November 2013 - ghc-tickets

Re: [GHC] #5996: fix for CSE
by GHC 13 Nov '13

13 Nov '13

#5996: fix for CSE --------------------------------------------+------------------------------ Reporter: michalt | Owner: simonpj Type: bug | Status: patch Priority: normal | Milestone: 7.8.1 Component: Compiler | Version: 7.5 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Runtime performance bug | Unknown/Multiple Test Case: | Difficulty: Unknown Blocking: | Blocked By: | Related Tickets: --------------------------------------------+------------------------------ Comment (by Simon Peyton Jones <simonpj@…>): In [changeset:"a80663d37b7a8c834537c700528383a65e50fbdf/testsuite"]: {{{ #!CommitTicketReference repository="testsuite" revision="a80663d37b7a8c834537c700528383a65e50fbdf" Test Trac #5996 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/5996#comment:11> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7229: Detecting if a process was killed by a signal is impossible
by GHC 13 Nov '13

13 Nov '13

#7229: Detecting if a process was killed by a signal is impossible --------------------------------------+------------------------------------ Reporter: benmachine | Owner: Type: bug | Status: new Priority: highest | Milestone: 7.8.1 Component: libraries/process | Version: 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 Herbert Valerio Riedel <hvr@…>): In [changeset:"ffe7773c7fd222a946d17f489020098a45b5c8af/process"]: {{{ #!CommitTicketReference repository="process" revision="ffe7773c7fd222a946d17f489020098a45b5c8af" Change exit code encoding of `waitForProcess` yet again This changes the exit code encoding from `(128+signum)` (as introduced via 5403824028) to {{{#!hs if coredump then 0x8000 else 0 .|. signum `shiftL` 8 .|. exitstatus }}} in order to address the `process`-package part of #7229 Signed-off-by: Herbert Valerio Riedel <hvr(a)gnu.org> }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7229#comment:38> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #4900: DEPENDS pragma
by GHC 13 Nov '13

13 Nov '13

#4900: DEPENDS pragma -------------------------------------+------------------------------------ Reporter: cdsmith | Owner: parcs Type: feature request | Status: patch Priority: normal | Milestone: 7.8.1 Component: Compiler | Version: Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: TH_Depends | Blocked By: Blocking: | Related Tickets: -------------------------------------+------------------------------------ Comment (by parcs): I hit a couple of obstacles regarding the implementation: 1. There is no way to distinguish between usage files added via TH and other usage files (e.g. #included files). This is necessary to avoid re- summarization when only the former kind of usage file has changed. 2. The usage files of a boot module get lost after compiling the corresponding source module. This means that modifying a usage file included by a boot module will not trigger recompilation in GHCi. The first obstacle could be solved by adding a new field to the `UsageFile` constructor containing the kind of usage file (LINE pragma, #include, TH, etc..) and checking only the relevant kinds of usage files during re-summarisation. I don't know what could be done about 2nd obstacle, though. It looks like we can't depend on reading the HPT during the downsweep since the the boot interface gets overwritten by the source interface after the source module gets compiled. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4900#comment:67> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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

13 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: | -------------------------------------+------------------------------------- Changes (by hvr): * cc: hvr (added) * priority: normal => high * os: Unknown/Multiple => POSIX * milestone: 7.6.2 => 7.8.1 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/2301#comment:33> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7229: Detecting if a process was killed by a signal is impossible
by GHC 12 Nov '13

12 Nov '13

#7229: Detecting if a process was killed by a signal is impossible --------------------------------------+------------------------------------ Reporter: benmachine | Owner: Type: bug | Status: new Priority: highest | Milestone: 7.8.1 Component: libraries/process | Version: 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 hvr): * priority: high => highest Comment: (just upgrading priority to increase visibility of this ticket) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7229#comment:37> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8514: Non-ideal error with a kind error in a tuple
by GHC 12 Nov '13

12 Nov '13

#8514: Non-ideal error with a kind error in a tuple -------------------------------------------+------------------------------- Reporter: monoidal | Owner: Type: bug | Status: new Priority: lowest | Milestone: Component: Compiler (Type checker) | Version: 7.6.3 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Blocked By: | None/Unknown Related Tickets: #7410 | Test Case: | Blocking: -------------------------------------------+------------------------------- The definition {{{ type T a = (a, Maybe) }}} gives an error: {{{ Expecting one more argument to ‛a’ The first argument of a tuple should have kind ‛*’, but ‛a’ has kind ‛* -> *’ }}} However, obviously that's not the problem - the error should point to the `Maybe` part. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8514> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7229: Detecting if a process was killed by a signal is impossible
by GHC 12 Nov '13

12 Nov '13

#7229: Detecting if a process was killed by a signal is impossible --------------------------------------+------------------------------------ Reporter: benmachine | Owner: Type: bug | Status: new Priority: high | Milestone: 7.8.1 Component: libraries/process | Version: 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): Unclear if we also want to do something with `fastExit`, as used by `runIOFastExit` and `topHandlerFastExit`. If so, we need an extra function like `shutdownHaskellAndSignal` but that doesn't do the hs_exit_() call. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7229#comment:36> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8522: exprType incorrect for let expressions which bind types
by GHC 12 Nov '13

12 Nov '13

#8522: exprType incorrect for let expressions which bind types ------------------------------------+------------------------------------- Reporter: afarmer | Owner: Type: bug | Status: new Priority: high | 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: | ------------------------------------+------------------------------------- The `exprType` function in CoreUtils doesn't handle let expressions which bind type variables correctly. Consider: {{{ let a = Int in \ $dNum x y -> (+) a $dNum x y }}} `exprType` on this expression will give: `Num a => a -> a -> a` instead of `Num Int => Int -> Int -> Int` Obviously the core lint checker does the right thing, so I modified exprType (see attached patch) to do what it does. I'm guessing that exprType isn't used in any crucial capacity (or let-bound types are not that common) or the fact that `a` is unbound in the result would be a big problem. That said, we use this function heavily in HERMIT... is there another we should be using instead? Any chance this can make the 7.8 window? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8522> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8518: panic ghci when probably using type families incorrectly
by GHC 12 Nov '13

12 Nov '13

#8518: panic ghci when probably using type families incorrectly ------------------------------+------------------------------------- Reporter: HanStolpo | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.6.3 Keywords: ghci panic | Operating System: Unknown/Multiple Architecture: x86 | Type of failure: GHCi crash Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------+------------------------------------- Hi I am a beginner and was playing around with type families when ghc gave me a panic message and suggested I log a bug. I am running Windows 7 with GHC 7.6.3 installed using Haskell Platform 2013.2.0.0. Here is the reduced code producing the panic: {{{ {-# LANGUAGE TypeFamilies #-} import Data.Maybe import Control.Applicative class Continuation c where type Z c type B c type F c continue :: c -> (Z c) -> (B c) -> Maybe ((F c), c) callCont :: Continuation c => c -> (Z c) -> (B c) -> Maybe (F c) callCont c z b = rpt (4 :: Int) c z b where rpt 0 c' z' b' = fromJust (fst <$> (continue c' z' b')) rpt i c' z' b' = let c'' = fromJust (snd <$> (continue c' z' b')) in rpt (i-1) c'' main = putStrLn "" }}} Loading the code in WinGHCi and calling main results in the following {{{ GHCi, version 7.6.3: http://www.haskell.org/ghc/ :? for help Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done. Prelude> :cd C:\Dev Prelude> :load "Crash.hs" [1 of 1] Compiling Main ( Crash.hs, interpreted ) Ok, modules loaded: Main. *Main> main ghc: panic! (the 'impossible' happened) (GHC version 7.6.3 for i386-unknown-mingw32): nameModule <<details unavailable>> Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug *Main> }}} There is obviously something degenerate with the code but I guess the compiler should give a better error message. Note it actually compiles, i.e. if the file itself is just compiled but not linked in it does not give any errors. If the degenerate function 'callCont' is changed as follows. {{{ {-# LANGUAGE TypeFamilies #-} import Data.Maybe import Control.Applicative class Continuation c where type Z c type B c type F c continue :: c -> (Z c) -> (B c) -> Maybe ((F c), c) callCont :: Continuation c => c -> (Z c) -> (B c) -> Maybe (F c) callCont c z b = rpt (4 :: Int) c z b where rpt i c' z' b' = fromJust (fst <$> (continue c' z' b')) main = putStrLn "" }}} Then you get the following compile error: {{{ Crash.hs|12 col 18 error| Occurs check: cannot construct the infinite type: uf0 = Maybe uf0 || Expected type: Maybe (F c) || Actual type: F c || In the return type of a call of `rpt' || In the expression: rpt (4 :: Int) c z b || In an equation for `callCont': || callCont c z b || = rpt (4 :: Int) c z b || where || rpt i c' z' b' = fromJust (fst <$> (continue c' z' b')) }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8518> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #5996: fix for CSE
by GHC 12 Nov '13

12 Nov '13

#5996: fix for CSE --------------------------------------------+------------------------------ Reporter: michalt | Owner: simonpj Type: bug | Status: patch Priority: normal | Milestone: 7.8.1 Component: Compiler | Version: 7.5 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Runtime performance bug | Unknown/Multiple Test Case: | Difficulty: Unknown Blocking: | Blocked By: | Related Tickets: --------------------------------------------+------------------------------ Comment (by simonpj): Commit message properly formatted {{{ Fix egregious omission in CSE (Trac #5996) This patch fixes a bad omission in CSE, thanks to 'michaelt' for spotting it, and correctly identifying the fix (in cseRhs). The trouble was with x1 = C a b x2 = C x1 b y1 = C a b y2 = C y1 b we were not commoning up y2=x2, because we failed to substitute y1:=x1, so y2's RHS looked different to x2's I also refactoring, so taht the cs_map in a CSEnv map is cs_map :: CoreMap (OutExpr, Id) instead of cs_map :: CoreMap (OutExpr, OutExpr) Much nicer! This doesn't make much difference to allocation, but it gives a surprisingly big benefit to binary size. -------------------------------------------------------------------------------- Program Size Allocs Runtime Elapsed TotalMem -------------------------------------------------------------------------------- ansi -1.7% -0.8% 0.00 0.00 +0.0% bspt -1.6% -1.5% 0.01 0.01 +0.0% cacheprof -1.8% -0.2% +1.6% +1.9% +2.7% fft -1.4% -1.3% 0.06 0.06 +11.1% ida -1.4% -1.0% 0.12 0.12 +0.0% rfib -1.4% -0.1% 0.03 0.03 +0.0% scs -1.6% -0.1% +1.5% +1.5% +0.0% spectral-norm -1.3% -0.1% -0.2% -0.2% +0.0% tak -1.4% -0.1% 0.02 0.02 +0.0% veritas -1.4% -0.1% 0.00 0.00 +0.0% -------------------------------------------------------------------------------- Min -2.5% -1.5% -11.8% -11.8% -8.0% Max -1.0% +0.0% +2.7% +2.5% +11.1% Geometric Mean -1.3% -0.1% -2.6% -2.6% +0.0% }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/5996#comment:10> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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