- Feb 19, 2024
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GHC Proposal 448 introduces binders for invisible type arguments (@a-binders) in various contexts. This patch implements @-binders in lambda patterns and function equations: {-# LANGUAGE TypeAbstractions #-} id1 :: a -> a id1 @t x = x :: t -- @t-binder on the LHS of a function equation higherRank :: (forall a. (Num a, Bounded a) => a -> a) -> (Int8, Int16) higherRank f = (f 42, f 42) ex :: (Int8, Int16) ex = higherRank (\ @a x -> maxBound @a - x ) -- @a-binder in a lambda pattern in an argument -- to a higher-order function Syntax ------ To represent those @-binders in the AST, the list of patterns in Match now uses ArgPat instead of Pat: data Match p body = Match { ... - m_pats :: [LPat p], + m_pats :: [LArgPat p], ... } + data ArgPat pass + = VisPat (XVisPat pass) (LPat pass) + | InvisPat (XInvisPat pass) (HsTyPat (NoGhcTc pass)) + | XArgPat !(XXArgPat pass) The VisPat constructor represents patterns for visible arguments, which include ordinary value-level arguments and required type arguments (neither is prefixed with a @), while InvisPat represents invisible type arguments (prefixed with a @). Parser ------ In the grammar (Parser.y), the lambda and lambda-cases productions of aexp non-terminal were updated to accept argpats instead of apats: aexp : ... - | '\\' apats '->' exp + | '\\' argpats '->' exp ... - | '\\' 'lcases' altslist(apats) + | '\\' 'lcases' altslist(argpats) ... + argpat : apat + | PREFIX_AT atype Function left-hand sides did not require any changes to the grammar, as they were already parsed with productions capable of parsing @-binders. Those binders were being rejected in post-processing (isFunLhs), and now we accept them. In Parser.PostProcess, patterns are constructed with the help of PatBuilder, which is used as an intermediate data structure when disambiguating between FunBind and PatBind. In this patch we define ArgPatBuilder to accompany PatBuilder. ArgPatBuilder is a short-lived data structure produced in isFunLhs and consumed in checkFunBind. Renamer ------- Renaming of @-binders builds upon prior work on type patterns, implemented in 2afbddb0, which guarantees proper scoping and shadowing behavior of bound type variables. This patch merely defines rnLArgPatsAndThen to process a mix of visible and invisible patterns: + rnLArgPatsAndThen :: NameMaker -> [LArgPat GhcPs] -> CpsRn [LArgPat GhcRn] + rnLArgPatsAndThen mk = mapM (wrapSrcSpanCps rnArgPatAndThen) where + rnArgPatAndThen (VisPat x p) = ... rnLPatAndThen ... + rnArgPatAndThen (InvisPat _ tp) = ... rnHsTyPat ... Common logic between rnArgPats and rnPats is factored out into the rn_pats_general helper. Type checker ------------ Type-checking of @-binders builds upon prior work on lazy skolemisation, implemented in f5d3e03c. This patch extends tcMatchPats to handle @-binders. Now it takes and returns a list of LArgPat rather than LPat: tcMatchPats :: ... - -> [LPat GhcRn] + -> [LArgPat GhcRn] ... - -> TcM ([LPat GhcTc], a) + -> TcM ([LArgPat GhcTc], a) Invisible binders in the Match are matched up with invisible (Specified) foralls in the type. This is done with a new clause in the `loop` worker of tcMatchPats: loop :: [LArgPat GhcRn] -> [ExpPatType] -> TcM ([LArgPat GhcTc], a) loop (L l apat : pats) (ExpForAllPatTy (Bndr tv vis) : pat_tys) ... -- NEW CLAUSE: | InvisPat _ tp <- apat, isSpecifiedForAllTyFlag vis = ... In addition to that, tcMatchPats no longer discards type patterns. This is done by filterOutErasedPats in the desugarer instead. x86_64-linux-deb10-validate+debug_info Metric Increase: MultiLayerModulesTH_OneShot
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- Jan 29, 2024
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- Jan 15, 2024
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When looking up a value, we want to be able to find both variables and record fields. So we should not use the lookupSameOccRn_maybe function, as we can't know ahead of time which record field namespace a record field with the given textual name will belong to. Fixes #24293
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- Aug 01, 2023
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This commit adds additional tests from ticket #23279 to ensure that we don't regress on reporting deprecated record fields in conjunction with HasField, either when using overloaded record dot syntax or directly through `getField`. Fixes #23279
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- Jul 23, 2023
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- Jul 17, 2023
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This commit adds similar name suggestions when importing. For example module A where { spelling = 'o' } module B where { import B ( speling ) } will give rise to the error message: Module ‘A’ does not export ‘speling’. Suggested fix: Perhaps use ‘spelling’ This also provides hints when users try to import record fields defined with NoFieldSelectors. -
In an import declaration such as import M ( var ) the import of the variable "var" should **not** bring into scope record fields named "var" which are defined with NoFieldSelectors. Doing so can cause spurious "unused import" warnings, as reported in ticket #23557. Fixes #23557
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- Jul 13, 2023
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This commit consolidates all the logic for looking up something in the Global Reader Environment into the single function lookupGRE. This allows us to declaratively specify all the different modes of looking up in the GlobalRdrEnv, and avoids manually passing around filtering functions as was the case in e.g. the function GHC.Rename.Env.lookupSubBndrOcc_helper. ------------------------- Metric Decrease: T8095 ------------------------- ------------------------- Metric Increase: T8095 ------------------------- -
Commit 3f374399 inadvertently broke the deprecation/warning mechanism for record fields due to its introduction of record field namespaces. This patch ensures that, when a top-level deprecation is applied to an identifier, it applies to all the record fields as well. This is achieved by refactoring GHC.Rename.Env.lookupLocalTcNames, and GHC.Rename.Env.lookupBindGroupOcc, to not look up a fixed number of NameSpaces but to look up all NameSpaces and filter out the irrelevant ones.
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- Jun 30, 2023
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- Jun 21, 2023
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Sylvain Henry authored
- Add ghc-interp.js bootstrap script for the JS interpreter - Interactively link and execute iserv code from the ghci package - Incrementally load and run JS code for splices into the running iserv Co-authored-by:Luite Stegeman <stegeman@gmail.com>
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- Jun 09, 2023
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- May 24, 2023
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This patch migrates the error messages in GHC.Tc.Validity to use the new diagnostic infrastructure. It adds the constructors: - TcRnSimplifiableConstraint - TcRnArityMismatch - TcRnIllegalInstanceDecl, with sub-datatypes for HasField errors and fundep coverage condition errors.
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- May 15, 2023
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- May 05, 2023
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Tracking ticket: #20115 MR: !10350 This converts uses of `mkTcRnUnknownMessage` to newly added constructors of `TcRnMessage`.
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- Apr 30, 2023
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Tracking ticket: #20115 MR: !10336 This converts uses of `mkTcRnUnknownMessage` to newly added constructors of `TcRnMessage`.
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- Apr 04, 2023
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When using Template Haskell, it is possible to re-parent a field OccName belonging to one data constructor to another data constructor. The lsp-types package did this in order to "extend" a data constructor with additional fields. This ran into an assertion in 'varToRecFieldOcc'. This assertion can simply be relaxed, as the resulting splices are perfectly sound. Fixes #23220
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- Apr 03, 2023
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I've turned all occurrences of TcRnUnknownMessage in GHC.Rename.HsType module into a proper TcRnMessage. Instead, these TcRnMessage messages were introduced: TcRnDataKindsError TcRnUnusedQuantifiedTypeVar TcRnIllegalKindSignature TcRnUnexpectedPatSigType TcRnSectionPrecedenceError TcRnPrecedenceParsingError TcRnIllegalKind TcRnNegativeNumTypeLiteral TcRnUnexpectedKindVar TcRnBindMultipleVariables TcRnBindVarAlreadyInScope
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- Apr 01, 2023
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Tracking ticket: #20117 MR: !10183 This converts uses of `mkTcRnUnknownMessage` to newly added constructors of `TcRnMessage`.
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- Mar 29, 2023
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sheaf authored
This patch moves the field-based logic for disambiguating record updates to the renamer. The type-directed logic, scheduled for removal, remains in the typechecker. To do this properly (and fix the myriad of bugs surrounding the treatment of duplicate record fields), we took the following main steps: 1. Create GREInfo, a renamer-level equivalent to TyThing which stores information pertinent to the renamer. This allows us to uniformly treat imported and local Names in the renamer, as described in Note [GREInfo]. 2. Remove GreName. Instead of a GlobalRdrElt storing GreNames, which distinguished between normal names and field names, we now store simple Names in GlobalRdrElt, along with the new GREInfo information which allows us to recover the FieldLabel for record fields. 3. Add namespacing for record fields, within the OccNames themselves. This allows us to remove the mangling of duplicate field selectors. This change ensures we don't print mangled names to the user in error messages, and allows us to handle duplicate record fields in Template Haskell. 4. Move record disambiguation to the renamer, and operate on the level of data constructors instead, to handle #21443. The error message text for ambiguous record updates has also been changed to reflect that type-directed disambiguation is on the way out. (3) means that OccEnv is now a bit more complex: we first key on the textual name, which gives an inner map keyed on NameSpace: OccEnv a ~ FastStringEnv (UniqFM NameSpace a) Note that this change, along with (2), both increase the memory residency of GlobalRdrEnv = OccEnv [GlobalRdrElt], which causes a few tests to regress somewhat in compile-time allocation. Even though (3) simplified a lot of code (in particular the treatment of field selectors within Template Haskell and in error messages), it came with one important wrinkle: in the situation of -- M.hs-boot module M where { data A; foo :: A -> Int } -- M.hs module M where { data A = MkA { foo :: Int } } we have that M.hs-boot exports a variable foo, which is supposed to match with the record field foo that M exports. To solve this issue, we add a new impedance-matching binding to M foo{var} = foo{fld} This mimics the logic that existed already for impedance-binding DFunIds, but getting it right was a bit tricky. See Note [Record field impedance matching] in GHC.Tc.Module. We also needed to be careful to avoid introducing space leaks in GHCi. So we dehydrate the GlobalRdrEnv before storing it anywhere, e.g. in ModIface. This means stubbing out all the GREInfo fields, with the function forceGlobalRdrEnv. When we read it back in, we rehydrate with rehydrateGlobalRdrEnv. This robustly avoids any space leaks caused by retaining old type environments. Fixes #13352 #14848 #17381 #17551 #19664 #21443 #21444 #21720 #21898 #21946 #21959 #22125 #22160 #23010 #23062 #23063 Updates haddock submodule ------------------------- Metric Increase: MultiComponentModules MultiLayerModules MultiLayerModulesDefsGhci MultiLayerModulesNoCode T13701 T14697 hard_hole_fits -------------------------
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- Feb 07, 2023
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- Oct 26, 2022
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Sylvain Henry authored
Necessary for newer cross-compiling backends (JS, Wasm) that don't support TH yet.
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- Oct 12, 2022
- Sep 13, 2022
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If a module `M` exports two fields `f` (using DuplicateRecordFields), we can still accept import M (f) import M hiding (f) and treat `f` as referencing both of them. This was accepted in GHC 9.0, but gave rise to an ambiguity error in GHC 9.2. See #21625. This patch also documents this behaviour in the user's guide, and updates the test for #16745 which is now treated differently. -
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- Aug 19, 2022
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This patch improves the uniformity of error message formatting by printing constraints in quotes, as we do for types. Fix #21167
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- May 17, 2022
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- Feb 08, 2022
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We perform validity checking on user-written HasField instances, for example to disallow: data Foo a = Foo { fld :: Int } instance HasField "fld" (Foo a) Bool However, these checks were also being made on quantified constraints, e.g. data Bar where Bar :: (forall a. HasField s (Foo a) Int) => Proxy s -> Bar This patch simply skips validity checking for quantified constraints, in line with what we already do for equality constraints such as Coercible. Fixes #20989
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- Feb 05, 2022
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This patch fixes #17469, by improving matters when you use non-existent field names in a record construction: data T = MkT { x :: Int } f v = MkT { y = 3 } The check is now made in the renamer, in GHC.Rename.Env.lookupRecFieldOcc. That in turn led to a spurious error in T9975a, which is fixed by making GHC.Rename.Names.extendGlobalRdrEnvRn fail fast if it finds duplicate bindings. See Note [Fail fast on duplicate definitions] in that module for more details. This patch was originated and worked on by Alex D (@nineonine)
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- Jan 17, 2022
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sheaf authored
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- Dec 28, 2021
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Matthew Pickering authoredMultiple home units allows you to load different packages which may depend on each other into one GHC session. This will allow both GHCi and HLS to support multi component projects more naturally. Public Interface ~~~~~~~~~~~~~~~~ In order to specify multiple units, the -unit @⟨filename⟩ flag is given multiple times with a response file containing the arguments for each unit. The response file contains a newline separated list of arguments. ``` ghc -unit @unitLibCore -unit @unitLib ``` where the `unitLibCore` response file contains the normal arguments that cabal would pass to `--make` mode. ``` -this-unit-id lib-core-0.1.0.0 -i -isrc LibCore.Utils LibCore.Types ``` The response file for lib, can specify a dependency on lib-core, so then modules in lib can use modules from lib-core. ``` -this-unit-id lib-0.1.0.0 -package-id lib-core-0.1.0.0 -i -isrc Lib.Parse Lib.Render ``` Then when the compiler starts in --make mode it will compile both units lib and lib-core. There is also very basic support for multiple home units in GHCi, at the moment you can start a GHCi session with multiple units but only the :reload is supported. Most commands in GHCi assume a single home unit, and so it is additional work to work out how to modify the interface to support multiple loaded home units. Options used when working with Multiple Home Units There are a few extra flags which have been introduced specifically for working with multiple home units. The flags allow a home unit to pretend it’s more like an installed package, for example, specifying the package name, module visibility and reexported modules. -working-dir ⟨dir⟩ It is common to assume that a package is compiled in the directory where its cabal file resides. Thus, all paths used in the compiler are assumed to be relative to this directory. When there are multiple home units the compiler is often not operating in the standard directory and instead where the cabal.project file is located. In this case the -working-dir option can be passed which specifies the path from the current directory to the directory the unit assumes to be it’s root, normally the directory which contains the cabal file. When the flag is passed, any relative paths used by the compiler are offset by the working directory. Notably this includes -i and -I⟨dir⟩ flags. -this-package-name ⟨name⟩ This flag papers over the awkward interaction of the PackageImports and multiple home units. When using PackageImports you can specify the name of the package in an import to disambiguate between modules which appear in multiple packages with the same name. This flag allows a home unit to be given a package name so that you can also disambiguate between multiple home units which provide modules with the same name. -hidden-module ⟨module name⟩ This flag can be supplied multiple times in order to specify which modules in a home unit should not be visible outside of the unit it belongs to. The main use of this flag is to be able to recreate the difference between an exposed and hidden module for installed packages. -reexported-module ⟨module name⟩ This flag can be supplied multiple times in order to specify which modules are not defined in a unit but should be reexported. The effect is that other units will see this module as if it was defined in this unit. The use of this flag is to be able to replicate the reexported modules feature of packages with multiple home units. Offsetting Paths in Template Haskell splices ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ When using Template Haskell to embed files into your program, traditionally the paths have been interpreted relative to the directory where the .cabal file resides. This causes problems for multiple home units as we are compiling many different libraries at once which have .cabal files in different directories. For this purpose we have introduced a way to query the value of the -working-dir flag to the Template Haskell API. By using this function we can implement a makeRelativeToProject function which offsets a path which is relative to the original project root by the value of -working-dir. ``` import Language.Haskell.TH.Syntax ( makeRelativeToProject ) foo = $(makeRelativeToProject "./relative/path" >>= embedFile) ``` > If you write a relative path in a Template Haskell splice you should use the makeRelativeToProject function so that your library works correctly with multiple home units. A similar function already exists in the file-embed library. The function in template-haskell implements this function in a more robust manner by honouring the -working-dir flag rather than searching the file system. Closure Property for Home Units ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ For tools or libraries using the API there is one very important closure property which must be adhered to: > Any dependency which is not a home unit must not (transitively) depend on a home unit. For example, if you have three packages p, q and r, then if p depends on q which depends on r then it is illegal to load both p and r as home units but not q, because q is a dependency of the home unit p which depends on another home unit r. If you are using GHC by the command line then this property is checked, but if you are using the API then you need to check this property yourself. If you get it wrong you will probably get some very confusing errors about overlapping instances. Limitations of Multiple Home Units ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ There are a few limitations of the initial implementation which will be smoothed out on user demand. * Package thinning/renaming syntax is not supported * More complicated reexports/renaming are not yet supported. * It’s more common to run into existing linker bugs when loading a large number of packages in a session (for example #20674, #20689) * Backpack is not yet supported when using multiple home units. * Dependency chasing can be quite slow with a large number of modules and packages. * Loading wired-in packages as home units is currently not supported (this only really affects GHC developers attempting to load template-haskell). * Barely any normal GHCi features are supported, it would be good to support enough for ghcid to work correctly. Despite these limitations, the implementation works already for nearly all packages. It has been testing on large dependency closures, including the whole of head.hackage which is a total of 4784 modules from 452 packages. Internal Changes ~~~~~~~~~~~~~~~~ * The biggest change is that the HomePackageTable is replaced with the HomeUnitGraph. The HomeUnitGraph is a map from UnitId to HomeUnitEnv, which contains information specific to each home unit. * The HomeUnitEnv contains: - A unit state, each home unit can have different package db flags - A set of dynflags, each home unit can have different flags - A HomePackageTable * LinkNode: A new node type is added to the ModuleGraph, this is used to place the linking step into the build plan so linking can proceed in parralel with other packages being built. * New invariant: Dependencies of a ModuleGraphNode can be completely determined by looking at the value of the node. In order to achieve this, downsweep now performs a more complete job of downsweeping and then the dependenices are recorded forever in the node rather than being computed again from the ModSummary. * Some transitive module calculations are rewritten to use the ModuleGraph which is more efficient. * There is always an active home unit, which simplifies modifying a lot of the existing API code which is unit agnostic (for example, in the driver). The road may be bumpy for a little while after this change but the basics are well-tested. One small metric increase, which we accept and also submodule update to haddock which removes ExtendedModSummary. Closes #10827 ------------------------- Metric Increase: MultiLayerModules ------------------------- Co-authored-by:Fendor <power.walross@gmail.com>
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- Nov 26, 2021
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There are quite a few keywords which are allowed to be used as variables. Such as "as", "dependency" etc. These weren't accepted by OverloadedDotSyntax. The fix is pretty simple, use the varid production rather than raw VARID. Fixes #20723
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- May 22, 2021
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Shayne Fletcher authored- Change the names of the fields in in `data FieldOcc` - Renames `HsRecFld` to `HsRecSel` - Replace `AmbiguousFieldOcc p` in `HsRecSel` with `FieldOcc p` - Contains a haddock submodule update The primary motivation of this change is to remove `AmbiguousFieldOcc`. This is one of a suite of changes improving how record syntax (most notably record update syntax) is represented in the AST.
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- Mar 29, 2021
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Alfredo Di Napoli authored
Other than that: * Fix T16167,json,json2,T7478,T10637 tests to reflect the introduction of the `MessageClass` type * Remove `makeIntoWarning` * Remove `warningsToMessages` * Refactor GHC.Tc.Errors 1. Refactors GHC.Tc.Errors so that we use `DiagnosticReason` for "choices" (defer types errors, holes, etc); 2. We get rid of `reportWarning` and `reportError` in favour of a general `reportDiagnostic`. * Introduce `DiagnosticReason`, `Severity` is an enum: This big commit makes `Severity` a simple enumeration, and introduces the concept of `DiagnosticReason`, which classifies the /reason/ why we are emitting a particular diagnostic. It also adds a monomorphic `DiagnosticMessage` type which is used for generic messages. * The `Severity` is computed (for now) from the reason, statically. Later improvement will add a `diagReasonSeverity` function to compute the `Severity` taking `DynFlags` into account. * Rename `logWarnings` into `logDiagnostics` * Add note and expand description of the `mkHoleError` function
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- Mar 10, 2021
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Previously, defining fields with DuplicateRecordFields in GHCi lead to strange shadowing behaviour, whereby fields would (accidentally) not shadow other fields. This simplifies things so that fields are shadowed in the same way whether or not DuplicateRecordFields is enabled.
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- Feb 26, 2021
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Fixes #18966. Adds a new warning -Wambiguous-fields for uses of field selectors or record updates that will be rejected in the future, when the DuplicateRecordFields extension is simplified per https://github.com/ghc-proposals/ghc-proposals/pull/366.
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- Feb 19, 2021
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Simon Peyton Jones authored
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
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- Feb 16, 2021
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This is a small fix that depends on the previous commit, because it corrected the rnExpr free variable calculation for HsVars which refer to ambiguous fields. Fixes #19213.
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