summaryrefslogtreecommitdiff
path: root/compiler/GHC/Tc/Solver.hs
Commit message (Collapse)AuthorAgeFilesLines
* Fixes #19627.Apoorv Ingle2023-03-091-2/+2
| | | | | | | | | Previously the solver failed with an unhelpful "solver reached too may iterations" error. With the fix for #21909 in place we no longer have the possibility of generating such an error if we have `-fconstraint-solver-iteration` > `-fgivens-fuel > `-fwanteds-fuel`. This is true by default, and the said fix also gives programmers a knob to control how hard the solver should try before giving up. This commit adds: * Reference to ticket #19627 in the Note [Expanding Recursive Superclasses and ExpansionFuel] * Test `typecheck/should_fail/T19627.hs` for regression purposes
* Constraint simplification loop now depends on `ExpansionFuel`Apoorv Ingle2023-03-061-0/+71
| | | | | | | | | | | | | | instead of a boolean flag for `CDictCan.cc_pend_sc`. Pending givens get a fuel of 3 while Wanted and quantified constraints get a fuel of 1. This helps pending given constraints to keep up with pending wanted constraints in case of `UndecidableSuperClasses` and superclass expansions while simplifying the infered type. Adds 3 dynamic flags for controlling the fuels for each type of constraints `-fgivens-expansion-fuel` for givens `-fwanteds-expansion-fuel` for wanteds and `-fqcs-expansion-fuel` for quantified constraints Fixes #21909 Added Tests T21909, T21909b Added Note [Expanding Recursive Superclasses and ExpansionFuel]
* Don't specialise incoherent instance applicationsGergő Érdi2023-02-271-4/+4
| | | | | | | | | | | | | | Using incoherent instances, there can be situations where two occurrences of the same overloaded function at the same type use two different instances (see #22448). For incoherently resolved instances, we must mark them with `nospec` to avoid the specialiser rewriting one to the other. This marking is done during the desugaring of the `WpEvApp` wrapper. Fixes #22448 Metric Increase: T15304
* Refactor the treatment of loopy superclass dictswip/T20666Richard Eisenberg2023-01-111-14/+66
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch completely re-engineers how we deal with loopy superclass dictionaries in instance declarations. It fixes #20666 and #19690 The highlights are * Recognise that the loopy-superclass business should use precisely the Paterson conditions. This is much much nicer. See Note [Recursive superclasses] in GHC.Tc.TyCl.Instance * With that in mind, define "Paterson-smaller" in Note [Paterson conditions] in GHC.Tc.Validity, and the new data type `PatersonSize` in GHC.Tc.Utils.TcType, along with functions to compute and compare PatsonSizes * Use the new PatersonSize stuff when solving superclass constraints See Note [Solving superclass constraints] in GHC.Tc.TyCl.Instance * In GHC.Tc.Solver.Monad.lookupInInerts, add a missing call to prohibitedSuperClassSolve. This was the original cause of #20666. * Treat (TypeError "stuff") as having PatersonSize zero. See Note [Paterson size for type family applications] in GHC.Tc.Utils.TcType. * Treat the head of a Wanted quantified constraint in the same way as the superclass of an instance decl; this is what fixes #19690. See GHC.Tc.Solver.Canonical Note [Solving a Wanted forall-constraint] (Thanks to Matthew Craven for this insight.) This entailed refactoring the GivenSc constructor of CtOrigin a bit, to say whether it comes from an instance decl or quantified constraint. * Some refactoring way in which redundant constraints are reported; we don't want to complain about the extra, apparently-redundant constraints that we must add to an instance decl because of the loopy-superclass thing. I moved some work from GHC.Tc.Errors to GHC.Tc.Solver. * Add a new section to the user manual to describe the loopy superclass issue and what rules it follows.
* Type vs Constraint: finally nailedSimon Peyton Jones2022-11-111-4/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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
* Fix typosKrzysztof Gogolewski2022-09-141-1/+1
|
* Fix typosEric Lindblad2022-09-141-5/+5
| | | | | | | This fixes various typos and spelling mistakes in the compiler. Fixes #21891
* Fix unification of ConcreteTvs, removing IsRefl#sheaf2022-04-281-34/+75
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch fixes the unification of concrete type variables. The subtlety was that unifying concrete metavariables is more subtle than other metavariables, as decomposition is possible. See the Note [Unifying concrete metavariables], which explains how we unify a concrete type variable with a type 'ty' by concretising 'ty', using the function 'GHC.Tc.Utils.Concrete.concretise'. This can be used to perform an eager syntactic check for concreteness, allowing us to remove the IsRefl# special predicate. Instead of emitting two constraints `rr ~# concrete_tv` and `IsRefl# rr concrete_tv`, we instead concretise 'rr'. If this succeeds we can fill 'concrete_tv', and otherwise we directly emit an error message to the typechecker environment instead of deferring. We still need the error message to be passed on (instead of directly thrown), as we might benefit from further unification in which case we will need to zonk the stored types. To achieve this, we change the 'wc_holes' field of 'WantedConstraints' to 'wc_errors', which stores general delayed errors. For the moement, a delayed error is either a hole, or a syntactic equality error. hasFixedRuntimeRep_MustBeRefl is now hasFixedRuntimeRep_syntactic, and hasFixedRuntimeRep has been refactored to directly return the most useful coercion for PHASE 2 of FixedRuntimeRep. This patch also adds a field ir_frr to the InferResult datatype, holding a value of type Maybe FRROrigin. When this value is not Nothing, this means that we must fill the ir_ref field with a type which has a fixed RuntimeRep. When it comes time to fill such an ExpType, we ensure that the type has a fixed RuntimeRep by performing a representation-polymorphism check with the given FRROrigin This is similar to what we already do to ensure we fill an Infer ExpType with a type of the correct TcLevel. This allows us to properly perform representation-polymorphism checks on 'Infer' 'ExpTypes'. The fillInferResult function had to be moved to GHC.Tc.Utils.Unify to avoid a cyclic import now that it calls hasFixedRuntimeRep. This patch also changes the code in matchExpectedFunTys to make use of the coercions, which is now possible thanks to the previous change. This implements PHASE 2 of FixedRuntimeRep in some situations. For example, the test cases T13105 and T17536b are now both accepted. Fixes #21239 and #21325 ------------------------- Metric Decrease: T18223 T5631 -------------------------
* decideMonoTyVars: account for CoVars in candidatessheaf2022-04-221-1/+1
| | | | | | | | | | | | The "candidates" passed to decideMonoTyVars can contain coercion holes. This is because we might well decide to quantify over some unsolved equality constraints, as long as they are not definitely insoluble. In that situation, decideMonoTyVars was passing a set of type variables that was not closed over kinds to closeWrtFunDeps, which was tripping up an assertion failure. Fixes #21404
* gitlab-ci: Use the linters image in hlint jobBen Gamari2022-03-111-1/+0
| | | | | | As the `hlint` executable is only available in the linters image. Fixes #21146.
* Introduce ConcreteTv metavariablessheaf2022-03-021-8/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch introduces a new kind of metavariable, by adding the constructor `ConcreteTv` to `MetaInfo`. A metavariable with `ConcreteTv` `MetaInfo`, henceforth a concrete metavariable, can only be unified with a type that is concrete (that is, a type that answers `True` to `GHC.Core.Type.isConcrete`). This solves the problem of dangling metavariables in `Concrete#` constraints: instead of emitting `Concrete# ty`, which contains a secret existential metavariable, we simply emit a primitive equality constraint `ty ~# concrete_tv` where `concrete_tv` is a fresh concrete metavariable. This means we can avoid all the complexity of canonicalising `Concrete#` constraints, as we can just re-use the existing machinery for `~#`. To finish things up, this patch then removes the `Concrete#` special predicate, and instead introduces the special predicate `IsRefl#` which enforces that a coercion is reflexive. Such a constraint is needed because the canonicaliser is quite happy to rewrite an equality constraint such as `ty ~# concrete_tv`, but such a rewriting is not handled by the rest of the compiler currently, as we need to make use of the resulting coercion, as outlined in the FixedRuntimeRep plan. The big upside of this approach (on top of simplifying the code) is that we can now selectively implement PHASE 2 of FixedRuntimeRep, by changing individual calls of `hasFixedRuntimeRep_MustBeRefl` to `hasFixedRuntimeRep` and making use of the obtained coercion.
* Kill derived constraintsRichard Eisenberg2022-02-231-120/+438
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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 -------------------------
* Tag inference work.Andreas Klebinger2022-02-121-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This does three major things: * Enforce the invariant that all strict fields must contain tagged pointers. * Try to predict the tag on bindings in order to omit tag checks. * Allows functions to pass arguments unlifted (call-by-value). The former is "simply" achieved by wrapping any constructor allocations with a case which will evaluate the respective strict bindings. The prediction is done by a new data flow analysis based on the STG representation of a program. This also helps us to avoid generating redudant cases for the above invariant. StrictWorkers are created by W/W directly and SpecConstr indirectly. See the Note [Strict Worker Ids] Other minor changes: * Add StgUtil module containing a few functions needed by, but not specific to the tag analysis. ------------------------- Metric Decrease: T12545 T18698b T18140 T18923 LargeRecord Metric Increase: LargeRecord ManyAlternatives ManyConstructors T10421 T12425 T12707 T13035 T13056 T13253 T13253-spj T13379 T15164 T18282 T18304 T18698a T1969 T20049 T3294 T4801 T5321FD T5321Fun T783 T9233 T9675 T9961 T19695 WWRec -------------------------
* Rework the handling of SkolemInfoMatthew Pickering2022-01-291-26/+44
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* Improve partial signaturesSimon Peyton Jones2022-01-271-18/+80
| | | | | | | | | | | As #20921 showed, with partial signatures, it is helpful to use the same algorithm (namely findInferredDiff) for * picking the constraints to retain for the /group/ in Solver.decideQuantification * picking the contraints to retain for the /individual function/ in Bind.chooseInferredQuantifiers This is still regrettably declicate, but it's a step forward.
* Fix typosKrzysztof Gogolewski2021-12-251-4/+4
|
* Improve redundant-constraints warningRichard Eisenberg2021-11-121-28/+74
| | | | | | | | | | | | | | Previously, we reported things wrong with f :: (Eq a, Ord a) => a -> Bool f x = x == x saying that Eq a was redundant. This is fixed now, along with some simplification in Note [Replacement vs keeping]. There's a tiny bit of extra complexity in setImplicationStatus, but it's explained in Note [Tracking redundant constraints]. Close #20602
* Default kind vars in tyfams with -XNoPolyKindssheaf2021-11-081-5/+7
| | | | | | | | | | | | | | | We should still default kind variables in type families in the presence of -XNoPolyKinds, to avoid suggesting enabling -XPolyKinds just because the function arrow introduced kind variables, e.g. type family F (t :: Type) :: Type where F (a -> b) = b With -XNoPolyKinds, we should still default `r :: RuntimeRep` in `a :: TYPE r`. Fixes #20584
* Don't default type variables in type familiessheaf2021-10-261-5/+14
| | | | | | | | | | | | | | | | | | | | | | | | | | This patch removes the following defaulting of type variables in type and data families: - type variables of kind RuntimeRep defaulting to LiftedRep - type variables of kind Levity defaulting to Lifted - type variables of kind Multiplicity defaulting to Many It does this by passing "defaulting options" to the `defaultTyVars` function; when calling from `tcTyFamInstEqnGuts` or `tcDataFamInstHeader` we pass options that avoid defaulting. This avoids wildcards being defaulted, which caused type families to unexpectedly fail to reduce. Note that kind defaulting, applicable only with -XNoPolyKinds, is not changed by this patch. Fixes #17536 ------------------------- Metric Increase: T12227 -------------------------
* Add defaulting plugins.Andrei Barbu2021-10-081-5/+29
| | | | | | | | | | | | | | | Like the built-in type defaulting rules these plugins can propose candidates to resolve ambiguous type variables. Machine learning and other large APIs like those for game engines introduce new numeric types and other complex typed APIs. The built-in defaulting mechanism isn't powerful enough to resolve ambiguous types in these cases forcing users to specify minutia that they might not even know how to do. There is an example defaulting plugin linked in the documentation. Applications include defaulting the device a computation executes on, if a gradient should be computed for a tensor, or the size of a tensor. See https://github.com/ghc-proposals/ghc-proposals/pull/396 for details.
* Speed up valid hole-fits by adding early abort and checks.Matthías Páll Gissurarson2021-10-051-1/+5
| | | | | | | | | | | | | | By adding an early abort flag in `TcSEnv`, we can fail fast in the presence of insoluble constraints. This helps us avoid a lot of work in valid hole-fits, and we geta massive speed-up by avoiding a lot of useless work solving constraints that never come into play. Additionally, we add a simple check for degenerate hole types, such as when the type of the hole is an immutable type variable (as is the case when the hole is completely unconstrained). Then the only valid fits are the locals, so we can ignore the global candidates. This fixes #16875
* Bump TcLevel of failing kind equality implicationsheaf2021-10-041-8/+28
| | | | | | | | Not bumping the TcLevel meant that we could end up trying to add evidence terms for the implication constraint created to wrap failing kind equalities (to avoid their deferral). fixes #20043
* Add and use new constructors to TcRnMessageAlfredo Di Napoli2021-09-071-12/+2
| | | | | | | | | | | | | This commit adds the following constructors to the TcRnMessage type and uses them to replace sdoc-based diagnostics in some parts of GHC (e.g. TcRnUnknownMessage). It includes: * Add TcRnMonomorphicBindings diagnostic * Convert TcRnUnknownMessage in Tc.Solver.Interact * Add and use the TcRnOrphanInstance constructor to TcRnMessage * Add TcRnFunDepConflict and TcRnDupInstanceDecls constructors to TcRnMessage * Add and use TcRnConflictingFamInstDecls constructor to TcRnMessage * Get rid of TcRnUnknownMessage from GHC.Tc.Instance.Family
* Detect TypeError when checking for insolubilitysheaf2021-08-151-1/+66
| | | | | | | | | | | | | | | We detect insoluble Givens by making getInertInsols take into account TypeError constraints, on top of insoluble equalities such as Int ~ Bool (which it already took into account). This allows pattern matches with insoluble contexts to be reported as redundant (tyOracle calls tcCheckGivens which calls getInertInsols). As a bonus, we get to remove a workaround in Data.Typeable.Internal: we can directly use a NotApplication type family, as opposed to needing to cook up an insoluble equality constraint. Fixes #11503 #14141 #16377 #20180
* Add TcRnSimplifierTooManyIterations to TcRnMessageAlfredo Di Napoli2021-07-091-6/+1
|
* Try to simplify zoo of functions in `Tc.Utils.Monad`Alfredo Di Napoli2021-06-281-5/+7
| | | | | | | | | | | This commit tries to untangle the zoo of diagnostic-related functions in `Tc.Utils.Monad` so that we can have the interfaces mentions only `TcRnMessage`s while we push the creation of these messages upstream. It also ports TcRnMessage diagnostics to use the new API, in particular this commit switch to use TcRnMessage in the external interfaces of the diagnostic functions, and port the old SDoc to be wrapped into TcRnUnknownMessage.
* Rip GHC.Tc.Solver.Monad asunder (only)Richard Eisenberg2021-05-291-1/+2
| | | | | | | | | | | This creates new modules GHC.Tc.Solver.InertSet and GHC.Tc.Solver.Types. The Monad module is still pretty big, but this is an improvement. Moreover, it means that GHC.HsToCore.Pmc.Solver.Types no longer depends on the constraint solver (it now depends on GHC.Tc.Solver.InertSet), making the error-messages work easier. This patch thus contributes to #18516.
* Remove useless {-# LANGUAGE CPP #-} pragmasSylvain Henry2021-05-121-1/+1
|
* Fully remove HsVersions.hSylvain Henry2021-05-121-2/+0
| | | | | | | | | | Replace uses of WARN macro with calls to: warnPprTrace :: Bool -> SDoc -> a -> a Remove the now unused HsVersions.h Bump haddock submodule
* Replace CPP assertions with Haskell functionsSylvain Henry2021-05-121-3/+4
| | | | | | | | | | | | | | | There is no reason to use CPP. __LINE__ and __FILE__ macros are now better replaced with GHC's CallStack. As a bonus, assert error messages now contain more information (function name, column). Here is the mapping table (HasCallStack omitted): * ASSERT: assert :: Bool -> a -> a * MASSERT: massert :: Bool -> m () * ASSERTM: assertM :: m Bool -> m () * ASSERT2: assertPpr :: Bool -> SDoc -> a -> a * MASSERT2: massertPpr :: Bool -> SDoc -> m () * ASSERTM2: assertPprM :: m Bool -> SDoc -> m ()
* Add GhcMessage and ancillary typesAlfredo Di Napoli2021-04-291-4/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This commit adds GhcMessage and ancillary (PsMessage, TcRnMessage, ..) types. These types will be expanded to represent more errors generated by different subsystems within GHC. Right now, they are underused, but more will come in the glorious future. See https://gitlab.haskell.org/ghc/ghc/-/wikis/Errors-as-(structured)-values for a design overview. Along the way, lots of other things had to happen: * Adds Semigroup and Monoid instance for Bag * Fixes #19746 by parsing OPTIONS_GHC pragmas into Located Strings. See GHC.Parser.Header.toArgs (moved from GHC.Utils.Misc, where it didn't belong anyway). * Addresses (but does not completely fix) #19709, now reporting desugarer warnings and errors appropriately for TH splices. Not done: reporting type-checker warnings for TH splices. * Some small refactoring around Safe Haskell inference, in order to keep separate classes of messages separate. * Some small refactoring around initDsTc, in order to keep separate classes of messages separate. * Separate out the generation of messages (that is, the construction of the text block) from the wrapping of messages (that is, assigning a SrcSpan). This is more modular than the previous design, which mixed the two. Close #19746. This was a collaborative effort by Alfredo di Napoli and Richard Eisenberg, with a key assist on #19746 by Iavor Diatchki. Metric Increase: MultiLayerModules
* More accurate SrcSpan when reporting redundant constraintsSimon Peyton Jones2021-04-121-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | We want an accurate SrcSpan for redundant constraints: • Redundant constraint: Eq a • In the type signature for: f :: forall a. Eq a => a -> () | 5 | f :: Eq a => a -> () | ^^^^ This patch adds some plumbing to achieve this * New data type GHC.Tc.Types.Origin.ReportRedundantConstraints (RRC) * This RRC value is kept inside - FunSigCtxt - ExprSigCtxt * Then, when reporting the error in GHC.Tc.Errors, use this SrcSpan to control the error message: GHC.Tc.Errors.warnRedundantConstraints Quite a lot of files are touched in a boring way.
* Introduce SevIgnore Severity to suppress warningsAlfredo Di Napoli2021-04-051-2/+1
| | | | | | | | | | | | | | | | | | | | | | This commit introduces a new `Severity` type constructor called `SevIgnore`, which can be used to classify diagnostic messages which are not meant to be displayed to the user, for example suppressed warnings. This extra constructor allows us to get rid of a bunch of redundant checks when emitting diagnostics, typically in the form of the pattern: ``` when (optM Opt_XXX) $ addDiagnosticTc (WarningWithFlag Opt_XXX) ... ``` Fair warning! Not all checks should be omitted/skipped, as evaluating some data structures used to produce a diagnostic might still be expensive (e.g. zonking, etc). Therefore, a case-by-case analysis must be conducted when deciding if a check can be removed or not. Last but not least, we remove the unnecessary `CmdLine.WarnReason` type, which is now redundant with `DiagnosticReason`.
* Add `MessageClass`, rework `Severity` and add `DiagnosticReason`.wip/adinapoli-message-class-new-designAlfredo Di Napoli2021-03-291-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Other than that: * Fix T16167,json,json2,T7478,T10637 tests to reflect the introduction of the `MessageClass` type * Remove `makeIntoWarning` * Remove `warningsToMessages` * Refactor GHC.Tc.Errors 1. Refactors GHC.Tc.Errors so that we use `DiagnosticReason` for "choices" (defer types errors, holes, etc); 2. We get rid of `reportWarning` and `reportError` in favour of a general `reportDiagnostic`. * Introduce `DiagnosticReason`, `Severity` is an enum: This big commit makes `Severity` a simple enumeration, and introduces the concept of `DiagnosticReason`, which classifies the /reason/ why we are emitting a particular diagnostic. It also adds a monomorphic `DiagnosticMessage` type which is used for generic messages. * The `Severity` is computed (for now) from the reason, statically. Later improvement will add a `diagReasonSeverity` function to compute the `Severity` taking `DynFlags` into account. * Rename `logWarnings` into `logDiagnostics` * Add note and expand description of the `mkHoleError` function
* Pmc: Consider Required Constraints when guessing PatSyn arg types (#19475)Sebastian Graf2021-03-141-6/+20
| | | | | | | | | | | | | | | | | | | | | | This patch makes `guessConLikeUnivTyArgsFromResTy` consider required Thetas of PatSynCons, by treating them as Wanted constraints to be discharged with the constraints from the Nabla's TyState and saying "does not match the match type" if the Wanted constraints are unsoluble. It calls out into a new function `GHC.Tc.Solver.tcCheckWanteds` to do so. In pushing the failure logic around call sites of `initTcDsForSolver` inside it by panicking, I realised that there was a bunch of dead code surrounding `pmTopMoraliseType`: I was successfully able to delete the `NoChange` data constructor of `TopNormaliseTypeResult`. The details are in `Note [Matching against a ConLike result type]` and `Note [Instantiating a ConLike]. The regression test is in `T19475`. It's pretty much a fork of `T14422` at the moment. Co-authored-by: Cale Gibbard <cgibbard@gmail.com>
* Fix typosBrian Wignall2021-02-061-2/+2
|
* Parameterise Messages over eAlfredo Di Napoli2021-01-221-2/+2
| | | | | | | | | This commit paves the way to a richer and more structured representation of GHC error messages, as per GHC proposal #306. More specifically 'Messages' from 'GHC.Types.Error' now gains an extra type parameter, that we instantiate to 'ErrDoc' for now. Later, this will allow us to replace ErrDoc with something more structure (for example messages coming from the parser, the typechecker etc).
* Fix error recovery in solveEqualitiesSimon Peyton Jones2021-01-221-4/+43
| | | | | | | | | | | | | | | | | | | As #19142 showed, with -fdefer-type-errors we were allowing compilation to proceed despite a fatal kind error. This patch fixes it, as described in the new note in GHC.Tc.Solver, Note [Wrapping failing kind equalities] Also fixes #19158 Also when checking default( ty1, ty2, ... ) only consider a possible default (C ty2) if ty2 is kind-compatible with C. Previously we could form kind-incompatible constraints, with who knows what kind of chaos resulting. (Actually, no chaos results, but that's only by accident. It's plain wrong to form the constraint (Num Either) for example.) I just happened to notice this during fixing #19142.
* Establish invariant (GivenInv)Simon Peyton Jones2021-01-021-68/+84
| | | | | | | | | | | | | | | | | | This patch establishes invariant (GivenInv) from GHC.Tc.Utils.TcType Note [TcLevel invariants]. (GivenInv) says that unification variables from level 'n' should not appear in the Givens for level 'n'. See Note [GivenInv] in teh same module. This invariant was already very nearly true, but a dark corner of partial type signatures made it false. The patch re-jigs partial type signatures a bit to avoid the problem, and documents the invariant much more thorughly Fixes #18646 along the way: see Note [Extra-constraints wildcards] in GHC.Tc.Gen.Bind I also simplified the interface to tcSimplifyInfer slightly, so that it /emits/ the residual constraint, rather than /returning/ it.
* Kill floatEqualities completelySimon Peyton Jones2020-12-201-396/+88
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch delivers on #17656, by entirel killing off the complex floatEqualities mechanism. Previously, floatEqualities would float an equality out of an implication, so that it could be solved at an outer level. But now we simply do unification in-place, without floating the constraint, relying on level numbers to determine untouchability. There are a number of important new Notes: * GHC.Tc.Utils.Unify Note [Unification preconditions] describes the preconditions for unification, including both skolem-escape and touchability. * GHC.Tc.Solver.Interact Note [Solve by unification] describes what we do when we do unify * GHC.Tc.Solver.Monad Note [The Unification Level Flag] describes how we control solver iteration under this new scheme * GHC.Tc.Solver.Monad Note [Tracking Given equalities] describes how we track when we have Given equalities * GHC.Tc.Types.Constraint Note [HasGivenEqs] is a new explanation of the ic_given_eqs field of an implication A big raft of subtle Notes in Solver, concerning floatEqualities, disappears. Main code changes: * GHC.Tc.Solver.floatEqualities disappears entirely * GHC.Tc.Solver.Monad: new fields in InertCans, inert_given_eq_lvl and inert_given_eq, updated by updateGivenEqs See Note [Tracking Given equalities]. * In exchange for updateGivenEqa, GHC.Tc.Solver.Monad.getHasGivenEqs is much simpler and more efficient * I found I could kill of metaTyVarUpdateOK entirely One test case T14683 showed a 5.1% decrease in compile-time allocation; and T5631 was down 2.2%. Other changes were small. Metric Decrease: T14683 T5631
* Rename the flattener to become the rewriter.Richard Eisenberg2020-12-011-6/+10
| | | | | | | | Now that flattening doesn't produce flattening variables, it's not really flattening anything: it's rewriting. This change also means that the rewriter can no longer be confused the core flattener (in GHC.Core.Unify), which is sometimes used during type-checking.
* Remove flattening variablesRichard Eisenberg2020-12-011-30/+72
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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 -------------------------
* Replace HsImplicitBndrs with HsOuterTyVarBndrsRyan Scott2020-11-061-14/+36
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* Add the proper HLint rules and remove redundant keywords from compilerHécate2020-11-011-3/+0
|
* Fix two constraint solving problemsSimon Peyton Jones2020-10-271-1/+23
| | | | | | | | | | | | | | | | | | | | | 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
* Lint the compiler for extraneous LANGUAGE pragmasHécate2020-10-101-2/+1
|
* PmCheck: Big refactor of module structureSebastian Graf2020-09-261-1/+1
| | | | | | | | | | | | | | * Move everything from `GHC.HsToCore.PmCheck.*` to `GHC.HsToCore.Pmc.*` in analogy to `GHC.Tc`, rename exported `covCheck*` functions to `pmc*` * Rename `Pmc.Oracle` to `Pmc.Solver` * Split off the LYG desugaring and checking steps into their own modules (`Pmc.Desugar` and `Pmc.Check` respectively) * Split off a `Pmc.Utils` module with stuff shared by `Pmc.{,Desugar,Check,Solver}` * Move `Pmc.Types` to `Pmc.Solver.Types`, add a new `Pmc.Types` module with all the LYG types, which form the interfaces between `Pmc.{Desugar,Check,Solver,}`.
* Improve kind generalisation, error messagesSimon Peyton Jones2020-09-241-110/+114
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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
* Care with implicit-parameter superclassesSimon Peyton Jones2020-09-151-1/+1
| | | | | | | | | | | | | | | | | | | | | | Two bugs, #18627 and #18649, had the same cause: we were not account for the fact that a constaint tuple might hide an implicit parameter. The solution is not hard: look for implicit parameters in superclasses. See Note [Local implicit parameters] in GHC.Core.Predicate. Then we use this new function in two places * The "short-cut solver" in GHC.Tc.Solver.Interact.shortCutSolver which simply didn't handle implicit parameters properly at all. This fixes #18627 * The specialiser, which should not specialise on implicit parameters This fixes #18649 There are some lingering worries (see Note [Local implicit parameters]) but things are much better.
* Make `tcCheckSatisfiability` incremental (#18645)Sebastian Graf2020-09-121-31/+28
| | | | | | | | | | | | | | | | | By taking and returning an `InertSet`. Every new `TcS` session can then pick up where a prior session left with `setTcSInerts`. Since we don't want to unflatten the Givens (and because it leads to infinite loops, see !3971), we introduced a new variant of `runTcS`, `runTcSInerts`, that takes and returns the `InertSet` and makes sure not to unflatten the Givens after running the `TcS` action. Fixes #18645 and #17836. Metric Decrease: T17977 T18478
View Lorry Controller Status