1. 15 Jan, 2019 1 commit
  2. 01 Nov, 2018 1 commit
    • Richard Eisenberg's avatar
      Actually fail in failIfEmitsConstraints · 74ed9c1c
      Richard Eisenberg authored
      The function TcHsType.failIfEmitsConstraints says that it fails.
      It even does so in its name. But it didn't! It *reported* constraints
      but didn't fail. Now it does.
      
      This is important in tcHsClsInstType; see the comments therein.
      
      This was discovered while looking at #15797, but that ticket
      requires visible kind application to exhibit the bug; the test
      case will come with the patch for #12045.
      74ed9c1c
  3. 02 Aug, 2018 1 commit
    • Richard Eisenberg's avatar
      Remove decideKindGeneralisationPlan · c955a514
      Richard Eisenberg authored
      TypeInType came with a new function: decideKindGeneralisationPlan.
      This type-level counterpart to the term-level decideGeneralisationPlan
      chose whether or not a kind should be generalized. The thinking was
      that if `let` should not be generalized, then kinds shouldn't either
      (under the same circumstances around -XMonoLocalBinds).
      
      However, this is too conservative -- the situation described in the
      motivation for "let should be be generalized" does not occur in types.
      
      This commit thus removes decideKindGeneralisationPlan, always
      generalizing.
      
      One consequence is that tc_hs_sig_type_and_gen no longer calls
      solveEqualities, which reports all unsolved constraints, instead
      relying on the solveLocalEqualities in tcImplicitTKBndrs. An effect
      of this is that reporing kind errors gets delayed more frequently.
      This seems to be a net benefit in error reporting; often, alongside
      a kind error, the type error is now reported (and users might find
      type errors easier to understand).
      
      Some of these errors ended up at the top level, where it was
      discovered that the GlobalRdrEnv containing the definitions in the
      local module was not in the TcGblEnv, and thus errors were reported
      with qualified names unnecessarily. This commit rejiggers some of
      the logic around captureTopConstraints accordingly.
      
      One error message (typecheck/should_fail/T1633)
      is a regression, mentioning the name of a default method. However,
      that problem is already reported as #10087, its solution is far from
      clear, and so I'm not addressing it here.
      
      This commit fixes #15141. As it's an internal refactor, there is
      no concrete test case for it.
      
      Along the way, we no longer need the hsib_closed field of
      HsImplicitBndrs (it was used only in decideKindGeneralisationPlan)
      and so it's been removed, simplifying the datatype structure.
      
      Along the way, I removed code in the validity checker that looks
      at coercions. This isn't related to this patch, really (though
      it was, at one point), but it's an improvement, so I kept it.
      
      This updates the haddock submodule.
      c955a514
  4. 05 Mar, 2018 1 commit
    • Simon Peyton Jones's avatar
      Simplify rnLHsInstType · 1c062b79
      Simon Peyton Jones authored
      This patch is preparatory for the main fix for Trac #13324
      
      Here, we simplify rnLHsInstType so that it does not try
      to figure out the class name.  This turns out to have a good
      (rather than bad) effect on error messages, and it prepares
      the way for the main event.
      
      Plus, less code!
      1c062b79
  5. 30 Mar, 2012 1 commit