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* Simple subsumptionwip/T17775Simon Peyton Jones2020-06-0530-1721/+1922
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch simplifies GHC to use simple subsumption. Ticket #17775 Implements GHC proposal #287 https://github.com/ghc-proposals/ghc-proposals/blob/master/ proposals/0287-simplify-subsumption.rst All the motivation is described there; I will not repeat it here. The implementation payload: * tcSubType and friends become noticably simpler, because it no longer uses eta-expansion when checking subsumption. * No deeplyInstantiate or deeplySkolemise That in turn means that some tests fail, by design; they can all be fixed by eta expansion. There is a list of such changes below. Implementing the patch led me into a variety of sticky corners, so the patch includes several othe changes, some quite significant: * I made String wired-in, so that "foo" :: String rather than "foo" :: [Char] This improves error messages, and fixes #15679 * The pattern match checker relies on knowing about in-scope equality constraints, andd adds them to the desugarer's environment using addTyCsDs. But the co_fn in a FunBind was missed, and for some reason simple-subsumption ends up with dictionaries there. So I added a call to addTyCsDs. This is really part of #18049. * I moved the ic_telescope field out of Implication and into ForAllSkol instead. This is a nice win; just expresses the code much better. * There was a bug in GHC.Tc.TyCl.Instance.tcDataFamInstHeader. We called checkDataKindSig inside tc_kind_sig, /before/ solveEqualities and zonking. Obviously wrong, easily fixed. * solveLocalEqualitiesX: there was a whole mess in here, around failing fast enough. I discovered a bad latent bug where we could successfully kind-check a type signature, and use it, but have unsolved constraints that could fill in coercion holes in that signature -- aargh. It's all explained in Note [Failure in local type signatures] in GHC.Tc.Solver. Much better now. * I fixed a serious bug in anonymous type holes. IN f :: Int -> (forall a. a -> _) -> Int that "_" should be a unification variable at the /outer/ level; it cannot be instantiated to 'a'. This was plain wrong. New fields mode_lvl and mode_holes in TcTyMode, and auxiliary data type GHC.Tc.Gen.HsType.HoleMode. This fixes #16292, but makes no progress towards the more ambitious #16082 * I got sucked into an enormous refactoring of the reporting of equality errors in GHC.Tc.Errors, especially in mkEqErr1 mkTyVarEqErr misMatchMsg misMatchMsgOrCND In particular, the very tricky mkExpectedActualMsg function is gone. It took me a full day. But the result is far easier to understand. (Still not easy!) This led to various minor improvements in error output, and an enormous number of test-case error wibbles. One particular point: for occurs-check errors I now just say Can't match 'a' against '[a]' rather than using the intimidating language of "occurs check". * Pretty-printing AbsBinds Tests review * Eta expansions T11305: one eta expansion T12082: one eta expansion (undefined) T13585a: one eta expansion T3102: one eta expansion T3692: two eta expansions (tricky) T2239: two eta expansions T16473: one eta determ004: two eta expansions (undefined) annfail06: two eta (undefined) T17923: four eta expansions (a strange program indeed!) tcrun035: one eta expansion * Ambiguity check at higher rank. Now that we have simple subsumption, a type like f :: (forall a. Eq a => Int) -> Int is no longer ambiguous, because we could write g :: (forall a. Eq a => Int) -> Int g = f and it'd typecheck just fine. But f's type is a bit suspicious, and we might want to consider making the ambiguity check do a check on each sub-term. Meanwhile, these tests are accepted, whereas they were previously rejected as ambiguous: T7220a T15438 T10503 T9222 * Some more interesting error message wibbles T13381: Fine: one error (Int ~ Exp Int) rather than two (Int ~ Exp Int, Exp Int ~ Int) T9834: Small change in error (improvement) T10619: Improved T2414: Small change, due to order of unification, fine T2534: A very simple case in which a change of unification order means we get tow unsolved constraints instead of one tc211: bizarre impredicative tests; just accept this for now Updates Cabal and haddock submodules. Metric Increase: T12150 T12234 T5837 haddock.base Metric Decrease: haddock.compiler haddock.Cabal haddock.base Merge note: This appears to break the `UnliftedNewtypesDifficultUnification` test. It has been marked as broken in the interest of merging. (cherry picked from commit 66b7b195cb3dce93ed5078b80bf568efae904cc5)
* Clean up boot vs non-boot disambiguating typesJohn Ericson2020-06-044-22/+23
| | | | | | | | | | | | | | | We often have (ModuleName, Bool) or (Module, Bool) pairs for "extended" module names (without or with a unit id) disambiguating boot and normal modules. We think this is important enough across the compiler that it deserves a new nominal product type. We do this with synnoyms and a functor named with a `Gen` prefix, matching other newly created definitions. It was also requested that we keep custom `IsBoot` / `NotBoot` sum type. So we have it too. This means changing many the many bools to use that instead. Updates `haddock` submodule.
* Rename the singleton tuple GHC.Tuple.Unit to GHC.Tuple.SoloTom Ellis2020-06-011-9/+9
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* Modify file paths to module paths for new module hierarchyTakenobu Tani2020-06-011-1/+1
| | | | | | | | | | | | | | | | | | | This updates comments only. This patch replaces module references according to new module hierarchy [1][2]. For files under the `compiler/` directory, I replace them as module paths instead of file paths. For instance, `GHC.Unit.State` instead of `compiler/GHC/Unit/State.hs` [3]. For current and future haddock's markup, this patch encloses the module name with "" [4]. [1]: https://gitlab.haskell.org/ghc/ghc/-/wikis/Make-GHC-codebase-more-modular [2]: https://gitlab.haskell.org/ghc/ghc/issues/13009 [3]: https://gitlab.haskell.org/ghc/ghc/-/merge_requests/3375#note_276613 [4]: https://haskell-haddock.readthedocs.io/en/latest/markup.html#linking-to-modules
* Clean up file paths for new module hierarchyTakenobu Tani2020-06-011-1/+1
| | | | | | | | | This updates comments only. This patch replaces file references according to new module hierarchy. See also: * https://gitlab.haskell.org/ghc/ghc/-/wikis/Make-GHC-codebase-more-modular * https://gitlab.haskell.org/ghc/ghc/issues/13009
* Avoid unnecessary allocations due to tracing utilitiesBen Gamari2020-05-283-12/+51
| | | | | | | | | | | | | | | | | | | | While ticky-profiling the typechecker I noticed that hundreds of millions of SDocs are being allocated just in case -ddump-*-trace is enabled. This is awful. We avoid this by ensuring that the dump flag check is inlined into the call site, ensuring that the tracing document needn't be allocated unless it's actually needed. See Note [INLINE conditional tracing utilities] for details. Fixes #18168. Metric Decrease: T9961 haddock.Cabal haddock.base haddock.compiler
* Rename GHC.Hs.Types into GHC.Hs.TypeSylvain Henry2020-05-245-9/+9
| | | | See discussion in https://gitlab.haskell.org/ghc/ghc/issues/13009#note_268610
* Fix spelling mistakes and typosbuggymcbugfix2020-05-211-2/+2
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* Use braces with do in `SplicePat` case for consistencyJohn Ericson2020-05-211-2/+2
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* Tiny cleaup eta-reduce away a function argumentJohn Ericson2020-05-211-2/+2
| | | | In GHC, not in the code being compiled!
* Put `PatEnv` first in `GHC.Tc.Gen.Pat.Checker`John Ericson2020-05-211-62/+65
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* More judiciously panic in `ts_pat`John Ericson2020-05-211-3/+3
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* Use `Checker` for `tc_lpat` and `tc_lpats`John Ericson2020-05-211-32/+25
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* Use `Checker` for `tc_pat`John Ericson2020-05-211-56/+58
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* Explicit SpecificityGert-Jan Bottu2020-05-2119-255/+368
| | | | | | | | | | | | | | | | | | | | Implementation for Ticket #16393. Explicit specificity allows users to manually create inferred type variables, by marking them with braces. This way, the user determines which variables can be instantiated through visible type application. The additional syntax is included in the parser, allowing users to write braces in type variable binders (type signatures, data constructors etc). This information is passed along through the renamer and verified in the type checker. The AST for type variable binders, data constructors, pattern synonyms, partial signatures and Template Haskell has been updated to include the specificity of type variables. Minor notes: - Bumps haddock submodule - Disables pattern match checking in GHC.Iface.Type with GHC 8.8
* Use Data.IntMap.disjointSimon Jakobi2020-05-143-5/+3
| | | | | | | | | Data.IntMap gained a dedicated `disjoint` function in containers-0.6.2.1. This patch applies this function where appropriate in hopes of modest compiler performance improvements. Closes #16806.
* Improve some folds over Uniq[D]FMSimon Jakobi2020-05-143-13/+29
| | | | | | | | | | | | | | | * Replace some non-deterministic lazy folds with strict folds. * Replace some O(n log n) folds in deterministic order with O(n) non-deterministic folds. * Replace some folds with set-operations on the underlying IntMaps. This reduces max residency when compiling `nofib/spectral/simple/Main.hs` with -O0 by about 1%. Maximum residency when compiling Cabal also seems reduced on the order of 3-9%.
* Factor out HsPatSigType for pat sigs/RULE term sigs (#16762)Ryan Scott2020-05-133-10/+10
| | | | | | | | | | | | | | | This implements chunks (2) and (3) of https://gitlab.haskell.org/ghc/ghc/issues/16762#note_270170. Namely, it introduces a dedicated `HsPatSigType` AST type, which represents the types that can appear in pattern signatures and term-level `RULE` binders. Previously, these were represented with `LHsSigWcType`. Although `LHsSigWcType` is isomorphic to `HsPatSigType`, the intended semantics of the two types are slightly different, as evidenced by the fact that they have different code paths in the renamer and typechecker. See also the new `Note [Pattern signature binders and scoping]` in `GHC.Hs.Types`.
* Fix specialisation for DFunsSimon Peyton Jones2020-05-081-5/+2
| | | | | | | When specialising a DFun we must take care to saturate the unfolding. See Note [Specialising DFuns] in Specialise. Fixes #18120
* Add `forAllOrNothing` function with noteJohn Ericson2020-05-081-1/+2
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* Remove further dead code found by a simple Python script.Brian Foley2020-05-082-45/+6
| | | | | Avoid removing some functions that are part of an API even though they're not used in-tree at the moment.
* Refactor hole constraints.Richard Eisenberg2020-05-0617-464/+481
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Previously, holes (both expression holes / out of scope variables and partial-type-signature wildcards) were emitted as *constraints* via the CHoleCan constructor. While this worked fine for error reporting, there was a fair amount of faff in keeping these constraints in line. In particular, and unlike other constraints, we could never change a CHoleCan to become CNonCanonical. In addition: * the "predicate" of a CHoleCan constraint was really the type of the hole, which is not a predicate at all * type-level holes (partial type signature wildcards) carried evidence, which was never used * tcNormalise (used in the pattern-match checker) had to create a hole constraint just to extract it again; it was quite messy The new approach is to record holes directly in WantedConstraints. It flows much more nicely now. Along the way, I did some cleaning up of commentary in GHC.Tc.Errors.Hole, which I had a hard time understanding. This was instigated by a future patch that will refactor the way predicates are handled. The fact that CHoleCan's "predicate" wasn't really a predicate is incompatible with that future patch. No test case, because this is meant to be purely internal. It turns out that this change improves the performance of the pattern-match checker, likely because fewer constraints are sloshing about in tcNormalise. I have not investigated deeply, but an improvement is not a surprise here: ------------------------- Metric Decrease: PmSeriesG -------------------------
* Don't return a panic in tcNestedSpliceSimon Peyton Jones2020-05-042-16/+19
| | | | | | | | | | | | | In GHC.Tc.Gen.Splice.tcNestedSplice we were returning a typechecked expression of "panic". That is usually OK, because the result is discarded. But it happens that tcApp now looks at the typechecked expression, trivially, to ask if it is tagToEnum. So being bottom is bad. Moreover a debug-trace might print it out. So better to return a civilised expression, even though it is usually discarded.
* PmCheck: Pick up `EvVar`s bound in `HsWrapper`s for long-distance infoSebastian Graf2020-05-011-1/+22
| | | | | | | | | | | | | | | | | | | | `HsWrapper`s introduce evidence bindings through `WpEvLam` which the pattern-match coverage checker should be made aware of. Failing to do so caused #18049, where the resulting impreciseness of imcompleteness warnings seemingly contradicted with `-Winaccessible-code`. The solution is simple: Collect all the evidence binders of an `HsWrapper` and add it to the ambient `Deltas` before desugaring the wrapped expression. But that means we pick up many more evidence bindings, even when they wrap around code without a single pattern match to check! That regressed `T3064` by over 300%, so now we are adding long-distance info lazily through judicious use of `unsafeInterleaveIO`. Fixes #18049.
* Remove PprStyle param of logging actionsSylvain Henry2020-05-011-3/+2
| | | | Use `withPprStyle` instead to apply a specific style to a SDoc.
* Refactor PprDebug handlingSylvain Henry2020-05-011-2/+2
| | | | | | | | | | | If `-dppr-debug` is set, then PprUser and PprDump styles are silently replaced with PprDebug style. This was done in `mkUserStyle` and `mkDumpStyle` smart constructors. As a consequence they needed a DynFlags parameter. Now we keep the original PprUser and PprDump styles until they are used to create an `SDocContext`. I.e. the substitution is only performed in `initSDocContext`.
* Allow LambdaCase to be used as a command in proc notationAlexis King2020-04-302-6/+25
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* Unit: split and rename modulesSylvain Henry2020-04-3021-24/+24
| | | | | | | Introduce GHC.Unit.* hierarchy for everything concerning units, packages and modules. Update Haddock submodule
* Refactoring unit management codeSylvain Henry2020-04-3013-80/+77
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Over the years the unit management code has been modified a lot to keep up with changes in Cabal (e.g. support for several library components in the same package), to integrate BackPack, etc. I found it very hard to understand as the terminology wasn't consistent, was referring to past concepts, etc. The terminology is now explained as clearly as I could in the Note "About Units" and the code is refactored to reflect it. ------------------- Many names were misleading: UnitId is not an Id but could be a virtual unit (an indefinite one instantiated on the fly), IndefUnitId constructor may contain a definite instantiated unit, etc. * Rename IndefUnitId into InstantiatedUnit * Rename IndefModule into InstantiatedModule * Rename UnitId type into Unit * Rename IndefiniteUnitId constructor into VirtUnit * Rename DefiniteUnitId constructor into RealUnit * Rename packageConfigId into mkUnit * Rename getPackageDetails into unsafeGetUnitInfo * Rename InstalledUnitId into UnitId Remove references to misleading ComponentId: a ComponentId is just an indefinite unit-id to be instantiated. * Rename ComponentId into IndefUnitId * Rename ComponentDetails into UnitPprInfo * Fix display of UnitPprInfo with empty version: this is now used for units dynamically generated by BackPack Generalize several types (Module, Unit, etc.) so that they can be used with different unit identifier types: UnitKey, UnitId, Unit, etc. * GenModule: Module, InstantiatedModule and InstalledModule are now instances of this type * Generalize DefUnitId, IndefUnitId, Unit, InstantiatedUnit, PackageDatabase Replace BackPack fake "hole" UnitId by a proper HoleUnit constructor. Add basic support for UnitKey. They should be used more in the future to avoid mixing them up with UnitId as we do now. Add many comments. Update Haddock submodule
* Refactor UnitInfoSylvain Henry2020-04-301-1/+1
| | | | | | | | | | | | | | | | | | | | | * Rename InstalledPackageInfo into GenericUnitInfo The name InstalledPackageInfo is only kept for alleged backward compatibility reason in Cabal. ghc-boot has its own stripped down copy of this datatype but it doesn't need to keep the name. Internally we already use type aliases (UnitInfo in GHC, PackageCacheFormat in ghc-pkg). * Rename UnitInfo fields: add "unit" prefix and fix misleading names * Add comments on every UnitInfo field * Rename SourcePackageId into PackageId "Package" already indicates that it's a "source package". Installed package components are called units. Update Haddock submodule
* Modules: Utils and Data (#13009)Sylvain Henry2020-04-2659-328/+328
| | | | | | | Update Haddock submodule Metric Increase: haddock.compiler
* Trees That Grow refactor for `ConPat` and `CoPat`John Ericson2020-04-239-70/+96
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - `ConPat{In,Out}` -> `ConPat` - `CoPat` -> `XPat (CoPat ..)` Note that `GHC.HS.*` still uses `HsWrap`, but only when `p ~ GhcTc`. After this change, moving the type family instances out of `GHC.HS.*` is sufficient to break the cycle. Add XCollectPat class to decide how binders are collected from XXPat based on the pass. Previously we did this with IsPass, but that doesn't work for Haddock's DocNameI, and the constraint doesn't express what actual distinction is being made. Perhaps a class for collecting binders more generally is in order, but we haven't attempted this yet. Pure refactor of code around ConPat - InPat/OutPat synonyms removed - rename several identifiers - redundant constraints removed - move extension field in ConPat to be first - make ConPat use record syntax more consistently Fix T6145 (ConPatIn became ConPat) Add comments from SPJ. Add comment about haddock's use of CollectPass. Updates haddock submodule.
* Create di_scoped_tvs for associated data family instances properlyRyan Scott2020-04-231-7/+57
| | | | | | | See `Note [Associated data family instances and di_scoped_tvs]` in `GHC.Tc.TyCl.Instance`, which explains all of the moving parts. Fixes #18055.
* Update commentary and slightly refactor GHC.Tc.Deriv.InferRyan Scott2020-04-221-10/+17
| | | | | | | | | There was some out-of-date commentary in `GHC.Tc.Deriv.Infer` that has been modernized. Along the way, I removed the `bad` constraints in `simplifyDeriv`, which did not serve any useful purpose (besides being printed in debugging output). Fixes #18073.
* Do eager instantation in termsSimon Peyton Jones2020-04-2219-712/+762
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch implements eager instantiation, a small but critical change to the type inference engine, #17173. The main change is this: When inferring types, always return an instantiated type (for now, deeply instantiated; in future shallowly instantiated) There is more discussion in https://www.tweag.io/posts/2020-04-02-lazy-eager-instantiation.html There is quite a bit of refactoring in this patch: * The ir_inst field of GHC.Tc.Utils.TcType.InferResultk has entirely gone. So tcInferInst and tcInferNoInst have collapsed into tcInfer. * Type inference of applications, via tcInferApp and tcInferAppHead, are substantially refactored, preparing the way for Quick Look impredicativity. * New pure function GHC.Tc.Gen.Expr.collectHsArgs and applyHsArgs are beatifully dual. We can see the zipper! * GHC.Tc.Gen.Expr.tcArgs is now much nicer; no longer needs to return a wrapper * In HsExpr, HsTypeApp now contains the the actual type argument, and is used in desugaring, rather than putting it in a mysterious wrapper. * I struggled a bit with good error reporting in Unify.matchActualFunTysPart. It's a little bit simpler than before, but still not great. Some smaller things * Rename tcPolyExpr --> tcCheckExpr tcMonoExpr --> tcLExpr * tcPatSig moves from GHC.Tc.Gen.HsType to GHC.Tc.Gen.Pat Metric Decrease: T9961 Reduction of 1.6% in comiler allocation on T9961, I think.
* Avoid DynFlags in Ppr code (#17957)Sylvain Henry2020-04-211-1/+2
| | | | | | | | | | * replace `DynFlags` parameters with `SDocContext` parameters for a few Ppr related functions: `bufLeftRenderSDoc`, `printSDoc`, `printSDocLn`, `showSDocOneLine`. * remove the use of `pprCols :: DynFlags -> Int` in Outputable. We already have the information via `sdocLineLength :: SDocContext -> Int`
* GHC.Runtime: avoid DynFlags (#17957)Sylvain Henry2020-04-211-0/+7
| | | | | * add `getPlatform :: TcM Platform` helper * remove unused `DynFlags` parameter from `emptyPLS`
* Fix a buglet in redundant-constraint warningsSimon Peyton Jones2020-04-201-3/+10
| | | | | | | | Ticket #18036 pointed out that we were reporting a redundant constraint when it really really wasn't. Turned out to be a buglet in the SkolemInfo for the relevant implication constraint. Easily fixed!
* Modules (#13009)Sylvain Henry2020-04-1842-107/+108
| | | | | | | | | | | | | | * SysTools * Parser * GHC.Builtin * GHC.Iface.Recomp * Settings Update Haddock submodule Metric Decrease: Naperian parsing001
* GHC.Core.Opt renamingSylvain Henry2020-04-181-1/+1
| | | | | | | | | | | * GHC.Core.Op => GHC.Core.Opt * GHC.Core.Opt.Simplify.Driver => GHC.Core.Opt.Driver * GHC.Core.Opt.Tidy => GHC.Core.Tidy * GHC.Core.Opt.WorkWrap.Lib => GHC.Core.Opt.WorkWrap.Utils As discussed in: * https://mail.haskell.org/pipermail/ghc-devs/2020-April/018758.html * https://gitlab.haskell.org/ghc/ghc/issues/13009#note_264650
* Add a missing zonk in tcHsPartialTypeSimon Peyton Jones2020-04-181-14/+81
| | | | | | | | | | | | | I omitted a vital zonk when refactoring tcHsPartialType in commit 48fb3482f8cbc8a4b37161021e846105f980eed4 Author: Simon Peyton Jones <simonpj@microsoft.com> Date: Wed Jun 5 08:55:17 2019 +0100 Fix typechecking of partial type signatures This patch fixes it and adds commentary to explain why. Fixes #18008
* Use FailOperator in more places, define a couple datatypes (XBindStmtRn and ↵Cale Gibbard2020-04-173-17/+33
| | | | XBindStmtTc) to help clarify the meaning of XBindStmt in the renamer and typechecker
* Use trees that grow for rebindable operators for `<-` bindsJohn Ericson2020-04-175-28/+27
| | | | Also add more documentation.
* Change the fail operator argument of BindStmt to be a MaybeCale Gibbard2020-04-173-13/+23
| | | | | Don't use noSyntaxExpr for it. There is no good way to defensively case on that, nor is it clear one ought to do so.
* Fix #18052 by using pprPrefixOcc in more placesRyan Scott2020-04-151-4/+4
| | | | | This fixes several small oversights in the choice of pretty-printing function to use. Fixes #18052.
* Change zipWith to zipWithEqual in a few placesKrzysztof Gogolewski2020-04-144-6/+10
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* Use conLikeUserTyVarBinders to quantify field selector typesRyan Scott2020-04-121-15/+54
| | | | | | | | | | | | | This patch: 1. Writes up a specification for how the types of top-level field selectors should be determined in a new section of the GHC User's Guide, and 2. Makes GHC actually implement that specification by using `conLikeUserTyVarBinders` in `mkOneRecordSelector` to preserve the order and specificity of type variables written by the user. Fixes #18023.
* Make NoExtCon fields strictwip/strict-NoExtConRyan Scott2020-04-0720-159/+10
| | | | | | | | | | | | | | | | This changes every unused TTG extension constructor to be strict in its field so that the pattern-match coverage checker is smart enough any such constructors are unreachable in pattern matches. This lets us remove nearly every use of `noExtCon` in the GHC API. The only ones we cannot remove are ones underneath uses of `ghcPass`, but that is only because GHC 8.8's and 8.10's coverage checkers weren't smart enough to perform this kind of reasoning. GHC HEAD's coverage checker, on the other hand, _is_ smart enough, so we guard these uses of `noExtCon` with CPP for now. Bumps the `haddock` submodule. Fixes #17992.
* Modules: type-checker (#13009)Sylvain Henry2020-04-0765-0/+82661
Update Haddock submodule
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