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* Fix linearity checking in LintKrzysztof Gogolewski2022-12-022-0/+13
| | | | | | | | Lint was not able to see that x*y <= x*y, because this inequality was decomposed to x <= x*y && y <= x*y, but there was no rule to see that x <= x*y. Fixes #22546.
* Print unticked promoted data constructors (#20531)Vladislav Zavialov2022-11-2528-47/+47
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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 Jones2022-11-111-2/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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
* 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 McIlwaine2022-10-131-1/+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 changessheaf2022-09-1340-64/+64
| | | | | | | | 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 Moreau2022-08-191-1/+1
| | | | | | | This patch improves the uniformity of error message formatting by printing constraints in quotes, as we do for types. Fix #21167
* Typecheck remaining ValArgs in rebuildHsAppssheaf2022-06-091-1/+1
| | | | | | | | | | | | | | | | | This patch refactors hasFixedRuntimeRep_remainingValArgs, renaming it to tcRemainingValArgs. The logic is moved to rebuildHsApps, which ensures consistent behaviour across tcApp and quickLookArg1/tcEValArg. This patch also refactors the treatment of stupid theta for data constructors, changing the place we drop stupid theta arguments from dsConLike to mkDataConRep (now the datacon wrapper drops these arguments). We decided not to implement PHASE 2 of the FixedRuntimeRep plan for these remaining ValArgs. Future directions are outlined on the wiki: https://gitlab.haskell.org/ghc/ghc/-/wikis/Remaining-ValArgs Fixes #21544 and #21650
* TTG: Rework and improve splicesromes2022-06-011-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This commit redefines the structure of Splices in the AST. We get rid of `HsSplice` which used to represent typed and untyped splices, quasi quotes, and the result of splicing either an expression, a type or a pattern. Instead we have `HsUntypedSplice` which models an untyped splice or a quasi quoter, which works in practice just like untyped splices. The `HsExpr` constructor `HsSpliceE` which used to be constructed with an `HsSplice` is split into `HsTypedSplice` and `HsUntypedSplice`. The former is directly constructed with an `HsExpr` and the latter now takes an `HsUntypedSplice`. Both `HsType` and `Pat` constructors `HsSpliceTy` and `SplicePat` now take an `HsUntypedSplice` instead of a `HsSplice` (remember only /untyped splices/ can be spliced as types or patterns). The result of splicing an expression, type, or pattern is now comfortably stored in the extension fields `XSpliceTy`, `XSplicePat`, `XUntypedSplice` as, respectively, `HsUntypedSpliceResult (HsType GhcRn)`, `HsUntypedSpliceResult (Pat GhcRn)`, and `HsUntypedSpliceResult (HsExpr GhcRn)` Overall the TTG extension points are now better used to make invalid states unrepresentable and model the progression between stages better. See Note [Lifecycle of an untyped splice, and PendingRnSplice] and Note [Lifecycle of an typed splice, and PendingTcSplice] for more details. Updates haddock submodule Fixes #21263 ------------------------- Metric Decrease: hard_hole_fits -------------------------
* Add tests for eta-expansion of data constructorssheaf2022-05-262-0/+18
| | | | | This patch adds several tests relating to the eta-expansion of data constructors, including UnliftedNewtypes and DataTypeContexts.
* Check for uninferrable variables in tcInferPatSynDeclSimon Peyton Jones2022-05-101-1/+1
| | | | | | | | | | This fixes #21479 See Note [Unquantified tyvars in a pattern synonym] While doing this, I found that some error messages pointed at the pattern synonym /name/, rather than the /declaration/ so I widened the SrcSpan to encompass the declaration.
* Introduce Concrete# for representation polymorphism checkssheaf2021-10-172-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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 pretty-printer defaulting logic (#19361)Krzysztof Gogolewski2021-09-173-0/+20
| | | | | | When determining whether to default a RuntimeRep or Multiplicity variable, use isMetaTyVar to distinguish between metavariables (which can be hidden) and skolems (which cannot).
* Linear types: fix linting of multiplicities (#19165)Krzysztof Gogolewski2021-08-041-1/+1
| | | | The previous version did not substitute the type used in the scrutinee.
* Disable -fdefer-type-errors for linear types (#20083)Krzysztof Gogolewski2021-08-044-2/+30
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* Disallow nonlinear fields in Template Haskell (#18378)Krzysztof Gogolewski2021-08-027-0/+29
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* Reject pattern synonyms with linear types (#18806)Krzysztof Gogolewski2021-07-295-2/+13
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* Add proper GHCHints for most PsMessage constructorswip/adinapoli-issue-20055Alfredo Di Napoli2021-07-122-2/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This commit adds proper hints to most diagnostic types in the `GHC.Parser.Errors.Types` module. By "proper" we mean that previous to this commit the hints were bundled together with the diagnostic message, whereas now we moved most of them as proper `[GhcHint]` in the implementation of `diagnosticHints`. More specifically, this is the list of constructors which now has proper hints: * PsErrIllegalBangPattern * PsWarnOperatorWhitespaceExtConflict * PsErrLambdaCase * PsErrIllegalPatSynExport * PsWarnOperatorWhitespace * PsErrMultiWayIf * PsErrIllegalQualifiedDo * PsErrNumUnderscores * PsErrLinearFunction * PsErrIllegalTraditionalRecordSyntax * PsErrIllegalExplicitNamespace * PsErrOverloadedRecordUpdateNotEnabled * PsErrIllegalDataTypeContext * PsErrSemiColonsInCondExpr * PsErrSemiColonsInCondCmd * PsWarnStarIsType * PsWarnImportPreQualified * PsErrImportPostQualified * PsErrEmptyDoubleQuotes * PsErrIllegalRoleName * PsWarnStarBinder For some reason, this patch increases the peak_megabyte_allocated of the T11545 test to 90 (from a baseline of 80) but that particular test doesn't emit any parsing diagnostic or hint and the metric increase happens only for the `aarch64-linux-deb10`. Metric Increase: T11545
* Fixes around incomplete guards (#20023, #20024)Krzysztof Gogolewski2021-06-244-13/+8
| | | | | | | | | | - Fix linearity error with incomplete MultiWayIf (#20023) - Fix partial pattern binding error message (#20024) - Remove obsolete test LinearPolyTest It tested the special typing rule for ($), which was removed during the implementation of Quick Look 97cff9190d3. - Fix ticket numbers in linear/*/all.T, they referred to linear types issue tracker
* Typos, minor comment fixesKrzysztof Gogolewski2021-06-221-2/+2
| | | | | | | | | | | | | | | | | | | - Remove fstName, sndName, fstIdKey, sndIdKey - no longer used, removed from basicKnownKeyNames - Remove breakpointId, breakpointCondId, opaqueTyCon, unknownTyCon - they were used in the old implementation of the GHCi debugger - Fix typos in comments - Remove outdated comment in Lint.hs - Use 'LitRubbish' instead of 'RubbishLit' for consistency - Remove comment about subkinding - superseded by Note [Kind Constraint and kind Type] - Mention ticket ID in a linear types error message - Fix formatting in using-warnings.rst and linear-types.rst - Remove comment about 'Any' in Dynamic.hs - Dynamic now uses Typeable + existential instead of Any - Remove codeGen/should_compile/T13233.hs This was added by accident, it is not used and T13233 is already in should_fail
* GHC Exactprint main commitAlan Zimmerman2021-03-202-2/+2
| | | | | | | | Metric Increase: T10370 parsing001 Updates haddock submodule
* Run linear Lint on the desugarer output (part of #19165)Krzysztof Gogolewski2021-03-051-1/+1
| | | | | | | | | | | | | | This addresses points (1a) and (1b) of #19165. - Move mkFailExpr to HsToCore/Utils, as it can be shared - Desugar incomplete patterns and holes to an empty case, as in Note [Incompleteness and linearity] - Enable linear linting of desugarer output - Mark MultConstructor as broken. It fails Lint, but I'd like to fix this separately. Metric Decrease: T6048
* Infer multiplicity in case expressionsKrzysztof Gogolewski2021-03-011-1/+1
| | | | This is a first step towards #18738.
* Fix assertion error with linear types, #19400Krzysztof Gogolewski2021-02-272-0/+15
| | | | | The previous code using TyCoMapper could promote the same metavar twice. Use a set instead.
* Improve handling of overloaded labels, literals, lists etcwip/T19154Simon Peyton Jones2021-02-191-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When implementing Quick Look I'd failed to remember that overloaded labels, like #foo, should be treated as a "head", so that they can be instantiated with Visible Type Application. This caused #19154. A very similar ticket covers overloaded literals: #19167. This patch fixes both problems, but (annoyingly, albeit temporarily) in two different ways. Overloaded labels I dealt with overloaded labels by buying fully into the Rebindable Syntax approach described in GHC.Hs.Expr Note [Rebindable syntax and HsExpansion]. There is a good overview in GHC.Rename.Expr Note [Handling overloaded and rebindable constructs]. That module contains much of the payload for this patch. Specifically: * Overloaded labels are expanded in the renamer, fixing #19154. See Note [Overloaded labels] in GHC.Rename.Expr. * Left and right sections used to have special code paths in the typechecker and desugarer. Now we just expand them in the renamer. This is harder than it sounds. See GHC.Rename.Expr Note [Left and right sections]. * Infix operator applications are expanded in the typechecker, specifically in GHC.Tc.Gen.App.splitHsApps. See Note [Desugar OpApp in the typechecker] in that module * ExplicitLists are expanded in the renamer, when (and only when) OverloadedLists is on. * HsIf is expanded in the renamer when (and only when) RebindableSyntax is on. Reason: the coverage checker treats HsIf specially. Maybe we could instead expand it unconditionally, and fix up the coverage checker, but I did not attempt that. Overloaded literals Overloaded literals, like numbers (3, 4.2) and strings with OverloadedStrings, were not working correctly with explicit type applications (see #19167). Ideally I'd also expand them in the renamer, like the stuff above, but I drew back on that because they can occur in HsPat as well, and I did not want to to do the HsExpanded thing for patterns. But they *can* now be the "head" of an application in the typechecker, and hence something like ("foo" @T) works now. See GHC.Tc.Gen.Head.tcInferOverLit. It's also done a bit more elegantly, rather than by constructing a new HsExpr and re-invoking the typechecker. There is some refactoring around tcShortCutLit. Ultimately there is more to do here, following the Rebindable Syntax story. There are a lot of knock-on effects: * HsOverLabel and ExplicitList no longer need funny (Maybe SyntaxExpr) fields to support rebindable syntax -- good! * HsOverLabel, OpApp, SectionL, SectionR all become impossible in the output of the typecheker, GhcTc; so we set their extension fields to Void. See GHC.Hs.Expr Note [Constructor cannot occur] * Template Haskell quotes for HsExpanded is a bit tricky. See Note [Quotation and rebindable syntax] in GHC.HsToCore.Quote. * In GHC.HsToCore.Match.viewLExprEq, which groups equal HsExprs for the purpose of pattern-match overlap checking, I found that dictionary evidence for the same type could have two different names. Easily fixed by comparing types not names. * I did quite a bit of annoying fiddling around in GHC.Tc.Gen.Head and GHC.Tc.Gen.App to get error message locations and contexts right, esp in splitHsApps, and the HsExprArg type. Tiresome and not very illuminating. But at least the tricky, higher order, Rebuilder function is gone. * Some refactoring in GHC.Tc.Utils.Monad around contexts and locations for rebindable syntax. * Incidentally fixes #19346, because we now print renamed, rather than typechecked, syntax in error mesages about applications. The commit removes the vestigial module GHC.Builtin.RebindableNames, and thus triggers a 2.4% metric decrease for test MultiLayerModules (#19293). Metric Decrease: MultiLayerModules T12545
* Fix typosBrian Wignall2021-02-061-1/+1
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* Add a test for #18736Krzysztof Gogolewski2021-02-062-0/+8
| | | | | | | Commit 65721691ce9c (Improve inference with linear types, !4632) fixed the bug. Closes #18736.
* Fix unsoundness for linear guards (#19120)Krzysztof Gogolewski2021-01-173-0/+16
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* Improve inference with linear typesKrzysztof Gogolewski2020-12-201-1/+1
| | | | | This fixes test Linear14. The code in Unify.hs was always using multiplicity Many instead of a new metavariable.
* Restrict Linear arrow %1 to exactly literal 1 onlyAlan Zimmerman2020-11-035-0/+21
| | | | | | | This disallows `a %001 -> b`, and makes sure the type literal is printed from its SourceText so it is clear why. Closes #18888
* Linear types: fix quantification in GADTs (#18790)Krzysztof Gogolewski2020-10-101-6/+21
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* Linear types: fix roles in GADTs (#18799)Krzysztof Gogolewski2020-10-093-0/+19
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* Fix linear types in TH splices (#18465)Krzysztof Gogolewski2020-10-053-0/+25
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* Reject linearity in kinds in checkValidType (#18780)Krzysztof Gogolewski2020-10-026-4/+29
| | | | Patch taken from https://gitlab.haskell.org/ghc/ghc/-/issues/18624#note_300673
* Fix pretty-printing of the mult-polymorphic arrowVladislav Zavialov2020-10-013-9/+9
| | | | A follow-up to !4020 (5830a12c46e7227c276a8a71213057595ee4fc04)
* Improve error messages for (a %m) without LinearTypesVladislav Zavialov2020-09-291-8/+1
| | | | | | | | Detect when the user forgets to enable the LinearTypes extension and produce a better error message. Steals the (a %m) syntax from TypeOperators, the workaround is to write (a % m) instead.
* New linear types syntax: a %p -> b (#18459)Vladislav Zavialov2020-09-2945-79/+96
| | | | | | Implements GHC Proposal #356 Updates the haddock submodule.
* Disallow linear types in FFI (#18472)Krzysztof Gogolewski2020-09-263-0/+29
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* Make 'undefined x' linear in 'x' (#18731)Krzysztof Gogolewski2020-09-262-0/+6
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* Fix typed holes causing linearity errors (#18491)Krzysztof Gogolewski2020-09-252-0/+8
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* Pattern guards BindStmt always use multiplicity ManyArnaud Spiwack2020-09-253-0/+13
| | | | | | | | | Fixes #18439 . The rhs of the pattern guard was consumed with multiplicity one, while the pattern assumed it was Many. We use Many everywhere instead. This is behaviour consistent with that of `case` expression. See #18738.
* Improve kind generalisation, error messagesSimon Peyton Jones2020-09-241-3/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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)
* Linear types (#15981)Krzysztof Gogolewski2020-06-17100-0/+1387
This is the first step towards implementation of the linear types proposal (https://github.com/ghc-proposals/ghc-proposals/pull/111). It features * A language extension -XLinearTypes * Syntax for linear functions in the surface language * Linearity checking in Core Lint, enabled with -dlinear-core-lint * Core-to-core passes are mostly compatible with linearity * Fields in a data type can be linear or unrestricted; linear fields have multiplicity-polymorphic constructors. If -XLinearTypes is disabled, the GADT syntax defaults to linear fields The following items are not yet supported: * a # m -> b syntax (only prefix FUN is supported for now) * Full multiplicity inference (multiplicities are really only checked) * Decent linearity error messages * Linear let, where, and case expressions in the surface language (each of these currently introduce the unrestricted variant) * Multiplicity-parametric fields * Syntax for annotating lambda-bound or let-bound with a multiplicity * Syntax for non-linear/multiple-field-multiplicity records * Linear projections for records with a single linear field * Linear pattern synonyms * Multiplicity coercions (test LinearPolyType) A high-level description can be found at https://ghc.haskell.org/trac/ghc/wiki/LinearTypes/Implementation Following the link above you will find a description of the changes made to Core. This commit has been authored by * Richard Eisenberg * Krzysztof Gogolewski * Matthew Pickering * Arnaud Spiwack With contributions from: * Mark Barbone * Alexander Vershilov Updates haddock submodule.
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