1. 15 Aug, 2020 1 commit
    • Alex D's avatar
      Implement -Wredundant-bang-patterns (#17340) · cec54b51
      Alex D authored
      Add new flag '-Wredundant-bang-patterns' that enables checks for "dead" bangs.
      Dead bangs are the ones that under no circumstances can force a thunk that
      wasn't already forced. Dead bangs are a form of redundant bangs. The new check
      is performed in Pattern-Match Coverage Checker along with other checks (namely,
      redundant and inaccessible RHSs). Given
      
          f :: Bool -> Int
          f True = 1
          f !x   = 2
      
      we can detect dead bang patterns by checking whether @x ~ ⊥@ is satisfiable
      where the PmBang appears in 'checkGrdTree'. If not, then clearly the bang is
      dead. Such a dead bang is then indicated in the annotated pattern-match tree by
      a 'RedundantSrcBang' wrapping. In 'redundantAndInaccessibles', we collect
      all dead bangs to warn about.
      
      Note that we don't want to warn for a dead bang that appears on a redundant
      clause. That is because in that case, we recommend to delete the clause wholly,
      including its leading pattern match.
      
      Dead bang patterns are redundant. But there are bang patterns which are
      redundant that aren't dead, for example
      
          f !() = 0
      
      the bang still forces the match variable, before we attempt to match on (). But
      it is redundant with the forcing done by the () match. We currently don't
      detect redundant bangs that aren't dead.
      cec54b51
  2. 14 Aug, 2020 3 commits
    • Ben Gamari's avatar
      llvm-targets: Add i686 targets · 55fd1dc5
      Ben Gamari authored
      Addresses #18422.
      55fd1dc5
    • Ben Gamari's avatar
      testsuite: Drop --io-manager flag from testsuite configuration · 9f66fdf6
      Ben Gamari authored
      This is no longer necessary as there are now dedicated testsuite ways
      which run tests with WinIO.
      9f66fdf6
    • Sylvain Henry's avatar
      Make IOEnv monad one-shot (#18202) · 8a51b2ab
      Sylvain Henry authored
      On CI (x86_64-linux-deb9-hadrian, compile_time/bytes_allocated):
      
          T10421     -1.8%    (threshold: +/- 1%)
          T10421a    -1.7%    (threshold: +/- 1%)
          T12150     -4.9%    (threshold: +/- 2%)
          T12227     -1.6     (threshold: +/- 1%)
          T12425     -1.5%    (threshold: +/- 1%)
          T12545     -3.8%    (threshold: +/- 1%)
          T12707     -3.0%    (threshold: +/- 1%)
          T13035     -3.0%    (threshold: +/- 1%)
          T14683     -10.3%   (threshold: +/- 2%)
          T3064      -6.9%    (threshold: +/- 2%)
          T4801      -4.3%    (threshold: +/- 2%)
          T5030      -2.6%    (threshold: +/- 2%)
          T5321FD    -3.6%    (threshold: +/- 2%)
          T5321Fun   -4.6%    (threshold: +/- 2%)
          T5631      -19.7%   (threshold: +/- 2%)
          T5642      -13.0%   (threshold: +/- 2%)
          T783       -2.7     (threshold: +/- 2%)
          T9020      -11.1    (threshold: +/- 2%)
          T9961      -3.4%    (threshold: +/- 2%)
      
          T1969 (compile_time/bytes_allocated)  -2.2%  (threshold: +/-1%)
          T1969 (compile_time/max_bytes_used)   +24.4% (threshold: +/-20%)
      
      Additionally on other CIs:
      
          haddock.Cabal                  -10.0%   (threshold: +/- 5%)
          haddock.compiler               -9.5%    (threshold: +/- 5%)
          haddock.base (max bytes used)  +24.6%   (threshold: +/- 15%)
          T10370 (max bytes used, i386)  +18.4%   (threshold: +/- 15%)
      
      Metric Decrease:
          T10421
          T10421a
          T12150
          T12227
          T12425
          T12545
          T12707
          T13035
          T14683
          T3064
          T4801
          T5030
          T5321FD
          T5321Fun
          T5631
          T5642
          T783
          T9020
          T9961
          haddock.Cabal
          haddock.compiler
      Metric Decrease 'compile_time/bytes allocated':
          T1969
      Metric Increase 'compile_time/max_bytes_used':
          T1969
          T10370
          haddock.base
      8a51b2ab
  3. 13 Aug, 2020 6 commits
    • Sylvain Henry's avatar
      Add HomeUnit type · ffc0d578
      Sylvain Henry authored
      Since Backpack the "home unit" is much more involved than what it was
      before (just an identifier obtained with `-this-unit-id`). Now it is
      used in conjunction with `-component-id` and `-instantiated-with` to
      configure module instantiations and to detect if we are type-checking an
      indefinite unit or compiling a definite one.
      
      This patch introduces a new HomeUnit datatype which is much easier to
      understand. Moreover to make GHC support several packages in the same
      instances, we will need to handle several HomeUnits so having a
      dedicated (documented) type is helpful.
      
      Finally in #14335 we will also need to handle the case where we have no
      HomeUnit at all because we are only loading existing interfaces for
      plugins which live in a different space compared to units used to
      produce target code. Several functions will have to be refactored to
      accept "Maybe HomeUnit" parameters instead of implicitly querying the
      HomeUnit fields in DynFlags. Having a dedicated type will make this
      easier.
      
      Bump haddock submodule
      ffc0d578
    • Hécate Moonlight's avatar
      Re-add BangPatterns to CodePage.hs · cf97889a
      Hécate Moonlight authored
      cf97889a
    • Sebastian Graf's avatar
      PmCheck: Better long-distance info for where bindings (#18533) · 55dec4dc
      Sebastian Graf authored
      Where bindings can see evidence from the pattern match of the `GRHSs`
      they belong to, but not from anything in any of the guards (which belong
      to one of possibly many RHSs).
      
      Before this patch, we did *not* consider said evidence, causing #18533,
      where the lack of considering type information from a case pattern match
      leads to failure to resolve the vanilla COMPLETE set of a data type.
      
      Making available that information required a medium amount of
      refactoring so that `checkMatches` can return a
      `[(Deltas, NonEmpty Deltas)]`; one `(Deltas, NonEmpty Deltas)` for each
      `GRHSs` of the match group. The first component of the pair is the
      covered set of the pattern, the second component is one covered set per
      RHS.
      
      Fixes #18533.
      Regression test case: T18533
      55dec4dc
    • Ben Gamari's avatar
      parser: Suggest ImportQualifiedPost in prepositive import warning · 7831fe05
      Ben Gamari authored
      As suggested in #18545.
      7831fe05
    • Alan Zimmerman's avatar
      25fdf25e
    • Sylvain Henry's avatar
      Rewrite and move the monad-state hack note · bee43aca
      Sylvain Henry authored
      The note has been rewritten by @simonpj in !3851
      
      [skip ci]
      bee43aca
  4. 12 Aug, 2020 6 commits
    • Ben Gamari's avatar
      testsuite: Increase tolerance of T16916 · db6dd810
      Ben Gamari authored
      T16916 (testing #16916) has been slightly fragile in CI due to its
      reliance on CPU times. While it's hard to see how to eliminate
      the time-dependence entirely, we can nevertheless make it more tolerant.
      
      Fixes #16966.
      db6dd810
    • Sylvain Henry's avatar
      DynFlags: disentangle Outputable · accbc242
      Sylvain Henry authored
      - put panic related functions into GHC.Utils.Panic
      - put trace related functions using DynFlags in GHC.Driver.Ppr
      
      One step closer making Outputable fully independent of DynFlags.
      
      Bump haddock submodule
      accbc242
    • Ben Gamari's avatar
      testsuite: Specify metrics collected by T17516 · f1088b3f
      Ben Gamari authored
      Previously it collected everything, including "max bytes used". This is
      problematic since the test makes no attempt to control for deviations in
      GC timing, resulting in high variability. Fix this by only collecting
      "bytes allocated".
      f1088b3f
    • Sven Tennie's avatar
      Add hie.yaml to ghc-heap · c43078d7
      Sven Tennie authored
      This enables IDE support by haskell-language-server for ghc-heap.
      c43078d7
    • Ben Gamari's avatar
      testsuite: Add test for #18118 · 0ac8c0a5
      Ben Gamari authored
      0ac8c0a5
    • Ben Gamari's avatar
      typecheck: Drop SPECIALISE pragmas when there is no unfolding · ab4d1589
      Ben Gamari authored
      Previously the desugarer would instead fall over when it realized that
      there was no unfolding for an imported function with a SPECIALISE
      pragma. We now rather drop the SPECIALISE pragma and throw a warning.
      
      Fixes #18118.
      ab4d1589
  5. 11 Aug, 2020 3 commits
  6. 10 Aug, 2020 2 commits
  7. 09 Aug, 2020 1 commit
  8. 08 Aug, 2020 2 commits
  9. 07 Aug, 2020 7 commits
  10. 06 Aug, 2020 7 commits
    • Takenobu Tani's avatar
      users-guide: Rename 8.12 to 9.0 · 9570c212
      Takenobu Tani authored
      GHC 8.12.1 has been renamed to GHC 9.0.1.
      
      See also:
        https://mail.haskell.org/pipermail/ghc-devs/2020-July/019083.html
      
      [skip ci]
      9570c212
    • Sylvain Henry's avatar
      Use a type alias for Ways · 63348155
      Sylvain Henry authored
      63348155
    • Richard Eisenberg's avatar
      Fail eagerly on a lev-poly datacon arg · d2a43225
      Richard Eisenberg authored
      Close #18534.
      
      See commentary in the patch.
      d2a43225
    • Vladislav Zavialov's avatar
      Fix visible forall in ppr_ty (#18522) · 0ddb4384
      Vladislav Zavialov authored
      Before this patch, this type:
        T :: forall k -> (k ~ k) => forall j -> k -> j -> Type
      was printed incorrectly as:
        T :: forall k j -> (k ~ k) => k -> j -> Type
      0ddb4384
    • Vladislav Zavialov's avatar
      Fix debug_ppr_ty ForAllTy (#18522) · 826d07db
      Vladislav Zavialov authored
      Before this change, GHC would
      pretty-print   forall k. forall a -> ()
                as   forall @k a. ()
      which isn't even valid Haskell.
      826d07db
    • Vladislav Zavialov's avatar
      Clean up the story around runPV/runECP_P/runECP_PV · 6770e199
      Vladislav Zavialov authored
      This patch started as a small documentation change, an attempt to make
      Note [Parser-Validator] and Note [Ambiguous syntactic categories]
      more clear and up-to-date.
      
      But it turned out that runECP_P/runECP_PV are weakly motivated,
      and it's easier to remove them than to find a good rationale/explanation
      for their existence.
      
      As the result, there's a bit of refactoring in addition to
      a documentation update.
      6770e199
    • Vladislav Zavialov's avatar
      Grammar for types and data/newtype constructors · 686e06c5
      Vladislav Zavialov authored
      Before this patch, we parsed types into a reversed sequence
      of operators and operands. For example, (F x y + G a b * X)
      would be parsed as [X, *, b, a, G, +, y, x, F],
      using a simple grammar:
      
      	tyapps
      	  : tyapp
      	  | tyapps tyapp
      
      	tyapp
      	  : atype
      	  | PREFIX_AT atype
      	  | tyop
      	  | unpackedness
      
      Then we used a hand-written state machine to assemble this
       either into a type,        using 'mergeOps',
           or into a constructor, using 'mergeDataCon'.
      
      This is due to a syntactic ambiguity:
      
      	data T1 a =          MkT1 a
      	data T2 a = Ord a => MkT2 a
      
      In T1, what follows after the = sign is a data/newtype constructor
      declaration. However, in T2, what follows is a type (of kind
      Constraint). We don't know which of the two we are parsing until we
      encounter =>, and we cannot check for => without unlimited lookahead.
      
      This poses a few issues when it comes to e.g. infix operators:
      
      	data I1 = Int :+ Bool :+ Char          -- bad
      	data I2 = Int :+ Bool :+ Char => MkI2  -- fine
      
      By this issue alone we are forced into parsing into an intermediate
      representation and doing a separate validation pass.
      
      However, should that intermediate representation be as low-level as a
      flat sequence of operators and operands?
      
      Before GHC Proposal #229, the answer was Yes, due to some particularly
      nasty corner cases:
      
      	data T = ! A :+ ! B          -- used to be fine, hard to parse
      	data T = ! A :+ ! B => MkT   -- bad
      
      However, now the answer is No, as this corner case is gone:
      
      	data T = ! A :+ ! B          -- bad
      	data T = ! A :+ ! B => MkT   -- bad
      
      This means we can write a proper grammar for types, overloading it in
      the DisambECP style, see Note [Ambiguous syntactic categories].
      
      With this patch, we introduce a new class, DisambTD. Just like
      DisambECP is used to disambiguate between expressions, commands, and patterns,
      DisambTD  is used to disambiguate between types and data/newtype constructors.
      
      This way, we get a proper, declarative grammar for constructors and
      types:
      
      	infixtype
      	  : ftype
      	  | ftype tyop infixtype
      	  | unpackedness infixtype
      
      	ftype
      	  : atype
      	  | tyop
      	  | ftype tyarg
      	  | ftype PREFIX_AT tyarg
      
      	tyarg
      	  : atype
      	  | unpackedness atype
      
      And having a grammar for types means we are a step closer to using a
      single grammar for types and expressions.
      686e06c5
  11. 05 Aug, 2020 2 commits
    • Ryan Scott's avatar
      Make CodeQ and TExpQ levity polymorphic · fbcb886d
      Ryan Scott authored
      The patch is quite straightforward. The only tricky part is that
      `Language.Haskell.TH.Lib.Internal` now must be `Trustworthy` instead
      of `Safe` due to the `GHC.Exts` import (in order to import `TYPE`).
      
      Since `CodeQ` has yet to appear in any released version of
      `template-haskell`, I didn't bother mentioning the change to `CodeQ`
      in the `template-haskell` release notes.
      
      Fixes #18521.
      fbcb886d
    • Hécate Moonlight's avatar
      eb7013c3