- Dec 18, 2020
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Issue #18914 revealed that `GeneralizedNewtypeDeriving` would generate code that mentions unbound type variables, which is dangerously fragile. The problem (and fix) is described in the new `Wrinkle: Use HsOuterExplicit` in `Note [GND and QuantifiedConstraints]`. The gist of it: make sure to put the top-level `forall`s in `deriving`-generated instance signatures in an `HsOuterExplicit` to ensure that they scope over the bodies of methods correctly. A side effect of this process is that it will expand any type synonyms in the instance signature, which will surface any `forall`s that are hidden underneath type synonyms (such as in the test case for #18914). While I was in town, I also performed some maintenance on `NewHsTypeX`, which powers `GeneralizedNewtypeDeriving`: * I renamed `NewHsTypeX` to `HsCoreTy`, which more accurately describes its intended purpose (#15706). I also made `HsCoreTy` a type synonym instead of a newtype, as making it a distinct data type wasn't buying us much. * To make sure that mistakes similar to #18914 do not occur later, I added an additional validity check when renaming `HsCoreTy`s that complains if an `HsCoreTy`s contains an out-of-scope type variable. See the new `Note [Renaming HsCoreTys]` in `GHC.Rename.HsType` for the details. Fixes #15706. Fixes #18914. Bumps the `haddock` submodule.
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- Dec 17, 2020
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See commentary in tcCheckUsage. Close #18998. Test case: typecheck/should_compile/T18998
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Needed for ghc/ghc#15656 as it stops the packages triggering incomplete-uni-patterns and incomplete-record-updates
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Commit e63518f5 tried to push all of the logic of detecting out-of-scope type variables on the RHSes of associated type family instances to `GHC.Tc.Validity` by deleting a similar check in the renamer. Unfortunately, this commit went a little too far, as there are some corner cases that `GHC.Tc.Validity` doesn't detect. Consider this example: ```hs class C a where data D a instance forall a. C Int where data instance D Int = MkD a ``` If this program isn't rejected by the time it reaches the typechecker, then GHC will believe the `a` in `MkD a` is existentially quantified and accept it. This is almost surely not what the user wants! The simplest way to reject programs like this is to restore the old validity check in the renamer (search for `improperly_scoped` in `rnFamEqn`). Note that this is technically a breaking change, since the program in the `polykinds/T9574` test case (which previously compiled) will now be rejected: ```hs instance Funct ('KProxy :: KProxy o) where type Codomain 'KProxy = NatTr (Proxy :: o -> *) ``` This is because the `o` on the RHS will now be rejected for being out of scope. Luckily, this is simple to repair: ```hs instance Funct ('KProxy :: KProxy o) where type Codomain ('KProxy @o) = NatTr (Proxy :: o -> *) ``` All of the discussion is now a part of the revamped `Note [Renaming associated types]` in `GHC.Rename.Module`. A different design would be to make associated type family instances have completely separate scoping from the parent instance declaration, much like how associated type family default declarations work today. See the discussion beginning at #18021 (comment 265729) for more on this point. This, however, would break even more programs that are accepted today and likely warrants a GHC proposal before going forward. In the meantime, this patch fixes the issue described in #18021 in the least invasive way possible. There are programs that are accepted today that will no longer be accepted after this patch, but they are arguably pathological programs, and they are simple to repair. Fixes #18021.
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Usually pre-compiled code is preferred to be loaded in ghci if available, which means that if we try to load module with '*' prefix and compilation artifacts are available on disc (.o and .hi files) or the source code was untouched, the driver would think no recompilation is required. Therefore, we need to force recompilation so that desired byte-code is generated and loaded. Forcing in this case should be ok, since this is what happens for interpreted code anyways when reloading modules.
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- Dec 16, 2020
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GHC GitLab CI authored
To adapt haddock for the nullary tyconapp optimisation patch.
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- Dec 15, 2020
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Ben Gamari authored
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Ben Gamari authored
Updates haddock submodule to revert a commit that does not build.
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Ben Gamari authored
This was inadvertently merged. This reverts commit 6c2eb223.
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Ben Gamari authored
Due to #18548.
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- Dec 14, 2020
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This implements the BoxedRep proposal, refacoring the `RuntimeRep` hierarchy from: ```haskell data RuntimeRep = LiftedPtrRep | UnliftedPtrRep | ... ``` to ```haskell data RuntimeRep = BoxedRep Levity | ... data Levity = Lifted | Unlifted ``` Closes #17526.
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Ben Gamari authored
During the compilation of programs GHC very frequently deals with the `Type` type, which is a synonym of `TYPE 'LiftedRep`. This patch teaches GHC to avoid expanding the `Type` synonym (and other nullary type synonyms) during type comparisons, saving a good amount of work. This optimisation is described in `Note [Comparing nullary type synonyms]`. To maximize the impact of this optimisation, we introduce a few special-cases to reduce `TYPE 'LiftedRep` to `Type`. See `Note [Prefer Type over TYPE 'LiftedPtrRep]`. Closes #17958. Metric Decrease: T18698b T1969 T12227 T12545 T12707 T14683 T3064 T5631 T5642 T9020 T9630 T9872a T13035 haddock.Cabal haddock.base
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Andreas Klebinger authoredThe naive way of putting out n characters of indent would be something like `hPutStr hdl (replicate n ' ')`. However this is quite inefficient as we allocate an absurd number of strings consisting of simply spaces as we don't cache them. To improve on this we now track if we can simply write ascii spaces via hPutBuf instead. This is the case when running with -ddump-to-file where we force the encoding to be UTF8. This avoids both the cost of going through encoding as well as avoiding allocation churn from all the white space. Instead we simply use hPutBuf on a preallocated unlifted string. When dumping stg like this: > nofib/spectral/simple/Main.hs -fforce-recomp -ddump-stg-final -ddump-to-file -c +RTS -s Allocations went from 1,778 MB to 1,702MB. About a 4% reduction of allocation! I did not measure the difference in runtime but expect it to be similar. Bumps the haddock submodule since the interface of GHC's Pretty slightly changed. ------------------------- Metric Decrease: T12227 ------------------------- -
Sylvain Henry authored
The unit database cache, the home unit and the unit state were stored in DynFlags while they ought to be stored in the compiler session state (HscEnv). This patch fixes this. It introduces a new UnitEnv type that should be used in the future to handle separate unit environments (especially host vs target units). Related to #17957 Bump haddock submodule
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Ben Gamari authored
This was inadvertently merged. This reverts commit 7e9debd4.
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Ben Gamari authored
During the compilation of programs GHC very frequently deals with the `Type` type, which is a synonym of `TYPE 'LiftedRep`. This patch teaches GHC to avoid expanding the `Type` synonym (and other nullary type synonyms) during type comparisons, saving a good amount of work. This optimisation is described in `Note [Comparing nullary type synonyms]`. To maximize the impact of this optimisation, we introduce a few special-cases to reduce `TYPE 'LiftedRep` to `Type`. See `Note [Prefer Type over TYPE 'LiftedPtrRep]`. Closes #17958. Metric Decrease: T18698b T1969 T12227 T12545 T12707 T14683 T3064 T5631 T5642 T9020 T9630 T9872a T13035 haddock.Cabal haddock.base
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The haddock submodule is also updated so that it understands the changes to patterns.
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- Dec 13, 2020
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- Dec 12, 2020
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adam authored
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Both sub-demands encode the same information. This is a trivial change and already affects a few regression tests (e.g. `T5075`), so no separate regression test is necessary.
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It's useful to annotate a non-exported top-level function like `g` in ```hs module Lib (h) where g :: Int -> Int -> (Int,Int) g m 1 = (m, 0) g m n = (2 * m, 2 `div` n) {-# NOINLINE g #-} h :: Int -> Int h 1 = 0 h m | odd m = snd (g m 2) | otherwise = uncurry (+) (g 2 m) ``` with its demand `UCU(CS(P(1P(U),SP(U))`, which tells us that whenever `g` was called, the second component of the returned pair was evaluated strictly. Since #18903 we do so for local functions, where we can see all calls. For top-level functions, we can assume that all *exported* functions are demanded according to `topDmd` and thus get sound demands for non-exported top-level functions. The demand on `g` is crucial information for Nested CPR, which may the go on and unbox `g` for the second pair component. That is true even if that pair component may diverge, as is the case for the call site `g 13 0`, which throws a div-by-zero exception. In `T18894b`, you can even see the new demand annotation enabling us to eta-expand a function that we wouldn't be able to eta-expand without Call Arity. We only track bindings of function type in order not to risk huge compile-time regressions, see `isInterestingTopLevelFn`. There was a CoreLint check that rejected strict demand annotations on recursive or top-level bindings, which seems completely unjustified. All the cases I investigated were fine, so I removed it. Fixes #18894. -
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Move code unrelated to runtime evaluation out of GHC.Runtime.Eval
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Fix parsing of "libffi-3.3.tar.gz". NB: switch to a newer libffi isn't done in this patch
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Consider the following code: proc (C x y) -> ... Before this patch, the evidence binding for the Arrow dictionary was attached to the C pattern: proc (C x y) { $dArrow = ... } -> ... But then when we desugar this, we use arrow operations ("arr", ">>>"...) specialised for this arrow: let arr_xy = arr $dArrow -- <-- Not in scope! ... in arr_xy (\(C x y) { $dArrow = ... } -> ...) This patch allows arrow operations to be type-checked before the proc itself, avoiding this issue. Fix #17423 -
This Note has severely bitrotted, as it has no references anywhere in the codebase, and none of the functions that it mentions exist anymore. Let's just delete this. While I was in town, I deleted some outdated comments from `checkFamPatBinders` of a similar caliber. Fixes #19008. [ci skip]
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- Dec 11, 2020
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Tests that the output of the `:doc` command is correct for duplicate record fields defined using -XDuplicateRecordFields.
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Do not print `<has no documentation>` alongside a valid doc. Additionally, if two matching symbols lack documentation then the message will only be printed once. Hence, `<has no documentation>` will be printed at most once and only if all matching symbols are lacking docs.
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It looks like I neglected to update this after introduce flavour transformers.
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Also refactor the job definition to eliminate the bug by construction.
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