November 2013 - ghc-tickets

Re: [GHC] #5212: waitForProcess: does not exist (No child processes)
by GHC 18 Nov '13

18 Nov '13

#5212: waitForProcess: does not exist (No child processes) ------------------------------------------------+-------------------------- Reporter: chrisdone | Owner: Type: bug | Status: closed Priority: normal | Milestone: Component: Runtime System | Version: 7.4.2 Resolution: invalid | Keywords: Operating System: Linux | Architecture: x86_64 Type of failure: Incorrect result at runtime | (amd64) Test Case: | Difficulty: Blocking: | Unknown | Blocked By: | Related Tickets: ------------------------------------------------+-------------------------- Changes (by chrisdone): * cc: simonmar (added) * status: new => closed * resolution: => invalid Comment: The reason is because XMonad (and presumably some other library I was using two years ago) installs signal handlers for SIGCHILD: {{{ import Data.Maybe import Control.Monad import System.Posix.Signals import Control.Monad.Fix import Control.Exception import Control.Monad.Extra import Control.Monad.Trans import Control.Concurrent import System.Process import System.Posix.Process.ByteString main = do installSignalHandlers readProcess "ghc" ["--version"] "" >>= putStrLn -- | Ignore SIGPIPE to avoid termination when a pipe is full, and SIGCHLD to -- avoid zombie processes, and clean up any extant zombie processes. installSignalHandlers :: MonadIO m => m () installSignalHandlers = io $ do installHandler openEndedPipe Ignore Nothing installHandler sigCHLD Ignore Nothing (try :: IO a -> IO (Either SomeException a)) $ fix $ \more -> do x <- getAnyProcessStatus False False when (isJust x) more return () }}} This is pretty annoying because it breaks other uses of readProcess. My solution was to use a patched version of readProcess which handles exceptions thrown on waitForProcess. I guess this ticket can be closed… -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/5212#comment:6> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8536: ghc panic on creating data type
by GHC 16 Nov '13

16 Nov '13

#8536: ghc panic on creating data type ----------------------------------+--------------------------------------- Reporter: xilexio | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.6.3 Keywords: data | Operating System: Unknown/Multiple Architecture: x86_64 (amd64) | Type of failure: Compile-time crash Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ----------------------------------+--------------------------------------- ghc 7.6.3 (or ghci) from Haskell Platform for Windows panics when compiling the following line: data X = A Int { p :: Int } | B { p :: Int } ghc.exe: panic! (the 'impossible' happened) (GHC version 7.6.3 for i386-unknown-mingw32): tc_hs_type: record -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8536> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #4426: Simplify the rules for implicit quantification
by GHC 16 Nov '13

16 Nov '13

#4426: Simplify the rules for implicit quantification -------------------------------------+------------------------------------ Reporter: simonpj | Owner: Type: feature request | Status: patch Priority: low | Milestone: 7.6.2 Component: Compiler | Version: 6.12.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: #7880 -------------------------------------+------------------------------------ Changes (by monoidal): * status: new => patch Comment: Patch attached. It adds a new warning `-fwarn-context-quantification` that reports when a variable is quantified only because it under a "=>" arrow. Later, as the proposal says, this warning will be made an out-of-scope error. Normally, `HsForAll` is either `HsForAll Implicit` or `HsForAll Explicit`, and a context `T => R` inserts `HsForAll Implicit`. This patch adds a new value, `HsForAll Qualified`, which is completely equivalent to `HsForAll Implicit` save for the warning message. Later, its behavior will be changed and the renamer will not do implicit quantification for variables under `HsForAll Quantified`. I made `-Wall` not imply this flag, in (doubtful) case there is still time to merge this to GHC 7.8. In this case, there is full backwards compatibility: no change in behavior except if the flag is explicitly supplied. However, the API is slightly changed and I had to make a tiny change to Haddock. If it's too late, in GHC 7.10 I'd like `-Wall` to enable `-fwarn-context-quantification`, so I'll amend the patch. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4426#comment:9> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #2233: Overhaul System.Process
by GHC 16 Nov '13

16 Nov '13

#2233: Overhaul System.Process --------------------------------------+------------------------------------ Reporter: simonmar | Owner: simonmar Type: task | Status: patch Priority: normal | Milestone: _|_ Component: libraries/process | Version: 6.8.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: --------------------------------------+------------------------------------ Comment (by duncan): Note, these patches depend on the ones from #2301 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/2233#comment:15> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #2301: Proper handling of SIGINT/SIGQUIT
by GHC 16 Nov '13

16 Nov '13

#2301: Proper handling of SIGINT/SIGQUIT -------------------------------------+------------------------------------- Reporter: duncan | Owner: Type: bug | Status: patch Priority: high | Milestone: 7.8.1 Component: | Version: 6.12.3 libraries/process | Keywords: Resolution: | Architecture: Unknown/Multiple Operating System: POSIX | Difficulty: Unknown Type of failure: Incorrect result | Blocked By: at runtime | Related Tickets: Test Case: | #3994,#5766,#7229,#4274,#3318,#1619 Blocking: | -------------------------------------+------------------------------------- Comment (by duncan): Simon: BTW, I didn't mean I'm dead set against changing it, I think it's rather unclear which is better. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/2301#comment:38> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #2233: Overhaul System.Process
by GHC 16 Nov '13

16 Nov '13

#2233: Overhaul System.Process --------------------------------------+------------------------------------ Reporter: simonmar | Owner: simonmar Type: task | Status: patch Priority: normal | Milestone: _|_ Component: libraries/process | Version: 6.8.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: --------------------------------------+------------------------------------ Changes (by duncan): * status: new => patch -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/2233#comment:14> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #2301: Proper handling of SIGINT/SIGQUIT
by GHC 16 Nov '13

16 Nov '13

#2301: Proper handling of SIGINT/SIGQUIT -------------------------------------+------------------------------------- Reporter: duncan | Owner: Type: bug | Status: patch Priority: high | Milestone: 7.8.1 Component: | Version: 6.12.3 libraries/process | Keywords: Resolution: | Architecture: Unknown/Multiple Operating System: POSIX | Difficulty: Unknown Type of failure: Incorrect result | Blocked By: at runtime | Related Tickets: Test Case: | #3994,#5766,#7229,#4274,#3318,#1619 Blocking: | -------------------------------------+------------------------------------- Changes (by duncan): * status: new => patch -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/2301#comment:37> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #6068: Panic in GHCi when using functional dependencies and promoted kinds
by GHC 16 Nov '13

16 Nov '13

#6068: Panic in GHCi when using functional dependencies and promoted kinds -------------------------------------+------------------------------------ Reporter: goldfire | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: GHCi | Version: 7.5 Resolution: | Keywords: PolyKinds Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: GHCi crash | Difficulty: Unknown Test Case: polykinds/T6068 | Blocked By: Blocking: | Related Tickets: -------------------------------------+------------------------------------ Comment (by Simon Peyton Jones <simonpj@…>): In [changeset:"1e0ef8265d67d05e5114310311804b6d51bec7dd/ghc"]: {{{ #!CommitTicketReference repository="ghc" revision="1e0ef8265d67d05e5114310311804b6d51bec7dd" Fix canIrredPred again This follows up the earlier patch to Trac #6068, which I obviously hadn't validated properly. }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/6068#comment:9> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #2301: Proper handling of SIGINT/SIGQUIT
by GHC 15 Nov '13

15 Nov '13

#2301: Proper handling of SIGINT/SIGQUIT -------------------------------------+------------------------------------- Reporter: duncan | Owner: Type: bug | Status: new Priority: high | Milestone: 7.8.1 Component: | Version: 6.12.3 libraries/process | Keywords: Resolution: | Architecture: Unknown/Multiple Operating System: POSIX | Difficulty: Unknown Type of failure: Incorrect result | Blocked By: at runtime | Related Tickets: Test Case: | #3994,#5766,#7229,#4274,#3318,#1619 Blocking: | -------------------------------------+------------------------------------- Comment (by duncan): Yes, I did think about whether it should throw the `UserInterrupt` sync locally or async to the main thread. As you say, the concern is that people do not properly propagate their exceptions from forkIO threads (which I still maintain is a deficiency in our thread system). On the other hand it gives people an opportunity to catch the user interrupt locally if that's what they want to do. If it were not for the annoying problem of forkIO swallowing our exceptions, then I'd say that throwing it locally is really the right thing to do, because by delegating ^C handling to the child process, we really are turning an async exception (being interrupted by a signal) into a sync exception (waiting on process exit, which exits due to a signal). -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/2301#comment:36> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #6068: Panic in GHCi when using functional dependencies and promoted kinds
by GHC 15 Nov '13

15 Nov '13

#6068: Panic in GHCi when using functional dependencies and promoted kinds -------------------------------------+------------------------------------ Reporter: goldfire | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: GHCi | Version: 7.5 Resolution: | Keywords: PolyKinds Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: GHCi crash | Difficulty: Unknown Test Case: polykinds/T6068 | Blocked By: Blocking: | Related Tickets: -------------------------------------+------------------------------------ Changes (by simonpj): * cc: goldfire (added) Comment: Tanks for pointing out this crash. As the comments show (`Note [Kicking out Irreds]` in `TcInteract`), it raises an interesting point. Simon -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/6068#comment:8> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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