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* Handle local fixity declarations in DsMeta properlyRyan Scott2020-01-251-15/+62
| | | | | | | | | | | | | | | | | | | | | `DsMeta.rep_sig` used to skip over `FixSig` entirely, which had the effect of causing local fixity declarations to be dropped when quoted in Template Haskell. But there is no good reason for this state of affairs, as the code in `DsMeta.repFixD` (which handles top-level fixity declarations) handles local fixity declarations just fine. This patch factors out the necessary parts of `repFixD` so that they can be used in `rep_sig` as well. There was one minor complication: the fixity signatures for class methods in each `HsGroup` were stored both in `FixSig`s _and_ the list of `LFixitySig`s for top-level fixity signatures, so I needed to take action to prevent fixity signatures for class methods being converted to `Dec`s twice. I tweaked `RnSource.add` to avoid putting these fixity signatures in two places and added `Note [Top-level fixity signatures in an HsGroup]` in `GHC.Hs.Decls` to explain the new design. Fixes #17608. Bumps the Haddock submodule.
* Fix more typos, via an improved Levenshtein-style correctorBrian Wignall2020-01-124-10/+10
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* Overloaded Quotation Brackets (#246)Matthew Pickering2020-01-121-2/+4
| | | | | | | | | | | | | | | | | | This patch implements overloaded quotation brackets which generalise the desugaring of all quotation forms in terms of a new minimal interface. The main change is that a quotation, for example, [e| 5 |], will now have type `Quote m => m Exp` rather than `Q Exp`. The `Quote` typeclass contains a single method for generating new names which is used when desugaring binding structures. The return type of functions from the `Lift` type class, `lift` and `liftTyped` have been restricted to `forall m . Quote m => m Exp` rather than returning a result in a Q monad. More details about the feature can be read in the GHC proposal. https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0246-overloaded-bracket.rst
* Module hierarchy: Renamer (cf #13009)Sylvain Henry2020-01-085-17/+18
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* Module hierarchy: Iface (cf #13009)Sylvain Henry2020-01-061-1/+1
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* Fix typos, via a Levenshtein-style correctorBrian Wignall2020-01-042-2/+2
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* Pretty-printing of the * kindVladislav Zavialov2019-12-051-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Before this patch, GHC always printed the * kind unparenthesized. This led to two issues: 1. Sometimes GHC printed invalid or incorrect code. For example, GHC would print: type F @* x = x when it meant to print: type F @(*) x = x In the former case, instead of a kind application we were getting a type operator (@*). 2. Sometimes GHC printed kinds that were correct but hard to read. Should Either * Int be read as Either (*) Int or as (*) Either Int ? This depends on whether -XStarIsType is enabled, but it would be easier if we didn't have to check for the flag when reading the code. We can solve both problems by assigning (*) a different precedence. Note that Haskell98 kinds are not affected: ((* -> *) -> *) -> * does NOT become (((*) -> (*)) -> (*)) -> (*) The parentheses are added when (*) is used in a function argument position: F * * * becomes F (*) (*) (*) F A * B becomes F A (*) B Proxy * becomes Proxy (*) a * -> * becomes a (*) -> *
* More Haddock syntax in GHC.Hs.UtilsBen Gamari2019-12-021-15/+16
| | | | As suggested by RyanGlScott in !2163.
* Remove HasSrcSpan (#17494)Vladislav Zavialov2019-11-304-73/+69
| | | | | Metric Decrease: haddock.compiler
* Factor out HsSCC/HsCoreAnn/HsTickPragma into HsPragEwip/hs-pragVladislav Zavialov2019-11-283-59/+77
| | | | | | | | | | | | | | | | | | | | | | | 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) }
* Fix typos, using Wikipedia list of common typosBrian Wignall2019-11-281-1/+1
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* Whitespace-sensitive bang patterns (#1087, #17162)wip/whitespace-and-lookaheadVladislav Zavialov2019-11-271-14/+9
| | | | | | | | | | | | | | | | | | This patch implements a part of GHC Proposal #229 that covers five operators: * the bang operator (!) * the tilde operator (~) * the at operator (@) * the dollar operator ($) * the double dollar operator ($$) Based on surrounding whitespace, these operators are disambiguated into bang patterns, lazy patterns, strictness annotations, type applications, splices, and typed splices. This patch doesn't cover the (-) operator or the -Woperator-whitespace warning, which are left as future work.
* Make warnings for TH splices opt-inSebastian Graf2019-11-271-11/+14
| | | | | | | | | | | | | | | | | | | | | | | In #17270 we have the pattern-match checker emit incorrect warnings. The reason for that behavior is ultimately an inconsistency in whether we treat TH splices as written by the user (`FromSource :: Origin`) or as generated code (`Generated`). This was first reported in #14838. The current solution is to TH splices as `Generated` by default and only treat them as `FromSource` when the user requests so (-fenable-th-splice-warnings). There are multiple reasons for opt-in rather than opt-out: * It's not clear that the user that compiles a splice is the author of the code that produces the warning. Think of the situation where she just splices in code from a third-party library that produces incomplete pattern matches. In this scenario, the user isn't even able to fix that warning. * Gathering information for producing the warnings (pattern-match check warnings in particular) is costly. There's no point in doing so if the user is not interested in those warnings. Fixes #17270, but not #14838, because the proper solution needs a GHC proposal extending the TH AST syntax.
* Remove prefix arrow support for GADTs (#17211)Krzysztof Gogolewski2019-11-251-16/+0
| | | | | | | This reverts the change in #9096. The specialcasing done for prefix (->) is brittle and does not support VTA, type families, type synonyms etc.
* Strip parentheses in expressions contexts in error messagesVladislav Zavialov2019-11-191-0/+4
| | | | This makes error messages a tad less noisy.
* Turn some comments into GHC.Hs.Utils into haddocksAndreas Klebinger2019-11-171-37/+46
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* Fix random typos [skip ci]nineonine2019-11-171-1/+1
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* Print name prefixly in the Outputable instance for StandaloneKindSigRyan Scott2019-11-131-1/+2
| | | | | | | | | Issue #17461 was occurring because the `Outputable` instance for standalone kind signatures was simply calling `ppr` on the name in the kind signature, which does not add parentheses to infix names. The solution is simple: use `pprPrefixOcc` instead. Fixes #17461.
* Ensure that coreView/tcView are able to inlineBen Gamari2019-11-131-1/+2
| | | | | | | | | | | | | | | | | | | | Previously an import cycle between Type and TyCoRep meant that several functions in TyCoRep ended up SOURCE import coreView. This is quite unfortunate as coreView is intended to be fused into a larger pattern match and not incur an extra call. Fix this with a bit of restructuring: * Move the functions in `TyCoRep` which depend upon things in `Type` into `Type` * Fold contents of `Kind` into `Type` and turn `Kind` into a simple wrapper re-exporting kind-ish things from `Type` * Clean up the redundant imports that popped up as a result Closes #17441. Metric Decrease: T4334
* Improve SPECIALIZE pragma error messages (Fixes #12126)Alina Banerjee2019-11-101-3/+5
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* Clean up TH's treatment of unary tuples (or, #16881 part two)Ryan Scott2019-11-073-3/+30
| | | | | | | | | | | | | | !1906 left some loose ends in regards to Template Haskell's treatment of unary tuples. This patch ends to tie up those loose ends: * In addition to having `TupleT 1` produce unary tuples, `TupE [exp]` and `TupP [pat]` also now produce unary tuples. * I have added various special cases in GHC's pretty-printers to ensure that explicit 1-tuples are printed using the `Unit` type. See `testsuite/tests/th/T17380`. * The GHC 8.10.1 release notes entry has been tidied up a little. Fixes #16881. Fixes #17371. Fixes #17380.
* Separate `LPat` from `Pat` on the type-levelSebastian Graf2019-11-023-32/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Since the Trees That Grow effort started, we had `type LPat = Pat`. This is so that `SrcLoc`s would only be annotated in GHC's AST, which is the reason why all GHC passes use the extension constructor `XPat` to attach source locations. See #15495 for the design discussion behind that. But now suddenly there are `XPat`s everywhere! There are several functions which dont't cope with `XPat`s by either crashing (`hsPatType`) or simply returning incorrect results (`collectEvVarsPat`). This issue was raised in #17330. I also came up with a rather clean and type-safe solution to the problem: We define ```haskell type family XRec p (f :: * -> *) = r | r -> p f type instance XRec (GhcPass p) f = Located (f (GhcPass p)) type instance XRec TH f = f p type LPat p = XRec p Pat ``` This is a rather modular embedding of the old "ping-pong" style, while we only pay for the `Located` wrapper within GHC. No ping-ponging in a potential Template Haskell AST, for example. Yet, we miss no case where we should've handled a `SrcLoc`: `hsPatType` and `collectEvVarsPat` are not callable at an `LPat`. Also, this gets rid of one indirection in `Located` variants: Previously, we'd have to go through `XPat` and `Located` to get from `LPat` to the wrapped `Pat`. Now it's just `Located` again. Thus we fix #17330.
* Use FlexibleInstances for `Outputable (* p)` instead of match-all instances ↵Sebastian Graf2019-10-2810-193/+196
| | | | | | | | | | | | | | with equality constraints In #17304, Richard and Simon dicovered that using `-XFlexibleInstances` for `Outputable` instances of AST data types means users can provide orphan `Outputable` instances for passes other than `GhcPass`. Type inference doesn't currently to suffer, and Richard gave an example in #17304 that shows how rare a case would be where the slightly worse type inference would matter. So I went ahead with the refactoring, attempting to fix #17304.
* Fix #15344: use fail when desugaring applicative-doJosef Svenningsson2019-10-282-17/+26
| | | | | | | | | | | | | | | | Applicative-do has a bug where it fails to use the monadic fail method when desugaring patternmatches which can fail. See #15344. This patch fixes that problem. It required more rewiring than I had expected. Applicative-do happens mostly in the renamer; that's where decisions about scheduling are made. This schedule is then carried through the typechecker and into the desugarer which performs the actual translation. Fixing this bug required sending information about the fail method from the renamer, through the type checker and into the desugarer. Previously, the desugarer didn't have enough information to actually desugar pattern matches correctly. As a side effect, we also fix #16628, where GHC wouldn't catch missing MonadFail instances with -XApplicativeDo.
* Solve constraints from top-level groups soonerRichard Eisenberg2019-10-081-107/+8
| | | | | | | | | | | | | | | | | | | | | | | | | Previously, all constraints from all top-level groups (as separated by top-level splices) were lumped together and solved at the end. This could leak metavariables to TH, though, and that's bad. This patch solves each group's constraints before running the next group's splice. Naturally, we now report fewer errors in some cases. One nice benefit is that this also fixes #11680, but in a much simpler way than the original fix for that ticket. Admittedly, the error messages degrade just a bit from the fix from #11680 (previously, we informed users about variables that will be brought into scope below a top-level splice, and now we just report an out-of-scope error), but the amount of complexity required throughout GHC to get that error was just not worth it. This patch thus reverts much of f93c9517a2c6e158e4a5c5bc7a3d3f88cb4ed119. Fixes #16980 Test cases: th/T16980{,a}
* Improve documentation around empty tuples/listsRichard Eisenberg2019-10-031-0/+67
| | | | | | | | | | | | | | This patch also changes the way we handle empty lists, simplifying them somewhat. See Note [Empty lists]. Previously, we had to special-case empty lists in the type-checker. Now no more! Finally, this patch improves some documentation around the ir_inst field used in the type-checker. This breaks a test case, but I really think the problem is #17251, not really related to this patch. Test case: typecheck/should_compile/T13680
* Standalone kind signatures (#16794)wip/top-level-kind-signaturesVladislav Zavialov2019-09-254-54/+120
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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 Henry2019-09-2015-0/+13320
Add GHC.Hs module hierarchy replacing hsSyn. Metric Increase: haddock.compiler