1. 07 Aug, 2020 8 commits
  2. 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:
      [skip ci]
    • Sylvain Henry's avatar
      Use a type alias for Ways · 63348155
      Sylvain Henry authored
    • Richard Eisenberg's avatar
      Fail eagerly on a lev-poly datacon arg · d2a43225
      Richard Eisenberg authored
      Close #18534.
      See commentary in the patch.
    • 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
    • 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.
    • 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.
    • 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:
      	  : tyapp
      	  | tyapps 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
      	  : ftype
      	  | ftype tyop infixtype
      	  | unpackedness infixtype
      	  : atype
      	  | tyop
      	  | ftype tyarg
      	  | ftype PREFIX_AT 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.
  3. 05 Aug, 2020 7 commits
  4. 03 Aug, 2020 2 commits
    • Alex Biehl's avatar
    • Niklas Hambüchen's avatar
      hadrian: Fix running stage0/bin/ghc with wrong package DB. Fixes #17468. · 947206f4
      Niklas Hambüchen authored
      In the invocation of `cabal configure`, `--ghc-pkg-option=--global-package-db`
      was already given correctly to tell `stage0/bin/ghc-pkg` that it should use
      the package DB in `stage1/`.
      However, `ghc` needs to be given this information as well, not only `ghc-pkg`!
      Until now that was not the case; the package DB in `stage0` was given to
      `ghc` instead.
      This was wrong, because there is no binary compatibility guarantee that says
      that the `stage0` DB's `package.cache` (which is written by the
      stage0 == system-provided ghc-pkg) can be deserialised by the `ghc-pkg`
      from the source code tree.
      As a result, when trying to add fields to `InstalledPackageInfo` that get
      serialised into / deserialised from the `package.cache`, errors like
          _build/stage0/lib/package.conf.d/package.cache: GHC.PackageDb.readPackageDb: inappropriate type (Not a valid Unicode code point!)
      would appear. This was because the `stage0/bin/ghc would try to
      deserialise the newly added fields from
      `_build/stage0/lib/package.conf.d/package.cache`, but they were not in there
      because the system `ghc-pkg` doesn't know about them and thus didn't write them
      It would try to do that because any GHC by default tries to read the global
      package db in `../lib/package.conf.d/package.cache`.
      For `stage0/bin/ghc` that *can never work* as explained above, so we
      must disable this default via `-no-global-package-db` and give it the
      correct package DB explicitly.
      This is the same problem as #16534, and the same fix as in MR !780
      (but in another context; that one was for developers trying out the
      `stage0/bin/ghc` == `_build/ghc-stage1` interactively, while this fix
      is for a `cabal configure` invocation).
      I also noticed that the fix for #16534 forgot to pass `-no-global-package-db`,
      and have fixed that in this commit as well.
      It only worked until now because nobody tried to add a new ghc-pkg `.conf`
      field since the introduction of Hadrian.
  5. 02 Aug, 2020 2 commits
  6. 01 Aug, 2020 1 commit
  7. 31 Jul, 2020 5 commits
  8. 30 Jul, 2020 6 commits
    • Simon Peyton Jones's avatar
      Add two bangs to improve perf of flattening · 9f71f697
      Simon Peyton Jones authored
      This tiny patch improves the compile time of flatten-heavy
      programs by 1-2%, by adding two bangs.
      Addresses (somewhat) #18502
      This reduces allocation by
         T9872b   -1.1%
         T9872d   -3.3%
         T5321Fun -0.2%
         T5631    -0.2%
         T5837    +0.1%
         T6048    +0.1%
      Metric Decrease:
    • Simon Peyton Jones's avatar
      Remove an incorrect WARN in extendLocalRdrEnv · ebe2cf45
      Simon Peyton Jones authored
      I noticed this warning going off, and discovered that it's
      really fine.  This small patch removes the warning, and docments
      what is going on.
    • Ryan Scott's avatar
      Don't mark closed type family equations as occurrences · d47324ce
      Ryan Scott authored
      Previously, `rnFamInstEqn` would mark the name of the type/data
      family used in an equation as an occurrence, regardless of what sort
      of family it is. Most of the time, this is the correct thing to do.
      The exception is closed type families, whose equations constitute its
      definition and therefore should not be marked as occurrences.
      Overzealously counting the equations of a closed type family as
      occurrences can cause certain warnings to not be emitted, as observed
      in #18470.  See `Note [Type family equations and occurrences]` in
      `GHC.Rename.Module` for the full story.
      This fixes #18470 with a little bit of extra-casing in
      `rnFamInstEqn`. To accomplish this, I added an extra
      `ClosedTyFamInfo` field to the `NonAssocTyFamEqn` constructor of
      `AssocTyFamInfo` and refactored the relevant call sites accordingly
      so that this information is propagated to `rnFamInstEqn`.
      While I was in town, I moved `wrongTyFamName`, which checks that the
      name of a closed type family matches the name in an equation for that
      family, from the renamer to the typechecker to avoid the need for an
      `ASSERT`. As an added bonus, this lets us simplify the details of
      `ClosedTyFamInfo` a bit.
    • Ryan Scott's avatar
      Clean up the inferred type variable restriction · 01c948eb
      Ryan Scott authored
      This patch primarily:
      * Documents `checkInferredVars` (previously called
        `check_inferred_vars`) more carefully. This is the
        function which throws an error message if a user quantifies an
        inferred type variable in a place where specificity cannot be
        observed. See `Note [Unobservably inferred type variables]` in
        Note that I now invoke `checkInferredVars` _alongside_
        `rnHsSigType`, `rnHsWcSigType`, etc. rather than doing so _inside_
        of these functions. This results in slightly more call sites for
        `checkInferredVars`, but it makes it much easier to enumerate the
        spots where the inferred type variable restriction comes into
      * Removes the inferred type variable restriction for default method
        type signatures, per the discussion in #18432. As a result, this
        patch fixes #18432.
      Along the way, I performed some various cleanup:
      * I moved `no_nested_foralls_contexts_err` into `GHC.Rename.Utils`
        (under the new name `noNestedForallsContextsErr`), since it now
        needs to be invoked from multiple modules. I also added a helper
        function `addNoNestedForallsContextsErr` that throws the error
        message after producing it, as this is a common idiom.
      * In order to ensure that users cannot sneak inferred type variables
        into `SPECIALISE instance` pragmas by way of nested `forall`s, I
        now invoke `addNoNestedForallsContextsErr` when renaming
        `SPECIALISE instance` pragmas, much like when we rename normal
        instance declarations. (This probably should have originally been
        done as a part of the fix for #18240, but this task was somehow
        overlooked.) As a result, this patch fixes #18455 as a side effect.
    • cgibbard's avatar
      Add haddock comment for unfilteredEdges · 502de556
      cgibbard authored
      and move the note about drop_hs_boot_nodes into it.
    • John Ericson's avatar
      For `-fkeep-going` do not duplicate dependency edge code · 6c68a842
      John Ericson authored
      We now compute the deps for `-fkeep-going` the same way that the
      original graph calculates them, so the edges are correct. Upsweep really
      ought to take the graph rather than a topological sort so we are never
      recalculating anything, but at least things are recaluclated
      consistently now.
  9. 29 Jul, 2020 2 commits
    • Krzysztof Gogolewski's avatar
      Fix validation errors (#18510) · e1dc3d7b
      Krzysztof Gogolewski authored
      Test T2632 is a stage1 test that failed because of the Q => Quote change.
      The remaining tests did not use quotation and failed when the path
      contained a space.
    • Sylvain Henry's avatar
      Fix bug in Natural multiplication (fix #18509) · 96c31ea1
      Sylvain Henry authored
      A bug was lingering in Natural multiplication (inverting two limbs)
      despite QuickCheck tests used during the development leading to wrong
      results (independently of the selected backend).