November 2014 - ghc-tickets

Re: [GHC] #4833: Finding the right loop breaker
by GHC 28 Nov '14

28 Nov '14

#4833: Finding the right loop breaker -------------------------------------+------------------------------------- Reporter: simonpj | Owner: Type: bug | Status: new Priority: low | Milestone: 7.10.1 Component: Compiler | Version: 7.0.1 Resolution: | Keywords: Operating System: | Architecture: Unknown/Multiple Unknown/Multiple | Difficulty: Unknown Type of failure: Runtime | Blocked By: performance bug | Related Tickets: Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Changes (by thomie): * difficulty: => Unknown * failure: None/Unknown => Runtime performance bug -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4833#comment:5> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #4896: Deriving Data does not work for attached code
by GHC 28 Nov '14

28 Nov '14

#4896: Deriving Data does not work for attached code -------------------------------------+------------------------------------- Reporter: mitar | Owner: Type: bug | Status: infoneeded Priority: low | Milestone: 7.10.1 Component: Compiler | Version: 7.1 Resolution: | Keywords: Operating System: | Architecture: Unknown/Multiple Unknown/Multiple | Difficulty: Unknown Type of failure: | Blocked By: None/Unknown | Related Tickets: Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Changes (by thomie): * status: new => infoneeded Comment: This is the error message with HEAD (7.9.20141125) for the example from the description. {{{ Main.hs:17:66: Couldn't match type ‘t'0 a0’ with ‘Bar’ Expected type: Maybe (c (Bar (D a b))) Actual type: Maybe (c (t'0 a0 (D a b))) In the expression: gcast2 f In an equation for ‘dataCast2’: dataCast2 f = gcast2 f When typechecking the code for ‘dataCast2’ in a derived instance for ‘Data (Bar (D a b))’: To see the code I am typechecking, use -ddump-deriv }}} And the error message for mojojojo's example from comment:6 with HEAD (see also #5863): {{{ test.hs:5:40: Deriving Typeable is not allowed for family instances; derive Typeable for ‘DF’ alone In the data instance declaration for ‘DF’ test.hs:6:42: Deriving Typeable is not allowed for family instances; derive Typeable for ‘DF’ alone In the data instance declaration for ‘DF’ }}} Is there still a problem here? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4896#comment:8> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #4900: Consider usage files in the GHCi recompilation check (was: DEPENDS pragma)
by GHC 28 Nov '14

28 Nov '14

#4900: Consider usage files in the GHCi recompilation check -------------------------------------+------------------------------------- Reporter: cdsmith | Owner: Type: feature | Status: new request | Milestone: 7.10.1 Priority: normal | Version: Component: Compiler | Keywords: Resolution: | Architecture: Unknown/Multiple Operating System: | Difficulty: Unknown Unknown/Multiple | Blocked By: Type of failure: | Related Tickets: None/Unknown | Test Case: TH_Depends | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Changes (by thomie): * differential: Phab:D481 => Comment: Current status: there's a [https://ghc.haskell.org/trac/ghc/attachment/ticket/4900/0001-Consider- usage-files-in-the-GHCi-recompilation-check.4.patch patch]. See comment:67 why it's not ready yet. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4900#comment:75> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #4921: report ambiguous type variables more consistently
by GHC 28 Nov '14

28 Nov '14

#4921: report ambiguous type variables more consistently -------------------------------------+------------------------------------- Reporter: Saizan | Owner: Type: feature | Status: new request | Milestone: 7.10.1 Priority: low | Version: 7.0.1 Component: Compiler | Keywords: (Type checker) | Architecture: Unknown/Multiple Resolution: | Difficulty: Unknown Operating System: | Blocked By: Unknown/Multiple | Related Tickets: Type of failure: | None/Unknown | Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Changes (by thomie): * difficulty: => Unknown Comment: This seems fixed, pending a regression test. The error messages for `x` and `y` are no longer completely different. Ghc shows for `y`, since version 7.6.3: `The type variable ‘b0’ is ambiguous`. And since version 7.8.3 it doesn't show anymore: `Possible fix: add an instance declaration for (C Int b)`. Here is the full error message with HEAD: {{{ $ ghc-7.9.20141125 test.hs [1 of 1] Compiling Amb ( test.hs, test.o ) test.hs:10:9: No instance for (C a0 b1) arising from a use of ‘f’ The type variables ‘a0’, ‘b1’ are ambiguous Relevant bindings include x :: a0 (bound at test.hs:10:1) Note: there is a potential instance available: instance C Int Char -- Defined at test.hs:7:10 In the first argument of ‘fst’, namely ‘f’ In the expression: fst f In an equation for ‘x’: x = fst f test.hs:11:9: No instance for (C Int b0) arising from a use of ‘f’ The type variable ‘b0’ is ambiguous Note: there is a potential instance available: instance C Int Char -- Defined at test.hs:7:10 In the first argument of ‘fst’, namely ‘f’ In the expression: fst f :: Int In an equation for ‘y’: y = fst f :: Int }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4921#comment:5> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #4937: Remove indirections caused by sum types, such as Maybe
by GHC 28 Nov '14

28 Nov '14

#4937: Remove indirections caused by sum types, such as Maybe -------------------------------------+------------------------------------- Reporter: tibbe | Owner: Type: feature | Status: new request | Milestone: 7.10.1 Priority: normal | Version: 7.0.1 Component: Compiler | Keywords: Resolution: | Architecture: Unknown/Multiple Operating System: | Difficulty: Unknown Unknown/Multiple | Blocked By: Type of failure: Runtime | Related Tickets: performance bug | Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Changes (by thomie): * difficulty: => Unknown * failure: None/Unknown => Runtime performance bug -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4937#comment:20> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8323: explore ways to possibly use more tag bits in x86_64 pointers
by GHC 28 Nov '14

28 Nov '14

#8323: explore ways to possibly use more tag bits in x86_64 pointers ------------------------------------+------------------------------------- Reporter: carter | Owner: Type: task | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.6.3 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- on x86_64, pointers only use 48 bits! currently we use 3bits for tagging / arity etc info on x86_64, we should explore more uses! -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8323> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #4938: Core2 CPU not detected correctly
by GHC 28 Nov '14

28 Nov '14

#4938: Core2 CPU not detected correctly -------------------------------------+------------------------------------- Reporter: altaic | Owner: Type: bug | Status: infoneeded Priority: low | Milestone: 7.10.1 Component: Compiler | Version: 7.1 Resolution: | Keywords: Operating System: MacOS X | Architecture: Unknown/Multiple Type of failure: Building | Difficulty: Unknown GHC failed | Blocked By: Test Case: | Related Tickets: Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Changes (by thomie): * status: new => infoneeded * difficulty: => Unknown * os: Unknown/Multiple => MacOS X Comment: Is this still a problem? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4938#comment:9> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #5941: Add compilation stage plugins
by GHC 28 Nov '14

28 Nov '14

#5941: Add compilation stage plugins -------------------------------------+------------------------------------- Reporter: tibbe | Owner: Type: feature | Status: infoneeded request | Milestone: 7.10.1 Priority: normal | Version: 7.4.1 Component: Compiler | Keywords: Resolution: | Architecture: Unknown/Multiple Operating System: | Difficulty: Unknown Unknown/Multiple | Blocked By: Type of failure: | Related Tickets: None/Unknown | Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Comment (by rodlogic): Now, from a user of this feature (or such feature), I would like to be able to do the following. Assuming I have, for example, two modules: {{{#!hs module A where import B main = sayHello "Joe" }}} {{{#!hs module B where sayHello :: String -> IO () sayHello = putStrLn }}} I would like to create a plugin, here named {{{DependenciesPlugin}}}, that is invoked with: {{{#!sh ghc -fplugin=DependenciesPlugin --make A.hs }}} This plugin would be called once to initialize itself, which in this case means creating a {{{A.dot}}} file: {{{ graph ModuleADependencies { }}} And once to terminate itself so that the {{{A.dot}}} file can be closed: {{{ } }}} In between the initialization and termination, the plugin would be called for each module to process the TypecheckedModule and generate a subgraph and the function dependencies: {{{ subgraph ModuleA { ModuleA.main [label="main"] } ModuleA.main -> ModuleB.sayHello subgraph ModuleB { ModuleB.sayHello [label="sayHello"] } }}} And command line options could be provided to tailor the DOT file generation (just module dependencies, only function dependencies, both, only dependencies from a specific functions, etc). Another option is to also take into account the packages these modules come from. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/5941#comment:5> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #4955: increase error message detail for module lookups failure due to hi references
by GHC 28 Nov '14

28 Nov '14

#4955: increase error message detail for module lookups failure due to hi references -------------------------------------+------------------------------------- Reporter: duncan | Owner: Type: feature | Status: new request | Milestone: 7.10.1 Priority: low | Version: 6.12.1 Component: Package | Keywords: system | Architecture: Unknown/Multiple Resolution: | Difficulty: Unknown Operating System: | Blocked By: Unknown/Multiple | Related Tickets: Type of failure: | None/Unknown | Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Changes (by thomie): * difficulty: => Unknown * component: Compiler => Package system * type: bug => feature request -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4955#comment:6> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #5941: Add compilation stage plugins
by GHC 28 Nov '14

28 Nov '14

#5941: Add compilation stage plugins -------------------------------------+------------------------------------- Reporter: tibbe | Owner: Type: feature | Status: infoneeded request | Milestone: 7.10.1 Priority: normal | Version: 7.4.1 Component: Compiler | Keywords: Resolution: | Architecture: Unknown/Multiple Operating System: | Difficulty: Unknown Unknown/Multiple | Blocked By: Type of failure: | Related Tickets: None/Unknown | Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Comment (by rodlogic): I find this a desirable feature, so I took a quick look. It seems that tcPlugin is currently focused on a pluggable constraint solver only: {{{#!hs data Plugin = Plugin { installCoreToDos :: [CommandLineOption] -> [CoreToDo] -> CoreM [CoreToDo] -- ^ Modify the Core pipeline that will be used for compilation. -- This is called as the Core pipeline is built for every module -- being compiled, and plugins get the opportunity to modify the -- pipeline in a nondeterministic order. , tcPlugin :: [CommandLineOption] -> Maybe TcPlugin -- ^ An optional typechecker plugin, which may modify the -- behaviour of the constraint solver. } data TcPlugin = forall s. TcPlugin { tcPluginInit :: TcPluginM s -- ^ Initialize plugin, when entering type-checker. , tcPluginSolve :: s -> TcPluginSolver -- ^ Solve some constraints. -- TODO: WRITE MORE DETAILS ON HOW THIS WORKS. , tcPluginStop :: s -> TcPluginM () -- ^ Clean up after the plugin, when exiting the type-checker. } type TcPluginSolver = [Ct] -- given -> [Ct] -- derived -> [Ct] -- wanted -> TcPluginM TcPluginResult }}} At this point it seems that there are two main venues: 1. extend TcPlugin to add a hook for processing the final type-checked module (and widening the scope of {{{tcPluginInit}}} and {{{tcPluginSolve}}}), or 2. Add another plugin for AST hooks (ParsedModule, RenamedModule, and TypecheckedModule). -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/5941#comment:4> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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