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* Fix #22742Simon Peyton Jones2023-01-233-0/+15
| | | | | | | | | | | | | runtimeRepLevity_maybe was panicing unnecessarily; and the error printing code made use of the case when it should return Nothing rather than panicing. For some bizarre reason perf/compiler/T21839r shows a 10% bump in runtime peak-megagbytes-used, on a single architecture (alpine). See !9753 for commentary, but I'm going to accept it. Metric Increase: T21839r
* Add a missing checkEscapingKindSimon Peyton Jones2023-01-133-0/+18
| | | | | | | | Ticket #22743 pointed out that there is a missing check, for type-inferred bindings, that the inferred type doesn't have an escaping kind. The fix is easy.
* Drop support for kind constraints.wip/p547Richard Eisenberg2022-12-243-11/+6
| | | | | | | | | | | | | | | | | | | | | | | | This implements proposal 547 and closes ticket #22298. See the proposal and ticket for motivation. Compiler perf improves a bit Metrics: compile_time/bytes allocated ------------------------------------- CoOpt_Singletons(normal) -2.4% GOOD T12545(normal) +1.0% T13035(normal) -13.5% GOOD T18478(normal) +0.9% T9872d(normal) -2.2% GOOD geo. mean -0.2% minimum -13.5% maximum +1.0% Metric Decrease: CoOpt_Singletons T13035 T9872d
* Killing cc_fundeps, streamlining kind equality orientation, and type ↵Apoorv Ingle2022-11-292-6/+4
| | | | | | | | | | | | | | | | | | | | equality processing order Fixes: #217093 Associated to #19415 This change * Flips the orientation of the the generated kind equality coercion in canEqLHSHetero; * Removes `cc_fundeps` in CDictCan as the check was incomplete; * Changes `canDecomposableTyConAppOk` to ensure we process kind equalities before type equalities and avoiding a call to `canEqLHSHetero` while processing wanted TyConApp equalities * Adds 2 new tests for validating the change - testsuites/typecheck/should_compile/T21703.hs and - testsuites/typecheck/should_fail/T19415b.hs (a simpler version of T19415.hs) * Misc: Due to the change in the equality direction some error messages now have flipped type mismatch errors * Changes in Notes: - Note [Fundeps with instances, and equality orientation] supercedes Note [Fundeps with instances] - Added Note [Kind Equality Orientation] to visualize the kind flipping - Added Note [Decomposing Dependent TyCons and Processing Wanted Equalties]
* Print unticked promoted data constructors (#20531)Vladislav Zavialov2022-11-253-14/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Before this patch, GHC unconditionally printed ticks before promoted data constructors: ghci> type T = True -- unticked (user-written) ghci> :kind! T T :: Bool = 'True -- ticked (compiler output) After this patch, GHC prints ticks only when necessary: ghci> type F = False -- unticked (user-written) ghci> :kind! F F :: Bool = False -- unticked (compiler output) ghci> data False -- introduce ambiguity ghci> :kind! F F :: Bool = 'False -- ticked by necessity (compiler output) The old behavior can be enabled by -fprint-redundant-promotion-ticks. Summary of changes: * Rename PrintUnqualified to NamePprCtx * Add QueryPromotionTick to it * Consult the GlobalRdrEnv to decide whether to print a tick (see mkPromTick) * Introduce -fprint-redundant-promotion-ticks Co-authored-by: Artyom Kuznetsov <hi@wzrd.ht>
* Type vs Constraint: finally nailedSimon Peyton Jones2022-11-112-4/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This big patch addresses the rats-nest of issues that have plagued us for years, about the relationship between Type and Constraint. See #11715/#21623. The main payload of the patch is: * To introduce CONSTRAINT :: RuntimeRep -> Type * To make TYPE and CONSTRAINT distinct throughout the compiler Two overview Notes in GHC.Builtin.Types.Prim * Note [TYPE and CONSTRAINT] * Note [Type and Constraint are not apart] This is the main complication. The specifics * New primitive types (GHC.Builtin.Types.Prim) - CONSTRAINT - ctArrowTyCon (=>) - tcArrowTyCon (-=>) - ccArrowTyCon (==>) - funTyCon FUN -- Not new See Note [Function type constructors and FunTy] and Note [TYPE and CONSTRAINT] * GHC.Builtin.Types: - New type Constraint = CONSTRAINT LiftedRep - I also stopped nonEmptyTyCon being built-in; it only needs to be wired-in * Exploit the fact that Type and Constraint are distinct throughout GHC - Get rid of tcView in favour of coreView. - Many tcXX functions become XX functions. e.g. tcGetCastedTyVar --> getCastedTyVar * Kill off Note [ForAllTy and typechecker equality], in (old) GHC.Tc.Solver.Canonical. It said that typechecker-equality should ignore the specified/inferred distinction when comparein two ForAllTys. But that wsa only weakly supported and (worse) implies that we need a separate typechecker equality, different from core equality. No no no. * GHC.Core.TyCon: kill off FunTyCon in data TyCon. There was no need for it, and anyway now we have four of them! * GHC.Core.TyCo.Rep: add two FunTyFlags to FunCo See Note [FunCo] in that module. * GHC.Core.Type. Lots and lots of changes driven by adding CONSTRAINT. The key new function is sORTKind_maybe; most other changes are built on top of that. See also `funTyConAppTy_maybe` and `tyConAppFun_maybe`. * Fix a longstanding bug in GHC.Core.Type.typeKind, and Core Lint, in kinding ForAllTys. See new tules (FORALL1) and (FORALL2) in GHC.Core.Type. (The bug was that before (forall (cv::t1 ~# t2). blah), where blah::TYPE IntRep, would get kind (TYPE IntRep), but it should be (TYPE LiftedRep). See Note [Kinding rules for types] in GHC.Core.Type. * GHC.Core.TyCo.Compare is a new module in which we do eqType and cmpType. Of course, no tcEqType any more. * GHC.Core.TyCo.FVs. I moved some free-var-like function into this module: tyConsOfType, visVarsOfType, and occCheckExpand. Refactoring only. * GHC.Builtin.Types. Compiletely re-engineer boxingDataCon_maybe to have one for each /RuntimeRep/, rather than one for each /Type/. This dramatically widens the range of types we can auto-box. See Note [Boxing constructors] in GHC.Builtin.Types The boxing types themselves are declared in library ghc-prim:GHC.Types. GHC.Core.Make. Re-engineer the treatment of "big" tuples (mkBigCoreVarTup etc) GHC.Core.Make, so that it auto-boxes unboxed values and (crucially) types of kind Constraint. That allows the desugaring for arrows to work; it gathers up free variables (including dictionaries) into tuples. See Note [Big tuples] in GHC.Core.Make. There is still work to do here: #22336. But things are better than before. * GHC.Core.Make. We need two absent-error Ids, aBSENT_ERROR_ID for types of kind Type, and aBSENT_CONSTRAINT_ERROR_ID for vaues of kind Constraint. Ditto noInlineId vs noInlieConstraintId in GHC.Types.Id.Make; see Note [inlineId magic]. * GHC.Core.TyCo.Rep. Completely refactor the NthCo coercion. It is now called SelCo, and its fields are much more descriptive than the single Int we used to have. A great improvement. See Note [SelCo] in GHC.Core.TyCo.Rep. * GHC.Core.RoughMap.roughMatchTyConName. Collapse TYPE and CONSTRAINT to a single TyCon, so that the rough-map does not distinguish them. * GHC.Core.DataCon - Mainly just improve documentation * Some significant renamings: GHC.Core.Multiplicity: Many --> ManyTy (easier to grep for) One --> OneTy GHC.Core.TyCo.Rep TyCoBinder --> GHC.Core.Var.PiTyBinder GHC.Core.Var TyCoVarBinder --> ForAllTyBinder AnonArgFlag --> FunTyFlag ArgFlag --> ForAllTyFlag GHC.Core.TyCon TyConTyCoBinder --> TyConPiTyBinder Many functions are renamed in consequence e.g. isinvisibleArgFlag becomes isInvisibleForAllTyFlag, etc * I refactored FunTyFlag (was AnonArgFlag) into a simple, flat data type data FunTyFlag = FTF_T_T -- (->) Type -> Type | FTF_T_C -- (-=>) Type -> Constraint | FTF_C_T -- (=>) Constraint -> Type | FTF_C_C -- (==>) Constraint -> Constraint * GHC.Tc.Errors.Ppr. Some significant refactoring in the TypeEqMisMatch case of pprMismatchMsg. * I made the tyConUnique field of TyCon strict, because I saw code with lots of silly eval's. That revealed that GHC.Settings.Constants.mAX_SUM_SIZE can only be 63, because we pack the sum tag into a 6-bit field. (Lurking bug squashed.) Fixes * #21530 Updates haddock submodule slightly. Performance changes ~~~~~~~~~~~~~~~~~~~ I was worried that compile times would get worse, but after some careful profiling we are down to a geometric mean 0.1% increase in allocation (in perf/compiler). That seems fine. There is a big runtime improvement in T10359 Metric Decrease: LargeRecord MultiLayerModulesTH_OneShot T13386 T13719 Metric Increase: T8095
* Add accurate skolem info when quantifyingSimon Peyton Jones2022-11-013-0/+63
| | | | | | | Ticket #22379 revealed that skolemiseQuantifiedTyVar was dropping the passed-in skol_info on the floor when it encountered a SkolemTv. Bad! Several TyCons thereby share a single SkolemInfo on their binders, which lead to bogus error reports.
* Testsuite: more precise test optionsSylvain Henry2022-10-261-1/+1
| | | | | Necessary for newer cross-compiling backends (JS, Wasm) that don't support TH yet.
* Clearer error msg for newtype GADTs with defaulted kindFinley McIlwaine2022-10-131-2/+2
| | | | | | | | | | | When a newtype introduces GADT eq_specs due to a defaulted RuntimeRep, we detect this and print the error message with explicit kinds. This also refactors newtype type checking to use the new diagnostic infra. Fixes #21447
* Diagnostic codes: acccept test changessheaf2022-09-1377-113/+113
| | | | | | | | The testsuite output now contains diagnostic codes, so many tests need to be updated at once. We decided it was best to keep the diagnostic codes in the testsuite output, so that contributors don't inadvertently make changes to the diagnostic codes.
* Print constraints in quotes (#21167)Swann Moreau2022-08-195-5/+5
| | | | | | | This patch improves the uniformity of error message formatting by printing constraints in quotes, as we do for types. Fix #21167
* testsuite: Use normalise_version more consistentlyBen Gamari2022-06-271-2/+2
| | | | | Previously several tests' output were unnecessarily dependent on version numbers, particularly of `base`. Fix this.
* Bump ghc-prim and base versionsBen Gamari2022-06-272-2/+2
| | | | | | | | | To 0.9.0 and 4.17.0 respectively. Bumps array, deepseq, directory, filepath, haskeline, hpc, parsec, stm, terminfo, text, unix, haddock, and hsc2hs submodules. (cherry picked from commit ba47b95122b7b336ce1cc00896a47b584ad24095)
* Deprecate TypeInType extensionHaskellMouse2022-06-0621-23/+32
| | | | | | | | | | | | | | | | This commit fixes #20312 It deprecates "TypeInType" extension according to the following proposal: https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0083-no-type-in-type.rst It has been already implemented. The migration strategy: 1. Disable TypeInType 2. Enable both DataKinds and PolyKinds extensions Metric Decrease: T16875
* Change GHC.Prim to GHC.Exts in docs and testsKrzysztof Gogolewski2022-04-011-1/+1
| | | | | Users are supposed to import GHC.Exts rather than GHC.Prim. Part of #18749.
* Export (~) from Data.Type.Equality (#18862)wip/eqtycon-rnVladislav Zavialov2022-03-152-3/+4
| | | | | | | | | | * Users can define their own (~) type operator * Haddock can display documentation for the built-in (~) * New transitional warnings implemented: -Wtype-equality-out-of-scope -Wtype-equality-requires-operators Updates the haddock submodule.
* Kill derived constraintsRichard Eisenberg2022-02-232-5/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Co-authored by: Sam Derbyshire Previously, GHC had three flavours of constraint: Wanted, Given, and Derived. This removes Derived constraints. Though serving a number of purposes, the most important role of Derived constraints was to enable better error messages. This job has been taken over by the new RewriterSets, as explained in Note [Wanteds rewrite wanteds] in GHC.Tc.Types.Constraint. Other knock-on effects: - Various new Notes as I learned about under-described bits of GHC - A reshuffling around the AST for implicit-parameter bindings, with better integration with TTG. - Various improvements around fundeps. These were caused by the fact that, previously, fundep constraints were all Derived, and Derived constraints would get dropped. Thus, an unsolved Derived didn't stop compilation. Without Derived, this is no longer possible, and so we have to be considerably more careful around fundeps. - A nice little refactoring in GHC.Tc.Errors to center the work on a new datatype called ErrorItem. Constraints are converted into ErrorItems at the start of processing, and this allows for a little preprocessing before the main classification. - This commit also cleans up the behavior in generalisation around functional dependencies. Now, if a variable is determined by functional dependencies, it will not be quantified. This change is user facing, but it should trim down GHC's strange behavior around fundeps. - Previously, reportWanteds did quite a bit of work, even on an empty WantedConstraints. This commit adds a fast path. - Now, GHC will unconditionally re-simplify constraints during quantification. See Note [Unconditionally resimplify constraints when quantifying], in GHC.Tc.Solver. Close #18398. Close #18406. Solve the fundep-related non-confluence in #18851. Close #19131. Close #19137. Close #20922. Close #20668. Close #19665. ------------------------- Metric Decrease: LargeRecord T9872b T9872b_defer T9872d TcPlugin_RewritePerf -------------------------
* Make implication tidying agree with Note [Tidying multiple names at once]Matthew Pickering2022-02-056-26/+27
| | | | | | | | | | | Note [Tidying multiple names at once] indicates that if multiple variables have the same name then we shouldn't prioritise one of them and instead rename them all to a1, a2, a3... etc This patch implements that change, some error message changes as expected. Closes #20932
* Rework the handling of SkolemInfoMatthew Pickering2022-01-2913-17/+17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The main purpose of this patch is to attach a SkolemInfo directly to each SkolemTv. This fixes the large number of bugs which have accumulated over the years where we failed to report errors due to having "no skolem info" for particular type variables. Now the origin of each type varible is stored on the type variable we can always report accurately where it cames from. Fixes #20969 #20732 #20680 #19482 #20232 #19752 #10946 #19760 #20063 #13499 #14040 The main changes of this patch are: * SkolemTv now contains a SkolemInfo field which tells us how the SkolemTv was created. Used when reporting errors. * Enforce invariants relating the SkolemInfoAnon and level of an implication (ic_info, ic_tclvl) to the SkolemInfo and level of the type variables in ic_skols. * All ic_skols are TcTyVars -- Check is currently disabled * All ic_skols are SkolemTv * The tv_lvl of the ic_skols agrees with the ic_tclvl * The ic_info agrees with the SkolInfo of the implication. These invariants are checked by a debug compiler by checkImplicationInvariants. * Completely refactor kcCheckDeclHeader_sig which kept doing my head in. Plus, it wasn't right because it wasn't skolemising the binders as it decomposed the kind signature. The new story is described in Note [kcCheckDeclHeader_sig]. The code is considerably shorter than before (roughly 240 lines turns into 150 lines). It still has the same awkward complexity around computing arity as before, but that is a language design issue. See Note [Arity inference in kcCheckDeclHeader_sig] * I added new type synonyms MonoTcTyCon and PolyTcTyCon, and used them to be clear which TcTyCons have "finished" kinds etc, and which are monomorphic. See Note [TcTyCon, MonoTcTyCon, and PolyTcTyCon] * I renamed etaExpandAlgTyCon to splitTyConKind, becuase that's a better name, and it is very useful in kcCheckDeclHeader_sig, where eta-expansion isn't an issue. * Kill off the nasty `ClassScopedTvEnv` entirely. Co-authored-by: Simon Peyton Jones <simon.peytonjones@gmail.com>
* Use diagnostic infrastructure in GHC.Tc.Errorssheaf2022-01-174-8/+8
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* Include "not more specific" info in overlap msgsheaf2021-11-201-4/+3
| | | | | | | | | When instances overlap, we now include additional information about why we weren't able to select an instance: perhaps one instance overlapped another but was not strictly more specific, so we aren't able to directly choose it. Fixes #20542
* Introduce Concrete# for representation polymorphism checkssheaf2021-10-174-29/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | PHASE 1: we never rewrite Concrete# evidence. This patch migrates all the representation polymorphism checks to the typechecker, using a new constraint form Concrete# :: forall k. k -> TupleRep '[] Whenever a type `ty` must be representation-polymorphic (e.g. it is the type of an argument to a function), we emit a new `Concrete# ty` Wanted constraint. If this constraint goes unsolved, we report a representation-polymorphism error to the user. The 'FRROrigin' datatype keeps track of the context of the representation-polymorphism check, for more informative error messages. This paves the way for further improvements, such as allowing type families in RuntimeReps and improving the soundness of typed Template Haskell. This is left as future work (PHASE 2). fixes #17907 #20277 #20330 #20423 #20426 updates haddock submodule ------------------------- Metric Decrease: T5642 -------------------------
* Improve overlap error for polykinded constraintssheaf2021-10-061-2/+2
| | | | | | | | | | | | | | There were two problems around `mkDictErr`: 1. An outdated call to `flattenTys` meant that we missed out on some instances. As we no longer flatten type-family applications, the logic is obsolete and can be removed. 2. We reported "out of scope" errors in a poly-kinded situation because `BoxedRep` and `Lifted` were considered out of scope. We fix this by using `pretendNameIsInScope`. fixes #20465
* Convert diagnostics in GHC.Tc.Validity to proper TcRnMessage.hainq2021-09-011-1/+1
| | | | | | | | | | | | | | | | | | | | - Add 19 new messages. Update test outputs accordingly. - Pretty print suggest-extensions hints: remove space before interspersed commas. - Refactor Rank's MonoType constructors. Each MonoType constructor should represent a specific case. With the Doc suggestion belonging to the TcRnMessage diagnostics instead. - Move Rank from Validity to its own `GHC.Tc.Types.Rank` module. - Remove the outdated `check_irred_pred` check. - Remove the outdated duplication check in `check_valid_theta`, which was subsumed by `redundant-constraints`. - Add missing test cases for quantified-constraints/T16474 & th/T12387a.
* Reword: representation instead of levitysheaf2021-06-102-5/+6
| | | | fixes #19756, updates haddock submodule
* Remove transitive information about modules and packages from interface filesMatthew Pickering2021-05-192-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This commit modifies interface files so that *only* direct information about modules and packages is stored in the interface file. * Only direct module and direct package dependencies are stored in the interface files. * Trusted packages are now stored separately as they need to be checked transitively. * hs-boot files below the compiled module in the home module are stored so that eps_is_boot can be calculated in one-shot mode without loading all interface files in the home package. * The transitive closure of signatures is stored separately This is important for two reasons * Less recompilation is needed, as motivated by #16885, a lot of redundant compilation was triggered when adding new imports deep in the module tree as all the parent interface files had to be redundantly updated. * Checking an interface file is cheaper because you don't have to perform a transitive traversal to check the dependencies are up-to-date. In the code, places where we would have used the transitive closure, we instead compute the necessary transitive closure. The closure is not computed very often, was already happening in checkDependencies, and was already happening in getLinkDeps. Fixes #16885 ------------------------- Metric Decrease: MultiLayerModules T13701 T13719 -------------------------
* Fix newtype eta-reductionSimon Peyton Jones2021-05-075-0/+48
| | | | | | | | The eta-reduction we do for newype axioms was generating an inhomogeneous axiom: see #19739. This patch fixes it in a simple way; see GHC.Tc.TyCl.Build Note [Newtype eta and homogeneous axioms]
* Fix an levity-polymorphism errorSimon Peyton Jones2021-03-202-0/+12
| | | | | | | | As #19522 points out, we did not account for visible type application when trying to reject naked levity-polymorphic functions that have no binding. This patch tidies up the code, and fixes the bug too.
* GHC Exactprint main commitAlan Zimmerman2021-03-201-1/+1
| | | | | | | | Metric Increase: T10370 parsing001 Updates haddock submodule
* Use GHC2021 as default languageJoachim Breitner2021-03-1048-44/+75
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* Implement BoxedRep proposalwip/boxed-repBen Gamari2021-03-074-6/+4
| | | | | | | | | | | | | | | | | | | | | | | This implements the BoxedRep proposal, refactoring the `RuntimeRep` hierarchy from: ```haskell data RuntimeRep = LiftedPtrRep | UnliftedPtrRep | ... ``` to ```haskell data RuntimeRep = BoxedRep Levity | ... data Levity = Lifted | Unlifted ``` Updates binary, haddock submodules. Closes #17526. Metric Increase: T12545
* Zonk the returned kind in tcFamTyPatsSimon Peyton Jones2021-01-302-0/+13
| | | | | | The motivation is given in Note [tcFamTyPats: zonking the result kind]. Fixes #19250 -- the fix is easy.
* Remove some redundant validity checks.Richard Eisenberg2021-01-273-5/+7
| | | | | | | | | | | | This commit also consolidates documentation in the user manual around UndecidableSuperClasses, UndecidableInstances, and FlexibleContexts. Close #19186. Close #19187. Test case: typecheck/should_compile/T19186, typecheck/should_fail/T19187{,a}
* Add instances for GHC.Tuple.SoloBen Gamari2021-01-271-1/+1
| | | | | | | | | | | | | | | The `Applicative` instance is the most important one (for array/vector/sequence indexing purposes), but it deserves all the usual ones. T12545 does silly 1% wibbles both ways, it seems, maybe depending on architecture. Metric Increase: T12545 Metric Decrease: T12545
* Never Anyify during kind inferenceRichard Eisenberg2021-01-093-1/+30
| | | | | | | | | See Note [Error on unconstrained meta-variables] in TcMType. Close #17301 Close #17567 Close #17562 Close #15474
* Clone the binders of a SAKS where necessarySimon Peyton Jones2020-12-244-0/+80
| | | | | | | | | | | | | | Given a kind signature type T :: forall k. k -> forall k. k -> blah data T a b = ... where those k's have the same unique (which is possible; see #19093) we were giving the tyConBinders in tycon T the same unique, which caused chaos. Fix is simple: ensure uniqueness when decomposing the kind signature. See GHC.Tc.Gen.HsType.zipBinders
* Reject dodgy scoping in associated family instance RHSesRyan Scott2020-12-172-1/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit e63518f5d6a93be111f9108c0990a1162f88d615 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 https://gitlab.haskell.org/ghc/ghc/-/issues/18021#note_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.
* Revert "Implement BoxedRep proposal"Ben Gamari2020-12-154-4/+6
| | | | | | This was inadvertently merged. This reverts commit 6c2eb2232b39ff4720fda0a4a009fb6afbc9dcea.
* Implement BoxedRep proposalAndrew Martin2020-12-144-6/+4
| | | | | | | | | | | | | | | | | | 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.
* Fix kind inference for data types. Again.Simon Peyton Jones2020-12-082-6/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch fixes several aspects of kind inference for data type declarations, especially data /instance/ declarations Specifically 1. In kcConDecls/kcConDecl make it clear that the tc_res_kind argument is only used in the H98 case; and in that case there is no result kind signature; and hence no need for the disgusting splitPiTys in kcConDecls (now thankfully gone). The GADT case is a bit different to before, and much nicer. This is what fixes #18891. See Note [kcConDecls: kind-checking data type decls] 2. Do not look at the constructor decls of a data/newtype instance in tcDataFamInstanceHeader. See GHC.Tc.TyCl.Instance Note [Kind inference for data family instances]. This was a new realisation that arose when doing (1) This causes a few knock-on effects in the tests suite, because we require more information than before in the instance /header/. New user-manual material about this in "Kind inference in data type declarations" and "Kind inference for data/newtype instance declarations". 3. Minor improvement in kcTyClDecl, combining GADT and H98 cases 4. Fix #14111 and #8707 by allowing the header of a data instance to affect kind inferece for the the data constructor signatures; as described at length in Note [GADT return types] in GHC.Tc.TyCl This led to a modest refactoring of the arguments (and argument order) of tcConDecl/tcConDecls. 5. Fix #19000 by inverting the sense of the test in new_locs in GHC.Tc.Solver.Canonical.canDecomposableTyConAppOK.
* Remove flattening variablesRichard Eisenberg2020-12-011-5/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch redesigns the flattener to simplify type family applications directly instead of using flattening meta-variables and skolems. The key new innovation is the CanEqLHS type and the new CEqCan constraint (Ct). A CanEqLHS is either a type variable or exactly-saturated type family application; either can now be rewritten using a CEqCan constraint in the inert set. Because the flattener no longer reduces all type family applications to variables, there was some performance degradation if a lengthy type family application is now flattened over and over (not making progress). To compensate, this patch contains some extra optimizations in the flattener, leading to a number of performance improvements. Close #18875. Close #18910. There are many extra parts of the compiler that had to be affected in writing this patch: * The family-application cache (formerly the flat-cache) sometimes stores coercions built from Given inerts. When these inerts get kicked out, we must kick out from the cache as well. (This was, I believe, true previously, but somehow never caused trouble.) Kicking out from the cache requires adding a filterTM function to TrieMap. * This patch obviates the need to distinguish "blocking" coercion holes from non-blocking ones (which, previously, arose from CFunEqCans). There is thus some simplification around coercion holes. * Extra commentary throughout parts of the code I read through, to preserve the knowledge I gained while working. * A change in the pure unifier around unifying skolems with other types. Unifying a skolem now leads to SurelyApart, not MaybeApart, as documented in Note [Binding when looking up instances] in GHC.Core.InstEnv. * Some more use of MCoercion where appropriate. * Previously, class-instance lookup automatically noticed that e.g. C Int was a "unifier" to a target [W] C (F Bool), because the F Bool was flattened to a variable. Now, a little more care must be taken around checking for unifying instances. * Previously, tcSplitTyConApp_maybe would split (Eq a => a). This is silly, because (=>) is not a tycon in Haskell. Fixed now, but there are some knock-on changes in e.g. TrieMap code and in the canonicaliser. * New function anyFreeVarsOf{Type,Co} to check whether a free variable satisfies a certain predicate. * Type synonyms now remember whether or not they are "forgetful"; a forgetful synonym drops at least one argument. This is useful when flattening; see flattenView. * The pattern-match completeness checker invokes the solver. This invocation might need to look through newtypes when checking representational equality. Thus, the desugarer needs to keep track of the in-scope variables to know what newtype constructors are in scope. I bet this bug was around before but never noticed. * Extra-constraints wildcards are no longer simplified before printing. See Note [Do not simplify ConstraintHoles] in GHC.Tc.Solver. * Whether or not there are Given equalities has become slightly subtler. See the new HasGivenEqs datatype. * Note [Type variable cycles in Givens] in GHC.Tc.Solver.Canonical explains a significant new wrinkle in the new approach. * See Note [What might match later?] in GHC.Tc.Solver.Interact, which explains the fix to #18910. * The inert_count field of InertCans wasn't actually used, so I removed it. Though I (Richard) did the implementation, Simon PJ was very involved in design and review. This updates the Haddock submodule to avoid #18932 by adding a type signature. ------------------------- Metric Decrease: T12227 T5030 T9872a T9872b T9872c Metric Increase: T9872d -------------------------
* [Sized Cmm] properly retain sizes.Moritz Angermann2020-11-262-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | This replaces all Word<N> = W<N># Word# and Int<N> = I<N># Int# with Word<N> = W<N># Word<N># and Int<N> = I<N># Int<N>#, thus providing us with properly sized primitives in the codegenerator instead of pretending they are all full machine words. This came up when implementing darwinpcs for arm64. The darwinpcs reqires us to pack function argugments in excess of registers on the stack. While most procedure call standards (pcs) assume arguments are just passed in 8 byte slots; and thus the caller does not know the exact signature to make the call, darwinpcs requires us to adhere to the prototype, and thus have the correct sizes. If we specify CInt in the FFI call, it should correspond to the C int, and not just be Word sized, when it's only half the size. This does change the expected output of T16402 but the new result is no less correct as it eliminates the narrowing (instead of the `and` as was previously done). Bumps the array, bytestring, text, and binary submodules. Co-Authored-By: Ben Gamari <ben@well-typed.com> Metric Increase: T13701 T14697
* Replace HsImplicitBndrs with HsOuterTyVarBndrsRyan Scott2020-11-0616-13/+82
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This refactors the GHC AST to remove `HsImplicitBndrs` and replace it with `HsOuterTyVarBndrs`, a type which records whether the outermost quantification in a type is explicit (i.e., with an outermost, invisible `forall`) or implicit. As a result of this refactoring, it is now evident in the AST where the `forall`-or-nothing rule applies: it's all the places that use `HsOuterTyVarBndrs`. See the revamped `Note [forall-or-nothing rule]` in `GHC.Hs.Type` (previously in `GHC.Rename.HsType`). Moreover, the places where `ScopedTypeVariables` brings lexically scoped type variables into scope are a subset of the places that adhere to the `forall`-or-nothing rule, so this also makes places that interact with `ScopedTypeVariables` easier to find. See the revamped `Note [Lexically scoped type variables]` in `GHC.Hs.Type` (previously in `GHC.Tc.Gen.Sig`). `HsOuterTyVarBndrs` are used in type signatures (see `HsOuterSigTyVarBndrs`) and type family equations (see `HsOuterFamEqnTyVarBndrs`). The main difference between the former and the latter is that the former cares about specificity but the latter does not. There are a number of knock-on consequences: * There is now a dedicated `HsSigType` type, which is the combination of `HsOuterSigTyVarBndrs` and `HsType`. `LHsSigType` is now an alias for an `XRec` of `HsSigType`. * Working out the details led us to a substantial refactoring of the handling of explicit (user-written) and implicit type-variable bindings in `GHC.Tc.Gen.HsType`. Instead of a confusing family of higher order functions, we now have a local data type, `SkolemInfo`, that controls how these binders are kind-checked. It remains very fiddly, not fully satisfying. But it's better than it was. Fixes #16762. Bumps the Haddock submodule. Co-authored-by: Simon Peyton Jones <simonpj@microsoft.com> Co-authored-by: Richard Eisenberg <rae@richarde.dev> Co-authored-by: Zubin Duggal <zubin@cmi.ac.in>
* Fix two constraint solving problemsSimon Peyton Jones2020-10-272-0/+19
| | | | | | | | | | | | | | | | | | | | | This patch fixes two problems in the constraint solver. * An actual bug #18555: we were floating out a constraint to eagerly, and that was ultimately fatal. It's explained in Note [Do not float blocked constraints] in GHC.Core.Constraint. This is all very delicate, but it's all going to become irrelevant when we stop floating constraints (#17656). * A major performance infelicity in the flattener. When flattening (ty |> co) we *never* generated Refl, even when there was nothing at all to do. Result: we would gratuitously rewrite the constraint to exactly the same thing, wasting work. Described in #18413, and came up again in #18855. Solution: exploit the special case by calling the new function castCoercionKind1. See Note [castCoercionKind1] in GHC.Core.Coercion
* Version bump: base-4.16 (#18712)Vladislav Zavialov2020-10-272-2/+2
| | | | Also bumps upper bounds on base in boot libraries (incl. submodules).
* Extend mAX_TUPLE_SIZE to 64GHC GitLab CI2020-10-152-11/+13
| | | | As well a ctuples and sums.
* Improve kind generalisation, error messagesSimon Peyton Jones2020-09-2419-52/+93
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch does two things: * It refactors GHC.Tc.Errors a bit. In debugging Quick Look I was forced to look in detail at error messages, and ended up doing a bit of refactoring, esp in mkTyVarEqErr'. It's still quite a mess, but a bit better, I think. * It makes a significant improvement to the kind checking of type and class declarations. Specifically, we now ensure that if kind checking fails with an unsolved constraint, all the skolems are in scope. That wasn't the case before, which led to some obscure error messages; and occasional failures with "no skolem info" (eg #16245). Both of these, and the main Quick Look patch itself, affect a /lot/ of error messages, as you can see from the number of files changed. I've checked them all; I think they are as good or better than before. Smaller things * I documented the various instances of VarBndr better. See Note [The VarBndr tyep and its uses] in GHC.Types.Var * Renamed GHC.Tc.Solver.simpl_top to simplifyTopWanteds * A bit of refactoring in bindExplicitTKTele, to avoid the footwork with Either. Simpler now. * Move promoteTyVar from GHC.Tc.Solver to GHC.Tc.Utils.TcMType Fixes #16245 (comment 211369), memorialised as typecheck/polykinds/T16245a Also fixes the three bugs in #18640
* Implement Quick Look impredicativitySimon Peyton Jones2020-09-241-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch implements Quick Look impredicativity (#18126), sticking very closely to the design in A quick look at impredicativity, Serrano et al, ICFP 2020 The main change is that a big chunk of GHC.Tc.Gen.Expr has been extracted to two new modules GHC.Tc.Gen.App GHC.Tc.Gen.Head which deal with typechecking n-ary applications, and the head of such applications, respectively. Both contain a good deal of documentation. Three other loosely-related changes are in this patch: * I implemented (partly by accident) points (2,3)) of the accepted GHC proposal "Clean up printing of foralls", namely https://github.com/ghc-proposals/ghc-proposals/blob/ master/proposals/0179-printing-foralls.rst (see #16320). In particular, see Note [TcRnExprMode] in GHC.Tc.Module - :type instantiates /inferred/, but not /specified/, quantifiers - :type +d instantiates /all/ quantifiers - :type +v is killed off That completes the implementation of the proposal, since point (1) was done in commit df08468113ab46832b7ac0a7311b608d1b418c4d Author: Krzysztof Gogolewski <krzysztof.gogolewski@tweag.io> Date: Mon Feb 3 21:17:11 2020 +0100 Always display inferred variables using braces * HsRecFld (which the renamer introduces for record field selectors), is now preserved by the typechecker, rather than being rewritten back to HsVar. This is more uniform, and turned out to be more convenient in the new scheme of things. * The GHCi debugger uses a non-standard unification that allows the unification variables to unify with polytypes. We used to hack this by using ImpredicativeTypes, but that doesn't work anymore so I introduces RuntimeUnkTv. See Note [RuntimeUnkTv] in GHC.Runtime.Heap.Inspect Updates haddock submodule. WARNING: this patch won't validate on its own. It was too hard to fully disentangle it from the following patch, on type errors and kind generalisation. Changes to tests * Fixes #9730 (test added) * Fixes #7026 (test added) * Fixes most of #8808, except function `g2'` which uses a section (which doesn't play with QL yet -- see #18126) Test added * Fixes #1330. NB Church1.hs subsumes Church2.hs, which is now deleted * Fixes #17332 (test added) * Fixes #4295 * This patch makes typecheck/should_run/T7861 fail. But that turns out to be a pre-existing bug: #18467. So I have just made T7861 into expect_broken(18467)
* Remove GADT self-reference check (#11554, #12081, #12174, fixes #15942)Artyom Kuznetsov2020-09-193-12/+12
| | | | Reverts 430f5c84dac1eab550110d543831a70516b5cac8
* Fix visible forall in ppr_ty (#18522)Vladislav Zavialov2020-08-063-0/+6
| | | | | | | 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
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