1. 27 Jul, 2017 13 commits
    • Richard Eisenberg's avatar
      Fix #12369 by being more flexible with data insts · 42392383
      Richard Eisenberg authored
      Previously, a data family's kind had to end in `Type`,
      and data instances had to list all the type patterns for the
      family. However, both of these restrictions were unnecessary:
      
      - A data family's kind can usefully end in a kind variable `k`.
        See examples on #12369.
      
      - A data instance need not list all patterns, much like how a
        GADT-style data declaration need not list all type parameters,
        when a kind signature is in place. This is useful, for example,
        here:
      
          data family Sing (a :: k)
          data instance Sing :: Bool -> Type where ...
      
      This patch also improved a few error messages, as some error
      plumbing had to be moved around.
      
      See new Note [Arity of data families] in FamInstEnv for more
      info.
      
      test case: indexed-types/should_compile/T12369
      42392383
    • Richard Eisenberg's avatar
      Fix #12176 by being a bit more careful instantiating. · 1696dbf4
      Richard Eisenberg authored
      Previously, looking up a TyCon that said "no" to mightBeUnsaturated
      would then instantiate all of its invisible binders. But this is
      wrong for vanilla type synonyms, whose RHS kind might legitimately
      start with invisible binders. So a little more care is taken now,
      only to instantiate those invisible binders that need to be (so that
      the TyCon isn't unsaturated).
      1696dbf4
    • Richard Eisenberg's avatar
      Document that type holes kill polymorphic recursion · ca471860
      Richard Eisenberg authored
      This "fixes" #11995.
      ca471860
    • Richard Eisenberg's avatar
      Fix #11963 by checking for more mixed type/kinds · 10d13b62
      Richard Eisenberg authored
      This is a straightforward fix -- there were just some omitted
      checks.
      
      test case: typecheck/should_fail/T11963
      10d13b62
    • Richard Eisenberg's avatar
      Track visibility in TypeEqOrigin · fb752133
      Richard Eisenberg authored
      A type equality error can arise from a mismatch between
      *invisible* arguments just as easily as from visible arguments.
      But we should really prefer printing out errors from visible
      arguments over invisible ones. Suppose we have a mismatch between
      `Proxy Int` and `Proxy Maybe`. Would you rather get an error
      between `Int` and `Maybe`? Or between `*` and `* -> *`? I thought
      so, too.
      
      There is a fair amount of plumbing with this one, but I think
      it's worth it.
      
      This commit introduces a performance regression in test
      perf/compiler/T5631. The cause of the regression is not the
      new visibility stuff, directly: it's due to a change from
      zipWithM to zipWith3M in TcUnify. To my surprise, zipWithM
      is nicely optimized (it fuses away), but zipWith3M is not.
      There are other examples of functions that could be made faster,
      so I've posted a separate ticket, #14037, to track these
      improvements. For now, I've accepted the small (6.6%) regression.
      fb752133
    • Richard Eisenberg's avatar
      Fix #13819 by refactoring TypeEqOrigin.uo_thing · c2417b87
      Richard Eisenberg authored
      The uo_thing field of TypeEqOrigin is used to track the
      "thing" (either term or type) that has the type (kind) stored
      in the TypeEqOrigin fields. Previously, this was sometimes a
      proper Core Type, which needed zonking and tidying. Now, it
      is only HsSyn: much simpler, and the error messages now use
      the user-written syntax.
      
      But this aspect of uo_thing didn't cause #13819; it was the
      sibling field uo_arity that did. uo_arity stored the number
      of arguments of uo_thing, useful when reporting something
      like "should have written 2 fewer arguments". We wouldn't want
      to say that if the thing didn't have two arguments. However,
      in practice, GHC was getting this wrong, and this message
      didn't seem all that helpful. Furthermore, the calculation
      of the number of arguments is what caused #13819 to fall over.
      This patch just removes uo_arity. In my opinion, the change
      to error messages is a nudge in the right direction.
      
      Test case: typecheck/should_fail/T13819
      c2417b87
    • Richard Eisenberg's avatar
      Remove old coercion pretty-printer · 79cfb199
      Richard Eisenberg authored
      Now, all coercions are printed from IfaceType, just like types.
      
      This also changes the rendering of TransCo to use ; instead of
      a prefix operator.
      79cfb199
    • Richard Eisenberg's avatar
      Preserve CoVar uniques during pretty printing · bb2a446a
      Richard Eisenberg authored
      Previously, we did this for Types, but not for Coercions.
      bb2a446a
    • Richard Eisenberg's avatar
      Don't tidy vars when dumping a type · ef39af72
      Richard Eisenberg authored
      This makes variables print more consistenty in, say,
      -ddump-tc-trace.
      ef39af72
    • Richard Eisenberg's avatar
      Test #11672 in typecheck/should_fail/T11672. · 9a549756
      Richard Eisenberg authored
      I believe this was fixed with the fix for #11198.
      9a549756
    • Richard Eisenberg's avatar
      Fix #11400, #11560 by documenting an infelicity. · c9667d32
      Richard Eisenberg authored
      Really, the fix for both of these is #11307.
      c9667d32
    • Richard Eisenberg's avatar
      Improve error messages around kind mismatches. · 8e15e3d3
      Richard Eisenberg authored
      Previously, when canonicalizing (or unifying, in uType) a
      heterogeneous equality, we emitted a kind equality and used the
      resulting coercion to cast one side of the heterogeneous equality.
      
      While sound, this led to terrible error messages. (See the bugs
      listed below.) The problem is that using the coercion built from
      the emitted kind equality is a bit like a wanted rewriting a wanted.
      The solution is to keep heterogeneous equalities as irreducible.
      
      See Note [Equalities with incompatible kinds] in TcCanonical.
      
      This commit also removes a highly suspicious switch to FM_SubstOnly
      when flattening in the kinds of a type variable. I have no idea
      why this was there, other than as a holdover from pre-TypeInType.
      I've not left a Note because there is simply no reason I can conceive
      of that the FM_SubstOnly should be there.
      
      One challenge with this patch is that the emitted derived equalities
      might get emitted several times: when a heterogeneous equality is
      in an implication and then gets floated out from the implication,
      the Derived is present both in and out of the implication. This
      causes a duplicate error message. (Test case:
      typecheck/should_fail/T7368) Solution: track the provenance of
      Derived constraints and refuse to float out a constraint that has
      an insoluble Derived.
      
      Lastly, this labels one test (dependent/should_fail/RAE_T32a)
      as expect_broken, because the problem is really #12919. The
      different handling of constraints in this patch exposes the error.
      
      This fixes bugs #11198, #12373, #13530, and #13610.
      
      test cases:
      typecheck/should_fail/{T8262,T8603,tcail122,T12373,T13530,T13610}
      8e15e3d3
    • Gabor Greif's avatar
      Remove unneeded import · 4a264157
      Gabor Greif authored
      4a264157
  2. 26 Jul, 2017 7 commits
    • Ryan Scott's avatar
      Fix #13968 by consulting isBuiltInOcc_maybe · d774b4e2
      Ryan Scott authored
      Summary:
      We were unconditionally reporting `Illegal binding of built-in syntax`
      in an error message, but this error doesn't make sense in certain Template
      Haskell scenarios which can trigger it. Let's give a more sensible error
      message by first checking if the name we're binding really is built-in syntax,
      using the handy `isBuiltInOcc_maybe` function.
      
      Test Plan: make test TEST=T13968
      
      Reviewers: bgamari, austin, goldfire
      
      Reviewed By: goldfire
      
      Subscribers: goldfire, rwbarton, thomie
      
      GHC Trac Issues: #13968
      
      Differential Revision: https://phabricator.haskell.org/D3789
      d774b4e2
    • Gabor Greif's avatar
      Fix note references and some typos · 362339dd
      Gabor Greif authored
      362339dd
    • Simon Peyton Jones's avatar
      Test Trac #14033 · d31181b9
      Simon Peyton Jones authored
      d31181b9
    • Simon Peyton Jones's avatar
      Comments only · f959624f
      Simon Peyton Jones authored
      f959624f
    • Simon Peyton Jones's avatar
      Comments and tc-tracing only · 6386fc32
      Simon Peyton Jones authored
      6386fc32
    • Simon Peyton Jones's avatar
      Fix binder visiblity for default methods · 75bf11c0
      Simon Peyton Jones authored
      Trac #13998 showed that default methods were getting bogus tyvar
      binder visiblity info; and that it matters in the code genreated
      by the default-method fill-in mechanism
      
      * The actual fix: in TcTyDecls.mkDefaultMethodType, make TyVarBinders
        with the right visibility info by getting TyConBinders from the
        class TyCon.  (Previously we made up visiblity info, but that
        caused #13998.)
      
      * Define TyCon.tyConTyVarBinders :: [TyConBinder] -> [TyVarBinder]
        which can build correct forall binders for
          a) default methods (Trac #13998)
          b) data constructors
        This was originally BuildTyCl.mkDataConUnivTyVarBinders
      
      * Move mkTyVarBinder, mkTyVarBinders from Type to Var
      75bf11c0
    • Simon Peyton Jones's avatar
      746ab0b4
  3. 25 Jul, 2017 7 commits
  4. 24 Jul, 2017 10 commits
  5. 23 Jul, 2017 3 commits
    • Ben Gamari's avatar
      Fix more documentation wibbles · 2dff2c7f
      Ben Gamari authored
      Fixes #14020, #14016, #14015, #14019
      2dff2c7f
    • Ben Gamari's avatar
      users-guide: Fix various wibbles · c9451959
      Ben Gamari authored
      c9451959
    • patrickdoc's avatar
      users-guide: Standardize and repair all flag references · 44b090be
      patrickdoc authored
      This patch does three things:
      
      1.) It simplifies the flag parsing code in `conf.py` to properly display
      flag definitions created by `.. (ghc|rts)-flag::`. Additionally, all flag
      references must include the associated arguments. Documentation has been
      added to `editing-guide.rst` to explain this.
      
      2.) It normalizes all flag definitions to a similar format. Notably, all
      instances of `<>` have been replaced with `⟨⟩`. All references across the
      users guide have been updated to match.
      
      3.) It fixes a couple issues with the flag reference table's generation code,
      which did not handle comma separated flags in the same cell and did not
      properly reference flags with arguments.
      
      Test Plan:
      `SPHINXOPTS = -n` to activate "nitpicky" mode, which reports all broken
      references. All remaining errors are references to flags without any
      documentation.
      
      Reviewers: austin, bgamari
      
      Reviewed By: bgamari
      
      Subscribers: rwbarton, thomie
      
      GHC Trac Issues: #13980
      
      Differential Revision: https://phabricator.haskell.org/D3778
      44b090be