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* Print which flag controls emitted desugaring warningsHerbert Valerio Riedel2016-02-271-1/+1
| | | | | | | | | | | This is extends bb5afd3c274011c5ea302210b4c290ec1f83209c to cover warnings emitted during the desugaring phase. This implements another part of #10752 Reviewed-by: quchen, bgamari Differential Revision: https://phabricator.haskell.org/D1954
* Fix and refactor strict pattern bindingsSimon Peyton Jones2016-02-261-21/+14
| | | | | | | | | | | | | | | | | | | | | | This patch was triggered by Trac #11601, where I discovered that -XStrict was really not doing the right thing. In particular, f y = let !(Just x) = blah[y] in body[y,x] This was evaluating 'blah' but not pattern matching it against Just until x was demanded. This is wrong. The patch implements a new semantics which ensures that strict patterns (i.e. ones with an explicit bang, or with -XStrict) are evaluated fully when bound. * There are extensive notes in DsUtils: Note [mkSelectorBinds] * To do this I found I need one-tuples; see Note [One-tuples] in TysWiredIn I updated the user manual to give the new semantics
* Overhaul the Overhauled Pattern Match CheckerGeorge Karachalias2016-02-041-14/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Overhaul the Overhauled Pattern Match Checker * Changed the representation of Value Set Abstractions. Instead of using a prefix tree, we now use a list of Value Vector Abstractions. The set of constraints Delta for every Value Vector Abstraction is the oracle state so that we solve everything only once. * Instead of doing everything lazily, we prune at once (and in general everything is much stricter). Hence, an example written with pattern guards is checked in almost the same time as the equivalent with pattern matching. * Do not store the covered and the divergent sets at all. Since what we only need is a yes/no (does this clause cover anything? Does it force any thunk?) We just keep a boolean for each. * Removed flags `-Wtoo-many-guards` and `-ffull-guard-reasoning`. Replaced with `fmax-pmcheck-iterations=n`. Still debatable what should the default `n` be. * When a guard is for sure not going to contribute anything, we treat it as such: The oracle is not called and cases `CGuard`, `UGuard` and `DGuard` from the paper are not happening at all (the generation of a fresh variable, the unfolding of the pattern list etc.). his combined with the above seems to be enough to drop the memory increase for test T783 down to 18.7%. * Do not export function `dsPmWarn` (it is now called directly from within `checkSingle` and `checkMatches`). * Make `PmExprVar` hold a `Name` instead of an `Id`. The term oracle does not handle type information so using `Id` was a waste of time/space. * Added testcases T11195, T11303b (data families) and T11374 The patch addresses at least the following: Trac #11195, #11276, #11303, #11374, #11162 Test Plan: validate Reviewers: goldfire, bgamari, hvr, austin Subscribers: simonpj, thomie Differential Revision: https://phabricator.haskell.org/D1795
* Refactor the typechecker to use ExpTypes.Richard Eisenberg2016-01-271-9/+23
| | | | | | | | | | | | | | | | | | | | | The idea here is described in [wiki:Typechecker]. Briefly, this refactor keeps solid track of "synthesis" mode vs "checking" in GHC's bidirectional type-checking algorithm. When in synthesis mode, the expected type is just an IORef to write to. In addition, this patch does a significant reworking of RebindableSyntax, allowing much more freedom in the types of the rebindable operators. For example, we can now have `negate :: Int -> Bool` and `(>>=) :: m a -> (forall x. a x -> m b) -> m b`. The magic is in tcSyntaxOp. This addresses tickets #11397, #11452, and #11458. Tests: typecheck/should_compile/{RebindHR,RebindNegate,T11397,T11458} th/T11452
* Adding flags: -ffull-guard-reasoning and too-many-guardsGeorge Karachalias2015-12-271-6/+20
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Introduction of two new flags, for more precise control over the new pattern match checker's behaviour when reasoning about guards. This is supposed to address #11195 (and maybe more performance bugs related to the NP-Hardness of coverage checking). Expected behaviour: * When `-ffull-guard-reasoning` is on, run the new pattern match checker in its full power * When `-ffull-guard-reasoning` is off (the default), for every match, check a metric to see whether pattern match checking for it has high probability of being non performant (at the the moment we check whether the number of guards is over 20 but I would like to use a more precise measure in the future). If the probability is high: - Oversimplify the guards (less expressive but more performant) and run the checker, and - Issue a warning about the simplification that happened. A new flag `-Wtoo-many-guards/-Wno-too-many-guards` suppresses the warning about the simplification (useful when combined with -Werror). Test Plan: validate Reviewers: goldfire, austin, hvr, bgamari Reviewed By: bgamari Subscribers: mpickering, thomie Differential Revision: https://phabricator.haskell.org/D1676 GHC Trac Issues: #11195
* Visible type applicationRichard Eisenberg2015-12-241-1/+1
| | | | | | | | | | | | | This re-working of the typechecker algorithm is based on the paper "Visible type application", by Richard Eisenberg, Stephanie Weirich, and Hamidhasan Ahmed, to be published at ESOP'16. This patch introduces -XTypeApplications, which allows users to say, for example `id @Int`, which has type `Int -> Int`. See the changes to the user manual for details. This patch addresses tickets #10619, #5296, #10589.
* Fix grouping for pattern synonymsSimon Peyton Jones2015-12-221-32/+54
| | | | | | | | | | | | | | | | | | | When grouping pattern synonyms in the desugarer, to find when a single match will work for the whole group, we use `Match.sameGroup`. But this function was declaring two pattern-synonym matches equal to often. Result: Lint errors and broken semantics. The fix is easy. See Note [Pattern synonym groups]. Re-do typechecking for pattern synonym signatures Test Plan: Validate Reviewers: austin Subscribers: thomie, mpickering, simonpj Differential Revision: https://phabricator.haskell.org/D1684
* Make binds in do-blocks strict when -XStrict (#11193)Adam Sandberg Eriksson2015-12-141-9/+11
| | | | | | | | | | | | | | | | | | | | | | | | | Previously bindings in `do` blocks were omitted. With `-XStrict` ```lang=hs do content <- action other_things ``` should be equivalent to ```lang=hs do !content <- action other_things ``` Fixes #11193. Reviewers: bgamari, austin Reviewed By: bgamari Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D1612 GHC Trac Issues: #11193
* Add kind equalities to GHC.Richard Eisenberg2015-12-111-13/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This implements the ideas originally put forward in "System FC with Explicit Kind Equality" (ICFP'13). There are several noteworthy changes with this patch: * We now have casts in types. These change the kind of a type. See new constructor `CastTy`. * All types and all constructors can be promoted. This includes GADT constructors. GADT pattern matches take place in type family equations. In Core, types can now be applied to coercions via the `CoercionTy` constructor. * Coercions can now be heterogeneous, relating types of different kinds. A coercion proving `t1 :: k1 ~ t2 :: k2` proves both that `t1` and `t2` are the same and also that `k1` and `k2` are the same. * The `Coercion` type has been significantly enhanced. The documentation in `docs/core-spec/core-spec.pdf` reflects the new reality. * The type of `*` is now `*`. No more `BOX`. * Users can write explicit kind variables in their code, anywhere they can write type variables. For backward compatibility, automatic inference of kind-variable binding is still permitted. * The new extension `TypeInType` turns on the new user-facing features. * Type families and synonyms are now promoted to kinds. This causes trouble with parsing `*`, leading to the somewhat awkward new `HsAppsTy` constructor for `HsType`. This is dispatched with in the renamer, where the kind `*` can be told apart from a type-level multiplication operator. Without `-XTypeInType` the old behavior persists. With `-XTypeInType`, you need to import `Data.Kind` to get `*`, also known as `Type`. * The kind-checking algorithms in TcHsType have been significantly rewritten to allow for enhanced kinds. * The new features are still quite experimental and may be in flux. * TODO: Several open tickets: #11195, #11196, #11197, #11198, #11203. * TODO: Update user manual. Tickets addressed: #9017, #9173, #7961, #10524, #8566, #11142. Updates Haddock submodule.
* Major Overhaul of Pattern Match Checking (Fixes #595)George Karachalias2015-12-031-138/+36
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch adresses several problems concerned with exhaustiveness and redundancy checking of pattern matching. The list of improvements includes: * Making the check type-aware (handles GADTs, Type Families, DataKinds, etc.). This fixes #4139, #3927, #8970 and other related tickets. * Making the check laziness-aware. Cases that are overlapped but affect evaluation are issued now with "Patterns have inaccessible right hand side". Additionally, "Patterns are overlapped" is now replaced by "Patterns are redundant". * Improved messages for literals. This addresses tickets #5724, #2204, etc. * Improved reasoning concerning cases where simple and overloaded patterns are matched (See #322). * Substantially improved reasoning for pattern guards. Addresses #3078. * OverloadedLists extension does not break exhaustiveness checking anymore (addresses #9951). Note that in general this cannot be handled but if we know that an argument has type '[a]', we treat it as a list since, the instance of 'IsList' gives the identity for both 'fromList' and 'toList'. If the type is not clear or is not the list type, then the check cannot do much still. I am a bit concerned about OverlappingInstances though, since one may override the '[a]' instance with e.g. an '[Int]' instance that is not the identity. * Improved reasoning for nested pattern matching (partial solution). Now we propagate type and (some) term constraints deeper when checking, so we can detect more inconsistencies. For example, this is needed for #4139. I am still not satisfied with several things but I would like to address at least the following before the next release: Term constraints are too many and not printed for non-exhaustive matches (with the exception of literals). This sometimes results in two identical (in appearance) uncovered warnings. Unless we actually show their difference, I would like to have a single warning.
* ApiAnnotations: Make all RdrName occurences LocatedAlan Zimmerman2015-11-231-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | At the moment the API Annotations can only be used on the ParsedSource, as there are changes made to the RenamedSource that prevent it from being used to round trip source code. It is possible to build a map from every Located Name in the RenamedSource from its location to the Name, which can then be used when resolved names are required when changing the ParsedSource. However, there are instances where the identifier is not located, specifically (GHC.VarPat name) (GHC.HsVar name) (GHC.UserTyVar name) (GHC.HsTyVar name) Replace each of the name types above with (Located name) Updates the haddock submodule. Test Plan: ./validate Reviewers: austin, goldfire, bgamari Reviewed By: bgamari Subscribers: goldfire, thomie, mpickering Differential Revision: https://phabricator.haskell.org/D1512 GHC Trac Issues: #11019
* Implement OverloadedLabelsAdam Gundry2015-11-171-0/+1
| | | | | | | | | | | | | | See https://ghc.haskell.org/trac/ghc/wiki/Records/OverloadedRecordFields/OverloadedLabels for the big picture. Reviewers: goldfire, simonpj, austin, hvr, bgamari Reviewed By: simonpj, bgamari Subscribers: kosmikus, thomie, mpickering Differential Revision: https://phabricator.haskell.org/D1331
* Implement the Strict language extensionAdam Sandberg Eriksson2015-11-141-2/+7
| | | | | | | | | | | | | | | | | | | | | Add a new language extension `-XStrict` which turns all bindings strict as if the programmer had written a `!` before it. This also upgrades ordinary Haskell to allow recursive and polymorphic strict bindings. See the wiki[1] and the Note [Desugar Strict binds] in DsBinds for specification and implementation details. [1] https://ghc.haskell.org/trac/ghc/wiki/StrictPragma Reviewers: austin, tibbe, simonpj, bgamari Reviewed By: tibbe, bgamari Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D1142 GHC Trac Issues: #8347
* APIAnnotations:add Locations in hsSyn for layoutAlan Zimmerman2015-11-131-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: At the moment ghc-exactprint, which uses the GHC API Annotations to provide a framework for roundtripping Haskell source code with optional AST edits, has to implement a horrible workaround to manage the points where layout needs to be captured. These are MatchGroup HsDo HsCmdDo HsLet LetStmt HsCmdLet GRHSs To provide a more natural representation, the contents subject to layout rules need to be wrapped in a SrcSpan. This commit does this. Trac ticket #10250 Test Plan: ./validate Reviewers: hvr, goldfire, bgamari, austin, mpickering Reviewed By: mpickering Subscribers: thomie, mpickering Differential Revision: https://phabricator.haskell.org/D1370 GHC Trac Issues: #10250
* Remove fun_infix from Funbind, as it is now in MatchAlan Zimmerman2015-11-111-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | One of the changes D538 introduced is to add `m_fun_id_infix` to `Match` ```lang=hs data Match id body = Match { m_fun_id_infix :: (Maybe (Located id,Bool)), -- fun_id and fun_infix for functions with multiple equations -- only present for a RdrName. See note [fun_id in Match] m_pats :: [LPat id], -- The patterns m_type :: (Maybe (LHsType id)), -- A type signature for the result of the match -- Nothing after typechecking m_grhss :: (GRHSs id body) } deriving (Typeable) ``` This was done to track the individual locations and fixity of the `fun_id` for each of the defining equations for a function when there are more than one. For example, the function `(&&&)` is defined with some prefix and some infix equations below. ```lang=hs (&&& ) [] [] = [] xs &&& [] = xs ( &&& ) [] ys = ys ``` This means that the fun_infix is now superfluous in the `FunBind`. This has not been removed as a potentially risky change just before 7.10 RC2, and so must be done after. This ticket captures that task, which includes processing these fields through the renamer and beyond. Ticket #9988 introduced these fields into `Match` through renaming, this ticket it to continue through type checking and then remove it from `FunBind` completely. The split happened so that #9988 could land in 7.10 Trac ticket : #10061 Test Plan: ./validate Reviewers: goldfire, austin, simonpj, bgamari Reviewed By: bgamari Subscribers: simonpj, thomie, mpickering Differential Revision: https://phabricator.haskell.org/D1285 GHC Trac Issues: #10061
* Refactor tuple constraintsSimon Peyton Jones2015-05-181-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Make tuple constraints be handled by a perfectly ordinary type class, with the component constraints being the superclasses: class (c1, c2) => (c2, c2) This change was provoked by #10359 inability to re-use a given tuple constraint as a whole #9858 confusion between term tuples and constraint tuples but it's generally a very nice simplification. We get rid of - In Type, the TuplePred constructor of PredTree, and all the code that dealt with TuplePreds - In TcEvidence, the constructors EvTupleMk, EvTupleSel See Note [How tuples work] in TysWiredIn. Of course, nothing is ever entirely simple. This one proved quite fiddly. - I did quite a bit of renaming, which makes this patch touch a lot of modules. In partiuclar tupleCon -> tupleDataCon. - I made constraint tuples known-key rather than wired-in. This is different to boxed/unboxed tuples, but it proved awkward to have all the superclass selectors wired-in. Easier just to use the standard mechanims. - While I was fiddling with known-key names, I split the TH Name definitions out of DsMeta into a new module THNames. That meant that the known-key names can all be gathered in PrelInfo, without causing module loops. - I found that the parser was parsing an import item like T( .. ) as a *data constructor* T, and then using setRdrNameSpace to fix it. Stupid! So I changed the parser to parse a *type constructor* T, which means less use of setRdrNameSpace. I also improved setRdrNameSpace to behave better on Exact Names. Largely on priciple; I don't think it matters a lot. - When compiling a data type declaration for a wired-in thing like tuples (,), or lists, we don't really need to look at the declaration. We have the wired-in thing! And not doing so avoids having to line up the uniques for data constructor workers etc. See Note [Declarations for wired-in things] - I found that FunDeps.oclose wasn't taking superclasses into account; easily fixed. - Some error message refactoring for invalid constraints in TcValidity - Haddock needs to absorb the change too; so there is a submodule update
* Revert multiple commitsAustin Seipp2015-05-141-2/+2
| | | | | | | | | | | | | | | | | | | | This reverts multiple commits from Simon: - 04a484eafc9eb9f8774b4bdd41a5dc6c9f640daf Test Trac #10359 - a9ccd37add8315e061c02e5bf26c08f05fad9ac9 Test Trac #10403 - c0aae6f699cbd222d826d0b8d78d6cb3f682079e Test Trac #10248 - eb6ca851f553262efe0824b8dcbe64952de4963d Make the "matchable-given" check happen first - ca173aa30467a0b1023682d573fcd94244d85c50 Add a case to checkValidTyCon - 51cbad15f86fca1d1b0e777199eb1079a1b64d74 Update haddock submodule - 6e1174da5b8e0b296f5bfc8b39904300d04eb5b7 Separate transCloVarSet from fixVarSet - a8493e03b89f3b3bfcdb6005795de050501f5c29 Fix imports in HscMain (stage2) - a154944bf07b2e13175519bafebd5a03926bf105 Two wibbles to fix the build - 5910a1bc8142b4e56a19abea104263d7bb5c5d3f Change in capitalisation of error msg - 130e93aab220bdf14d08028771f83df210da340b Refactor tuple constraints - 8da785d59f5989b9a9df06386d5bd13f65435bc0 Delete commented-out line These break the build by causing Haddock to fail mysteriously when trying to examine GHC.Prim it seems.
* Refactor tuple constraintsSimon Peyton Jones2015-05-131-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Make tuple constraints be handled by a perfectly ordinary type class, with the component constraints being the superclasses: class (c1, c2) => (c2, c2) This change was provoked by #10359 inability to re-use a given tuple constraint as a whole #9858 confusion between term tuples and constraint tuples but it's generally a very nice simplification. We get rid of - In Type, the TuplePred constructor of PredTree, and all the code that dealt with TuplePreds - In TcEvidence, the constructors EvTupleMk, EvTupleSel See Note [How tuples work] in TysWiredIn. Of course, nothing is ever entirely simple. This one proved quite fiddly. - I did quite a bit of renaming, which makes this patch touch a lot of modules. In partiuclar tupleCon -> tupleDataCon. - I made constraint tuples known-key rather than wired-in. This is different to boxed/unboxed tuples, but it proved awkward to have all the superclass selectors wired-in. Easier just to use the standard mechanims. - While I was fiddling with known-key names, I split the TH Name definitions out of DsMeta into a new module THNames. That meant that the known-key names can all be gathered in PrelInfo, without causing module loops. - I found that the parser was parsing an import item like T( .. ) as a *data constructor* T, and then using setRdrNameSpace to fix it. Stupid! So I changed the parser to parse a *type constructor* T, which means less use of setRdrNameSpace. I also improved setRdrNameSpace to behave better on Exact Names. Largely on priciple; I don't think it matters a lot. - When compiling a data type declaration for a wired-in thing like tuples (,), or lists, we don't really need to look at the declaration. We have the wired-in thing! And not doing so avoids having to line up the uniques for data constructor workers etc. See Note [Declarations for wired-in things] - I found that FunDeps.oclose wasn't taking superclasses into account; easily fixed. - Some error message refactoring for invalid constraints in TcValidity
* Revert "API Annotations : add Locations in hsSyn were layout occurs"Austin Seipp2015-05-061-1/+1
| | | | | | | This reverts commit fb54b2c11cc7f2cfbafa35b6a1819d7443aa5494. As Alan pointed out, this will make cherry picking a lot harder until 7.10.2, so lets back it out until after the release.
* API Annotations : add Locations in hsSyn were layout occursAlan Zimmerman2015-05-061-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | At the moment ghc-exactprint, which uses the GHC API Annotations to provide a framework for roundtripping Haskell source code with optional AST edits, has to implement a horrible workaround to manage the points where layout needs to be captured. These are MatchGroup HsDo HsCmdDo HsLet LetStmt HsCmdLet GRHSs To provide a more natural representation, the contents subject to layout rules need to be wrapped in a SrcSpan. This commit does this. Trac ticket #10250 Reviewed By: austin Differential Revision: https://phabricator.haskell.org/D815 GHC Trac Issues: #10250
* API Annotations tweaks.Alan Zimmerman2015-01-161-4/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: HsTyLit now has SourceText Update documentation of HsSyn to reflect which annotations are attached to which element. Ensure that the parser always keeps HsSCC and HsTickPragma values, to be ignored in the desugar phase if not needed Bringing in SourceText for pragmas Add Location in NPlusKPat Add Location in FunDep Make RecCon payload Located Explicitly add AnnVal to RdrName where it is compound Add Location in IPBind Add Location to name in IEThingAbs Add Maybe (Located id,Bool) to Match to track fun_id,infix This includes converting Match into a record and adding a note about why the fun_id needs to be replicated in the Match. Add Location in KindedTyVar Sort out semi-colons for parsing - import statements - stmts - decls - decls_cls - decls_inst This updates the haddock submodule. Test Plan: ./validate Reviewers: hvr, austin, goldfire, simonpj Reviewed By: simonpj Subscribers: thomie, carter Differential Revision: https://phabricator.haskell.org/D538
* compiler: de-lhs deSugar/Austin Seipp2014-12-031-0/+1090
Signed-off-by: Austin Seipp <austin@well-typed.com>