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* Improve error reporting in generated codeSimon Peyton Jones2022-05-043-7/+13
| | | | | | Our error reporting in generated code (via desugaring before typechecking) only worked when the generated code was just a simple call. This commit makes it work in nested cases.
* Convert More Diagnostics (#20116)Ben Gamari2022-04-307-7/+7
| | | | | Replaces uses of `TcRnUnknownMessage` with proper diagnostics constructors.
* Make mkFunCo take AnonArgFlags into accountRyan Scott2022-04-303-0/+16
| | | | | | | | | | | | | | | | | | | | | | Previously, whenever `mkFunCo` would produce reflexive coercions, it would use `mkVisFunTy` to produce the kind of the coercion. However, `mkFunCo` is also used to produce coercions between types of the form `ty1 => ty2` in certain places. This has the unfortunate side effect of causing the type of the coercion to appear as `ty1 -> ty2` in certain error messages, as spotted in #21328. This patch address this by changing replacing the use of `mkVisFunTy` with `mkFunctionType` in `mkFunCo`. `mkFunctionType` checks the kind of `ty1` and makes the function arrow `=>` instead of `->` if `ty1` has kind `Constraint`, so this should always produce the correct `AnonArgFlag`. As a result, this patch fixes part (2) of #21328. This is not the only possible way to fix #21328, as the discussion on that issue lists some possible alternatives. Ultimately, it was concluded that the alternatives would be difficult to maintain, and since we already use `mkFunctionType` in `coercionLKind` and `coercionRKind`, using `mkFunctionType` in `mkFunCo` is consistent with this choice. Moreover, using `mkFunctionType` does not regress the performance of any test case we have in GHC's test suite.
* Fix unification of ConcreteTvs, removing IsRefl#sheaf2022-04-281-4/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch fixes the unification of concrete type variables. The subtlety was that unifying concrete metavariables is more subtle than other metavariables, as decomposition is possible. See the Note [Unifying concrete metavariables], which explains how we unify a concrete type variable with a type 'ty' by concretising 'ty', using the function 'GHC.Tc.Utils.Concrete.concretise'. This can be used to perform an eager syntactic check for concreteness, allowing us to remove the IsRefl# special predicate. Instead of emitting two constraints `rr ~# concrete_tv` and `IsRefl# rr concrete_tv`, we instead concretise 'rr'. If this succeeds we can fill 'concrete_tv', and otherwise we directly emit an error message to the typechecker environment instead of deferring. We still need the error message to be passed on (instead of directly thrown), as we might benefit from further unification in which case we will need to zonk the stored types. To achieve this, we change the 'wc_holes' field of 'WantedConstraints' to 'wc_errors', which stores general delayed errors. For the moement, a delayed error is either a hole, or a syntactic equality error. hasFixedRuntimeRep_MustBeRefl is now hasFixedRuntimeRep_syntactic, and hasFixedRuntimeRep has been refactored to directly return the most useful coercion for PHASE 2 of FixedRuntimeRep. This patch also adds a field ir_frr to the InferResult datatype, holding a value of type Maybe FRROrigin. When this value is not Nothing, this means that we must fill the ir_ref field with a type which has a fixed RuntimeRep. When it comes time to fill such an ExpType, we ensure that the type has a fixed RuntimeRep by performing a representation-polymorphism check with the given FRROrigin This is similar to what we already do to ensure we fill an Infer ExpType with a type of the correct TcLevel. This allows us to properly perform representation-polymorphism checks on 'Infer' 'ExpTypes'. The fillInferResult function had to be moved to GHC.Tc.Utils.Unify to avoid a cyclic import now that it calls hasFixedRuntimeRep. This patch also changes the code in matchExpectedFunTys to make use of the coercions, which is now possible thanks to the previous change. This implements PHASE 2 of FixedRuntimeRep in some situations. For example, the test cases T13105 and T17536b are now both accepted. Fixes #21239 and #21325 ------------------------- Metric Decrease: T18223 T5631 -------------------------
* Refactor: simplify lexing of the dotVladislav Zavialov2022-04-091-7/+7
| | | | | | | | | | | | Before this patch, the lexer did a truly roundabout thing with the dot: 1. look up the varsym in reservedSymsFM and turn it into ITdot 2. under OverloadedRecordDot, turn it into ITvarsym 3. in varsym_(prefix|suffix|...) turn it into ITvarsym, ITdot, or ITproj, depending on extensions and whitespace Turns out, the last step is sufficient to handle the dot correctly. This patch removes the first two steps.
* Correctly report SrcLoc of redundant constraintssheaf2022-04-083-0/+11
| | | | | | | | | We were accidentally dropping the source location information in certain circumstances when reporting redundant constraints. This patch makes sure that we set the TcLclEnv correctly before reporting the warning. Fixes #21315
* Add test for #21338sheaf2022-04-083-0/+74
| | | | | | | | This no-skolem-info bug was fixed by the no-skolem-info patch that will be part of GHC 9.4. This patch adds a regression test for the issue reported in issue #21338. Fixes #21338.
* Ensure implicit parameters are liftedsheaf2022-04-013-0/+16
| | | | | | | | `tcExpr` typechecked implicit parameters by introducing a metavariable of kind `TYPE kappa`, without enforcing that `kappa ~ LiftedRep`. This patch instead creates a metavariable of kind `Type`. Fixes #21327
* Add a regression test for #21323sheaf2022-04-012-0/+56
| | | | | This bug was fixed at some point between GHC 9.0 and GHC 9.2; this patch simply adds a regression test.
* Implement \cases (Proposal 302)Jakob Bruenker2022-04-018-3/+75
| | | | | | | | | | | | This commit implements proposal 302: \cases - Multi-way lambda expressions. This adds a new expression heralded by \cases, which works exactly like \case, but can match multiple apats instead of a single pat. Updates submodule haddock to support the ITlcases token. Closes #20768
* Change GHC.Prim to GHC.Exts in docs and testsKrzysztof Gogolewski2022-04-0111-12/+12
| | | | | Users are supposed to import GHC.Exts rather than GHC.Prim. Part of #18749.
* Unify RuntimeRep arguments in ty_co_matchsheaf2022-04-012-1/+26
| | | | | | | | | | | | | | | | | The `ty_co_match` function ignored the implicit RuntimeRep coercions that occur in a `FunCo`. Even though a comment explained that this should be fine, #21205 showed that it could result in discarding a RuntimeRep coercion, and thus discarding an important cast entirely. With this patch, we first match the kinds in `ty_co_match`. Fixes #21205 ------------------------- Metric Increase: T12227 T18223 -------------------------
* Add test for T21306Matthew Pickering2022-03-293-0/+55
| | | | Fixes #21306
* Add Red Herring to Note [What might equal later?]Richard Eisenberg2022-03-282-0/+19
| | | | Close #21208.
* Add a regression test for #21130sheaf2022-03-163-0/+45
| | | | | | | | | This problem was due to a bug in cloneWanted, which was incorrectly creating a coercion hole to hold an evidence variable. This bug was introduced by 8bb52d91 and fixed in 81740ce8. Fixes #21130
* Export (~) from Data.Type.Equality (#18862)wip/eqtycon-rnVladislav Zavialov2022-03-1512-5/+12
| | | | | | | | | | * Users can define their own (~) type operator * Haddock can display documentation for the built-in (~) * New transitional warnings implemented: -Wtype-equality-out-of-scope -Wtype-equality-requires-operators Updates the haddock submodule.
* Fix isLiftedType_maybe and handle falloutsheaf2022-03-144-4/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | As #20837 pointed out, `isLiftedType_maybe` returned `Just False` in many situations where it should return `Nothing`, because it didn't take into account type families or type variables. In this patch, we fix this issue. We rename `isLiftedType_maybe` to `typeLevity_maybe`, which now returns a `Levity` instead of a boolean. We now return `Nothing` for types with kinds of the form `TYPE (F a1 ... an)` for a type family `F`, as well as `TYPE (BoxedRep l)` where `l` is a type variable. This fix caused several other problems, as other parts of the compiler were relying on `isLiftedType_maybe` returning a `Just` value, and were now panicking after the above fix. There were two main situations in which panics occurred: 1. Issues involving the let/app invariant. To uphold that invariant, we need to know whether something is lifted or not. If we get an answer of `Nothing` from `isLiftedType_maybe`, then we don't know what to do. As this invariant isn't particularly invariant, we can change the affected functions to not panic, e.g. by behaving the same in the `Just False` case and in the `Nothing` case (meaning: no observable change in behaviour compared to before). 2. Typechecking of data (/newtype) constructor patterns. Some programs involving patterns with unknown representations were accepted, such as T20363. Now that we are stricter, this caused further issues, culminating in Core Lint errors. However, the behaviour was incorrect the whole time; the incorrectness only being revealed by this change, not triggered by it. This patch fixes this by overhauling where the representation polymorphism involving pattern matching are done. Instead of doing it in `tcMatches`, we instead ensure that the `matchExpected` functions such as `matchExpectedFunTys`, `matchActualFunTySigma`, `matchActualFunTysRho` allow return argument pattern types which have a fixed RuntimeRep (as defined in Note [Fixed RuntimeRep]). This ensures that the pattern matching code only ever handles types with a known runtime representation. One exception was that patterns with an unknown representation type could sneak in via `tcConPat`, which points to a missing representation-polymorphism check, which this patch now adds. This means that we now reject the program in #20363, at least until we implement PHASE 2 of FixedRuntimeRep (allowing type families in RuntimeRep positions). The aforementioned refactoring, in which checks have been moved to `matchExpected` functions, is a first step in implementing PHASE 2 for patterns. Fixes #20837
* Always generalise top-level bindingsSimon Peyton Jones2022-03-073-0/+12
| | | | | Fix #21023 by always generalising top-level binding; change the documentation of -XMonoLocalBinds to match.
* Make Constraint not *apart* from Type.Richard Eisenberg2022-03-022-9/+2
| | | | | | More details in Note [coreView vs tcView] Close #21092.
* Make inert_cycle_breakers into a stack.Richard Eisenberg2022-03-022-0/+21
| | | | Close #20231.
* Kill derived constraintsRichard Eisenberg2022-02-2388-238/+1166
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Co-authored by: Sam Derbyshire Previously, GHC had three flavours of constraint: Wanted, Given, and Derived. This removes Derived constraints. Though serving a number of purposes, the most important role of Derived constraints was to enable better error messages. This job has been taken over by the new RewriterSets, as explained in Note [Wanteds rewrite wanteds] in GHC.Tc.Types.Constraint. Other knock-on effects: - Various new Notes as I learned about under-described bits of GHC - A reshuffling around the AST for implicit-parameter bindings, with better integration with TTG. - Various improvements around fundeps. These were caused by the fact that, previously, fundep constraints were all Derived, and Derived constraints would get dropped. Thus, an unsolved Derived didn't stop compilation. Without Derived, this is no longer possible, and so we have to be considerably more careful around fundeps. - A nice little refactoring in GHC.Tc.Errors to center the work on a new datatype called ErrorItem. Constraints are converted into ErrorItems at the start of processing, and this allows for a little preprocessing before the main classification. - This commit also cleans up the behavior in generalisation around functional dependencies. Now, if a variable is determined by functional dependencies, it will not be quantified. This change is user facing, but it should trim down GHC's strange behavior around fundeps. - Previously, reportWanteds did quite a bit of work, even on an empty WantedConstraints. This commit adds a fast path. - Now, GHC will unconditionally re-simplify constraints during quantification. See Note [Unconditionally resimplify constraints when quantifying], in GHC.Tc.Solver. Close #18398. Close #18406. Solve the fundep-related non-confluence in #18851. Close #19131. Close #19137. Close #20922. Close #20668. Close #19665. ------------------------- Metric Decrease: LargeRecord T9872b T9872b_defer T9872d TcPlugin_RewritePerf -------------------------
* Tag inference work.Andreas Klebinger2022-02-121-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This does three major things: * Enforce the invariant that all strict fields must contain tagged pointers. * Try to predict the tag on bindings in order to omit tag checks. * Allows functions to pass arguments unlifted (call-by-value). The former is "simply" achieved by wrapping any constructor allocations with a case which will evaluate the respective strict bindings. The prediction is done by a new data flow analysis based on the STG representation of a program. This also helps us to avoid generating redudant cases for the above invariant. StrictWorkers are created by W/W directly and SpecConstr indirectly. See the Note [Strict Worker Ids] Other minor changes: * Add StgUtil module containing a few functions needed by, but not specific to the tag analysis. ------------------------- Metric Decrease: T12545 T18698b T18140 T18923 LargeRecord Metric Increase: LargeRecord ManyAlternatives ManyConstructors T10421 T12425 T12707 T13035 T13056 T13253 T13253-spj T13379 T15164 T18282 T18304 T18698a T1969 T20049 T3294 T4801 T5321FD T5321Fun T783 T9233 T9675 T9961 T19695 WWRec -------------------------
* Relax TyEq:N: allow out-of-scope newtype DataConsheaf2022-02-084-0/+49
| | | | | | | | | | The 'bad_newtype' assertion in GHC.Tc.Solver.Canonical.canEqCanLHSFinish failed to account for the possibility that the newtype constructor might not be in scope, in which case we don't provide any guarantees about canonicalising away a newtype on the RHS of a representational equality. Fixes #21010
* Make implication tidying agree with Note [Tidying multiple names at once]Matthew Pickering2022-02-0513-74/+74
| | | | | | | | | | | Note [Tidying multiple names at once] indicates that if multiple variables have the same name then we shouldn't prioritise one of them and instead rename them all to a1, a2, a3... etc This patch implements that change, some error message changes as expected. Closes #20932
* compiler: Introduce and use RoughMap for instance environmentsBen Gamari2022-02-042-10/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Here we introduce a new data structure, RoughMap, inspired by the previous `RoughTc` matching mechanism for checking instance matches. This allows [Fam]InstEnv to be implemented as a trie indexed by these RoughTc signatures, reducing the complexity of instance lookup and FamInstEnv merging (done during the family instance conflict test) from O(n) to O(log n). The critical performance improvement currently realised by this patch is in instance matching. In particular the RoughMap mechanism allows us to discount many potential instances which will never match for constraints involving type variables (see Note [Matching a RoughMap]). In realistic code bases matchInstEnv was accounting for 50% of typechecker time due to redundant work checking instances when simplifying instance contexts when deriving instances. With this patch the cost is significantly reduced. The larger constants in InstEnv creation do mean that a few small tests regress in allocations slightly. However, the runtime of T19703 is reduced by a factor of 4. Moreover, the compilation time of the Cabal library is slightly improved. A couple of test cases are included which demonstrate significant improvements in compile time with this patch. This unfortunately does not fix the testcase provided in #19703 but does fix #20933 ------------------------- Metric Decrease: T12425 Metric Increase: T13719 T9872a T9872d hard_hole_fits ------------------------- Co-authored-by: Matthew Pickering <matthewtpickering@gmail.com>
* Unbreak T13168 on windowsMatthew Pickering2022-02-031-2/+1
| | | | Fixes #14276
* T13168: Filter out rtsopts for consistency between dynamic and static waysMatthew Pickering2022-02-032-5/+1
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* Rework the handling of SkolemInfoMatthew Pickering2022-01-2930-25/+419
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The main purpose of this patch is to attach a SkolemInfo directly to each SkolemTv. This fixes the large number of bugs which have accumulated over the years where we failed to report errors due to having "no skolem info" for particular type variables. Now the origin of each type varible is stored on the type variable we can always report accurately where it cames from. Fixes #20969 #20732 #20680 #19482 #20232 #19752 #10946 #19760 #20063 #13499 #14040 The main changes of this patch are: * SkolemTv now contains a SkolemInfo field which tells us how the SkolemTv was created. Used when reporting errors. * Enforce invariants relating the SkolemInfoAnon and level of an implication (ic_info, ic_tclvl) to the SkolemInfo and level of the type variables in ic_skols. * All ic_skols are TcTyVars -- Check is currently disabled * All ic_skols are SkolemTv * The tv_lvl of the ic_skols agrees with the ic_tclvl * The ic_info agrees with the SkolInfo of the implication. These invariants are checked by a debug compiler by checkImplicationInvariants. * Completely refactor kcCheckDeclHeader_sig which kept doing my head in. Plus, it wasn't right because it wasn't skolemising the binders as it decomposed the kind signature. The new story is described in Note [kcCheckDeclHeader_sig]. The code is considerably shorter than before (roughly 240 lines turns into 150 lines). It still has the same awkward complexity around computing arity as before, but that is a language design issue. See Note [Arity inference in kcCheckDeclHeader_sig] * I added new type synonyms MonoTcTyCon and PolyTcTyCon, and used them to be clear which TcTyCons have "finished" kinds etc, and which are monomorphic. See Note [TcTyCon, MonoTcTyCon, and PolyTcTyCon] * I renamed etaExpandAlgTyCon to splitTyConKind, becuase that's a better name, and it is very useful in kcCheckDeclHeader_sig, where eta-expansion isn't an issue. * Kill off the nasty `ClassScopedTvEnv` entirely. Co-authored-by: Simon Peyton Jones <simon.peytonjones@gmail.com>
* Add test supplied in T20996 which uses data family result kind polymorphismDavid Feuer2022-01-272-0/+112
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | David (@treeowl) writes: > Following @kcsongor, I've used ridiculous data family result kind > polymorphism in `linear-generics`, and am currently working on getting > it into `staged-gg`. If it should be removed, I'd appreciate a heads up, > and I imagine Csongor would too. > > What do I need by ridiculous polymorphic result kinds? Currently, data > families are allowed to have result kinds that end in `Type` (or maybe > `TYPE r`? I'm not sure), but not in concrete data kinds. However, they > *are* allowed to have polymorphic result kinds. This leads to things I > think most of us find at least quite *weird*. For example, I can write > > ```haskell > data family Silly :: k > data SBool :: Bool -> Type where > SFalse :: SBool False > STrue :: SBool True > SSSilly :: SBool Silly > type KnownBool b where > kb :: SBool b > instance KnownBool False where kb = SFalse > instance KnownBool True where kb = STrue > instance KnownBool Silly where kb = Silly > ``` > > Basically, every kind now has potentially infinitely many "legit" inhabitants. > > As horrible as that is, it's rather useful for GHC's current native > generics system. It's possible to use these absurdly polymorphic result > kinds to probe the structure of generic representations in a relatively > pleasant manner. It's a sort of "formal type application" reminiscent of > the notion of a formal power series (see the test case below). I suspect > a system more like `kind-generics` wouldn't need this extra probing > power, but nothing like that is natively available as yet. > > If the ridiculous result kind polymorphism is banished, we'll still be > able to do what we need as long as we have stuck type families. It's > just rather less ergonomical: a stuck type family has to be used with a > concrete marker type argument. Closes #20996 Co-authored-by: Matthew Pickering <matthewtpickering@gmail.com>
* Ensure that order of instances doesn't mattersheaf2022-01-262-0/+64
| | | | | | | | | | | | | | | | | The insert_overlapping used in lookupInstEnv used to return different results depending on the order in which instances were processed. The problem was that we could end up discarding an overlapping instance in favour of a more specific non-overlapping instance. This is a problem because, even though we won't choose the less-specific instance for matching, it is still useful for pruning away other instances, because it has the overlapping flag set while the new instance doesn't. In insert_overlapping, we now keep a list of "guard" instances, which are instances which are less-specific that one that matches (and hence which we will discard in the end), but want to keep around solely for the purpose of eliminating other instances. Fixes #20946
* Add test for using type families with static pointersMatthew Pickering2022-01-182-1/+18
| | | | Issue was reported on #13306
* Use diagnostic infrastructure in GHC.Tc.Errorssheaf2022-01-1719-52/+58
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* Fix parsing & printing of unboxed sumssheaf2022-01-111-7/+5
| | | | | | | | | | | | | | | | | The pretty-printing of partially applied unboxed sums was incorrect, as we incorrectly dropped the first half of the arguments, even for a partial application such as (# | #) @IntRep @DoubleRep Int# which lead to the nonsensical (# DoubleRep | Int# #). This patch also allows users to write unboxed sum type constructors such as (# | #) :: TYPE r1 -> TYPE r2 -> TYPE (SumRep '[r1,r2]). Fixes #20858 and #20859.
* Kind TyCons: require KindSignatures, not DataKindssheaf2022-01-117-0/+61
| | | | | | | | | | | | | | | | | | Uses of a TyCon in a kind signature required users to enable DataKinds, which didn't make much sense, e.g. in type U = Type type MyMaybe (a :: U) = MyNothing | MyJust a Now the DataKinds error is restricted to data constructors; the use of kind-level type constructors is instead gated behind -XKindSignatures. This patch also adds a convenience pattern synonym for patching on both a TyCon or a TcTyCon stored in a TcTyThing, used in tcTyVar and tc_infer_id. fixes #20873
* Check quoted TH names are in the correct namespacesheaf2022-01-041-6/+6
| | | | | | | | | | | | When quoting (using a TH single or double quote) a built-in name such as the list constructor (:), we didn't always check that the resulting 'Name' was in the correct namespace. This patch adds a check in GHC.Rename.Splice to ensure we get a Name that is in the term-level/type-level namespace, when using a single/double tick, respectively. Fixes #20884.
* Multiple Home UnitsMatthew Pickering2021-12-282-7/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Multiple 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>
* Fix typosKrzysztof Gogolewski2021-12-251-1/+1
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* testsuite: Remove reqlib modifierMatthew Pickering2021-12-224-94/+0
| | | | | | | | | | | | | | | | | | | | The reqlib modifer was supposed to indicate that a test needed a certain library in order to work. If the library happened to be installed then the test would run as normal. However, CI has never run these tests as the packages have not been installed and we don't want out tests to depend on things which might get externally broken by updating the compiler. The new strategy is to run these tests in head.hackage, where the tests have been cabalised as well as possible. Some tests couldn't be transferred into the normal style testsuite but it's better than never running any of the reqlib tests. https://gitlab.haskell.org/ghc/head.hackage/-/merge_requests/169 A few submodules also had reqlib tests and have been updated to remove it. Closes #16264 #20032 #17764 #16561
* Add regression test for T20189Matthew Pickering2021-12-173-0/+20
| | | | Closes #20189
* Use HasCallStack and error in GHC.List and .NonEmptyOleg Grenrus2021-12-125-37/+47
| | | | | | | | | | | | | | | | | In addition to providing stack traces, the scary HasCallStack will hopefully make people think whether they want to use these functions, i.e. act as a documentation hint that something weird might happen. A single metric increased, which doesn't visibly use any method with `HasCallStack`. ------------------------- Metric Decrease: T9630 Metric Decrease: T19695 T9630 -------------------------
* Re-export GHC.Types from GHC.Extssheaf2021-12-071-2/+1
| | | | | | | | | | | | | | Several times in the past, it has happened that things from GHC.Types were not re-exported from GHC.Exts, forcing users to import either GHC.Types or GHC.Prim, which are subject to internal change without notice. We now re-export GHC.Types from GHC.Exts, which should avoid this happening again in the future. In particular, we now re-export `Multiplicity` and `MultMul`, which we didn't before. Fixes #20695
* Revert "Data.List specialization to []"Matthew Pickering2021-12-031-2/+2
| | | | | | | | | | This reverts commit bddecda1a4c96da21e3f5211743ce5e4c78793a2. This implements the first step in the plan formulated in #20025 to improve the communication and migration strategy for the proposed changes to Data.List. Requires changing the haddock submodule to update the test output.
* Allow boring class declarations in hs-boot filessheaf2021-11-2512-0/+92
| | | | | | | | | | | | | | | | | | | | | | | There are two different ways of declaring a class in an hs-boot file: - a full declaration, where everything is written as it is in the .hs file, - an abstract declaration, where class methods and superclasses are left out. However, a declaration with no methods and a trivial superclass, such as: class () => C a was erroneously considered to be an abstract declaration, because the superclass is trivial. This is remedied by a one line fix in GHC.Tc.TyCl.tcClassDecl1. This patch also further clarifies the documentation around class declarations in hs-boot files. Fixes #20661, #20588.
* Enable UnboxedTuples in `genInst`, Fixes #20524CarrieMY2021-11-253-0/+27
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* Add a warning for GADT match + NoMonoLocalBinds (#20485)Krzysztof Gogolewski2021-11-231-1/+1
| | | | | | | | | Previously, it was an error to pattern match on a GADT without GADTs or TypeFamilies. This is now allowed. Instead, we check the flag MonoLocalBinds; if it is not enabled, we issue a warning, controlled by -Wgadt-mono-local-binds. Also fixes #20485: pattern synonyms are now checked too.
* CmmSink: Be more aggressive in removing no-op assignments.Andreas Klebinger2021-11-234-0/+752
| | | | | | | | | | No-op assignments like R1 = R1 are not only wasteful. They can also inhibit other optimizations like inlining assignments that read from R1. We now check for assignments being a no-op before and after we simplify the RHS in Cmm sink which should eliminate most of these no-ops.
* Include "not more specific" info in overlap msgsheaf2021-11-2030-110/+122
| | | | | | | | | When instances overlap, we now include additional information about why we weren't able to select an instance: perhaps one instance overlapped another but was not strictly more specific, so we aren't able to directly choose it. Fixes #20542
* testsuite: check for FlexibleContexts in T17563Vladislav Zavialov2021-11-182-8/+9
| | | | | | | | | | | | | | | | | | | | | The purpose of testsuite/tests/typecheck/should_fail/T17563.hs is to make sure we do validity checking on quantified constraints. In particular, see the following functions in GHC.Tc.Validity: * check_quant_pred * check_pred_help * check_class_pred The original bug report used a~b constraints as an example of a constraint that requires validity checking. But with GHC Proposal #371, equality constraints no longer require GADTs or TypeFamilies; instead, they require TypeOperators, which are checked earlier in the pipeline, in the renamer. Rather than simply remove this test, we change the example to use another extension: FlexibleContexts. Since we decide whether a constraint requires this extension in check_class_pred, the regression test continues to exercise the relevant code path.
* Increase type sharingBen Gamari2021-11-175-21/+18
| | | | | | | | | | | | | | | | | | | | | | | | | | | Fixes #20541 by making mkTyConApp do more sharing of types. In particular, replace * BoxedRep Lifted ==> LiftedRep * BoxedRep Unlifted ==> UnliftedRep * TupleRep '[] ==> ZeroBitRep * TYPE ZeroBitRep ==> ZeroBitType In each case, the thing on the right is a type synonym for the thing on the left, declared in ghc-prim:GHC.Types. See Note [Using synonyms to compress types] in GHC.Core.Type. The synonyms for ZeroBitRep and ZeroBitType are new, but absolutely in the same spirit as the other ones. (These synonyms are mainly for internal use, though the programmer can use them too.) I also renamed GHC.Core.Ty.Rep.isVoidTy to isZeroBitTy, to be compatible with the "zero-bit" nomenclature above. See discussion on !6806. There is a tricky wrinkle: see GHC.Core.Types Note [Care using synonyms to compress types] Compiler allocation decreases by up to 0.8%.
* Instantiate field types properly in stock-derived instancesRyan Scott2021-11-154-22/+144
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Previously, the `deriving` machinery was very loosey-goosey about how it used the types of data constructor fields when generating code. It would usually just consult `dataConOrigArgTys`, which returns the _uninstantiated_ field types of each data constructor. Usually, you can get away with this, but issues #20375 and #20387 revealed circumstances where this approach fails. Instead, when generated code for a stock-derived instance `C (T arg_1 ... arg_n)`, one must take care to instantiate the field types of each data constructor with `arg_1 ... arg_n`. The particulars of how this is accomplished is described in the new `Note [Instantiating field types in stock deriving]` in `GHC.Tc.Deriv.Generate`. Some highlights: * `DerivInstTys` now has a new `dit_dc_inst_arg_env :: DataConEnv [Type]` field that caches the instantiated field types of each data constructor. Whenever we need to consult the field types somewhere in `GHC.Tc.Deriv.*` we avoid using `dataConOrigArgTys` and instead look it up in `dit_dc_inst_arg_env`. * Because `DerivInstTys` now stores the instantiated field types of each constructor, some of the details of the `GHC.Tc.Deriv.Generics.mkBindsRep` function were able to be simplified. In particular, we no longer need to apply a substitution to instantiate the field types in a `Rep(1)` instance, as that is already done for us by `DerivInstTys`. We still need a substitution to implement the "wrinkle" section of `Note [Generating a correctly typed Rep instance]`, but the code is nevertheless much simpler than before. * The `tyConInstArgTys` function has been removed in favor of the new `GHC.Core.DataCon.dataConInstUnivs` function, which is really the proper tool for the job. `dataConInstUnivs` is much like `tyConInstArgTys` except that it takes a data constructor, not a type constructor, as an argument, and it adds extra universal type variables from that data constructor at the end of the returned list if need be. `dataConInstUnivs` takes care to instantiate the kinds of the universal type variables at the end, thereby avoiding a bug in `tyConInstArgTys` discovered in https://gitlab.haskell.org/ghc/ghc/-/issues/20387#note_377037. Fixes #20375. Fixes #20387.
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