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* Module hierarchy: Renamer (cf #13009)Sylvain Henry2020-01-081-2415/+0
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* Fix more typosBrian Wignall2019-12-021-1/+1
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* Remove HasSrcSpan (#17494)Vladislav Zavialov2019-11-301-78/+74
| | | | | Metric Decrease: haddock.compiler
* Fix typos, using Wikipedia list of common typosBrian Wignall2019-11-281-1/+1
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* Break up TcRnTypes, among other modules.Richard Eisenberg2019-10-161-1/+1
| | | | | | | | | | | | | | | | | | | | | This introduces three new modules: - basicTypes/Predicate.hs describes predicates, moving this logic out of Type. Predicates don't really exist in Core, and so don't belong in Type. - typecheck/TcOrigin.hs describes the origin of constraints and types. It was easy to remove from other modules and can often be imported instead of other, scarier modules. - typecheck/Constraint.hs describes constraints as used in the solver. It is taken from TcRnTypes. No work other than module splitting is in this patch. This is the first step toward homogeneous equality, which will rely more strongly on predicates. And homogeneous equality is the next step toward a dependently typed core language.
* Solve constraints from top-level groups soonerRichard Eisenberg2019-10-081-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | Previously, all constraints from all top-level groups (as separated by top-level splices) were lumped together and solved at the end. This could leak metavariables to TH, though, and that's bad. This patch solves each group's constraints before running the next group's splice. Naturally, we now report fewer errors in some cases. One nice benefit is that this also fixes #11680, but in a much simpler way than the original fix for that ticket. Admittedly, the error messages degrade just a bit from the fix from #11680 (previously, we informed users about variables that will be brought into scope below a top-level splice, and now we just report an out-of-scope error), but the amount of complexity required throughout GHC to get that error was just not worth it. This patch thus reverts much of f93c9517a2c6e158e4a5c5bc7a3d3f88cb4ed119. Fixes #16980 Test cases: th/T16980{,a}
* Standalone kind signatures (#16794)wip/top-level-kind-signaturesVladislav Zavialov2019-09-251-38/+127
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Implements GHC Proposal #54: .../ghc-proposals/blob/master/proposals/0054-kind-signatures.rst With this patch, a type constructor can now be given an explicit standalone kind signature: {-# LANGUAGE StandaloneKindSignatures #-} type Functor :: (Type -> Type) -> Constraint class Functor f where fmap :: (a -> b) -> f a -> f b This is a replacement for CUSKs (complete user-specified kind signatures), which are now scheduled for deprecation. User-facing changes ------------------- * A new extension flag has been added, -XStandaloneKindSignatures, which implies -XNoCUSKs. * There is a new syntactic construct, a standalone kind signature: type <name> :: <kind> Declarations of data types, classes, data families, type families, and type synonyms may be accompanied by a standalone kind signature. * A standalone kind signature enables polymorphic recursion in types, just like a function type signature enables polymorphic recursion in terms. This obviates the need for CUSKs. * TemplateHaskell AST has been extended with 'KiSigD' to represent standalone kind signatures. * GHCi :info command now prints the kind signature of type constructors: ghci> :info Functor type Functor :: (Type -> Type) -> Constraint ... Limitations ----------- * 'forall'-bound type variables of a standalone kind signature do not scope over the declaration body, even if the -XScopedTypeVariables is enabled. See #16635 and #16734. * Wildcards are not allowed in standalone kind signatures, as partial signatures do not allow for polymorphic recursion. * Associated types may not be given an explicit standalone kind signature. Instead, they are assumed to have a CUSK if the parent class has a standalone kind signature and regardless of the -XCUSKs flag. * Standalone kind signatures do not support multiple names at the moment: type T1, T2 :: Type -> Type -- rejected type T1 = Maybe type T2 = Either String See #16754. * Creative use of equality constraints in standalone kind signatures may lead to GHC panics: type C :: forall (a :: Type) -> a ~ Int => Constraint class C a where f :: C a => a -> Int See #16758. Implementation notes -------------------- * The heart of this patch is the 'kcDeclHeader' function, which is used to kind-check a declaration header against its standalone kind signature. It does so in two rounds: 1. check user-written binders 2. instantiate invisible binders a la 'checkExpectedKind' * 'kcTyClGroup' now partitions declarations into declarations with a standalone kind signature or a CUSK (kinded_decls) and declarations without either (kindless_decls): * 'kinded_decls' are kind-checked with 'checkInitialKinds' * 'kindless_decls' are kind-checked with 'getInitialKinds' * DerivInfo has been extended with a new field: di_scoped_tvs :: ![(Name,TyVar)] These variables must be added to the context in case the deriving clause references tcTyConScopedTyVars. See #16731.
* Module hierarchy: Hs (#13009)Sylvain Henry2019-09-201-3/+3
| | | | | | | Add GHC.Hs module hierarchy replacing hsSyn. Metric Increase: haddock.compiler
* Remove Bag fold specialisations (#16969)Richard Lupton2019-08-191-1/+1
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* Banish reportFloatingViaTvs to the shadow realm (#15831, #16181)Ryan Scott2019-07-261-81/+19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | GHC used to reject programs of this form: ``` newtype Age = MkAge Int deriving Eq via Const Int a ``` That's because an earlier implementation of `DerivingVia` would generate the following instance: ``` instance Eq Age where (==) = coerce @(Const Int a -> Const Int a -> Bool) @(Age -> Age -> Bool) (==) ``` Note that the `a` in `Const Int a` is not bound anywhere, which causes all sorts of issues. I figured that no one would ever want to write code like this anyway, so I simply banned "floating" `via` type variables like `a`, checking for their presence in the aptly named `reportFloatingViaTvs` function. `reportFloatingViaTvs` ended up being implemented in a subtly incorrect way, as #15831 demonstrates. Following counsel with the sage of gold fire, I decided to abandon `reportFloatingViaTvs` entirely and opt for a different approach that would _accept_ the instance above. This is because GHC now generates this instance instead: ``` instance forall a. Eq Age where (==) = coerce @(Const Int a -> Const Int a -> Bool) @(Age -> Age -> Bool) (==) ``` Notice that we now explicitly quantify the `a` in `instance forall a. Eq Age`, so everything is peachy scoping-wise. See `Note [Floating `via` type variables]` in `TcDeriv` for the full scoop. A pleasant benefit of this refactoring is that it made it much easier to catch the problem observed in #16181, so this patch fixes that issue too. Fixes #15831. Fixes #16181.
* Make DefUses = OrdList DefUseRyan Scott2019-07-251-1/+2
| | | | | | | | | Before, `type DefUses = [DefUse]`. But lists are a terrible choice of data structure here, as we frequently append to the right of a `DefUses`, which yields some displeasing asymptotics. Let's instead use `OrdList`, which has constant-time appending to the right. This is one step on the way to #10347.
* Drop the orphan roles check (#16941)Vladislav Zavialov2019-07-191-34/+11
| | | | | | | | 9366e019 introduced a check for orphan roles to fix #8485 6ab5da99 changed the lookup code and made the check redundant. Now it is removed.
* Use an empty data type in TTG extension constructors (#15247)Ryan Scott2019-07-091-65/+65
| | | | | | | | | | | | | | | To avoid having to `panic` any time a TTG extension constructor is consumed, this MR introduces an uninhabited 'NoExtCon' type and uses that in every extension constructor's type family instance where it is appropriate. This also introduces a 'noExtCon' function which eliminates a 'NoExtCon', much like 'Data.Void.absurd' eliminates a 'Void'. I also renamed the existing `NoExt` type to `NoExtField` to better distinguish it from `NoExtCon`. Unsurprisingly, there is a lot of code churn resulting from this. Bumps the Haddock submodule. Fixes #15247.
* Implement the -XUnliftedNewtypes extension.Andrew Martin2019-06-141-7/+47
| | | | | | | | | | | | | | | | | | | | | | | | | | | GHC Proposal: 0013-unlifted-newtypes.rst Discussion: https://github.com/ghc-proposals/ghc-proposals/pull/98 Issues: #15219, #1311, #13595, #15883 Implementation Details: Note [Implementation of UnliftedNewtypes] Note [Unifying data family kinds] Note [Compulsory newtype unfolding] This patch introduces the -XUnliftedNewtypes extension. When this extension is enabled, GHC drops the restriction that the field in a newtype must be of kind (TYPE 'LiftedRep). This allows types like Int# and ByteArray# to be used in a newtype. Additionally, coerce is made levity-polymorphic so that it can be used with newtypes over unlifted types. The bulk of the changes are in TcTyClsDecls.hs. With -XUnliftedNewtypes, getInitialKind is more liberal, introducing a unification variable to return the kind (TYPE r0) rather than just returning (TYPE 'LiftedRep). When kind-checking a data constructor with kcConDecl, we attempt to unify the kind of a newtype with the kind of its field's type. When typechecking a data declaration with tcTyClDecl, we again perform a unification. See the implementation note for more on this. Co-authored-by: Richard Eisenberg <rae@richarde.dev>
* Use HsTyPats in associated type family defaultsRyan Scott2019-05-221-51/+47
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | Associated type family default declarations behave strangely in a couple of ways: 1. If one tries to bind the type variables with an explicit `forall`, the `forall`'d part will simply be ignored. (#16110) 2. One cannot use visible kind application syntax on the left-hand sides of associated default equations, unlike every other form of type family equation. (#16356) Both of these issues have a common solution. Instead of using `LHsQTyVars` to represent the left-hand side arguments of an associated default equation, we instead use `HsTyPats`, which is what other forms of type family equations use. In particular, here are some highlights of this patch: * `FamEqn` is no longer parameterized by a `pats` type variable, as the `feqn_pats` field is now always `HsTyPats`. * The new design for `FamEqn` in chronicled in `Note [Type family instance declarations in HsSyn]`. * `TyFamDefltEqn` now becomes the same thing as `TyFamInstEqn`. This means that many of `TyFamDefltEqn`'s code paths can now reuse the code paths for `TyFamInstEqn`, resulting in substantial simplifications to various parts of the code dealing with associated type family defaults. Fixes #16110 and #16356.
* Guard CUSKs behind a language pragmaVladislav Zavialov2019-05-141-1/+2
| | | | | | | | | | | | | | GHC Proposal #36 describes a transition plan away from CUSKs and to top-level kind signatures: 1. Introduce a new extension, -XCUSKs, on by default, that detects CUSKs as they currently exist. 2. We turn off the -XCUSKs extension in a few releases and remove it sometime thereafter. This patch implements phase 1 of this plan, introducing a new language extension to control whether CUSKs are enabled. When top-level kind signatures are implemented, we can transition to phase 2.
* base: Remove `Monad(fail)` method and reexport `MonadFail(fail)` insteadHerbert Valerio Riedel2019-03-221-43/+0
| | | | | | As per https://prime.haskell.org/wiki/Libraries/Proposals/MonadFail Coauthored-by: Ben Gamari <ben@well-typed.com>
* Update Trac ticket URLs to point to GitLabRyan Scott2019-03-151-11/+11
| | | | | This moves all URL references to Trac tickets to their corresponding GitLab counterparts.
* Stop inferring over-polymorphic kindsSimon Peyton Jones2019-03-091-3/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | Before this patch GHC was trying to be too clever (Trac #16344); it succeeded in kind-checking this polymorphic-recursive declaration data T ka (a::ka) b = MkT (T Type Int Bool) (T (Type -> Type) Maybe Bool) As Note [No polymorphic recursion] discusses, the "solution" was horribly fragile. So this patch deletes the key lines in TcHsType, and a wodge of supporting stuff in the renamer. There were two regressions, both the same: a closed type family decl like this (T12785b) does not have a CUSK: type family Payload (n :: Peano) (s :: HTree n x) where Payload Z (Point a) = a Payload (S n) (a `Branch` stru) = a To kind-check the equations we need a dependent kind for Payload, and we don't get that any more. Solution: make it a CUSK by giving the result kind -- probably a good thing anyway. The other case (T12442) was very similar: a close type family declaration without a CUSK.
* Be more careful when naming TyCon bindersSimon Peyton Jones2019-03-051-3/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch fixes two rather gnarly test cases: * Trac #16342 (mutual recursion) See Note [Tricky scoping in generaliseTcTyCon] * Trac #16221 (shadowing) See Note [Unification variables need fresh Names] The main changes are: * Substantial reworking of TcTyClsDecls.generaliseTcTyCon This is the big change, and involves the rather tricky function TcHsSyn.zonkRecTyVarBndrs. See Note [Inferring kinds for type declarations] and Note [Tricky scoping in generaliseTcTyCon] for the details. * bindExplicitTKBndrs_Tv and bindImplicitTKBndrs_Tv both now allocate /freshly-named/ unification variables. Indeed, more generally, unification variables are always fresh; see Note [Unification variables need fresh Names] in TcMType * Clarify the role of tcTyConScopedTyVars. See Note [Scoped tyvars in a TcTyCon] in TyCon As usual, this dragged in some more refactoring: * Renamed TcMType.zonkTyCoVarBndr to zonkAndSkolemise * I renamed checkValidTelescope to checkTyConTelescope; it's only used on TyCons, and indeed takes a TyCon as argument. * I folded the slightly-mysterious reportFloatingKvs into checkTyConTelescope. (Previously all its calls immediately followed a call to checkTyConTelescope.) It makes much more sense there. * I inlined some called-once functions to simplify checkValidTyFamEqn. It's less spaghetti-like now. * This patch also fixes Trac #16251. I'm not quite sure why #16251 went wrong in the first place, nor how this patch fixes it, but hey, it's good, and life is short.
* Treat kind/type variables identically, demolish FKTVVladislav Zavialov2019-02-271-10/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Implements GHC Proposal #24: .../ghc-proposals/blob/master/proposals/0024-no-kind-vars.rst Fixes Trac #16334, Trac #16315 With this patch, scoping rules for type and kind variables have been unified: kind variables no longer receieve special treatment. This simplifies both the language and the implementation. User-facing changes ------------------- * Kind variables are no longer implicitly quantified when an explicit forall is used: p :: Proxy (a :: k) -- still accepted p :: forall k a. Proxy (a :: k) -- still accepted p :: forall a. Proxy (a :: k) -- no longer accepted In other words, now we adhere to the "forall-or-nothing" rule more strictly. Related function: RnTypes.rnImplicitBndrs * The -Wimplicit-kind-vars warning has been deprecated. * Kind variables are no longer implicitly quantified in constructor declarations: data T a = T1 (S (a :: k) | forall (b::k). T2 (S b) -- no longer accepted data T (a :: k) = T1 (S (a :: k) | forall (b::k). T2 (S b) -- still accepted Related function: RnTypes.extractRdrKindSigVars * Implicitly quantified kind variables are no longer put in front of other variables: f :: Proxy (a :: k) -> Proxy (b :: j) f :: forall k j (a :: k) (b :: j). Proxy a -> Proxy b -- old order f :: forall k (a :: k) j (b :: j). Proxy a -> Proxy b -- new order This is a breaking change for users of TypeApplications. Note that we still respect the dpendency order: 'k' before 'a', 'j' before 'b'. See "Ordering of specified variables" in the User's Guide. Related function: RnTypes.rnImplicitBndrs * In type synonyms and type family equations, free variables on the RHS are no longer implicitly quantified unless used in an outermost kind annotation: type T = Just (Nothing :: Maybe a) -- no longer accepted type T = Just Nothing :: Maybe (Maybe a) -- still accepted The latter form is a workaround due to temporary lack of an explicit quantification method. Ideally, we would write something along these lines: type T @a = Just (Nothing :: Maybe a) Related function: RnTypes.extractHsTyRdrTyVarsKindVars * Named wildcards in kinds are fixed (Trac #16334): x :: (Int :: _t) -- this compiles, infers (_t ~ Type) Related function: RnTypes.partition_nwcs Implementation notes -------------------- * One of the key changes is the removal of FKTV in RnTypes: - data FreeKiTyVars = FKTV { fktv_kis :: [Located RdrName] - , fktv_tys :: [Located RdrName] } + type FreeKiTyVars = [Located RdrName] We used to keep track of type and kind variables separately, but now that they are on equal footing when it comes to scoping, we can put them in the same list. * extract_lty and family are no longer parametrized by TypeOrKind, as we now do not distinguish kind variables from type variables. * PatSynExPE and the related Note [Pattern synonym existentials do not scope] have been removed (Trac #16315). With no implicit kind quantification, we can no longer trigger the error. * reportFloatingKvs and the related Note [Free-floating kind vars] have been removed. With no implicit kind quantification, we can no longer trigger the error.
* Fix #16116 by removing badAssocRhsRyan Scott2019-01-151-15/+15
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* Fix #16114 by adding a validity check to rnClsInstDeclRyan Scott2019-01-151-6/+20
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* Add -Wmissing-deriving-strategieschessai2019-01-061-0/+25
| | | | | | | | | | | | | | | Warn users when -XDerivingStrategies is enabled but not used, at each potential use site. add -Wmissing-deriving-strategies Reviewers: bgamari, RyanGlScott Subscribers: andrewthad, rwbarton, carter GHC Trac Issues: #15798 Differential Revision: https://phabricator.haskell.org/D5451
* Visible kind applicationmynguyen2019-01-031-18/+13
| | | | | | | | | | | | | | | | | | | | | | | Summary: This patch implements visible kind application (GHC Proposal 15/#12045), as well as #15360 and #15362. It also refactors unnamed wildcard handling, and requires that type equations in type families in Template Haskell be written with full type on lhs. PartialTypeSignatures are on and warnings are off automatically with visible kind application, just like in term-level. There are a few remaining issues with this patch, as documented in ticket #16082. Includes a submodule update for Haddock. Test Plan: Tests T12045a/b/c/TH1/TH2, T15362, T15592a Reviewers: simonpj, goldfire, bgamari, alanz, RyanGlScott, Iceland_jack Subscribers: ningning, Iceland_jack, RyanGlScott, int-index, rwbarton, mpickering, carter GHC Trac Issues: `#12045`, `#15362`, `#15592`, `#15788`, `#15793`, `#15795`, `#15797`, `#15799`, `#15801`, `#15807`, `#15816` Differential Revision: https://phabricator.haskell.org/D5229
* Comments onlySimon Peyton Jones2018-12-211-2/+4
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* Fix #16002 by moving a validity check to the renamerRyan Scott2018-12-201-14/+43
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: The validity check which rejected things like: ```lang=haskell type family B x where A x = x ``` Used to live in the typechecker. But it turns out that this validity check was //only// being run on closed type families without CUSKs! This meant that GHC would silently accept something like this: ```lang=haskell type family B (x :: *) :: * where A x = x ``` This patch fixes the issue by moving this validity check to the renamer, where we can be sure that the check will //always// be run. Test Plan: make test TEST=T16002 Reviewers: simonpj, bgamari Reviewed By: simonpj Subscribers: goldfire, rwbarton, carter GHC Trac Issues: #16002 Differential Revision: https://phabricator.haskell.org/D5420
* Fix #15828, from `More explicit foralls`Matthew Yacavone2018-11-291-1/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: Fix a bug in commit 12eeb9 which permits the following: ``` class C a where type T a b instance C (Maybe a) where type forall a b. T (Maybe a) b = b ``` where instead, the user should write: ``` instance C (Maybe a) where type forall b. T (Maybe a) b = b ``` Update the users guide to discuss scoping of type variables in explicit foralls in type family instances. Test Plan: validate Reviewers: bgamari, goldfire, monoidal Reviewed By: goldfire Subscribers: monoidal, rwbarton, carter GHC Trac Issues: #15828 Differential Revision: https://phabricator.haskell.org/D5283
* [TTG: Handling Source Locations] Foundation and PatShayan-Najd2018-11-241-93/+112
| | | | | | | | | | | | | | | | | | This patch removes the ping-pong style from HsPat (only, for now), using the plan laid out at https://ghc.haskell.org/trac/ghc/wiki/ImplementingTreesThatGrow/HandlingSourceLocations (solution A). - the class `HasSrcSpan`, and its functions (e.g., `cL` and `dL`), are introduced - some instances of `HasSrcSpan` are introduced - some constructors `L` are replaced with `cL` - some patterns `L` are replaced with `dL->L` view pattern - some type annotation are necessarily updated (e.g., `Pat p` --> `Pat (GhcPass p)`) Phab diff: D5036 Trac Issues #15495 Updates haddock submodule
* Fix unused-import warningsDavid Eichmann2018-11-221-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch fixes a fairly long-standing bug (dating back to 2015) in RdrName.bestImport, namely commit 9376249b6b78610db055a10d05f6592d6bbbea2f Author: Simon Peyton Jones <simonpj@microsoft.com> Date: Wed Oct 28 17:16:55 2015 +0000 Fix unused-import stuff in a better way In that patch got the sense of the comparison back to front, and thereby failed to implement the unused-import rules described in Note [Choosing the best import declaration] in RdrName This led to Trac #13064 and #15393 Fixing this bug revealed a bunch of unused imports in libraries; the ones in the GHC repo are part of this commit. The two important changes are * Fix the bug in bestImport * Modified the rules by adding (a) in Note [Choosing the best import declaration] in RdrName Reason: the previosu rules made Trac #5211 go bad again. And the new rule (a) makes sense to me. In unravalling this I also ended up doing a few other things * Refactor RnNames.ImportDeclUsage to use a [GlobalRdrElt] for the things that are used, rather than [AvailInfo]. This is simpler and more direct. * Rename greParentName to greParent_maybe, to follow GHC naming conventions * Delete dead code RdrName.greUsedRdrName Bumps a few submodules. Reviewers: hvr, goldfire, bgamari, simonmar, jrtc27 Subscribers: rwbarton, carter Differential Revision: https://phabricator.haskell.org/D5312
* More explicit foralls (GHC Proposal 0007)Matthew Yacavone2018-10-271-43/+80
| | | | | | | | | | | | | | | | | | | | | | | | | | | Allow the user to explicitly bind type/kind variables in type and data family instances (including associated instances), closed type family equations, and RULES pragmas. Follows the specification of GHC Proposal 0007, also fixes #2600. Advised by Richard Eisenberg. This modifies the Template Haskell AST -- old code may break! Other Changes: - convert HsRule to a record - make rnHsSigWcType more general - add repMaybe to DsMeta Includes submodule update for Haddock. Test Plan: validate Reviewers: goldfire, bgamari, alanz Subscribers: simonpj, RyanGlScott, goldfire, rwbarton, thomie, mpickering, carter GHC Trac Issues: #2600, #14268 Differential Revision: https://phabricator.haskell.org/D4894
* De-monadise the 'extract' functions in RnTypesSimon Peyton Jones2018-10-261-13/+13
| | | | | | | | | | | As Trac #15765 says, Once upon a time, the extract functions at the bottom of RnTypes were pure. Then, along came -XTypeInType, which needed to do a check in these functions for users mixing type variables with kind variables. Now, however, with -XTypeInType gone again, we no longer do this check. Thus, there is no reason to keep these functions monadic.
* Buglet in reporting out of scope errors in rulesSimon Peyton Jones2018-09-231-4/+4
| | | | | | | | Most out of scope errors get reported by the type checker these days, but not all. Example, the function on the LHS of a RULE. Trace #15659 pointed out that this less-heavily-used code path produce a "wacky" error message. Indeed so. Easily fixed.
* Fix redundant imports of ClassBen Gamari2018-08-211-1/+0
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* Add a solveEqualities to tcClassDecl1Simon Peyton Jones2018-08-211-2/+1
| | | | | | | | | | | | | | Trac #15505 showed that, when we have a type error, we could have an unfilled-in coercion hole. We don't want an assertion error in that case. The underlying cause is that tcClassDecl1 should call solveEqualities to fully solve all top-level equalities (or fail in the attempt). I also refactored the ClassDecl case for tcTyClDecl1 into a new function tcClassDecl1. That makes it symmetrical with the others.
* Add comment explaining change in syntax error suggestion for #12146.Aditya2018-08-171-0/+4
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* Remove decideKindGeneralisationPlanRichard Eisenberg2018-08-021-3/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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.
* Instantiate GND bindings with an explicit type signatureRyan Scott2018-07-051-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: Before, we were using visible type application to apply impredicative types to `coerce` in `GeneralizedNewtypeDeriving`-generated bindings. This approach breaks down when combined with `QuantifiedConstraints` in certain ways, which #14883 and #15290 provide examples of. See Note [GND and QuantifiedConstraints] for all the gory details. To avoid this issue, we instead use an explicit type signature to instantiate each GND binding, and use that to bind any type variables that might be bound by a class method's type signature. This reduces the need to impredicative type applications, and more importantly, makes the programs from #14883 and #15290 work again. Test Plan: make test TEST="T15290b T15290c T15290d T14883" Reviewers: simonpj, bgamari Reviewed By: simonpj Subscribers: rwbarton, thomie, carter GHC Trac Issues: #14883, #15290 Differential Revision: https://phabricator.haskell.org/D4895
* Fix API Annotations for GADT constructorsAlan Zimmerman2018-06-191-1/+1
| | | | | | | | | | | | | | | | | | | Summary: This patch completes the work for #14529 by making sure that all API Annotations end up attached to a SrcSpan that appears in the final ParsedSource. Updates Haddock submodule Test Plan: ./validate Reviewers: goldfire, bgamari Subscribers: rwbarton, thomie, mpickering, carter GHC Trac Issues: #14529 Differential Revision: https://phabricator.haskell.org/D4867
* Typofixes in docs and comments [ci skip]Gabor Greif2018-06-181-1/+1
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* Embrace -XTypeInType, add -XStarIsTypeVladislav Zavialov2018-06-141-3/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: Implement the "Embrace Type :: Type" GHC proposal, .../ghc-proposals/blob/master/proposals/0020-no-type-in-type.rst GHC 8.0 included a major change to GHC's type system: the Type :: Type axiom. Though casual users were protected from this by hiding its features behind the -XTypeInType extension, all programs written in GHC 8+ have the axiom behind the scenes. In order to preserve backward compatibility, various legacy features were left unchanged. For example, with -XDataKinds but not -XTypeInType, GADTs could not be used in types. Now these restrictions are lifted and -XTypeInType becomes a redundant flag that will be eventually deprecated. * Incorporate the features currently in -XTypeInType into the -XPolyKinds and -XDataKinds extensions. * Introduce a new extension -XStarIsType to control how to parse * in code and whether to print it in error messages. Test Plan: Validate Reviewers: goldfire, hvr, bgamari, alanz, simonpj Reviewed By: goldfire, simonpj Subscribers: rwbarton, thomie, mpickering, carter GHC Trac Issues: #15195 Differential Revision: https://phabricator.haskell.org/D4748
* Introduce DerivingViaRyan Scott2018-06-041-22/+136
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This implements the `DerivingVia` proposal put forth in https://github.com/ghc-proposals/ghc-proposals/pull/120. This introduces the `DerivingVia` deriving strategy. This is a generalization of `GeneralizedNewtypeDeriving` that permits the user to specify the type to `coerce` from. The major change in this patch is the introduction of the `ViaStrategy` constructor to `DerivStrategy`, which takes a type as a field. As a result, `DerivStrategy` is no longer a simple enumeration type, but rather something that must be renamed and typechecked. The process by which this is done is explained more thoroughly in section 3 of this paper ( https://www.kosmikus.org/DerivingVia/deriving-via-paper.pdf ), although I have inlined the relevant parts into Notes where possible. There are some knock-on changes as well. I took the opportunity to do some refactoring of code in `TcDeriv`, especially the `mkNewTypeEqn` function, since it was bundling all of the logic for (1) deriving instances for newtypes and (2) `GeneralizedNewtypeDeriving` into one huge broth. `DerivingVia` reuses much of part (2), so that was factored out as much as possible. Bumps the Haddock submodule. Test Plan: ./validate Reviewers: simonpj, bgamari, goldfire, alanz Subscribers: alanz, goldfire, rwbarton, thomie, mpickering, carter GHC Trac Issues: #15178 Differential Revision: https://phabricator.haskell.org/D4684
* vectorise: Put it out of its miseryBen Gamari2018-06-021-59/+7
| | | | | | | | | | | | | | | | | | | | | Poor DPH and its vectoriser have long been languishing; sadly it seems there is little chance that the effort will be rekindled. Every few years we discuss what to do with this mass of code and at least once we have agreed that it should be archived on a branch and removed from `master`. Here we do just that, eliminating heaps of dead code in the process. Here we drop the ParallelArrays extension, the vectoriser, and the `vector` and `primitive` submodules. Test Plan: Validate Reviewers: simonpj, simonmar, hvr, goldfire, alanz Reviewed By: simonmar Subscribers: goldfire, rwbarton, thomie, mpickering, carter Differential Revision: https://phabricator.haskell.org/D4761
* Used named fields for DataDeclRnSimon Peyton Jones2018-05-081-3/+6
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* TTG : complete for balance of hsSyn ASTAlan Zimmerman2018-04-271-102/+157
| | | | | | | | | | | | | | | | | | Summary: - remove PostRn/PostTc fields - remove the HsVect In/Out distinction for Type, Class and Instance - remove PlaceHolder in favour of NoExt - Simplify OutputableX constraint Updates haddock submodule Test Plan: ./validate Reviewers: goldfire, bgamari Subscribers: goldfire, thomie, mpickering, carter Differential Revision: https://phabricator.haskell.org/D4625
* Fix #14710 with more validity checks during renamingRyan Scott2018-04-191-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: #14710 revealed two unfortunate regressions related to kind polymorphism that had crept in in recent GHC releases: 1. While GHC was able to catch illegal uses of kind polymorphism (i.e., if `PolyKinds` wasn't enabled) in limited situations, it wasn't able to catch kind polymorphism of the following form: ```lang=haskell f :: forall a. a -> a f x = const x g where g :: Proxy (x :: a) g = Proxy ``` Note that the variable `a` is being used as a kind variable in the type signature of `g`, but GHC happily accepts it, even without the use of `PolyKinds`. 2. If you have `PolyKinds` (but not `TypeInType`) enabled, then GHC incorrectly accepts the following definition: ```lang=haskell f :: forall k (a :: k). Proxy a f = Proxy ``` Even though `k` is explicitly bound and then later used as a kind variable within the same telescope. This patch fixes these two bugs as follows: 1. Whenever we rename any `HsTyVar`, we check if the following three criteria are met: (a) It's a type variable (b) It's used at the kind level (c) `PolyKinds` is not enabled If so, then we have found an illegal use of kind polymorphism, so throw an error. This check replaces the `checkBadKindBndrs` function, which could only catch illegal uses of kind polymorphism in very limited situations (when the bad kind variable happened to be implicitly quantified in the same type signature). 2. In `extract_hs_tv_bndrs`, we must error if `TypeInType` is not enabled and either of the following criteria are met: (a) An explicitly bound type variable is used in kind position in the body of a `forall` type. (b) An explicitly bound type variable is used in kind position in the kind of a bound type variable in a `forall` type. `extract_hs_tv_bndrs` was checking (a), but not (b). Easily fixed. Test Plan: ./validate Reviewers: goldfire, simonpj, bgamari, hvr Reviewed By: simonpj Subscribers: thomie, carter GHC Trac Issues: #14710 Differential Revision: https://phabricator.haskell.org/D4554
* Comments onlySimon Peyton Jones2018-04-171-3/+1
| | | | Deleting misleading comments, to fix Trac #15047
* TTG for HsBinds and Data instances Plan BAlan Zimmerman2018-04-131-7/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: - Add the balance of the TTG extensions for hsSyn/HsBinds - Move all the (now orphan) data instances into hsSyn/HsInstances and use TTG Data instances Plan B https://ghc.haskell.org/trac/ghc/wiki/ImplementingTreesThatGrow/Instances#PLANB Updates haddock submodule. Illustrative numbers Compiling HsInstances before using Plan B. Max residency ~ 5G <<ghc: 629,864,691,176 bytes, 5300 GCs, 321075437/1087762592 avg/max bytes residency (23 samples), 2953M in use, 0.000 INIT (0.000 elapsed), 383.511 MUT (384.986 elapsed), 37.426 GC (37.444 elapsed) :ghc>> Using Plan B Max residency 1.1G <<ghc: 78,832,782,968 bytes, 2884 GCs, 222140352/386470152 avg/max bytes residency (34 samples), 1062M in use, 0.001 INIT (0.001 elapsed), 56.612 MUT (62.917 elapsed), 32.974 GC (32.923 elapsed) :ghc>> Test Plan: ./validate Reviewers: shayan-najd, goldfire, bgamari Subscribers: goldfire, thomie, mpickering, carter Differential Revision: https://phabricator.haskell.org/D4581
* Restore Trees That Grow reverted commitsAlan Zimmerman2018-04-091-14/+15
| | | | | | | | | | | | | | | | | | The following commits were reverted prior to the release of GHC 8.4.1, because the time to derive Data instances was too long [1]. 438dd1cbba13d35f3452b4dcef3f94ce9a216905 Phab:D4147 e3ec2e7ae94524ebd111963faf34b84d942265b4 Phab:D4177 47ad6578ea460999b53eb4293c3a3b3017a56d65 Phab:D4186 The work is continuing, as the minimum bootstrap compiler is now GHC 8.2.1, and this allows Plan B[2] for instances to be used. This will land in a following commit. Updates Haddock submodule [1] https://ghc.haskell.org/trac/ghc/wiki/ImplementingTreesThatGrow/Instances [2] https://ghc.haskell.org/trac/ghc/wiki/ImplementingTreesThatGrow/Instances#PLANB
* Allow PartialTypeSignatures in standalone deriving contextsRyan Scott2018-03-231-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: At its core, this patch is a simple tweak that allows a user to write: ```lang=haskell deriving instance _ => Eq (Foo a) ``` Which is functionally equivalent to: ```lang=haskell data Foo a = ... deriving Eq ``` But with the added flexibility that `StandaloneDeriving` gives you (namely, the ability to use it anywhere, not just in the same module that `Foo` was declared in). This fixes #13324, and should hopefully address a use case brought up in #10607. Currently, only the use of a single, extra-constraints wildcard is permitted in a standalone deriving declaration. Any other wildcard is rejected, so things like `deriving instance (Eq a, _) => Eq (Foo a)` are currently forbidden. There are quite a few knock-on changes brought on by this change: * The `HsSyn` type used to represent standalone-derived instances was previously `LHsSigType`, which isn't sufficient to hold wildcard types. This needed to be changed to `LHsSigWcType` as a result. * Previously, `DerivContext` was a simple type synonym for `Maybe ThetaType`, under the assumption that you'd only ever be in the `Nothing` case if you were in a `deriving` clause. After this patch, that assumption no longer holds true, as you can also be in this situation with standalone deriving when an extra-constraints wildcard is used. As a result, I changed `DerivContext` to be a proper datatype that reflects the new wrinkle that this patch adds, and plumbed this through the relevant parts of `TcDeriv` and friends. * Relatedly, the error-reporting machinery in `TcErrors` also assumed that if you have any unsolved constraints in a derived instance, then you should be able to fix it by switching over to standalone deriving. This was always sound advice before, but with this new feature, it's possible to have unsolved constraints even when you're standalone-deriving something! To rectify this, I tweaked some constructors of `CtOrigin` a bit to reflect this new subtlety. This requires updating the Haddock submodule. See my fork at https://github.com/RyanGlScott/haddock/commit/067d52fd4be15a1842cbb05f42d9d482de0ad3a7 Test Plan: ./validate Reviewers: simonpj, goldfire, bgamari Reviewed By: simonpj Subscribers: goldfire, rwbarton, thomie, mpickering, carter GHC Trac Issues: #13324 Differential Revision: https://phabricator.haskell.org/D4383
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