May 2016 - ghc-tickets

[GHC] #10367: "ghc: panic! (the 'impossible' happened)"
by GHC 13 Apr '18

13 Apr '18

#10367: "ghc: panic! (the 'impossible' happened)" -------------------------------------+------------------------------------- Reporter: bgwines | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.1 Keywords: panic | Operating System: MacOS X Architecture: | Type of failure: Runtime crash Unknown/Multiple | Blocked By: Test Case: | Related Tickets: Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- When running tasty-hunit tests through `cabal repl`, I get the following error: {{{ ghc: panic! (the 'impossible' happened) (GHC version 7.8.3 for x86_64-apple-darwin): Loading temp shared object failed: dlopen(/var/folders/l6/v2vhn_3j6bb1yvp6k5sh2hv80000gp/T/ghc80357_0/ghc80357_61.dylib, 9): Symbol not found: __hpc_tickboxes_horsezmcontrolzm0zi1zi0zi0_HorseziCommands_hpc Referenced from: /var/folders/l6/v2vhn_3j6bb1yvp6k5sh2hv80000gp/T/ghc80357_0/ghc80357_61.dylib Expected in: flat namespace in /var/folders/l6/v2vhn_3j6bb1yvp6k5sh2hv80000gp/T/ghc80357_0/ghc80357_61.dylib Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} I have a hunch that it's because I enabled the following flags in my .cabal file, since I didn't get the exception before adding them: {{{ Test-Suite test-horse ... GHC-Options: -fhpc -hpcdir dist/hpc/horse-control-1.0 }}} When I run the tests via `cabal test`, I don't get the exception. I've created a branch that showcases the crash: https://github.com/bgwines /horse-control/tree/ghc-panic Repro steps: * clone repo * cd to repo * run `cabal repl` * run `:l Tests/test-horse.hs` * run `main` Reproducability: 100% Please feel free to contact me if there's information lacking, here! :) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10367> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8165: Use GeneralizedNewtypeDeriving to automatically create associated type families
by GHC 12 Apr '18

12 Apr '18

#8165: Use GeneralizedNewtypeDeriving to automatically create associated type families ------------------------------------+------------------------------------- Reporter: MikeIzbicki | Owner: Type: feature request | 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: | ------------------------------------+------------------------------------- Here's a simple example: {{{ class C a where type T a instance C Int where type T Int = Bool newtype NT = NT Int deriving C }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8165> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10010: LLVM/optimized code for sqrt incorrect for negative values
by GHC 10 Apr '18

10 Apr '18

#10010: LLVM/optimized code for sqrt incorrect for negative values -------------------------------------+------------------------------------- Reporter: glguy | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.4 (LLVM) | Operating System: Unknown/Multiple Keywords: | Type of failure: Incorrect result Architecture: | at runtime Unknown/Multiple | Blocked By: Test Case: | Related Tickets: Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- The LLVM sqrt intrinsic is undefined below values of -0.0 See http://llvm.org/docs/LangRef.html#llvm-sqrt-intrinsic In some versions of LLVM it returns 0.0 in this case, but in newer versions the return value is undefined. This causes the result of Haskell's sqrt to vary at negative values based on the codegen and optimization flags chosen. {{{ main = print (sqrt (-7 :: Double)) }}} {{{ $ ghc -O -fllvm Sqrt.hs [1 of 1] Compiling Main ( Sqrt.hs, Sqrt.o ) Linking Sqrt ... $ ./Sqrt 0.0 $ ghc -O Sqrt.hs [1 of 1] Compiling Main ( Sqrt.hs, Sqrt.o ) Linking Sqrt ... $ ./Sqrt NaN }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10010> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8118: <stdout>: commitAndReleaseBuffer: invalid argument (invalid character)
by GHC 10 Apr '18

10 Apr '18

#8118: <stdout>: commitAndReleaseBuffer: invalid argument (invalid character) ----------------------------------+---------------------------------- Reporter: guest | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.6.3 Keywords: | Operating System: OpenBSD Architecture: x86_64 (amd64) | Type of failure: Runtime crash Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ----------------------------------+---------------------------------- I get the following error... {{{ <stdout>: commitAndReleaseBuffer: invalid argument (invalid character) }}} When running following program: {{{#!haskell {-# LANGUAGE OverloadedStrings #-} import qualified Data.Text as T import qualified Data.Text.IO as T main = T.putStrLn "čušpajž日本語" }}} Was tested in #haskell and I have all the UTF-8 Settings set and so forth. It compiles just fine, but crashes during runtime. gcc -v: {{{ Reading specs from /usr/lib/gcc-lib/amd64-unknown-openbsd5.4/4.2.1/specs Target: amd64-unknown-openbsd5.4 Configured with: OpenBSD/amd64 system compiler Thread model: posix gcc version 4.2.1 20070719 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8118> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10424: Build path leaks into ABI hashes
by GHC 09 Apr '18

09 Apr '18

#10424: Build path leaks into ABI hashes -------------------------------------+------------------------------------- Reporter: nomeata | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.4 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Blocked By: Test Case: | Related Tickets: Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- The build path of GHC leaks into the ABI hashes, i.e. if you build GHC in /tmp/fooADDF and then in /tmp/fooSDFS, you get different ABI hashes. This is a serious problem for distributions, as it means that we cannot rebuild the GHC package without rebuilding all Haskell packages as well. The (or at least one) problem is include paths. We have {{{ include-dirs: /home/jojo/build/haskell/ghc/rts/dist/build /home/jojo/build/haskell/ghc/includes /home/jojo/build/haskell/ghc/includes/dist- derivedconstants/header }}} in `inplace/lib/package.conf.d/builtin_rts.conf`, so when running the preprocessor, GHC passes this full path to the preprocessor: {{{ /usr/bin/gcc -E -undef -traditional -DOPTIMISE_INTEGER_GCD_LCM -include libraries/base/dist-install/build/autogen/cabal_macros.h -I libraries/base /dist-install/build -I libraries/base/dist-install/build -I libraries/base /dist-install/build/autogen -I libraries/base/include -I /home/jojo/build/haskell/ghc/libraries/integer-gmp/include -I /home/jojo/build/haskell/ghc/rts/dist/build -I /home/jojo/build/haskell/ghc/includes -I /home/jojo/build/haskell/ghc/includes/dist-derivedconstants/header '-D__GLASGOW_HASKELL__=711' -include /home/jojo/build/haskell/ghc/includes/ghcversion.h '-Dlinux_BUILD_OS=1' '-Dx86_64_BUILD_ARCH=1' '-Dlinux_HOST_OS=1' '-Dx86_64_HOST_ARCH=1' '-D__GLASGOW_HASKELL_TH__=YES' '-D__SSE__=1' '-D__SSE2__=1' -x assembler- with-cpp libraries/base/System/Info.hs -o /tmp/ghc14804_0/ghc14804_1.hscpp }}} It then reads the included files from the `hscpp` file : {{{ $ grep home /tmp/ghc14830_0/ghc14830_1.hscpp # 1 "/home/jojo/build/haskell/ghc/includes/ghcversion.h" 1 # 1 "/home/jojo/build/haskell/ghc/includes/ghcplatform.h" 1 }}} and puts it into the interface, where it becomes part of the hash: {{{ $ ./inplace/bin/ghc-stage1 --show-iface ./libraries/base/dist- install/build/System/Info.hi |grep Dep addDependentFile "/home/jojo/build/haskell/ghc/includes/ghcplatform.h" addDependentFile "/home/jojo/build/haskell/ghc/includes/ghcversion.h" addDependentFile "libraries/base/dist- install/build/autogen/cabal_macros.h" addDependentFile "/usr/include/stdc-predef.h" }}} Clearly, the end result is undesirable (changing hashes due to path names) and actually useless, as the build path will not be there later anyways. I’m not sure what the best way to fix this is. Here are a few ideas: * Do not include the path of `addDependentFile` entries in the hash, but only the file hash. Should solve the ABI hash. * Use relative paths in `inplace/lib/package.conf.d/builtin_rts.conf`. Not sure what breaks. This bug appeared in 7.8.4 and is present in both 7.10 and current HEAD. Any other ideas? (Debian bugreport at http://bugs.debian.org/785282) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10424> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11815: Data.List: Add a function to get consecutive elements (mapConsecutives)
by GHC 06 Apr '18

06 Apr '18

#11815: Data.List: Add a function to get consecutive elements (mapConsecutives) -------------------------------------+------------------------------------- Reporter: holmisen | Owner: Type: feature | Status: new request | Priority: low | Milestone: Component: | Version: libraries/base | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- A recurring pattern is to get a list of all consecutive elements of a list, for further processing. I propose adding the following function to `Data.List` for this: {{{ mapConsecutives :: (a -> a -> b) -> [a] -> [b] mapConsecutives _ [] = [] mapConsecutives f xs = zipWith f xs (tail xs) }}} Since it requires pattern matching, to separate the empty case, it is not practical to inline at each use site. Sidenote: A similar function `mapAdjacent` is available in the `utility- ht` library (with a partial implementation(!)) [1]. I realise that `Data.List` is often imported unqualified and hence additions may cause trouble. I would have raised this on the libraries mailing list first, but the guidelines for proposals pointed me here. [1] http://hackage.haskell.org/package/utility-ht-0.0.11/docs/Data-List- HT.html#v:mapAdjacent -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11815> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10016: UNPACK support for existentials
by GHC 03 Apr '18

03 Apr '18

#10016: UNPACK support for existentials -------------------------------------+------------------------------------- Reporter: simonpj | Owner: Type: feature | Status: new request | Milestone: Priority: normal | Version: 7.8.4 Component: Compiler | Operating System: Unknown/Multiple Keywords: | Type of failure: None/Unknown Architecture: | Blocked By: Unknown/Multiple | Related Tickets: Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Consider {{{ data Foo = forall a. Show a => Foo !a !a data Bar = Bar {-# UNPACK #-} !Foo }}} The UNPACK pragma should really be able to unpack the `Foo` field, so that (implementation-wise) it would be as if you'd declared `Bar` thus: {{{ data Bar = forall a. Show a => Bar !a !a }}} But currently we get {{{ Ignoring unusable UNPACK pragma on the first argument of ‘Bar’ }}} Suggested by Nicholas Clarke [https://www.haskell.org/pipermail/glasgow- haskell-users/2015-January/025590.html here]. Vaguely related tickets: #7647, #9214. But unlike those ones, this one looks quite feasible to me. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10016> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11186: Give strong preference to type variable names in scope when reporting hole contexts
by GHC 02 Apr '18

02 Apr '18

#11186: Give strong preference to type variable names in scope when reporting hole contexts -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: Type: feature | Status: new request | Priority: normal | Milestone: Component: Compiler | Version: 7.10.2 (Type checker) | Keywords: typed-holes | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- When using `ScopedTypeVariables` with typed holes, I want GHC to bend over backwards to preserve the names of type variables that the user has chosen to bring into scope. I can't immediately reproduce the situations I've run into recently where that hasn't happened, but sometimes I've had a signature like {{{#!hs foo :: forall bar . ... foo = ... _ ... }}} and yet the typed hole message shows that `bar` has been lost in unification and replaced by some unrelated name. I would very much prefer if this never happened. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11186> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10954: Add class/context information to typed hole relevant bindings
by GHC 02 Apr '18

02 Apr '18

#10954: Add class/context information to typed hole relevant bindings -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: Type: feature | Status: new request | Priority: normal | Milestone: Component: Compiler | Version: 7.10.2 (Type checker) | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: #9479 Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- GHC's typed hole messages don't currently include any known context information for relevant bindings. For example: {{{#!hs bar :: a ~ b => a -> b -> Int bar x y = _ }}} gets me {{{ Found hole ‘_’ with type: Int Relevant bindings include y :: b (bound at <interactive>:8:42) x :: a (bound at <interactive>:8:40) bar :: a -> b -> Int (bound at <interactive>:8:36) In the expression: _ In an equation for ‘bar’: bar x y = _ }}} The types `a` and `b` are not unified, and the `a ~ b` constraint is not shown. {{{#!hs foo :: Show a => a -> Int foo x = _ }}} gets me {{{ Found hole ‘_’ with type: Int Relevant bindings include x :: a (bound at <interactive>:4:36) foo :: a -> Int (bound at <interactive>:4:32) In the expression: _ In an equation for ‘foo’: foo x = _ }}} The `Show` constraint is lost. === What I want === I'd like context information for all type variables in known bindings, so I can see all the pieces available to help me fill in the hole. === Related ticket === In #9479, Dominique Devriese wants to see any constraints ''on'' an ambiguously-typed hole. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10954> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10267: Add support for typed holes in Template Haskell
by GHC 02 Apr '18

02 Apr '18

#10267: Add support for typed holes in Template Haskell -------------------------------------+------------------------------------- Reporter: jstolarek | 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: | -------------------------------------+------------------------------------- I want to be able to work with typed holes using Template Haskell. These are currently rejected: {{{#!hs [d| i :: a -> a i x = _ |] }}} {{{ Expression form not (yet) handled by Template Haskell _ }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10267> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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