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Re: [GHC] #5273: error and undefined should print a location
by GHC 02 Sep '15

02 Sep '15

#5273: error and undefined should print a location -------------------------------------+------------------------------------- Reporter: augustss | Owner: Type: feature request | Status: closed Priority: low | Milestone: 7.12.1 Component: Compiler | Version: 7.1 Resolution: fixed | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: 9049 | Differential Revisions: Phab:D861 -------------------------------------+------------------------------------- Comment (by bgamari): One remaining question here is how this should interact with DWARF-based stacktraces (see Phab:D1198). The two mechanisms exhibit different strengths, * IP-based stacktraces: * Always accurate * Cheap to gather stack but have small effect on code generation * Can only provide limited stack depth * DWARF-based stacktraces: * May not point you at exactly the right place * More expensive to gather stack but no effect on code generation * Can provide full stack (but perhaps it's best if we capped the depth to avoid costly unwinding of deep stacks) * Requires that code be built with `-g` Given they are to some extent complementary, perhaps we should produce both if available? Note: technically there are two costs to DWARF stack collection: 1. Unwinding the stack: the task of actually walking the stack and collection the relevant addresses 2. Looking up the addresses: the task of looking up symbol names and source location information for the addresses we collected in step 1. In my experience (2) tend to be much more expensive than (1). In Phab:D1198 step (2) should occur lazily, so it will only be paid if the necessary. Step (1) however necessarily happens unconditionally. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/5273#comment:12> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #5273: error and undefined should print a location
by GHC 02 Sep '15

02 Sep '15

#5273: error and undefined should print a location -------------------------------------+------------------------------------- Reporter: augustss | Owner: Type: feature request | Status: closed Priority: low | Milestone: 7.12.1 Component: Compiler | Version: 7.1 Resolution: fixed | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: 9049 | Differential Revisions: Phab:D861 -------------------------------------+------------------------------------- Changes (by bgamari): * status: patch => closed * resolution: => fixed -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/5273#comment:11> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #5273: error and undefined should print a location
by GHC 02 Sep '15

02 Sep '15

#5273: error and undefined should print a location -------------------------------------+------------------------------------- Reporter: augustss | Owner: Type: feature request | Status: patch Priority: low | Milestone: 7.12.1 Component: Compiler | Version: 7.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: 9049 | Differential Revisions: Phab:D861 -------------------------------------+------------------------------------- Comment (by Ben Gamari <ben@…>): In [changeset:"6740d70d95cb81cea3859ff847afc61ec439db4f/ghc" 6740d70d/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="6740d70d95cb81cea3859ff847afc61ec439db4f" Use IP based CallStack in error and undefined This patch modifies `error`, `undefined`, and `assertError` to use implicit call-stacks to provide better error messages to users. There are a few knock-on effects: - `GHC.Classes.IP` is now wired-in so it can be used in the wired-in types for `error` and `undefined`. - `TysPrim.tyVarList` has been replaced with a new function `TysPrim.mkTemplateTyVars`. `tyVarList` made it easy to introduce subtle bugs when you need tyvars of different kinds. The naive ``` tv1 = head $ tyVarList kind1 tv2 = head $ tyVarList kind2 ``` would result in `tv1` and `tv2` sharing a `Unique`, thus substitutions would be applied incorrectly, treating `tv1` and `tv2` as the same tyvar. `mkTemplateTyVars` avoids this pitfall by taking a list of kinds and producing a single tyvar of each kind. - The types `GHC.SrcLoc.SrcLoc` and `GHC.Stack.CallStack` now live in ghc-prim. - The type `GHC.Exception.ErrorCall` has a new constructor `ErrorCallWithLocation` that takes two `String`s instead of one, the 2nd one being arbitrary metadata about the error (but usually the call-stack). A bi-directional pattern synonym `ErrorCall` continues to provide the old API. Updates Cabal, array, and haddock submodules. Reviewers: nh2, goldfire, simonpj, hvr, rwbarton, austin, bgamari Reviewed By: simonpj Subscribers: rwbarton, rodlogic, goldfire, maoe, simonmar, carter, liyang, bgamari, thomie Differential Revision: https://phabricator.haskell.org/D861 GHC Trac Issues: #5273 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/5273#comment:10> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10541: Expose kind information for type variables with reify
by GHC 01 Sep '15

01 Sep '15

#10541: Expose kind information for type variables with reify -------------------------------------+------------------------------------- Reporter: spinda | Owner: Type: feature | Status: new request | Milestone: Priority: normal | Version: 7.10.1 Component: Template | Operating System: Unknown/Multiple Haskell | Type of failure: None/Unknown Keywords: | Blocked By: Architecture: | Related Tickets: Unknown/Multiple | Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- The comment on [https://hackage.haskell.org/package/template- haskell-2.10.0.0/docs/Language-Haskell-TH-Syntax.html#v:TyVarI TyVarI] notes that the attached Type is always {{{VarT theName}}}, and that this could potentially be extended. Currently, there isn't a way to access kind information for a type variable through the Template Haskell API. It would be useful (at least for me) to have this ability here. The limitation on the returned Type comes from the [https://github.com/ghc/ghc/blob/master/compiler/typecheck/TcSplice.hs#L1060 ATyVar clause of reifyThing], which zonks the TyVar to a GHC type and then uses reifyType to convert it to a TH type. For a TyVarTy, [https://github.com/ghc/ghc/blob/master/compiler/typecheck/TcSplice.hs#L1281 reifyType] always returns {{{VarT theName}}}. I can see a few possible ways of exposing kind information here: (a) Fill the Type argument to TyVarI with {{{SigT (VarT theName) theKind}}}. This could be done either as a special case in place of the call to reifyType in reifyThing, or as a modification to reifyType's behavior. The question of when SigT should be included is open: all the time? when the kind isn't {{{*}}}? when the kind is something that involves more than {{{*}}} and {{{->}}}? (b) Change TyVarI from {{{TyVarI Name Type}}} to {{{TyVarI Name TyVarBndr}}}. This seems like the most straightforward, stable way of exposing kind information, but it requires a breaking API change. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10541> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #4012: Compilation results are not deterministic
by GHC 31 Aug '15

31 Aug '15

#4012: Compilation results are not deterministic -------------------------------------+------------------------------------- Reporter: kili | Owner: niteria Type: bug | Status: patch Priority: high | Milestone: 7.12.1 Component: Compiler | Version: 6.12.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: Other | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Revisions: Phab:D910, | Phab:D1073, Phab:D1133, Phab:D1192 -------------------------------------+------------------------------------- Comment (by Simon Marlow <marlowsd@…>): In [changeset:"10a07753ff4ac0c1285454567c926d580d0f0470/ghc" 10a0775/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="10a07753ff4ac0c1285454567c926d580d0f0470" Anchor type family instances deterministically Summary: This is very similar to D1073. It makes type family instances to be attached to a binding with a least `OccName`, therefore not depending on `Unique` ordering. Test Plan: * this makes `Language.Haskell.Exts.SrcLoc` deterministic * ./validate Reviewers: simonmar, austin, bgamari, simonpj Reviewed By: simonpj Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D1192 GHC Trac Issues: #4012 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4012#comment:116> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10792: Bounded Enums [minBound..maxBound] produces runtime error
by GHC 31 Aug '15

31 Aug '15

#10792: Bounded Enums [minBound..maxBound] produces runtime error -------------------------------------+------------------------------------- Reporter: | Owner: ekmett AlexanderThiemann | Type: bug | Status: new Priority: normal | Milestone: Component: Core | Version: 7.10.2 Libraries | Keywords: | Operating System: Linux Architecture: | Type of failure: Runtime crash Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- Consider this code: {{{#!hs data MultiHeader = MultiHeaderCacheControl | MultiHeaderConnection | MultiHeaderContentEncoding -- ... deriving (Show, Eq, Enum, Bounded, Generic) instance Hashable MultiHeader multiHeaderCI :: MultiHeader -> CI.CI BS.ByteString multiHeaderCI mh = case mh of MultiHeaderCacheControl -> "Cache-Control" MultiHeaderConnection -> "Connection" MultiHeaderContentEncoding -> "Content-Encoding" -- ... multiHeaderMap :: HM.HashMap (CI.CI BS.ByteString) MultiHeader multiHeaderMap = HM.fromList $ flip map [minBound..maxBound] $ \mh -> (multiHeaderCI mh, mh) }}} (derived from https://github.com/agrafix/Spock/blob/9c19c0159d99783aabf896d2742e231a5e85e… ) When the multiHeaderMap accessed, a runtime error on GHC7.10.2 running on *some* [0] [1] Linux architectures is thrown. It does not occur on Mac or the travis build infrastructure [2]. {{{ uncaught exception: ErrorCall (toEnum{MultiHeader}: tag (-12565) is outside of enumeration's range (0,12)) }}} I've marked the bug with 'core libraries', but I am not certain that that's the origin of it. [0]: https://github.com/agrafix/Spock/issues/44 (Hydra / NixOS?) [1]: We've also seen it happen when used in docker with ubuntu:14.04 base image [2]: https://travis-ci.org/agrafix/Spock/builds/76877783 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10792> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7259: Eta expansion of products in System FC
by GHC 31 Aug '15

31 Aug '15

#7259: Eta expansion of products in System FC -------------------------------------+------------------------------------- Reporter: simonpj | Owner: simonpj Type: bug | Status: new Priority: normal | Milestone: 7.12.1 Component: Compiler | Version: 7.6.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Revisions: -------------------------------------+------------------------------------- Comment (by goldfire): Josef and I chatted about this ticket at HIW today. Now that `Any` is moved out of the way, it seems quite possible to revisit this. Shouldn't be too hard. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7259#comment:13> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #4012: Compilation results are not deterministic
by GHC 31 Aug '15

31 Aug '15

#4012: Compilation results are not deterministic -------------------------------------+------------------------------------- Reporter: kili | Owner: niteria Type: bug | Status: patch Priority: high | Milestone: 7.12.1 Component: Compiler | Version: 6.12.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: Other | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Revisions: Phab:D910, | Phab:D1073, Phab:D1133, Phab:D1192 -------------------------------------+------------------------------------- Changes (by niteria): * differential: Phab:D910, Phab:D1073, Phab:D1133 => Phab:D910, Phab:D1073, Phab:D1133, Phab:D1192 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4012#comment:115> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7259: Eta expansion of products in System FC
by GHC 31 Aug '15

31 Aug '15

#7259: Eta expansion of products in System FC -------------------------------------+------------------------------------- Reporter: simonpj | Owner: simonpj Type: bug | Status: new Priority: normal | Milestone: 7.12.1 Component: Compiler | Version: 7.6.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Revisions: -------------------------------------+------------------------------------- Changes (by josef): * cc: josef.svenningsson@… (added) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7259#comment:12> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #1409: Allow recursively dependent modules transparently (without .hs-boot or anything)
by GHC 31 Aug '15

31 Aug '15

#1409: Allow recursively dependent modules transparently (without .hs-boot or anything) -------------------------------------+------------------------------------- Reporter: Isaac Dupree | Owner: Type: feature request | Status: new Priority: normal | Milestone: ⊥ Component: Compiler | Version: 6.10.2 Resolution: | Keywords: backpack Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #9256 | Differential Revisions: -------------------------------------+------------------------------------- Changes (by ekmett): * cc: ekmett (added) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/1409#comment:68> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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