January 2019 - ghc-tickets

[GHC] #14419: Check kinds for ambiguity
by GHC 27 Feb '19

27 Feb '19

#14419: Check kinds for ambiguity -------------------------------------+------------------------------------- Reporter: goldfire | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.1 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: -------------------------------------+------------------------------------- GHC does an ambiguity check on types. It should also do the same for kinds. Here is a program that should be rejected: {{{#!hs type family F a data T :: F a -> Type }}} `T`'s kind is ambiguous, and any occurrence of `T` will be rejected. Instead of rejecting usage sites, let's just reject the definition site. This check would be disabled by `AllowAmbiguousTypes`. Happily, I think the implementation should be easy, and that the current algorithm to check for ambiguous types should work for kinds, too. After all, types and kinds are the same these days. This was inspired by #14203, but no need to read that ticket to understand this one. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14419> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13408: Consider inferring a higher-rank kind for type synonyms
by GHC 27 Feb '19

27 Feb '19

#13408: Consider inferring a higher-rank kind for type synonyms -------------------------------------+------------------------------------- Reporter: goldfire | Owner: (none) Type: feature | Status: new request | Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: TypeInType | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- In terms, a definition comprising one non-recursive equation may have a higher-rank type inferred. For example: {{{#!hs f :: (forall a. a -> a -> a) -> Int f z = z 0 1 g = f }}} `g` gets an inferred type equal to `f`'s. However, this fails at the type level: {{{#!hs type F (z :: forall a. a -> a -> a) = z 0 1 type G = F }}} If anything is strange here, it's that the term-level definition is accepted. GHC should not be in the business of inferring higher-rank types. But there is an exception for definitions comprising one non- recursive equation. This ticket proposes expanding this behavior to the type level, allowing `G` to be accepted. This is spun off from #13399, but is not tightly coupled to that ticket. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13408> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15755: randomRIO panic on (GHC version 8.4.3 for x86_64-apple-darwin)
by GHC 27 Feb '19

27 Feb '19

#15755: randomRIO panic on (GHC version 8.4.3 for x86_64-apple-darwin) -------------------------------------+------------------------------------- Reporter: cmal | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.4.3 Keywords: randomRIO | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- randomRIO (1,100) ghc: panic! (the 'impossible' happened) (GHC version 8.4.3 for x86_64-apple-darwin): nameModule system $dShow_a78p Call stack: CallStack (from HasCallStack): callStackDoc, called at compiler/utils/Outputable.hs:1150:37 in ghc:Outputable pprPanic, called at compiler/basicTypes/Name.hs:241:3 in ghc:Name Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15755> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #16080: runTestTT from ghci caused a panic.
by GHC 27 Feb '19

27 Feb '19

#16080: runTestTT from ghci caused a panic. -------------------------------------+------------------------------------- Reporter: | Owner: (none) emacstheviking | Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.4.4 Keywords: | Operating System: Unknown/Multiple Architecture: x86 | Type of failure: Compile-time | crash or panic Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Inside a REPL within Emacs+Intero-mode, running a stack project. I am writing a simple lexer for fun and I decided to try to see why I wasn't getting expected behaviour from an HUnit function. {{{ runTestTT classificationTests ghc: panic! (the 'impossible' happened) (GHC version 8.4.4 for x86_64-unknown-linux): nameModule system $dShow_a5Xw Call stack: CallStack (from HasCallStack): callStackDoc, called at compiler/utils/Outputable.hs:1150:37 in ghc:Outputable pprPanic, called at compiler/basicTypes/Name.hs:241:3 in ghc:Name }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16080> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #16088: The 'impossible' happened when I was trying to use getCurrentDirectory in repl in spacemacs.
by GHC 27 Feb '19

27 Feb '19

#16088: The 'impossible' happened when I was trying to use getCurrentDirectory in repl in spacemacs. -------------------------------------+------------------------------------- Reporter: hanrai | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.4.4 Keywords: | Operating System: Windows Architecture: x86_64 | Type of failure: None/Unknown (amd64) | Test Case: | Blocked By: getCurrentDirectory | Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I got this message when I type 'getCurrentDirectory' in repl in spacemacs. ghc.exe: panic! (the 'impossible' happened) (GHC version 8.4.4 for x86_64-unknown-mingw32): nameModule system $dShow_adyn Call stack: CallStack (from HasCallStack): callStackDoc, called at compiler\utils\Outputable.hs:1150:37 in ghc:Outputable pprPanic, called at compiler\basicTypes\Name.hs:241:3 in ghc:Name Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16088> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15463: "Serious" validation failures on i686
by GHC 26 Feb '19

26 Feb '19

#15463: "Serious" validation failures on i686 -------------------------------------+------------------------------------- Reporter: alpmestan | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.5 Keywords: | Operating System: Linux Architecture: x86 | Type of failure: None/Unknown Test Case: T3171, | Blocked By: heapprof001 | Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- A very recent run of `./validate` on i686 revealed 6 failures, 4 of which I'm hopefully fixing with [https://phabricator.haskell.org/D5031 D5031], but the other two look more serious. The circle ci build logs are here: https://circleci.com/gh/ghc/ghc/7578 One of the remaining failures in particular seems somewhat critical: {{{ Wrong exit code for heapprof001(prof_hc_hb)(expected 0 , actual 139 ) Stdout ( heapprof001 ): a <= a <= a <= a <= a <= a <= a <= Stderr ( heapprof001 ): Segmentation fault *** unexpected failure for heapprof001(prof_hc_hb) }}} While the other one might be a lot simpler: {{{ Actual stdout output differs from expected: --- ./ghci/should_run/T3171.run/T3171.stdout.normalised 2018-07-31 05:27:01.821192706 +0000 +++ ./ghci/should_run/T3171.run/T3171.run.stdout.normalised 2018-07-31 05:27:01.821192706 +0000 @@ -1 +0,0 @@ -Interrupted. *** unexpected failure for T3171(normal) }}} I have not investigated any of those yet, but the first one does seem like a bug. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15463> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15936: Rethink Choice of Baseline Commit for Performance Tests
by GHC 25 Feb '19

25 Feb '19

#15936: Rethink Choice of Baseline Commit for Performance Tests -------------------------------------+------------------------------------- Reporter: davide | Owner: (none) Type: task | Status: new Priority: normal | Milestone: 8.6.3 Component: Test Suite | Version: 8.6.2 Keywords: performance | Operating System: Unknown/Multiple tests git notes | Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- = Intro = Currently we always use the previous commit when running performance tests. This works well in CI where we fully test each commit in sequence (and hence always have test results for the previous commit). Remember, test results are stored in git notes and are not by default shared between repositories (i.e. your local repo will only have performance results run locally on your machine). This is by design: we want to avoid comparing results form different machines. Unfortunately This is not so effective when testing locally. The programmer may have only run a subset of performance tests on the previous commit, and often have not run the tests at all (this is notably true after performing a rebase: the previous commit has changed). We need to rethink how we pick a baseline commit. = Goals = * In all cases, do something sensible. * Giving a warning if conditions are not idea. Provide clear and simple instructions on how to get to the ideal case. * Give control over the baseline commit to the programmer via command line options. * In general, performance tests should just work! No extra knowledge needed by the programmer. * If tests pass without warning now, then they should pass without warning later. = Proposed Solution = * Choose baseline commit * Provide command line arguments to set the baseline commit * If not baseline commit is provided use the "Ideal baseline commit". * If local test results for the baseline are available use those results. * Else if results from CI are available (without fetching), then use those results. * Else Warn user that there are no results available (tests trivially pass), then suggest fetching CI results (quick and easy, give full command, mention you may have to wait for CI to finish if the commit is recent) or running locally (more accurate, mention exact commit to checkout), or manually select a baseline commit. == Ideal baseline commit == * If there are no new changes: 0 ahead and 0 or more behind master. * Ideal baseline commit is the previous commit. * Else 1 or more ahead and 0 or more behind master. * Ideal baseline commit is `merge-base master HEAD` * Assume that the intention is to create a patch where all new commits will ultimately be squashed and placed on top of master. We only want to consider performance changes caused by the new commits, so we use the merge base instead of master HEAD (though these may be the same commit). = Open issues = If commits between HEAD and the baseline commit [https://ghc.haskell.org/trac/ghc/wiki/Performance/Tests#ExpectedPerformance… allow changes] in performance numbers, what should the behaviour be? What happens if this is merged? The commits will be squashed: this could affect the commit message and hence the allowed changes which is parsed from the commit messages. = Use cases = TODO This section is a WIP We generally will assume that the master branch corresponds to ghc's master branch (though may be slightly out of date). ||= Case =||= Details =||= Baseline =|| || 0 commits ahead of master || May be on master or branched off master with no new commits || previous commit || || CI pre-merge || || CI post-merge -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15936> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10170: Find versioned versions of LLVM tools
by GHC 25 Feb '19

25 Feb '19

#10170: Find versioned versions of LLVM tools -------------------------------------+------------------------------------- Reporter: erikd | Owner: erikd Type: bug | Status: new Priority: normal | Milestone: 7.12.1 Component: Compiler | Version: 7.11 (LLVM) | Operating System: Unknown/Multiple Keywords: | Type of failure: None/Unknown Architecture: | Blocked By: Unknown/Multiple | Related Tickets: Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Since it has become more widely know that the LLVM developers often make breaking changes to the IR language between releases, some Linu distributions (eg Debain and hence Ubuntu) have started doing multi- version LLVM installs. For instance on Debian, the llvm-3.6 programs are installed in `/usr/lib/llvm-3.6/bin` as `llc` and `opt`. I propose that the `configure.ac` and `aclocal.m4` configuration goop be modified to look for `llc` and `opt` in these versioned `/usr/lib/llvm-X.Y` locations. I'm also willing to do the hard yards on implementing this if people think its a good idea. This can be seen as a step along the way to more stringent LLVM versioning requirements. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10170> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #16087: TH tests fail in ext-interp way when ghc-stage2 is built using LLVM
by GHC 25 Feb '19

25 Feb '19

#16087: TH tests fail in ext-interp way when ghc-stage2 is built using LLVM -------------------------------------+------------------------------------- Reporter: bgamari | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.8.1 Component: Compiler | Version: 8.6.3 (LLVM) | 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: -------------------------------------+------------------------------------- This is a continuation of #15274. Currently the testsuite fails with around 40 test failures, all in `th/` in the `ext-interp` way when building GHC with `BUILD_FLAVOUR=perf-llvm`: {{{ Unexpected results from: TEST="ClosedFam1TH T10620 T10828 T11721_TH T11797 T12478_1 T12646 T13642 T14060 T15502 T15738 T15792 T15845 T1835 T3920 T4135 T4188 T5037 T5362 T7477 T8761 T8884 T8953 T9262 T9692 T9738 TH_RichKinds TH_RichKinds2 TH_Roles3 TH_TyInstWhere2 TH_implicitParams TH_reifyDecl1 TH_reifyExplicitForAllFams TH_reifyInstances TH_reifyMkName TH_repE2 TH_repGuard TH_repPrim TH_repPrim2 TH_repUnboxedTuples" SUMMARY for test run started at Sun Dec 23 06:01:39 2018 UTC 0:10:09 spent to go through 6745 total tests, which gave rise to 26266 test cases, of which 19055 were skipped 42 had missing libraries 7040 expected passes 89 expected failures 0 caused framework failures 0 caused framework warnings 0 unexpected passes 40 unexpected failures 0 unexpected stat failures Unexpected failures: th/TH_repE2.run TH_repE2 [exit code non-0] (ext- interp) th/TH_repPrim.run TH_repPrim [exit code non-0] (ext- interp) th/TH_repPrim2.run TH_repPrim2 [exit code non-0] (ext- interp) th/TH_repUnboxedTuples.run TH_repUnboxedTuples [exit code non-0] (ext-interp) th/TH_repGuard.run TH_repGuard [exit code non-0] (ext- interp) th/TH_reifyDecl1.run TH_reifyDecl1 [exit code non-0] (ext-interp) th/TH_reifyMkName.run TH_reifyMkName [exit code non-0] (ext-interp) th/TH_reifyInstances.run TH_reifyInstances [exit code non-0] (ext-interp) th/TH_reifyExplicitForAllFams.run TH_reifyExplicitForAllFams [exit code non-0] (ext-interp) th/T3920.run T3920 [exit code non-0] (ext-interp) th/T4188.run T4188 [exit code non-0] (ext-interp) th/T1835.run T1835 [exit code non-0] (ext-interp) th/T5037.run T5037 [exit code non-0] (ext-interp) th/T5362.run T5362 [exit code non-0] (ext-interp) th/TH_RichKinds.run TH_RichKinds [exit code non-0] (ext- interp) th/TH_RichKinds2.run TH_RichKinds2 [exit code non-0] (ext-interp) th/T4135.run T4135 [exit code non-0] (ext-interp) th/TH_TyInstWhere2.run TH_TyInstWhere2 [exit code non-0] (ext-interp) th/ClosedFam1TH.run ClosedFam1TH [exit code non-0] (ext- interp) th/TH_Roles3.run TH_Roles3 [exit code non-0] (ext- interp) th/T7477.run T7477 [exit code non-0] (ext-interp) th/T8884.run T8884 [exit code non-0] (ext-interp) th/T9262.run T9262 [exit code non-0] (ext-interp) th/T9692.run T9692 [exit code non-0] (ext-interp) th/T8953.run T8953 [exit code non-0] (ext-interp) th/T9738.run T9738 [exit code non-0] (ext-interp) th/T10620.run T10620 [exit code non-0] (ext- interp) th/T10828.run T10828 [exit code non-0] (ext- interp) th/T11721_TH.run T11721_TH [exit code non-0] (ext- interp) th/T11797.run T11797 [exit code non-0] (ext- interp) th/T8761.run T8761 [exit code non-0] (ext-interp) th/T12478_1.run T12478_1 [exit code non-0] (ext- interp) th/T12646.run T12646 [exit code non-0] (ext- interp) th/T13642.run T13642 [exit code non-0] (ext- interp) th/T14060.run T14060 [exit code non-0] (ext- interp) th/T15502.run T15502 [exit code non-0] (ext- interp) th/TH_implicitParams.run TH_implicitParams [exit code non-0] (ext-interp) th/T15738.run T15738 [exit code non-0] (ext- interp) th/T15792.run T15792 [exit code non-0] (ext- interp) th/T15845.run T15845 [exit code non-0] (ext- interp) }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16087> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #16130: GHC Panic on OS X: Data.Binary.Get.runGet: Invalid magic number "INPUT(-l"
by GHC 25 Feb '19

25 Feb '19

#16130: GHC Panic on OS X: Data.Binary.Get.runGet: Invalid magic number "INPUT(-l" ----------------------------------------+--------------------------------- Reporter: basvandijk | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.6.3 Keywords: | Operating System: MacOS X Architecture: Unknown/Multiple | Type of failure: None/Unknown Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: ----------------------------------------+--------------------------------- When building the latest `opencv-extra` library on OS X I'm getting a GHC panic. To reproduce git clone https://github.com/LumiGuide/haskell-opencv, make sure Nix is installed and execute: {{{ > nix-build -A haskellPackages.opencv-extra ... [11 of 11] Compiling OpenCV.Extra ( src/OpenCV/Extra.hs, dist/build/OpenCV/Extra.p_o ) ghc: panic! (the 'impossible' happened) (GHC version 8.6.3 for x86_64-apple-darwin): Data.Binary.Get.runGet at position 8: Invalid magic number "INPUT(-l" CallStack (from HasCallStack): error, called at libraries/binary/src/Data/Binary/Get.hs:351:5 in binary-0.8.6.0:Data.Binary.Get }}} The library builds successfully on Linux. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16130> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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