      
      Updates haddock submodule.
      
      Test Plan: Validate
      
      Reviewers: niteria, simonpj, austin, hvr
      
      Reviewed By: simonpj
      
      Subscribers: simonmar, niteria, thomie
      
      Differential Revision: https://phabricator.haskell.org/D2467
      
      GHC Trac Issues: #12532, #12415
      34d933d6
  29. 13 Oct, 2016 1 commit
    • Simon Peyton Jones's avatar
      Further improve error handling in TcRn monad · 2fdf21bf
      Simon Peyton Jones authored
      This patch builds on the one for Trac #12124, by dealing properly
      with out-of-scope "hole" errors.
      
      This fixes Trac #12529. The hard error coming from visible type application
      is still there, but the out-of-scope error is no longer suppressed.
      
      (Arguably the VTA message should be suppressed somehow, but that's a
      battle for another day.)
      2fdf21bf
  30. 12 Oct, 2016 1 commit
  31. 08 Oct, 2016 3 commits