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* Fix renamer panicSimon Peyton Jones2016-06-241-7/+15
| | | | | | | | | | | This patch fixes Trac #12216 and #12127. The 'combine' function in 'imp_occ_env' in RnNames.filterImports checked for an empty field-selector list, which was (a) unnecessary and (b) wrong. I've elaborated the comments. This does NOT fix #11959 which is related but not the same (it concerns bundling of pattern synonyms).
* Provide Uniquable version of SCCBartosz Nitka2016-06-231-2/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | We want to remove the `Ord Unique` instance because there's no way to implement it in deterministic way and it's too easy to use by accident. We sometimes compute SCC for datatypes whose Ord instance is implemented in terms of Unique. The Ord constraint on SCC is just an artifact of some internal data structures. We can have an alternative implementation with a data structure that uses Uniquable instead. This does exactly that and I'm pleased that I didn't have to introduce any duplication to do that. Test Plan: ./validate I looked at performance tests and it's a tiny bit better. Reviewers: bgamari, simonmar, ezyang, austin, goldfire Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D2359 GHC Trac Issues: #4012
* Narrow the use of record wildcards slightlySimon Peyton Jones2016-06-231-16/+23
| | | | | | | | | | | | | | | | | | | | | | | | | | | In reviewing the fix to Trac #12130 I found the wild-card fill-in code for ".." notation in record constructions hard to understand. It went to great contortions (including the find_tycon code) to allow data T = C { x, y :: Int } f x = C { .. } to expand to f x = C { x = x, y = y } where 'y' is an /imported function/! That seems way over the top for what record wildcards are supposed to do. So I have narrowed the record-wildcard expansion to include only /locally-bound/ variables; i.e. not top level, and certainly not imported. I don't think anyone is using record wildcards in this bizarre way, so I don't expect any fallout. Even if there is, you can easily initialise fields with eponymous but imported values by hand. An intermediate position would be to allow /local/ top-level definitions. But I doubt anyone is doing that either. Let's see if there's any fallout. It's a local change, easy to revert, so I've just gone ahead to save everyone's time.
* Give lookupGRE_Name a better APISimon Peyton Jones2016-06-234-11/+12
| | | | | | | | | | lookupGRE_Name should return either zero or one GREs, never several. This is a consequence of INVARIANT 1 on GlobalRdrEnv. So it's better if it returns a Maybe; the panic on multiple results is put in one place, instead of being scattered or ignored. Just refactoring, no change in behaviour
* More typos in comments [skip ci]Gabor Greif2016-06-221-1/+1
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* ApplicativeDo: allow "return $ e"Simon Marlow2016-06-201-9/+13
| | | | | | | | | | | | | | | | Summary: There's a precedent for special-casing $, as we already have special typing rules for it. Test Plan: validate; new test cases Reviewers: ezyang, austin, niteria, bgamari, simonpj, erikd Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D2345 GHC Trac Issues: #11835
* Avoid find_tycon panic if datacon is not in scopeAdam Gundry2016-06-191-3/+4
| | | | | | | | | | | | | | | | | | | When using TH to splice expressions involving record field construction, the parent datacon may not be in scope. We shouldn't panic about this, because we will be renaming Exact RdrNames which don't require any disambiguation. Test Plan: new test th/T12130 Reviewers: austin, bgamari Reviewed By: bgamari Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D2321 GHC Trac Issues: #12130
* Improve typechecking of let-bindingsSimon Peyton Jones2016-06-131-104/+80
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This major commit was initially triggered by #11339, but it spiraled into a major review of the way in which type signatures for bindings are handled, especially partial type signatures. On the way I fixed a number of other bugs, namely #12069 #12033 #11700 #11339 #11670 The main change is that I completely reorganised the way in which type signatures in bindings are handled. The new story is in TcSigs Note [Overview of type signatures]. Some specific: * Changes in the data types for signatures in TcRnTypes: TcIdSigInfo and new TcIdSigInst * New module TcSigs deals with typechecking type signatures and pragmas. It contains code mostly moved from TcBinds, which is already too big * HsTypes: I swapped the nesting of HsWildCardBndrs and HsImplicitBndsrs, so that the wildcards are on the oustide not the insidde in a LHsSigWcType. This is just a matter of convenient, nothing deep. There are a host of other changes as knock-on effects, and it all took FAR longer than I anticipated :-). But it is a significant improvement, I think. Lots of error messages changed slightly, some just variants but some modest improvements. New tests * typecheck/should_compile * SigTyVars: a scoped-tyvar test * ExPat, ExPatFail: existential pattern bindings * T12069 * T11700 * T11339 * partial-sigs/should_compile * T12033 * T11339a * T11670 One thing to check: * Small change to output from ghc-api/landmines. Need to check with Alan Zimmerman
* Comments onlySimon Peyton Jones2016-06-101-1/+7
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* Merge MatchFixity and HsMatchContextAlan Zimmerman2016-06-061-13/+14
| | | | | | | | | | | | | | | | | | | | | | | | | Summary: MatchFixity was introduced to facilitate use of API Annotations. HsMatchContext does the same thing with more detail, but is chased through all over the place to provide context when processing a Match. Since we already have MatchFixity in the Match, it may as well provide the full context. updates submodule haddock Test Plan: ./validate Reviewers: austin, goldfire, bgamari Subscribers: thomie, mpickering Differential Revision: https://phabricator.haskell.org/D2271 GHC Trac Issues: #12105 (cherry picked from commit 306ecad591951521ac3f5888ca8be85bf749d271)
* Desugar ApplicativeDo and RecDo deterministicallyBartosz Nitka2016-06-061-7/+36
| | | | | | | | | | | | | | | | | This fixes a problem described in Note [Deterministic ApplicativeDo and RecursiveDo desugaring]. Test Plan: ./validate + new testcase Reviewers: simonpj, bgamari, austin, simonmar Reviewed By: simonmar Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D2287 GHC Trac Issues: #4012
* Kill nameSetElems in rnCmdTopBartosz Nitka2016-06-021-1/+1
| | | | | | | | | | | | | | | | | | | | This change isn't necessary for determinism. appAName, choiceAName, loopAName all have pre-allocated Uniques and their relative order can't change. I opted to use nameSetElemsStable here because: * the cost is negligible * it's less fragile than just documenting Test Plan: ./validate Reviewers: simonpj, austin, bgamari, simonmar Reviewed By: simonmar Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D2292 GHC Trac Issues: #4012
* Kill nameSetElems in findImportUsageBartosz Nitka2016-06-021-1/+1
| | | | | | | | | | | | | | | | | nameSetElems is nondeterministic and while I think we don't need determinism here it doesn't hurt. Test Plan: ./validate Reviewers: ezyang, bgamari, austin, simonmar Reviewed By: simonmar Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D2293 GHC Trac Issues: #4012
* Document some benign nondeterminismBartosz Nitka2016-05-241-1/+3
| | | | | | | | | | | | | | | | | | I've changed the functions to their nonDet equivalents and explained why they're OK there. This allowed me to remove foldNameSet, foldVarEnv, foldVarEnv_Directly, foldVarSet and foldUFM_Directly. Test Plan: ./validate, there should be no change in behavior Reviewers: simonpj, simonmar, austin, goldfire, bgamari Reviewed By: bgamari Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D2244 GHC Trac Issues: #4012
* Document SCC determinismBartosz Nitka2016-05-112-2/+10
| | | | | | | | | | | | | | | | | | | | | | I've documented the guarantees that stronglyConnCompFromEdgedVertices provides and commented on the call sites to explain why they are OK from determinism standpoint. I've changed the functions to nonDetUFM versions, so that it's explicit they could introduce nondeterminism. I haven't defined container (VarSet, NameSet) specific versions, so that we have less functions to worry about. Test Plan: this is mostly just documentation, it should have no runtime effect Reviewers: bgamari, simonmar, austin, simonpj Reviewed By: simonpj Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D2194 GHC Trac Issues: #4012
* Forbid variables to be parents in import lists.Matthew Pickering2016-05-102-24/+3
| | | | | | | | | | | | | | | | | | | | | | In the long discussion on #11432, it was decided that when a type constructor is parsed as a variable ((--.->) is one example) then in order to export the type constructor then the user should be required to use the ExplicitNamespaces keyword. This was implemented in quite an indirect manner in the renamer. It is much more direct to enforce this in the parser at the expense of slighty worse error messages. Further to this, the check in the renamer was actually slightly wrong. If the variable was in scope then no error was raised, this was causing panics, see #12026 for an example. Reviewers: austin, bgamari Subscribers: davean, skvadrik, thomie Differential Revision: https://phabricator.haskell.org/D2181 GHC Trac Issues: #12026
* StaticPointers: Allow closed vars in the static form.Facundo Domínguez2016-05-021-19/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: With this patch closed variables are allowed regardless of whether they are bound at the top level or not. The FloatOut pass is always performed. When optimizations are disabled, only expressions that go to the top level are floated. Thus, the applications of the StaticPtr data constructor are always floated. The CoreTidy pass makes sure the floated applications appear in the symbol table of object files. It also collects the floated bindings and inserts them in the static pointer table. The renamer does not check anymore if free variables appearing in the static form are top-level. Instead, the typechecker looks at the tct_closed flag to decide if the free variables are closed. The linter checks that applications of StaticPtr only occur at the top of top-level bindings after the FloatOut pass. The field spInfoName of StaticPtrInfo has been removed. It used to contain the name of the top-level binding that contains the StaticPtr application. However, this information is no longer available when the StaticPtr is constructed, as the binding name is determined now by the FloatOut pass. Test Plan: ./validate Reviewers: goldfire, simonpj, austin, hvr, bgamari Reviewed By: simonpj Subscribers: thomie, mpickering, mboes Differential Revision: https://phabricator.haskell.org/D2104 GHC Trac Issues: #11656
* Add uniqSetAny and uniqSetAll and use themBartosz Nitka2016-04-281-2/+1
| | | | | | | | | | | | | | | | | | There are couple of places where we do `foldUniqSet` just to compute `any` or `all`. `foldUniqSet` is non-deterministic in the general case and `any` and `all` also read nicer. Test Plan: ./validate Reviewers: simonmar, goldfire, simonpj, bgamari, austin Reviewed By: simonpj Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D2156 GHC Trac Issues: #4012
* Refactor RecordPatSynField, FieldLabelSimon Peyton Jones2016-04-282-9/+9
| | | | | | | | | | | | This patch uses the named fields of * FieldLabel * RecordPatSynField in construction and pattern matching. The fields existed before, but we were often using positional notation. Also a minor refactor of the API of mkPatSynRecSelBinds No change in functionality
* Comments onlySimon Peyton Jones2016-04-281-3/+3
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* Improve the behaviour of warnIfSimon Peyton Jones2016-04-221-10/+7
| | | | | | Now that warnIf takes a "reason", we can test the reason in warnIf rather than in the caller. Less code, and less risk of getting the test and the reason out of sync.
* SCC analysis for instances as well as types/classesSimon Peyton Jones2016-04-203-202/+432
| | | | | | | | | | | | | | | | | | | | | | | | | | | | This big patch is in pursuit of Trac #11348. It is largely the work of Alex Veith (thank you!), with some follow-up simplification and refactoring from Simon PJ. The main payload is described in RnSource Note [Dependency analysis of type, class, and instance decls] which is pretty detailed. * There is a new data type HsDecls.TyClGroup, for a strongly connected component of type/class/instance/role decls. The hs_instds field of HsGroup disappears, in consequence This forces some knock-on changes, including a minor haddock submodule update Smaller, weakly-related things * I found that both the renamer and typechecker were building an identical env for RoleAnnots, so I put common code for RoleAnnotEnv in RnEnv. * I found that tcInstDecls1 had very clumsy error handling, so I put it together into TcInstDcls.doClsInstErrorChecks
* Tighten checking for associated type instancesSimon Peyton Jones2016-04-191-10/+30
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch finishes off Trac #11450. Following debate on that ticket, the patch tightens up the rules for what the instances of an associated type can look like. Now they must match the instance header exactly. Eg class C a b where type T a x b With this class decl, if we have an instance decl instance C ty1 ty2 where ... then the type instance must look like type T ty1 v ty2 = ... with exactly - 'ty1' for 'a' - 'ty2' for 'b', and - a variable for 'x' For example: instance C [p] Int type T [p] y Int = (p,y,y) Previously we allowed multiple instance equations and now, in effect, we don't since they would all overlap. If you want multiple cases, use an auxiliary type family. This is consistent with the treatment of generic-default instances, and the user manual always said "WARNING: this facility (multiple instance equations may be withdrawn in the future". I also improved error messages, and did other minor refactoring.
* Fix #11811.Richard Eisenberg2016-04-122-31/+35
| | | | | | | Previously, I had forgotten to omit variables already in scope from the TypeInType CUSK check. Simple enough to fix. Test case: typecheck/should_compile/T11811
* Fix suggestions for unbound variables (#11680)Jason Eisenberg2016-04-103-6/+10
| | | | | | | | | | | | | | | | | | | | | | | | | When the typechecker generates the error message for an out-of-scope variable, it now uses the GlobalRdrEnv with respect to which the variable is unbound, not the GlobalRdrEnv which is available at the time the error is reported. Doing so ensures we do not provide suggestions which themselves are out-of-scope (because they are bound in a later inter-splice group). Nonetheless, we do note in the error message if an unambiguous, exact match to the out-of-scope variable is found in a later inter-splice group, and we specify where that match is not in scope. Test Plan: ./validate Reviewers: goldfire, austin, bgamari Reviewed By: goldfire Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D2000 GHC Trac Issues: #11680
* Fix Template Haskell bug reported in #11809.Dominik Bollmann2016-04-101-6/+13
| | | | | | | | | | | | | | | | | | Record selectors of data types spliced in with Template Haskell are not renamer-resolved correctly in GHC HEAD. The culprit is `newRecordSelector` which violates notes `Note [Binders in Template Haskell] in Convert.hs` and `Note [Looking up Exact RdrNames] in RnEnv.hs`. This commit fixes `newRecordSelector` accordingly. Test Plan: ./validate Reviewers: thomie, mpickering, bgamari, austin, simonpj, goldfire Reviewed By: goldfire Differential Revision: https://phabricator.haskell.org/D2091 GHC Trac Issues: #11809
* Fix misattribution of `-Wunused-local-binds` warningsHerbert Valerio Riedel2016-04-051-8/+9
| | | | | | | | | | | | | | | | | | | | | | | | This fixes a bug where warnings actually controlled by - `Opt_WarnUnusedMatches` - `Opt_WarnUnusedTypePatterns` - `Opt_WarnUnusedTopBinds` were incorrectly reported as being controlled by `Opt_WarnUnusedLocalBinds` as well This bug was introduced in bb5afd3c274011c5ea302210b4c290ec1f83209c while implementing #10752 Test Plan: ./validate still running -- testsuite output wiggles expected Reviewers: barrucadu, quchen, austin, bgamari Reviewed By: bgamari Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D2077
* Improve printing of pattern synonym typesRik Steenkamp2016-04-021-24/+30
| | | | | | | | | | | | | | | | | | | | | Add the function `pprPatSynType :: PatSyn -> SDoc` for printing pattern synonym types, and remove the ambiguous `patSynType` function. Also, the types in a `PatSyn` are now tidy. Haddock submodule updated to reflect the removal of `patSynType` by mpickering. Fixes: #11213. Reviewers: goldfire, simonpj, austin, mpickering, bgamari Reviewed By: simonpj, mpickering Subscribers: bollmann, simonpj, thomie Differential Revision: https://phabricator.haskell.org/D1896 GHC Trac Issues: #11213
* Refactor in TcMatchesSimon Peyton Jones2016-03-311-3/+2
| | | | | | | | | | * Move the several calls of tauifyMultipleMatches into tcMatches, so that it can be called only once, and the invariants are clearer * I discovered in doing this that HsLamCase had a redundant and tiresome argument, so I removed it. That in turn allowed some modest but nice code simplification
* rename: Disallow type signatures in patterns in plain HaskellBen Gamari2016-03-291-1/+10
| | | | | | | | | | | | | | | | | | | | This should require -XScopedTypeVariables. It seems this was previously handled by RnTypes.rnHsBndrSig which called RnTypes.badKindSigErr but this was broken in Simon's refactor of wildcards, 1e041b7382b6aa329e4ad9625439f811e0f27232. Here we re-introduce a check in RnPat. See #11663. Test Plan: Validate with `T11663` Reviewers: austin, simonpj Reviewed By: austin Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D2054 GHC Trac Issues: #11663
* Fix #11648.Richard Eisenberg2016-03-142-40/+65
| | | | | | | | | | | | We now check that a CUSK is really a CUSK and issue an error if it isn't. This also involves more solving and zonking in kcHsTyVarBndrs, which was the outright bug reported in #11648. Test cases: polykinds/T11648{,b} This updates the haddock submodule. [skip ci]
* Refactor visible type application.Richard Eisenberg2016-03-142-4/+7
| | | | | | | | | | | | | This replaces the old HsType and HsTypeOut constructors with HsAppType and HsAppTypeOut, leading to some simplification. (This refactoring addresses #11329.) This also fixes #11456, which stumbled over HsType (which is not an expression). test case: ghci/scripts/T11456 [skip ci]
* Add -foptimal-applicative-doSimon Marlow2016-03-111-76/+150
| | | | | | | | | | | | | | | | | | | | Summary: The algorithm for ApplicativeDo rearrangement is based on a heuristic that runs in O(n^2). This patch adds the optimal algorithm, which is O(n^3), selected by a flag (-foptimal-applicative-do). It finds better solutions in a small number of cases (about 2% of the cases where ApplicativeDo makes a difference), but it can be very slow for large do expressions. I'm mainly adding it for experimental reasons. ToDo: user guide docs Test Plan: validate Reviewers: simonpj, bgamari, austin, niteria, erikd Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D1969
* Add Note [Running splices in the Renamer]Owen Stephens2016-03-111-1/+43
| | | | | | | | | | Reviewers: austin, goldfire, bgamari Reviewed By: goldfire, bgamari Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D1985
* Fix #11624, cannot declare hs-boot if already one in scope.Edward Z. Yang2016-03-113-18/+16
| | | | | | | | | | | | | | | | | | | | | I'm not sure if this fix is the "right way" to do it, but it solves the proximal problem, which is that lookupBindGroupOcc was picking out the wrong renaming for hs-boot signatures, which then lead to an interface file error. Signed-off-by: Edward Z. Yang <ezyang@cs.stanford.edu> Test Plan: validate Reviewers: simonpj, hvr, austin, bgamari Reviewed By: bgamari Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D1963 GHC Trac Issues: #11624
* Drop module qualifier from punned record fields (#11662)Adam Gundry2016-03-051-2/+6
| | | | | | | | | | | | | | | | | | A record pattern match, construction or update like `Rec { Mod.f }` should expand to `Rec { Mod.f = f }` rather than `Rec { Mod.f = Mod.f }`. Test Plan: New test rename/should_compile/T11662 Reviewers: austin, bgamari Reviewed By: bgamari Subscribers: hesselink, thomie Differential Revision: https://phabricator.haskell.org/D1965 GHC Trac Issues: #11662
* Refactor `warnMissingSignatures` in `RnNames.hs`Rik Steenkamp2016-02-291-69/+32
| | | | | | | | Reviewers: austin, thomie, bgamari Reviewed By: thomie, bgamari Differential Revision: https://phabricator.haskell.org/D1955
* Typos in comments, etc.Gabor Greif2016-02-261-1/+1
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* Print which warning-flag controls an emitted warningMichael Walker2016-02-255-59/+91
| | | | | | | | | | | | | | | | | Both gcc and clang tell which warning flag a reported warning can be controlled with, this patch makes ghc do the same. More generally, this allows for annotated compiler output, where an optional annotation is displayed in brackets after the severity. This also adds a new flag `-f(no-)show-warning-groups` to control whether to show which warning-group (such as `-Wall` or `-Wcompat`) a warning belongs to. This flag is on by default. This implements #10752 Reviewed By: quchen, bgamari, hvr Differential Revision: https://phabricator.haskell.org/D1943
* Improve accuracy of suggestion to use TypeApplicationsMatthew Pickering2016-02-251-6/+7
| | | | | | | | | | | | | | | | The suggestion only makes sense when we try to use an as pattern in an expression context. It is misleading in the case of a lazy pattern and view pattern. Reviewers: austin, bgamari Reviewed By: bgamari Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D1948
* Make warning names more consistentManav Rathi2016-02-251-6/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | - Replace "Sigs" with "Signatures" in WarningFlag data constructors. - Replace "PatSyn" with "PatternSynonym" in WarningFlag data constructors. - Deprecate "missing-local-sigs" in favor of "missing-local-signatures". - Deprecate "missing-exported-sigs" in favor of "missing-exported-signatures". - Deprecate "missing-pat-syn-signatures" in favor of "missing-pattern-synonym-signatures". - Replace "ddump-strsigs" with "ddump-str-signatures" These complete the tasks that were explicitly mentioned in #11583 Test Plan: Executed `ghc --show-options` and verified that the flags were changed as expected. Reviewers: svenpanne, austin, bgamari Reviewed By: austin, bgamari Subscribers: mpickering, thomie Differential Revision: https://phabricator.haskell.org/D1939 GHC Trac Issues: #11583
* ApplicativeDo: Handle terminal `pure` statementsBen Gamari2016-02-251-1/+1
| | | | | | | | | | | | | | | | | ApplicativeDo handled terminal `return` statements properly, but not `pure`. Test Plan: Validate with included testcase Reviewers: austin, simonmar Reviewed By: austin, simonmar Subscribers: simonpj, thomie Differential Revision: https://phabricator.haskell.org/D1931 GHC Trac Issues: #11607
* Fix a bug in ApplicativeDo (#11612)Simon Marlow2016-02-201-6/+21
| | | | | In some cases ApplicativeDo would miss some opportunities, due to a wrong calculation of free variables in RnExpr.segments.
* Refactoring only: use ExprLStmtSimon Marlow2016-02-201-19/+19
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* Fix #11241.Richard Eisenberg2016-02-171-1/+8
| | | | | | | When renaming a type, now looks for wildcards in bound variables' kinds. testcase: dependent/should_compile/T11241
* Improved error message about exported type operators.Ulya Trofimovich2016-02-162-3/+24
| | | | | | | | | | | | | | | | | | | | | | | | | | | There is ambiguty between (1) type constructors and (2) data constructors in export lists, e.g. '%%' can stand for both of them. This ambiguity is resolved in favor of (2). If the exported data constructor is not in scope, but type constructor with the same name is in scope, GHC should suggest adding 'type' keyword to resolve ambiguity in favor of (1) and enabling 'TypeOperators' extension. The patch only extends the error message. See Trac #11432. Test Plan: `make test` Reviewers: simonpj, bgamari, austin Reviewed By: simonpj Subscribers: mpickering, thomie, goldfire, kosmikus Differential Revision: https://phabricator.haskell.org/D1902 GHC Trac Issues: #11432
* renamer discards name location for HsRecFieldAlan Zimmerman2016-02-141-2/+3
| | | | | | | When renaming a HsVar it can be converted to a HsRecField. In the process the location of the enclosed name is converted to a noLoc Closes #11576
* Allow foralls in instance declsSimon Peyton Jones2016-02-081-2/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch finally makes it possible to have explicit foralls in an instance decl instance forall (a :: *). Eq a => Eq [a] where ... This is useful to allow kind signatures or indeed explicicit kind for-alls; see Trac #11519 I thought it would be really easy, because an instance declaration already contains an actual HsSigType, so all the syntactic baggage is there. But in fact it turned out that instance declarations were kind-checked a little differently, because the body kind of the forall is 'Constraint' rather than '*'. So I fixed that. There a slight kludge (see Note [Body kind of a HsQualTy], but it's still a significant improvement. I also did the usual other round of refactoring, improved a few error messages, tidied up comments etc. The only significant aspect of all that was * Kill mkNakedSpecSigmaTy, mkNakedPhiTy, mkNakedFunTy These function names suggest that they do something complicated, but acutally they do nothing. So I killed them. * Swap the arg order of mkNamedBinder, just so that it is convenient to say 'map (mkNamedBinder Invisible) tvs' * I had to improve isPredTy, to deal with (illegal) types like (Eq a => Eq [a]) => blah See Note [isPeredTy complications] in Type.hs Still to come: user manual documentation for the instance-decl change.
* Refactor the typechecker to use ExpTypes.Richard Eisenberg2016-01-273-48/+72
| | | | | | | | | | | | | | | | | | | | | 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
* Split off -Wunused-type-variables from -Wunused-matchesRyanGlScott2016-01-263-8/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: Previously, `-Wunused-matches` would fire whenever it detected unused type variables in a type family or data family instance. This can be annoying for users who wish to use type variable names as documentation, as being `-Wall`-compliant would mean that they'd have to prefix many of their type variable names with underscores, making the documentation harder to read. To avoid this, a new warning `-Wunused-type-variables` was created that only encompasses unused variables in family instances. `-Wunused-matches` reverts back to its role of only warning on unused term-level pattern names. Unlike `-Wunused-matches`, `-Wunused-type-variables` is not implied by `-Wall`. Fixes #11451. Test Plan: ./validate Reviewers: goldfire, ekmett, austin, hvr, simonpj, bgamari Reviewed By: simonpj, bgamari Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D1825 GHC Trac Issues: #11451