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* Move pattern match checker modules to GHC.HsToCore.PmCheckSebastian Graf2019-09-301-1471/+0
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* PmCheck: No ConLike instantiation in pmcheckSebastian Graf2019-09-281-102/+166
| | | | | | | | | | | | | | | | | | | | | | | `pmcheck` used to call `refineToAltCon` which would refine the knowledge we had about a variable by equating it to a `ConLike` application. Since we weren't particularly smart about this in the Check module, we simply freshened the constructors existential and term binders utimately through a call to `mkOneConFull`. But that instantiation is unnecessary for when we match against a concrete pattern! The pattern will already have fresh binders and field types. So we don't call `refineToAltCon` from `Check` anymore. Subsequently, we can simplify a couple of call sites and functions in `PmOracle`. Also implementing `computeCovered` becomes viable and we don't have to live with the hack that was `addVarPatVecCt` anymore. A side-effect of not indirectly calling `mkOneConFull` anymore is that we don't generate the proper strict argument field constraints anymore. Instead we now desugar ConPatOuts as if they had bangs on their strict fields. This implies that `PmVar` now carries a `HsImplBang` that we need to respect by a (somewhat ephemeral) non-void check. We fix #17234 in doing so.
* PmCheck: Only ever check constantly many models against a single patternSebastian Graf2019-09-251-178/+160
| | | | | | | | | | | | | | | | | | | | | | | | | Introduces a new flag `-fmax-pmcheck-deltas` to achieve that. Deprecates the old `-fmax-pmcheck-iter` mechanism in favor of this new flag. From the user's guide: Pattern match checking can be exponential in some cases. This limit makes sure we scale polynomially in the number of patterns, by forgetting refined information gained from a partially successful match. For example, when matching `x` against `Just 4`, we split each incoming matching model into two sub-models: One where `x` is not `Nothing` and one where `x` is `Just y` but `y` is not `4`. When the number of incoming models exceeds the limit, we continue checking the next clause with the original, unrefined model. This also retires the incredibly hard to understand "maximum number of refinements" mechanism, because the current mechanism is more general and should catch the same exponential cases like PrelRules at the same time. ------------------------- Metric Decrease: T11822 -------------------------
* Get rid of PmFakewip/pmcheck-nofakeSebastian Graf2019-09-211-229/+48
| | | | | | | | | | | | | | | | | | | The pattern match oracle can now cope with the abundance of information that ViewPatterns, NPlusKPats, overloaded lists, etc. provide. No need to have PmFake anymore! Also got rid of a spurious call to `allCompleteMatches`, which we used to call *for every constructor* match. Naturally this blows up quadratically for programs like `ManyAlternatives`. ------------------------- Metric Decrease: ManyAlternatives Metric Increase: T11822 -------------------------
* PredType for type constraints in the pattern match checker instead of EvVarSebastian Graf2019-09-211-4/+3
| | | | | | | | | | | | | | | | Using EvVars for capturing type constraints implied side-effects in DsM when we just wanted to *construct* type constraints. But giving names to type constraints is only necessary when passing Givens to the type checker, of which the majority of the pattern match checker should be unaware. Thus, we simply generate `newtype TyCt = TyCt PredType`, which are nicely stateless. But at the same time this means we have to allocate EvVars when we want to query the type oracle! So we keep the type oracle state as `newtype TyState = TySt (Bag EvVar)`, which nicely makes a distinction between new, unchecked `TyCt`s and the inert set in `TyState`.
* Module hierarchy: Hs (#13009)Sylvain Henry2019-09-201-2/+2
| | | | | | | Add GHC.Hs module hierarchy replacing hsSyn. Metric Increase: haddock.compiler
* Extract PmTypes module from PmExpr and PmOracleSebastian Graf2019-09-191-7/+4
| | | | | | | | | | | Apparently ghc-lib-parser's API blew up because the newly induced cyclic dependency between TcRnTypes and PmOracle pulled in the other half of GHC into the relevant strongly-connected component. This patch arranges it so that PmTypes exposes mostly data type definitions and type class instances to be used within PmOracle, without importing the any of the possibly offending modules DsMonad, TcSimplify and FamInst.
* Encode shape information in `PmOracle`Sebastian Graf2019-09-161-1687/+629
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Previously, we had an elaborate mechanism for selecting the warnings to generate in the presence of different `COMPLETE` matching groups that, albeit finely-tuned, produced wrong results from an end user's perspective in some cases (#13363). The underlying issue is that at the point where the `ConVar` case has to commit to a particular `COMPLETE` group, there's not enough information to do so and the status quo was to just enumerate all possible complete sets nondeterministically. The `getResult` function would then pick the outcome according to metrics defined in accordance to the user's guide. But crucially, it lacked knowledge about the order in which affected clauses appear, leading to the surprising behavior in #13363. In !1010 we taught the term oracle to reason about literal values a variable can certainly not take on. This MR extends that idea to `ConLike`s and thereby fixes #13363: Instead of committing to a particular `COMPLETE` group in the `ConVar` case, we now split off the matching constructor incrementally and record the newly covered case as a refutable shape in the oracle. Whenever the set of refutable shapes covers any `COMPLETE` set, the oracle recognises vacuosity of the uncovered set. This patch goes a step further: Since at this point the information in value abstractions is merely a cut down representation of what the oracle knows, value abstractions degenerate to a single `Id`, the semantics of which is determined by the oracle state `Delta`. Value vectors become lists of `[Id]` given meaning to by a single `Delta`, value set abstractions (of which the uncovered set is an instance) correspond to a union of `Delta`s which instantiate the same `[Id]` (akin to models of formula). Fixes #11528 #13021, #13363, #13965, #14059, #14253, #14851, #15753, #17096, #17149 ------------------------- Metric Decrease: ManyAlternatives T11195 -------------------------
* Fix #17112Sebastian Graf2019-08-281-27/+20
| | | | | | | | | | | | | The `mkOneConFull` function of the pattern match checker used to try to guess the type arguments of the data type's type constructor by looking at the ambient type of the match. This doesn't work well for Pattern Synonyms, where the result type isn't even necessarily a TyCon application, and it shows in #11336 and #17112. Also the effort seems futile; why try to try hard when the type checker has already done the hard lifting? After this patch, we instead supply the type constructors arguments as an argument to the function and lean on the type-annotated AST.
* Use an empty data type in TTG extension constructors (#15247)Ryan Scott2019-07-091-7/+7
| | | | | | | | | | | | | | | To avoid having to `panic` any time a TTG extension constructor is consumed, this MR introduces an uninhabited 'NoExtCon' type and uses that in every extension constructor's type family instance where it is appropriate. This also introduces a 'noExtCon' function which eliminates a 'NoExtCon', much like 'Data.Void.absurd' eliminates a 'Void'. I also renamed the existing `NoExt` type to `NoExtField` to better distinguish it from `NoExtCon`. Unsurprisingly, there is a lot of code churn resulting from this. Bumps the Haddock submodule. Fixes #15247.
* Fix typo in error messageAiken Cairncross2019-06-151-1/+1
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* TmOracle: Replace negative term equalities by refutable PmAltConsSebastian Graf2019-06-071-117/+33
| | | | | | | | | | | | | | | | | | | | | | | | | The `PmExprEq` business was a huge hack and was at the same time vastly too powerful and not powerful enough to encode negative term equalities, i.e. facts of the form "forall y. x ≁ Just y". This patch introduces the concept of 'refutable shapes': What matters for the pattern match checker is being able to encode knowledge of the kind "x can no longer be the literal 5". We encode this knowledge in a `PmRefutEnv`, mapping a set of newly introduced `PmAltCon`s (which are just `PmLit`s at the moment) to each variable denoting above inequalities. So, say we have `x ≁ 42 ∈ refuts` in the term oracle context and try to solve an equality like `x ~ 42`. The entry in the refutable environment will immediately lead to a contradiction. This machinery renders the whole `PmExprEq` and `ComplexEq` business unnecessary, getting rid of a lot of (mostly dead) code. See the Note [Refutable shapes] in TmOracle for a place to start. Metric Decrease: T11195
* Fix missing unboxed tuple RuntimeReps (#16565)Krzysztof Gogolewski2019-05-291-2/+8
| | | | | | | | | | | | | Unboxed tuples and sums take extra RuntimeRep arguments, which must be manually passed in a few places. This was not done in deSugar/Check. This error was hidden because zipping functions in TyCoRep ignored lists with mismatching length. This is now fixed; the lengths are now checked by calling zipEqual. As suggested in #16565, I moved checking for isTyVar and isCoVar to zipTyEnv and zipCoEnv.
* Stop misusing EWildPat in pattern match coverage checkingVladislav Zavialov2019-04-221-27/+22
| | | | | | | | | | | | | | | | EWildPat is a constructor of HsExpr used in the parser to represent wildcards in ambiguous positions: * in expression context, EWildPat is turned into hsHoleExpr (see rnExpr) * in pattern context, EWildPat is turned into WildPat (see checkPattern) Since EWildPat exists solely for the needs of the parser, we could remove it by improving the parser. However, EWildPat has also been used for a different purpose since 8a50610: to represent patterns that the coverage checker cannot handle. Not only this is a misuse of EWildPat, it also stymies the removal of EWildPat.
* Make `singleConstructor` cope with pattern synonymsSebastian Graf2019-04-081-53/+92
| | | | | | | | | | | | | | | Previously, `singleConstructor` didn't handle singleton `COMPLETE` sets of a single pattern synonym, resulting in incomplete pattern warnings in #15753. This is fixed by making `singleConstructor` (now named `singleMatchConstructor`) query `allCompleteMatches`, necessarily making it effectful. As a result, most of this patch is concerned with threading the side-effect through to `singleMatchConstructor`. Unfortunately, this is not enough to completely fix the original reproduction from #15753 and #15884, which are related to function applications in pattern guards being translated too conservatively.
* Fix Uncovered set of literal patternsSebastian Graf2019-04-031-4/+11
| | | | | | | | | | | | | | | | Issues #16289 and #15713 are proof that the pattern match checker did an unsound job of estimating the value set abstraction corresponding to the uncovered set. The reason is that the fix from #11303 introducing `NLit` was incomplete: The `LitCon` case desugared to `Var` rather than `LitVar`, which would have done the necessary case splitting analogous to the `ConVar` case. This patch rectifies that by introducing the fresh unification variable in `LitCon` in value abstraction position rather than pattern postition, recording a constraint equating it to the constructor expression rather than the literal. Fixes #16289 and #15713.
* Fix a few broken Trac links [skip ci]Chaitanya Koparkar2019-03-271-1/+1
| | | | This patch only attempts to fix links that don't automatically re-direct to the correct URL.
* Update Wiki URLs to point to GitLabTakenobu Tani2019-03-251-1/+1
| | | | | | | | | | | | | | | | | | | | | | | This moves all URL references to Trac Wiki to their corresponding GitLab counterparts. This substitution is classified as follows: 1. Automated substitution using sed with Ben's mapping rule [1] Old: ghc.haskell.org/trac/ghc/wiki/XxxYyy... New: gitlab.haskell.org/ghc/ghc/wikis/xxx-yyy... 2. Manual substitution for URLs containing `#` index Old: ghc.haskell.org/trac/ghc/wiki/XxxYyy...#Zzz New: gitlab.haskell.org/ghc/ghc/wikis/xxx-yyy...#zzz 3. Manual substitution for strings starting with `Commentary` Old: Commentary/XxxYyy... New: commentary/xxx-yyy... See also !539 [1]: https://gitlab.haskell.org/bgamari/gitlab-migration/blob/master/wiki-mapping.json
* Check.hs: Fix a few typosSimon Jakobi2019-03-201-5/+5
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* Update Trac ticket URLs to point to GitLabRyan Scott2019-03-151-6/+6
| | | | | This moves all URL references to Trac tickets to their corresponding GitLab counterparts.
* Fix #14729 by making the normaliser homogeneousRichard Eisenberg2019-02-081-2/+6
| | | | | | | | | | | | | | | | This ports the fix to #12919 to the normaliser. (#12919 was about the flattener.) Because the fix is involved, this is done by moving the critical piece of code to Coercion, and then calling this from both the flattener and the normaliser. The key bit is: simplifying type families in a type is always a *homogeneous* operation. See #12919 for a discussion of why this is the Right Way to simplify type families. Also fixes #15549. test case: dependent/should_compile/T14729{,kind} typecheck/should_compile/T15549[ab]
* [TTG: Handling Source Locations] Foundation and PatShayan-Najd2018-11-241-16/+18
| | | | | | | | | | | | | | | | | | This patch removes the ping-pong style from HsPat (only, for now), using the plan laid out at https://ghc.haskell.org/trac/ghc/wiki/ImplementingTreesThatGrow/HandlingSourceLocations (solution A). - the class `HasSrcSpan`, and its functions (e.g., `cL` and `dL`), are introduced - some instances of `HasSrcSpan` are introduced - some constructors `L` are replaced with `cL` - some patterns `L` are replaced with `dL->L` view pattern - some type annotation are necessarily updated (e.g., `Pat p` --> `Pat (GhcPass p)`) Phab diff: D5036 Trac Issues #15495 Updates haddock submodule
* More explicit foralls (GHC Proposal 0007)Matthew Yacavone2018-10-271-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | Allow the user to explicitly bind type/kind variables in type and data family instances (including associated instances), closed type family equations, and RULES pragmas. Follows the specification of GHC Proposal 0007, also fixes #2600. Advised by Richard Eisenberg. This modifies the Template Haskell AST -- old code may break! Other Changes: - convert HsRule to a record - make rnHsSigWcType more general - add repMaybe to DsMeta Includes submodule update for Haddock. Test Plan: validate Reviewers: goldfire, bgamari, alanz Subscribers: simonpj, RyanGlScott, goldfire, rwbarton, thomie, mpickering, carter GHC Trac Issues: #2600, #14268 Differential Revision: https://phabricator.haskell.org/D4894
* Normalise EmptyCase types using the constraint solverRyan Scott2018-09-281-29/+60
| | | | | | | | | | | | | | | | | | | | | Summary: Certain `EmptyCase` expressions were mistakently producing warnings since their types did not have as many type families reduced as they could have. The most direct way to fix this is to normalise these types initially using the constraint solver to solve for any local equalities that may be in scope. Test Plan: make test TEST=T14813 Reviewers: simonpj, bgamari, goldfire Reviewed By: simonpj Subscribers: rwbarton, carter GHC Trac Issues: #14813 Differential Revision: https://phabricator.haskell.org/D5094
* Add a recursivity check in nonVoidRyan Scott2018-09-231-49/+142
| | | | | | | | | | | | | | | | | | | | | | | Summary: Previously `nonVoid` outright refused to call itself recursively to avoid the risk of hitting infinite loops when checking recurisve types. But this is too conservative—we //can// call `nonVoid` recursively as long as we incorporate a way to detect the presence of recursive types, and bail out if we do detect one. Happily, such a mechanism already exists in the form of `checkRecTc`, so let's use it. Test Plan: make test TEST=T15584 Reviewers: simonpj, bgamari Reviewed By: simonpj Subscribers: rwbarton, carter GHC Trac Issues: #15584 Differential Revision: https://phabricator.haskell.org/D5116
* Take strict fields into account in coverage checkingRyan Scott2018-08-271-60/+257
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: The current pattern-match coverage checker implements the formalism presented in the //GADTs Meet Their Match// paper in a fairly faithful matter. However, it was discovered recently that there is a class of unreachable patterns that //GADTs Meet Their Match// does not handle: unreachable code due to strict argument types, as demonstrated in #15305. This patch therefore goes off-script a little and implements an extension to the formalism presented in the paper to handle this case. Essentially, when determining if each constructor can be matched on, GHC checks if its associated term and type constraints are satisfiable. This patch introduces a new form of constraint, `NonVoid(ty)`, and checks if each constructor's strict argument types satisfy `NonVoid`. If any of them do not, then that constructor is deemed uninhabitable, and thus cannot be matched on. For the full story of how this works, see `Note [Extensions to GADTs Meet Their Match]`. Along the way, I did a little bit of much-needed refactoring. In particular, several functions in `Check` were passing a triple of `(ValAbs, ComplexEq, Bag EvVar)` around to represent a constructor and its constraints. Now that we're adding yet another form of constraint to the mix, I thought it appropriate to turn this into a proper data type, which I call `InhabitationCandidate`. Test Plan: make test TEST=T15305 Reviewers: simonpj, bgamari Reviewed By: simonpj Subscribers: rwbarton, carter GHC Trac Issues: #15305 Differential Revision: https://phabricator.haskell.org/D5087
* Fix #15450 by refactoring checkEmptyCase'Ryan Scott2018-08-011-40/+97
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | `checkEmptyCase'` (the code path for coverage-checking `EmptyCase` expressions) had a fair bit of code duplication from the code path for coverage-checking non-`EmptyCase` expressions, and to make things worse, it behaved subtly different in some respects (for instance, emitting different warnings under unsatisfiable constraints, as shown in #15450). This patch attempts to clean up both this discrepancy and the code duplication by doing the following: * Factor out a `pmInitialTmTyCs` function, which returns the initial set of term and type constraints to use when beginning coverage checking. If either set of constraints is unsatisfiable, we use an empty set in its place so that we can continue to emit as many warnings as possible. (The code path for non-`EmptyCase` expressions was doing this already, but not the code path for `EmptyCase` expressions, which is the root cause of #15450.) Along the way, I added a `Note` to explain why we do this. * Factor out a `pmIsSatisfiable` constraint which checks if a set of term and type constraints are satisfiable. This does not change any existing behavior; this is just for the sake of deduplicating code. Test Plan: make test TEST=T15450 Reviewers: simonpj, bgamari Subscribers: rwbarton, thomie, carter GHC Trac Issues: #15450 Differential Revision: https://phabricator.haskell.org/D5017
* Fix #15385 by using addDictsDs in matchGuardsRyan Scott2018-07-301-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: When coverage checking pattern-matches, we rely on the call sites in the desugarer to populate the local dictionaries and term evidence in scope using `addDictsDs` and `addTmCsDs`. But it turns out that only the call site for desugaring `case` expressions was actually doing this properly. In another part of the desugarer, `matchGuards` (which handles pattern guards), it did not update the local dictionaries in scope at all, leading to #15385. Fixing this is relatively straightforward: just augment the `BindStmt` case of `matchGuards` to use `addDictsDs` and `addTmCsDs`. Accomplishing this took a little bit of import/export tweaking: * We now need to export `collectEvVarsPat` from `HsPat.hs`. * To avoid an import cycle with `Check.hs`, I moved `isTrueLHsExpr` from `DsGRHSs.hs` to `DsUtils.hs`, which resides lower on the import chain. Test Plan: make test TEST=T15385 Reviewers: simonpj, bgamari Reviewed By: simonpj Subscribers: rwbarton, thomie, carter GHC Trac Issues: #15385 Differential Revision: https://phabricator.haskell.org/D4968
* Fix broken test T14547.HE, Tao2018-06-041-12/+26
| | | | | | | | | | | | | | | | | | | | | | Phab:D4571 lags behind HEAD for too many commits. The commit of Phab:4571 1f88f541aad1e36d01f22f9e71dfbc247e6558e2 brought some unintentional changes (not belong to [Phab:4571's Diff 16314](https://phabricator.haskell.org/differential/diff/16314/)) into ghc-head, breaking T14557. Let's fix that. Test Plan: make test TEST="T14547" Reviewers: bgamari Reviewed By: bgamari Subscribers: rwbarton, thomie, carter GHC Trac Issues: #15222 Differential Revision: https://phabricator.haskell.org/D4778
* Improve exhaustiveness checking for literal values and patterns, fix #14546HE, Tao2018-06-031-55/+108
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, we parse both the **integral literal** value and the patterns as `OverLit HsIntegral`. For example: ``` case 0::Int of 0 -> putStrLn "A" 1 -> putStrLn "B" _ -> putStrLn "C" ``` When checking the exhaustiveness of pattern matching, we translate the `0` in value position as `PmOLit`, but translate the `0` and `1` in pattern position as `PmSLit`. The inconsistency leads to the failure of `eqPmLit` to detect the equality and report warning of "Pattern match is redundant" on pattern `0`, as reported in #14546. In this patch we remove the specialization of `OverLit` patterns, and keep the overloaded number literal in pattern as it is to maintain the consistency. Now we can capture the exhaustiveness of pattern `0` and the redundancy of pattern `1` and `_`. For **string literals**, we parse the string literals as `HsString`. When `OverloadedStrings` is enabled, it further be turned as `HsOverLit HsIsString`, whether it's type is `String` or not. For example: ``` case "foo" of "foo" -> putStrLn "A" "bar" -> putStrLn "B" "baz" -> putStrLn "C" ``` Previously, the overloaded string values are translated to `PmOLit` and the non-overloaded string values are translated to `PmSLit`. However the string patterns, both overloaded and non-overloaded, are translated to list of characters. The inconsistency leads to wrong warnings about redundant and non-exhaustive pattern matching warnings, as reported in #14546. In order to catch the redundant pattern in following case: ``` case "foo" of ('f':_) -> putStrLn "A" "bar" -> putStrLn "B" ``` In this patch, we translate non-overloaded string literals, both in value position and pattern position, as list of characters. For overloaded string literals, we only translate it to list of characters only when it's type is `stringTy`, since we know nothing about the `toString` methods. But we know that if two overloaded strings are syntax equal, then they are equal. Then if it's type is not `stringTy`, we just translate it to `PmOLit`. We can still capture the exhaustiveness of pattern `"foo"` and the redundancy of pattern `"bar"` and `"baz"` in the following code: ``` {-# LANGUAGE OverloadedStrings #-} main = do case "foo" of "foo" -> putStrLn "A" "bar" -> putStrLn "B" "baz" -> putStrLn "C" ``` Test Plan: make test TEST="T14546" Reviewers: bgamari, simonpj Reviewed By: bgamari, simonpj Subscribers: simonpj, thomie, carter GHC Trac Issues: #14546 Differential Revision: https://phabricator.haskell.org/D4571
* Fix a bad interaction between GADTs and COMPLETE setsRyan Scott2018-06-021-5/+62
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | As observed in #14059 (starting at comment 5), the error messages surrounding a program involving GADTs and a `COMPLETE` set became worse between 8.2 and 8.4. The culprit was a new validity check in 8.4 which filters out `COMPLETE` set candidates if a return type of any conlike in the set doesn't match the type of the scrutinee. However, this check was too conservative, since it removed perfectly valid `COMPLETE` sets that contained GADT constructors, which quite often have return types that don't match the type of a scrutinee. To fix this, I adopted the most straightforward possible solution of only performing this validity check on //pattern synonym// constructors, not //data// constructors. Note that this does not fix #14059 entirely, but instead simply fixes a particular buglet that was discovered in that ticket. Test Plan: make test TEST=T14059 Reviewers: bgamari, mpickering Reviewed By: mpickering Subscribers: rwbarton, thomie, carter GHC Trac Issues: #14059 Differential Revision: https://phabricator.haskell.org/D4752
* vectorise: Put it out of its miseryBen Gamari2018-06-021-5/+0
| | | | | | | | | | | | | | | | | | | | | Poor DPH and its vectoriser have long been languishing; sadly it seems there is little chance that the effort will be rekindled. Every few years we discuss what to do with this mass of code and at least once we have agreed that it should be archived on a branch and removed from `master`. Here we do just that, eliminating heaps of dead code in the process. Here we drop the ParallelArrays extension, the vectoriser, and the `vector` and `primitive` submodules. Test Plan: Validate Reviewers: simonpj, simonmar, hvr, goldfire, alanz Reviewed By: simonmar Subscribers: goldfire, rwbarton, thomie, mpickering, carter Differential Revision: https://phabricator.haskell.org/D4761
* Remove TcType.toTcTypeSimon Peyton Jones2018-05-211-4/+4
| | | | | | | | | | In the olden days we insisted that only TcTyVars could appear in a TcType. But now we are more accommodating; see TcType Note [TcTyVars and TyVars in the typechecker] This patch removes a function that converted a Type to a TcType. It didn't do anything useful except statisfy an invariant that we no longer have. Now it's gone.
* Normalize the element type of ListPat, fix #14547HE, Tao2018-05-081-13/+27
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: The element type of `List` maybe a type family instacen, rather than a trivial type. For example in Trac #14547, ``` {-# LANGUAGE TypeFamilies, OverloadedLists #-} class Foo f where type It f foo :: [It f] -> f data List a = Empty | a :! List a deriving Show instance Foo (List a) where type It (List a) = a foo [] = Empty foo (x : xs) = x :! foo xs ``` Here the element type of `[]` is `It (List a)`, we should also normalize it as `a`. Test Plan: make test TEST="T14547" Reviewers: bgamari Reviewed By: bgamari Subscribers: thomie, carter GHC Trac Issues: #14547 Differential Revision: https://phabricator.haskell.org/D4624
* Revert "Normalize the element type of ListPat, fix #14547"Ben Gamari2018-05-081-4/+1
| | | | This reverts commit 981bf4718de7daef7817a363ccc14030c2688632.
* Normalize the element type of ListPat, fix #14547Ben Gamari2018-05-081-1/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The element type of `List` maybe a type family instacen, rather than a trivial type. For example in Trac #14547, ``` {-# LANGUAGE TypeFamilies, OverloadedLists #-} class Foo f where type It f foo :: [It f] -> f data List a = Empty | a :! List a deriving Show instance Foo (List a) where type It (List a) = a foo [] = Empty foo (x : xs) = x :! foo xs ``` Here the element type of `[]` is `It (List a)`, we should also normalize it as `a`. Test Plan: make test TEST="T14547" Reviewers: bgamari Reviewed By: bgamari Subscribers: thomie, carter GHC Trac Issues: #14547 Differential Revision: https://phabricator.haskell.org/D4624
* Revert "Normalize the element type of ListPat, fix #14547"Ben Gamari2018-05-081-4/+1
| | | | This reverts commit 361d23a8ebb44f5df5167306d7b98d8bd1724e06.
* Normalize the element type of ListPat, fix #14547HE, Tao2018-05-051-1/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The element type of `List` maybe a type family instacen, rather than a trivial type. For example in Trac #14547, ``` {-# LANGUAGE TypeFamilies, OverloadedLists #-} class Foo f where type It f foo :: [It f] -> f data List a = Empty | a :! List a deriving Show instance Foo (List a) where type It (List a) = a foo [] = Empty foo (x : xs) = x :! foo xs ``` Here the element type of `[]` is `It (List a)`, we should also normalize it as `a`. Test Plan: make test TEST="T14547" Reviewers: bgamari Reviewed By: bgamari Subscribers: thomie, carter GHC Trac Issues: #14547 Differential Revision: https://phabricator.haskell.org/D4624
* TTG : complete for balance of hsSyn ASTAlan Zimmerman2018-04-271-9/+15
| | | | | | | | | | | | | | | | | | Summary: - remove PostRn/PostTc fields - remove the HsVect In/Out distinction for Type, Class and Instance - remove PlaceHolder in favour of NoExt - Simplify OutputableX constraint Updates haddock submodule Test Plan: ./validate Reviewers: goldfire, bgamari Subscribers: goldfire, thomie, mpickering, carter Differential Revision: https://phabricator.haskell.org/D4625
* Restore Trees That Grow reverted commitsAlan Zimmerman2018-04-091-30/+31
| | | | | | | | | | | | | | | | | | The following commits were reverted prior to the release of GHC 8.4.1, because the time to derive Data instances was too long [1]. 438dd1cbba13d35f3452b4dcef3f94ce9a216905 Phab:D4147 e3ec2e7ae94524ebd111963faf34b84d942265b4 Phab:D4177 47ad6578ea460999b53eb4293c3a3b3017a56d65 Phab:D4186 The work is continuing, as the minimum bootstrap compiler is now GHC 8.2.1, and this allows Plan B[2] for instances to be used. This will land in a following commit. Updates Haddock submodule [1] https://ghc.haskell.org/trac/ghc/wiki/ImplementingTreesThatGrow/Instances [2] https://ghc.haskell.org/trac/ghc/wiki/ImplementingTreesThatGrow/Instances#PLANB
* Fix the coverage checker's treatment of existential tyvarsRyan Scott2018-03-021-6/+137
| | | | | | | | | | | | | | | | | | | | | | | | Previously, the pattern-match coverage checker was far too eager to freshen the names of existentially quantified type variables, which led to incorrect sets of type constraints that misled GHC into thinking that certain programs that involve nested GADT pattern matches were non-exhaustive (when in fact they were). Now, we generate extra equality constraints in the ConCon case of the coverage algorithm to ensure that these fresh tyvars align with existing existential tyvars. See `Note [Coverage checking and existential tyvars]` for the full story. Test Plan: make test TEST="T11984 T14098" Reviewers: gkaracha, bgamari, simonpj Reviewed By: simonpj Subscribers: simonpj, rwbarton, thomie, carter GHC Trac Issues: #11984, #14098 Differential Revision: https://phabricator.haskell.org/D4434
* Improve exhaustive checking for guards in pattern bindings and MultiIf.HE, Tao2018-03-021-4/+20
| | | | | | | | | | | | | | | | | | | | | | | Previously we didn't do exhaustive checking on MultiIf expressions and guards in pattern bindings. We can construct the `LMatch` directly from GRHSs or [LHsExpr] (MultiIf's alts) then feed it to checkMatches, without construct the MatchGroup and using function `matchWrapper`. Signed-off-by: HE, Tao <sighingnow@gmail.com> Test Plan: make test TEST="T14773a T14773b" Reviewers: bgamari, RyanGlScott, simonpj Reviewed By: bgamari, simonpj Subscribers: rwbarton, thomie, carter GHC Trac Issues: #14773 Differential Revision: https://phabricator.haskell.org/D4400
* Fix #14135 by validity checking matchesCarlos Tomé2017-12-141-9/+17
| | | | | | | | | | | | | | | | | | We filter the complete patterns given in a COMPLETE set to only those that subsume the type we are matching. Otherwise we end up introducing an ill-typed equation into the overlap checking, provoking a crash. This was the cause of Trac #14135. Reviewers: austin, bgamari, mpickering, gkaracha, simonpj, RyanGlScott, carlostome Reviewed By: bgamari Subscribers: carter, dfeuer, RyanGlScott, goldfire, rwbarton, thomie GHC Trac Issues: #14135 Differential Revision: https://phabricator.haskell.org/D3981
* Revert "trees that grow" workBen Gamari2017-11-211-31/+30
| | | | | | | | | | | | | | As documented in #14490, the Data instances currently blow up compilation time by too much to stomach. Alan will continue working on this in a branch and we will perhaps merge to 8.2 before 8.2.1 to avoid having to perform painful cherry-picks in 8.2 minor releases. Reverts haddock submodule. This reverts commit 47ad6578ea460999b53eb4293c3a3b3017a56d65. This reverts commit e3ec2e7ae94524ebd111963faf34b84d942265b4. This reverts commit 438dd1cbba13d35f3452b4dcef3f94ce9a216905. This reverts commit 0ff152c9e633accca48815e26e59d1af1fe44ceb.
* WIP on combined Step 1 and 3 for Trees That Grow, HsExprAlan Zimmerman2017-11-111-4/+4
| | | | | | | | | | | | | | | | | See https://ghc.haskell.org/trac/ghc/wiki/ImplementingTreesThatGrow Trees that grow extension points are added for - HsExpr Updates haddock submodule Test Plan: ./validate Reviewers: bgamari, goldfire Subscribers: rwbarton, thomie, shayan-najd, mpickering Differential Revision: https://phabricator.haskell.org/D4177
* WIP on Doing a combined Step 1 and 3 for Trees That GrowAlan Zimmerman2017-11-081-26/+27
| | | | | | | | | | | | | | | | | | | | | | | | | See https://ghc.haskell.org/trac/ghc/wiki/ImplementingTreesThatGrow Trees that grow extension points are added for - ValBinds - HsPat - HsLit - HsOverLit - HsType - HsTyVarBndr - HsAppType - FieldOcc - AmbiguousFieldOcc Updates haddock submodule Test Plan: ./validate Reviewers: shayan-najd, simonpj, austin, goldfire, bgamari Subscribers: goldfire, rwbarton, thomie, mpickering Differential Revision: https://phabricator.haskell.org/D4147
* Revert "WIP on combining Step 1 and 3 of Trees That Grow"Ben Gamari2017-11-071-27/+26
| | | | | | | | This reverts commit 0ff152c9e633accca48815e26e59d1af1fe44ceb. Sadly this broke when bootstrapping with 8.0.2 due to #14396. Reverts haddock submodule.
* WIP on combining Step 1 and 3 of Trees That GrowAlan Zimmerman2017-11-071-26/+27
| | | | | | | | | | | | | | | | | | | | | | | | | See https://ghc.haskell.org/trac/ghc/wiki/ImplementingTreesThatGrow Trees that grow extension points are added for - ValBinds - HsPat - HsLit - HsOverLit - HsType - HsTyVarBndr - HsAppType - FieldOcc - AmbiguousFieldOcc Updates haddock submodule Test Plan: ./validate Reviewers: shayan-najd, simonpj, austin, goldfire, bgamari Subscribers: goldfire, rwbarton, thomie, mpickering Differential Revision: https://phabricator.haskell.org/D4147
* Fix typo in accessor nameGabor Greif2017-10-301-3/+3
| | | | and in comments
* Minor refactoringSimon Peyton Jones2017-10-111-16/+16
| | | | | I'm trying to understand Check.hs. This patch is a very minor refactoring. No change in behaviour.
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