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* Refactor renamer datastructureswip/amg/renamer-refactorAdam Gundry2020-12-231-0/+5
| | | | | | | | | | | | | | | This patch significantly refactors key renamer datastructures (primarily Avail and GlobalRdrElt) in order to treat DuplicateRecordFields in a more robust way. In particular it allows the extension to be used with pattern synonyms (fixes where mangled record selector names could be printed instead of field labels (e.g. with -Wpartial-fields or hole fits, see new tests). The key idea is the introduction of a new type GreName for names that may represent either normal entities or field labels. This is then used in GlobalRdrElt and AvailInfo, in place of the old way of representing fields using FldParent (yuck) and an extra list in AvailTC. Updates the haddock submodule.
* Replace HsImplicitBndrs with HsOuterTyVarBndrsRyan Scott2020-11-061-4/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* Split HsConDecl{H98,GADT}DetailsRyan Scott2020-10-301-0/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Haskell98 and GADT constructors both use `HsConDeclDetails`, which includes `InfixCon`. But `InfixCon` is never used for GADT constructors, which results in an awkward unrepresentable state. This removes the unrepresentable state by: * Renaming the existing `HsConDeclDetails` synonym to `HsConDeclH98Details`, which emphasizes the fact that it is now only used for Haskell98-style data constructors, and * Creating a new `HsConDeclGADTDetails` data type with `PrefixConGADT` and `RecConGADT` constructors that closely resemble `PrefixCon` and `InfixCon` in `HsConDeclH98Details`. The key difference is that `HsConDeclGADTDetails` lacks any way to represent infix constructors. The rest of the patch is refactoring to accommodate the new structure of `HsConDecl{H98,GADT}Details`. Some highlights: * The `getConArgs` and `hsConDeclArgTys` functions have been removed, as there is no way to implement these functions uniformly for all `ConDecl`s. For the most part, their previous call sites now pattern match on the `ConDecl`s directly and do different things for `ConDeclH98`s and `ConDeclGADT`s. I did introduce one new function to make the transition easier: `getRecConArgs_maybe`, which extracts the arguments from a `RecCon(GADT)`. This is still possible since `RecCon(GADT)`s still use the same representation in both `HsConDeclH98Details` and `HsConDeclGADTDetails`, and since the pattern that `getRecConArgs_maybe` implements is used in several places, I thought it worthwhile to factor it out into its own function. * Previously, the `con_args` fields in `ConDeclH98` and `ConDeclGADT` were both of type `HsConDeclDetails`. Now, the former is of type `HsConDeclH98Details`, and the latter is of type `HsConDeclGADTDetails`, which are distinct types. As a result, I had to rename the `con_args` field in `ConDeclGADT` to `con_g_args` to make it typecheck. A consequence of all this is that the `con_args` field is now partial, so using `con_args` as a top-level field selector is dangerous. (Indeed, Haddock was using `con_args` at the top-level, which caused it to crash at runtime before I noticed what was wrong!) I decided to add a disclaimer in the 9.2.1 release notes to advertise this pitfall. Fixes #18844. Bumps the `haddock` submodule.
* Introduce and use DerivClauseTys (#18662)Ryan Scott2020-09-151-0/+5
| | | | | | | | | | | | This switches `deriv_clause_tys` so that instead of using a list of `LHsSigType`s to represent the types in a `deriving` clause, it now uses a sum type. `DctSingle` represents a `deriving` clause with no enclosing parentheses, while `DctMulti` represents a clause with enclosing parentheses. This makes pretty-printing easier and avoids confusion between `HsParTy` and the enclosing parentheses in `deriving` clauses, which are different semantically. Fixes #18662.
* Remove ConDeclGADTPrefixPsRyan Scott2020-08-021-2/+0
| | | | | | | | | | | | | | | | This removes the `ConDeclGADTPrefixPs` per the discussion in #18517. Most of this patch simply removes code, although the code in the `rnConDecl` case for `ConDeclGADTPrefixPs` had to be moved around a bit: * The nested `forall`s check now lives in the `rnConDecl` case for `ConDeclGADT`. * The `LinearTypes`-specific code that used to live in the `rnConDecl` case for `ConDeclGADTPrefixPs` now lives in `GHC.Parser.PostProcess.mkGadtDecl`, which is now monadic so that it can check if `-XLinearTypes` is enabled. Fixes #18157.
* Simplify XRec definitionZubin Duggal2020-07-251-3/+5
| | | | | | | | | | | | Change `Located X` usage to `XRec pass X` This increases the scope of the LPat experiment to almost all of GHC. Introduce UnXRec and MapXRec classes Fixes #17587 and #18408 Updates haddock submodule Co-authored-by: Philipp Krüger <philipp.krueger1@gmail.com>
* compiler: re-engineer the treatment of rebindable ifAlp Mestanogullari2020-07-141-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Executing on the plan described in #17582, this patch changes the way if expressions are handled in the compiler in the presence of rebindable syntax. We get rid of the SyntaxExpr field of HsIf and instead, when rebindable syntax is on, we rewrite the HsIf node to the appropriate sequence of applications of the local `ifThenElse` function. In order to be able to report good error messages, with expressions as they were written by the user (and not as desugared by the renamer), we make use of TTG extensions to extend GhcRn expression ASTs with an `HsExpansion` construct, which keeps track of a source (GhcPs) expression and the desugared (GhcRn) expression that it gives rise to. This way, we can typecheck the latter while reporting the former in error messages. In order to discard the error context lines that arise from typechecking the desugared expressions (because they talk about expressions that the user has not written), we carefully give a special treatment to the nodes fabricated by this new renaming-time transformation when typechecking them. See Note [Rebindable syntax and HsExpansion] for more details. The note also includes a recipe to apply the same treatment to other rebindable constructs. Tests 'rebindable11' and 'rebindable12' have been added to make sure we report identical error messages as before this patch under various circumstances. We also now disable rebindable syntax when processing untyped TH quotes, as per the discussion in #18102 and document the interaction of rebindable syntax and Template Haskell, both in Note [Template Haskell quotes and Rebindable Syntax] and in the user guide, adding a test to make sure that we do not regress in that regard.
* Implement the proposed -XQualifiedDo extensionMatthias Pall Gissurarson2020-06-261-0/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Co-authored-by: Facundo Domínguez <facundo.dominguez@tweag.io> QualifiedDo is implemented using the same placeholders for operation names in the AST that were devised for RebindableSyntax. Whenever the renamer checks which names to use for do syntax, it first checks if the do block is qualified (e.g. M.do { stmts }), in which case it searches for qualified names in the module M. This allows users to write {-# LANGUAGE QualifiedDo #-} import qualified SomeModule as M f x = M.do -- desugars to: y <- M.return x -- M.return x M.>>= \y -> M.return y -- M.return y M.>> M.return y -- M.return y See Note [QualifiedDo] and the users' guide for more details. Issue #18214 Proposal: https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0216-qualified-do.rst Since we change the constructors `ITdo` and `ITmdo` to carry the new module name, we need to bump the haddock submodule to account or the new shape of these constructors.
* Linear types (#15981)Krzysztof Gogolewski2020-06-171-0/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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.
* Use HsForAllTelescope to avoid inferred, visible forallsRyan Scott2020-06-131-0/+5
| | | | | | | | | | | | | Currently, `HsForAllTy` permits the combination of `ForallVis` and `Inferred`, but you can't actually typecheck code that uses it (e.g., `forall {a} ->`). This patch refactors `HsForAllTy` to use a new `HsForAllTelescope` data type that makes a type-level distinction between visible and invisible `forall`s such that visible `forall`s do not track `Specificity`. That part of the patch is actually quite small; the rest is simply changing consumers of `HsType` to accommodate this new type. Fixes #18235. Bumps the `haddock` submodule.
* Make GADT constructors adhere to the forall-or-nothing rule properlyRyan Scott2020-06-091-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Issue #18191 revealed that the types of GADT constructors don't quite adhere to the `forall`-or-nothing rule. This patch serves to clean up this sad state of affairs somewhat. The main change is not in the code itself, but in the documentation, as this patch introduces two sections to the GHC User's Guide: * A "Formal syntax for GADTs" section that presents a BNF-style grammar for what is and isn't allowed in GADT constructor types. This mostly exists to codify GHC's existing behavior, but it also imposes a new restriction that addresses #18191: the outermost `forall` and/or context in a GADT constructor is not allowed to be surrounded by parentheses. Doing so would make these `forall`s/contexts nested, and GADTs do not support nested `forall`s/contexts at present. * A "`forall`-or-nothing rule" section that describes exactly what the `forall`-or-nothing rule is all about. Surprisingly, there was no mention of this anywhere in the User's Guide up until now! To adhere the new specification in the "Formal syntax for GADTs" section of the User's Guide, the following code changes were made: * A new function, `GHC.Hs.Type.splitLHsGADTPrefixTy`, was introduced. This is very much like `splitLHsSigmaTy`, except that it avoids splitting apart any parentheses, which can be syntactically significant for GADT types. See `Note [No nested foralls or contexts in GADT constructors]` in `GHC.Hs.Type`. * `ConDeclGADTPrefixPs`, an extension constructor for `XConDecl`, was introduced so that `GHC.Parser.PostProcess.mkGadtDecl` can return it when given a prefix GADT constructor. Unlike `ConDeclGADT`, `ConDeclGADTPrefixPs` does not split the GADT type into its argument and result types, as this cannot be done until after the type is renamed (see `Note [GADT abstract syntax]` in `GHC.Hs.Decls` for why this is the case). * `GHC.Renamer.Module.rnConDecl` now has an additional case for `ConDeclGADTPrefixPs` that (1) splits apart the full `LHsType` into its `forall`s, context, argument types, and result type, and (2) checks for nested `forall`s/contexts. Step (2) used to be performed the typechecker (in `GHC.Tc.TyCl.badDataConTyCon`) rather than the renamer, but now the relevant code from the typechecker can simply be deleted. One nice side effect of this change is that we are able to give a more accurate error message for GADT constructors that use visible dependent quantification (e.g., `MkFoo :: forall a -> a -> Foo a`), which improves the stderr in the `T16326_Fail6` test case. Fixes #18191. Bumps the Haddock submodule.
* GHC.Hs.Instances: Compile with -O0Ben Gamari2020-06-041-0/+7
| | | | | | | This module contains exclusively Data instances, which are going to be slow no matter what we do. Furthermore, they are incredibly slow to compile with optimisation (see #9557). Consequently we compile this with -O0. See #18254.
* Rename GHC.Hs.Types into GHC.Hs.TypeSylvain Henry2020-05-241-2/+2
| | | | See discussion in https://gitlab.haskell.org/ghc/ghc/issues/13009#note_268610
* Explicit SpecificityGert-Jan Bottu2020-05-211-3/+3
| | | | | | | | | | | | | | | | | | | | 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
* Factor out HsPatSigType for pat sigs/RULE term sigs (#16762)Ryan Scott2020-05-131-0/+5
| | | | | | | | | | | | | | | 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`.
* Modules: Utils and Data (#13009)Sylvain Henry2020-04-261-1/+1
| | | | | | | Update Haddock submodule Metric Increase: haddock.compiler
* Trees That Grow refactor for `ConPat` and `CoPat`John Ericson2020-04-231-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - `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.
* Use FailOperator in more places, define a couple datatypes (XBindStmtRn and ↵Cale Gibbard2020-04-171-0/+3
| | | | XBindStmtTc) to help clarify the meaning of XBindStmt in the renamer and typechecker
* Introduce IsPass; refactor wrappers.Richard Eisenberg2020-02-081-9/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There are two main payloads of this patch: 1. This introduces IsPass, which allows e.g. printing code to ask what pass it is running in (Renamed vs Typechecked) and thus print extension fields. See Note [IsPass] in Hs.Extension 2. This moves the HsWrap constructor into an extension field, where it rightly belongs. This is done for HsExpr and HsCmd, but not for HsPat, which is left as an exercise for the reader. There is also some refactoring around SyntaxExprs, but this is really just incidental. This patch subsumes !1721 (sorry @chreekat). Along the way, there is a bit of refactoring in GHC.Hs.Extension, including the removal of NameOrRdrName in favor of NoGhcTc. This meant that we had no real need for GHC.Hs.PlaceHolder, so I got rid of it. Updates haddock submodule. ------------------------- Metric Decrease: haddock.compiler -------------------------
* Factor out HsSCC/HsCoreAnn/HsTickPragma into HsPragEwip/hs-pragVladislav Zavialov2019-11-281-0/+5
| | | | | | | | | | | | | | | | | | | | | | | This is a refactoring with no user-visible changes (except for GHC API users). Consider the HsExpr constructors that correspond to user-written pragmas: HsSCC representing {-# SCC ... #-} HsCoreAnn representing {-# CORE ... #-} HsTickPragma representing {-# GENERATED ... #-} We can factor them out into a separate datatype, HsPragE. It makes the code a bit tidier, especially in the parser. Before this patch: hpc_annot :: { Located ( (([AddAnn],SourceText),(StringLiteral,(Int,Int),(Int,Int))), ((SourceText,SourceText),(SourceText,SourceText)) ) } After this patch: prag_hpc :: { Located ([AddAnn], HsPragE GhcPs) }
* Standalone kind signatures (#16794)wip/top-level-kind-signaturesVladislav Zavialov2019-09-251-0/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Implements GHC Proposal #54: .../ghc-proposals/blob/master/proposals/0054-kind-signatures.rst With this patch, a type constructor can now be given an explicit standalone kind signature: {-# LANGUAGE StandaloneKindSignatures #-} type Functor :: (Type -> Type) -> Constraint class Functor f where fmap :: (a -> b) -> f a -> f b This is a replacement for CUSKs (complete user-specified kind signatures), which are now scheduled for deprecation. User-facing changes ------------------- * A new extension flag has been added, -XStandaloneKindSignatures, which implies -XNoCUSKs. * There is a new syntactic construct, a standalone kind signature: type <name> :: <kind> Declarations of data types, classes, data families, type families, and type synonyms may be accompanied by a standalone kind signature. * A standalone kind signature enables polymorphic recursion in types, just like a function type signature enables polymorphic recursion in terms. This obviates the need for CUSKs. * TemplateHaskell AST has been extended with 'KiSigD' to represent standalone kind signatures. * GHCi :info command now prints the kind signature of type constructors: ghci> :info Functor type Functor :: (Type -> Type) -> Constraint ... Limitations ----------- * 'forall'-bound type variables of a standalone kind signature do not scope over the declaration body, even if the -XScopedTypeVariables is enabled. See #16635 and #16734. * Wildcards are not allowed in standalone kind signatures, as partial signatures do not allow for polymorphic recursion. * Associated types may not be given an explicit standalone kind signature. Instead, they are assumed to have a CUSK if the parent class has a standalone kind signature and regardless of the -XCUSKs flag. * Standalone kind signatures do not support multiple names at the moment: type T1, T2 :: Type -> Type -- rejected type T1 = Maybe type T2 = Either String See #16754. * Creative use of equality constraints in standalone kind signatures may lead to GHC panics: type C :: forall (a :: Type) -> a ~ Int => Constraint class C a where f :: C a => a -> Int See #16758. Implementation notes -------------------- * The heart of this patch is the 'kcDeclHeader' function, which is used to kind-check a declaration header against its standalone kind signature. It does so in two rounds: 1. check user-written binders 2. instantiate invisible binders a la 'checkExpectedKind' * 'kcTyClGroup' now partitions declarations into declarations with a standalone kind signature or a CUSK (kinded_decls) and declarations without either (kindless_decls): * 'kinded_decls' are kind-checked with 'checkInitialKinds' * 'kindless_decls' are kind-checked with 'getInitialKinds' * DerivInfo has been extended with a new field: di_scoped_tvs :: ![(Name,TyVar)] These variables must be added to the context in case the deriving clause references tcTyConScopedTyVars. See #16731.
* Module hierarchy: Hs (#13009)Sylvain Henry2019-09-201-0/+420
Add GHC.Hs module hierarchy replacing hsSyn. Metric Increase: haddock.compiler