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[GHC] #12587: InstanceSigs doesn't work with ambigous types
by GHC 30 Nov '16

30 Nov '16

#12587: InstanceSigs doesn't work with ambigous types -------------------------------------+------------------------------------- Reporter: vagarenko | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: GHC rejects Unknown/Multiple | valid program Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Why this code: {{{#!hs {-# LANGUAGE ScopedTypeVariables, InstanceSigs, AllowAmbiguousTypes #-} module Bug where class Foo a class Bar a where bar :: forall b. (Foo b) => a instance Bar Int where bar :: forall b. (Foo b) => Int -- error here bar = undefined where x :: b x = undefined }}} is rejected with message: {{{ Error: * Could not deduce (Foo b0) from the context: Foo b bound by the type signature for: bar :: Foo b => Int at Bug.hs:11:12-35 The type variable `b0' is ambiguous * When checking that: forall b. Foo b => Int is more polymorphic than: forall b. Foo b => Int When checking that instance signature for `bar' is more general than its signature in the class Instance sig: forall b. Foo b => Int Class sig: forall b. Foo b => Int In the instance declaration for `Bar Int' }}} ? Where does `b0` type var come from? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12587> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12902: Improve handle decoding error messages
by GHC 30 Nov '16

30 Nov '16

#12902: Improve handle decoding error messages -------------------------------------+------------------------------------- Reporter: Profpatsch | Owner: Type: feature | Status: new request | Priority: normal | Milestone: Component: | Version: 8.0.1 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: -------------------------------------+------------------------------------- When handle decoding encounters a byte sequence it cannot handle and `ErrorOnCodingFailure` is set, at the moment [https://hackage.haskell.org/package/base-4.9.0.0/docs/src/GHC.IO.Encoding.F… an IO error with a pretty non-descriptive messages is thrown] (`invalid byte sequence`). The user should get a bit more Information in that case: 1) What was the byte sequence that caused the error (and if possible where in the input, of course hard with handles) 2) A stack trace of the functions that caused this (probably from `hGetContents` and similar upwards It’s a very hard-to-debug error with the current implementation. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12902> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12828: Generalize functions from Data.Maybe (‘catMaybes’, ‘mapMaybe’)
by GHC 30 Nov '16

30 Nov '16

#12828: Generalize functions from Data.Maybe (‘catMaybes’, ‘mapMaybe’) -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: Type: feature | Status: new request | Priority: lowest | Milestone: Component: Core | Version: 8.0.1 Libraries | 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: -------------------------------------+------------------------------------- Opening a ticket for discussion. As mentioned in [https://www.reddit.com/r/haskell/comments/2y2pe5/shouldnt_ftp_propagate_cha… this comment], more functions can be generalized to `Foldable` {{{#!hs catMaybes :: Foldable f => f (Maybe a) -> [a] mapMaybe :: Foldable f => (a -> Maybe b) -> (f a -> [b]) listToMaybe :: Foldable f => f a -> Maybe a }}} I think `catMaybes` and `mapMaybe` are fine candidates. The comment offers more extreme changes, {{{#!hs catMaybes :: (Foldable f, Foldable g) => Foldable f => f (g a) -> [a] mapMaybes :: (Foldable f, Foldable g) => (a -> f b) -> (f a -> [b]) }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12828> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #11445: Turn on SplitSections by default
by GHC 30 Nov '16

30 Nov '16

#11445: Turn on SplitSections by default -------------------------------------+------------------------------------- Reporter: ezyang | Owner: Type: task | Status: new Priority: normal | Milestone: 8.2.1 Component: Build System | Version: 8.0.1-rc1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: 11285 Related Tickets: | Differential Rev(s): Phab:D1800 Wiki Page: | -------------------------------------+------------------------------------- Comment (by Phyx-): @awson never put his patches up. So at the moment, `-split-sections` does not work on PE targets. So no, you can't flip it on yet. I'm working on getting things up and running. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11445#comment:9> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8974: 64 bit windows executable built with ghc-7.9.20140405+LLVM segfaults
by GHC 30 Nov '16

30 Nov '16

#8974: 64 bit windows executable built with ghc-7.9.20140405+LLVM segfaults -----------------------------------+---------------------------------- Reporter: awson | Owner: Type: bug | Status: new Priority: high | Milestone: 7.8.2 Component: Compiler (LLVM) | Version: 7.9 Keywords: | Operating System: Windows Architecture: x86_64 (amd64) | Type of failure: Runtime crash Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | -----------------------------------+---------------------------------- {{{ -- test.hs import System.Mem (performMajorGC) main = performMajorGC >> putStrLn "Done" }}} built with `ghc -pgmlo opt -pgmlc llc -fllvm --make test.hs` segfaults both for LLVM 3.4 and 3.5svn (taken from http://sourceforge.net/projects/msys2/files/REPOS/MINGW/x86_64) 32-bit ghc-7.9.20140404+llvm produces good executable. Adding `ArchX86_64` `OSMinGW32` case to `moduleLayout` in `compiler/llvmGen/LlvmCodeGen/Ppr.hs` improves things slightly (some code segfaulting without it starts to work) but still does not cure the code above. Also I've found the Cmm produced for LLVM CG differs from that produced for NCG. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8974> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12725: T7037 is broken on Windows
by GHC 30 Nov '16

30 Nov '16

#12725: T7037 is broken on Windows --------------------------------------+--------------------------------- Reporter: bgamari | Owner: Type: bug | Status: new Priority: normal | Milestone: 8.2.1 Component: Compiler | Version: 8.1 Keywords: | Operating System: Windows Architecture: x86_64 (amd64) | Type of failure: None/Unknown Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: --------------------------------------+--------------------------------- `T7037` appears to fail on Windows. Namely, `stdout` appears to be empty, whereas the expected output is `"ok"`. I had suspected that the issue was the `execv` call failing but this doesn't seem to be thew case; no code after `execv` is executed. A problem for another day... -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12725> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12554: Testsuite exibits large amount of framework failures
by GHC 30 Nov '16

30 Nov '16

#12554: Testsuite exibits large amount of framework failures -------------------------------------+------------------------------------- Reporter: Phyx- | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Test Suite | Version: 8.0.1 Keywords: | Operating System: Windows Architecture: | Type of failure: Incorrect result Unknown/Multiple | at runtime Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I've tried this on multiple computers and they all have the same issue. I get around 400 testsuite failures with the error: {{{ r:/temp/ghctest-0u4c8o/test spaces/./th/T11680.run T11680 [ext-interp] ([Error 183] Cannot create a file when that file already exists: 'r:/temp/ghctest-0u4c8o/test spaces/./th/T11680.run') r:/temp/ghctest-0u4c8o/test spaces/./th/T11797.run T11797 [ext-interp] ([Error 183] Cannot create a file when that file already exists: 'r:/temp/ghctest-0u4c8o/test spaces/./th/T11797.run') r:/temp/ghctest-0u4c8o/test spaces/./th/T10734.run T10734 [ext-interp] ([Error 183] Cannot create a file when that file already exists: 'r:/temp/ghctest-0u4c8o/test spaces/./th/T10734.run') r:/temp/ghctest-0u4c8o/test spaces/./th/T11345.run T11345 [ext-interp] ([Error 183] Cannot create a file when that file already exists: 'r:/temp/ghctest-0u4c8o/test spaces/./th/T11345.run') r:/temp/ghctest-0u4c8o/test spaces/./th/T10820.run T10820 [ext-interp] ([Error 183] Cannot create a file when that file already exists: 'r:/temp/ghctest-0u4c8o/test spaces/./th/T10820.run') r:/temp/ghctest-0u4c8o/test spaces/./th/T11484.run T11484 [ext-interp] ([Error 183] Cannot create a file when that file already exists: 'r:/temp/ghctest-0u4c8o/test spaces/./th/T11484.run') r:/temp/ghctest-0u4c8o/test spaces/./th/T9022.run T9022 [ext-interp] ([Error 183] Cannot create a file when that file already exists: 'r:/temp/ghctest-0u4c8o/test spaces/./th/T9022.run') r:/temp/ghctest-0u4c8o/test spaces/./th/T12130.run T12130 [ext-interp] ([Error 183] Cannot create a file when that file already exists: 'r:/temp/ghctest-0u4c8o/test spaces/./th/T12130.run') r:/temp/ghctest-0u4c8o/test spaces/./th/T8761.run T8761 [ext-interp] ([Error 183] Cannot create a file when that file already exists: 'r:/temp/ghctest-0u4c8o/test spaces/./th/T8761.run') r:/temp/ghctest-0u4c8o/test spaces/./th/T12407.run T12407 [ext-interp] ([Error 183] Cannot create a file when that file already exists: 'r:/temp/ghctest-0u4c8o/test spaces/./th/T12407.run') r:/temp/ghctest-0u4c8o/test spaces/./th/T11463.run T11463 [ext-interp] ([Error 183] Cannot create a file when that file already exists: 'r:/temp/ghctest-0u4c8o/test spaces/./th/T11463.run') r:/temp/ghctest-0u4c8o/test spaces/./th/T12478_4.run T12478_4 [ext-interp] ([Error 183] Cannot create a file when that file already exists: 'r:/temp/ghctest-0u4c8o/test spaces/./th/T12478_4.run') r:/temp/ghctest-0u4c8o/test spaces/./th/T12478_3.run T12478_3 [ext-interp] ([Error 183] Cannot create a file when that file already exists: 'r:/temp/ghctest-0u4c8o/test spaces/./th/T12478_3.run') r:/temp/ghctest-0u4c8o/test spaces/./th/T12513.run T12513 [ext-interp] ([Error 183] Cannot create a file when that file already exists: 'r:/temp/ghctest-0u4c8o/test spaces/./th/T12513.run') r:/temp/ghctest-0u4c8o/test spaces/./th/T12530.run T12530 [ext-interp] ([Error 183] Cannot create a file when that file already exists: 'r:/temp/ghctest-0u4c8o/test spaces/./th/T12530.run') }}} What they all have in common is that they are all using the latest MSYS2 and tools: {{{ Tamar@Squid MINGW64 ~/ghc $ python3 --version Python 3.5.2 Tamar@Squid MINGW64 ~/ghc $ uname -a MINGW64_NT-10.0 Kino 2.5.2(0.297/5/3) 2016-07-15 08:31 x86_64 Msys }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12554> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #11445: Turn on SplitSections by default
by GHC 30 Nov '16

30 Nov '16

#11445: Turn on SplitSections by default -------------------------------------+------------------------------------- Reporter: ezyang | Owner: Type: task | Status: new Priority: normal | Milestone: 8.2.1 Component: Build System | Version: 8.0.1-rc1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: 11285 Related Tickets: | Differential Rev(s): Phab:D1800 Wiki Page: | -------------------------------------+------------------------------------- Comment (by dobenour): Is there anything left before we can do this? If not I will go ahead and put a patch up on Phabricator that makes `-split-objs` a deprecated synonym for `-split-sections`. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11445#comment:8> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #2168: ghci should show haddock comments for identifier
by GHC 30 Nov '16

30 Nov '16

#2168: ghci should show haddock comments for identifier -------------------------------------+------------------------------------- Reporter: j.waldmann | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: GHCi | Version: 6.8.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by adamse): Doing some more investigations it might make more sense to add the docs to `HscTypes.ModIface` in a fashion similar to how Haddock does in its `Interface` type. This would also add the possibility of docs for unexported entities as Haddock currently supports. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/2168#comment:27> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11219: Implement fine-grained `-Werror=...` facility
by GHC 30 Nov '16

30 Nov '16

#11219: Implement fine-grained `-Werror=...` facility -------------------------------------+------------------------------------- Reporter: hvr | Owner: quchen Type: feature | Status: new request | Priority: normal | Milestone: 8.2.1 Component: Compiler | Version: 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: Design/Warnings -------------------------------------+------------------------------------- ...copied from Design/Warnings: Introduce variant of `-Werror` (c.f. GCC's `-Werror=*`) which allows to specify the individual warnings to be promoted to errors, e.g. - `-Wall -Werror=orphans` would only promote `-Worphans` warnings into errors - `-Wall -Werror -Wno-error=missing-methods` would promote all warnings //except// `-Wmissing-methods` into errors TODO: specify semantics a bit more exactly (the basic idea is to follow gcc/clang as much as sensible, and only deviate where it's necessary) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11219> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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