March 2018 - ghc-tickets

[GHC] #14957: Build failure in brew
by GHC 21 Mar '18

21 Mar '18

#14957: Build failure in brew -------------------------------------+------------------------------------- Reporter: cafeface | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.2 Keywords: | Operating System: Unknown/Multiple Architecture: x86_64 | Type of failure: None/Unknown (amd64) | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- {{{ <<ghc: 363750120 bytes, 52 GCs, 13614472/30938760 avg/max bytes residency (5 samples), 66M in use, 0.001 INIT (0.004 elapsed), 0.334 MUT (0.568 elapsed), 0.258 GC (0.282 elapsed) :ghc>> <<ghc: 397153072 bytes, 78 GCs, 21276817/54983536 avg/max bytes residency (6 samples), 114M in use, 0.000 INIT (0.002 elapsed), 0.365 MUT (0.657 elapsed), 0.441 GC (0.483 elapsed) :ghc>> <<ghc: 719939400 bytes, 98 GCs, 19391118/49063352 avg/max bytes residency (6 samples), 105M in use, 0.001 INIT (0.003 elapsed), 0.595 MUT (0.893 elapsed), 0.478 GC (0.524 elapsed) :ghc>> ghc: internal error: evacuate(static): strange closure type 0 (GHC version 8.4.1 for x86_64_apple_darwin) Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug make[1]: *** [libraries/Cabal/Cabal/dist- boot/build/Distribution/Simple/Setup.o] Abort trap: 6 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14957> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14869: Documentation for isLiftedTypeKind is incorrect
by GHC 21 Mar '18

21 Mar '18

#14869: Documentation for isLiftedTypeKind is incorrect -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.2 (Type checker) | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Documentation Unknown/Multiple | bug Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I [https://github.com/ghc-proposals/ghc- proposals/pull/32#issuecomment-369252383 noticed recently] that Template Haskell reifies `Constraint` as `Type`: {{{#!hs $ ~/Software/ghc2/inplace/bin/ghc-stage2 --interactive GHCi, version 8.5.20180221: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/rgscott/.ghci λ> :set -XTypeFamilies -XTemplateHaskell λ> :m + Data.Kind Language.Haskell.TH λ> type family Foo :: Constraint λ> putStrLn $(reify ''Foo >>= stringE . pprint) type family Ghci1.Foo :: * }}} The root of the issue can be traced back to the `isLiftedTypeKind` function, which `TcSplice` uses to distinguish `Type` from `Constraint`. At least, that's what its [http://git.haskell.org/ghc.git/blob/df2c3b3364834d2fd038192c89348fc50a2e047… documentation] claims: {{{ -- | This version considers Constraint to be distinct from *. Returns True -- if the argument is equivalent to Type and False otherwise. isLiftedTypeKind :: Kind -> Bool isLiftedTypeKind = is_TYPE is_lifted where is_lifted (TyConApp lifted_rep []) = lifted_rep `hasKey` liftedRepDataConKey is_lifted _ = False }}} However, in practice this claim about treating `Constraint` and `Type` as distinct is false: {{{ $ ~/Software/ghc2/inplace/bin/ghc-stage2 --interactive -package ghc GHCi, version 8.5.20180221: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/rgscott/.ghci λ> :m + TyCoRep TysWiredIn λ> isLiftedTypeKind liftedTypeKind True λ> isLiftedTypeKind constraintKind True }}} Either we should change the implementation of `isLiftedTypeKind` to match the documentation's claim, or change the documentation. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14869> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14598: 32-bit Linux environment
by GHC 21 Mar '18

21 Mar '18

#14598: 32-bit Linux environment -------------------------------------+------------------------------------- Reporter: bgamari | Owner: bgamari Type: bug | Status: new Priority: normal | Milestone: Component: Continuous | Version: 8.2.1 Integration | 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: -------------------------------------+------------------------------------- Currently we lack any 32-bit test environment on CircleCI. This will need to change as we still provide 32-bit binary distributions and Harbormaster currently does have a 32-bit test target. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14598> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14935: Vary default RTS settings so that performance does not degrade with increasing number of capabilities
by GHC 21 Mar '18

21 Mar '18

#14935: Vary default RTS settings so that performance does not degrade with increasing number of capabilities -------------------------------------+------------------------------------- Reporter: YitzGale | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.2 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 the number of capabilities increases to 32 or more, which is common nowadays, performance of GHC-compiled applications, hence also of GHC itself, begins to degrade considerably with default RTS settings. It should not be required to optimize RTS settings manually to get applications to be usable. By default, GHC should use at least sane RTS settings appropriate for the number of capabilities, even if not optimized. See: https://www.reddit.com/r/haskell/comments/83e6dq/need_advice_on_compile_and… for some of the RTS settings you need to change to get things working. Here is a sample use case - we needed to increase memory by a lot to work around #14928. We don't care about extra cores, but we get them automatically when we enlarge our EC2 instance to have enough memory. The compile is run by deployment engineers - non-Haskell-programmers - via build tools that normally do not give easy access to RTS options on the individual {{{ghc}}} commands that run during the build ({{{yesod keter}}} in this case). We just want the build to run no worse than if there were 4 cores, or even 1 core. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14935> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #5129: "evaluate" optimized away
by GHC 21 Mar '18

21 Mar '18

#5129: "evaluate" optimized away -------------------------------------+------------------------------------- Reporter: dons | Owner: (none) Type: bug | Status: merge Priority: normal | Milestone: 8.4.2 Component: Compiler | Version: 7.0.3 Resolution: | Keywords: seq, evaluate Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect result | Unknown/Multiple at runtime | Test Case: Blocked By: | Blocking: Related Tickets: #13930 | Differential Rev(s): Phab:D615, Wiki Page: | Phab:D4514 -------------------------------------+------------------------------------- Changes (by osa1): * status: new => merge Comment: Thanks Simon, the notes are really helpful. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/5129#comment:37> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14946: GHC Calls CPP for HS with -undef
by GHC 21 Mar '18

21 Mar '18

#14946: GHC Calls CPP for HS with -undef -------------------------------------+------------------------------------- Reporter: Phyx- | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.2 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Incorrect result Unknown/Multiple | at runtime Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- GHC Is calling the C preprocessor when processing HS files with `-undef` which unsets and compiler pre-defines. Essentially it means you cannot use any normal compiler defines to check for platform or intrinsics support. Is this really the intended behavior? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14946> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14844: SpecConstr also non-recursive function
by GHC 21 Mar '18

21 Mar '18

#14844: SpecConstr also non-recursive function -------------------------------------+------------------------------------- Reporter: nomeata | Owner: (none) Type: task | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.5 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: -------------------------------------+------------------------------------- In order to fix the regressions introduced by loopification (#14068), we probably need to get !SpecConstr also do something about non-recursive functions. In a first iteration, we might want to enable it for non-recursive functions straight-away, and see if it fixes the regressions introduced by Loopification. But if this turns out to be too slow/too expensive, we should try specializing non-recursive ''local'' functions ''if there is only one call-patterns''. That ought to be a straight win in all cases anyways. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14844> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14952: Warning messages use white text which is unreadable on white background terminals
by GHC 21 Mar '18

21 Mar '18

#14952: Warning messages use white text which is unreadable on white background terminals -------------------------------------+------------------------------------- Reporter: Koterpillar | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.2 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 using a terminal with white background, the error messages such as "addDependentFile path (Template Haskell) listed in [...] does not exist" are partially unreadable, see screenshot. No text should be output as explicitly white, at least not without checking the terminal colors. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14952> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #5129: "evaluate" optimized away
by GHC 20 Mar '18

20 Mar '18

#5129: "evaluate" optimized away -------------------------------------+------------------------------------- Reporter: dons | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.4.2 Component: Compiler | Version: 7.0.3 Resolution: | Keywords: seq, evaluate Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect result | Unknown/Multiple at runtime | Test Case: Blocked By: | Blocking: Related Tickets: #13930 | Differential Rev(s): Phab:D615, Wiki Page: | Phab:D4514 -------------------------------------+------------------------------------- Comment (by Simon Peyton Jones <simonpj@…>): In [changeset:"abaf43d9d88d6fdf7345b936a571d17cfe1fa140/ghc" abaf43d/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="abaf43d9d88d6fdf7345b936a571d17cfe1fa140" Fix seq# case of exprOkForSpeculation This subtle patch fixes Trac #5129 (again; comment:20 and following). I took the opportunity to document seq# properly; see Note [seq# magic] in PrelRules, and Note [seq# and expr_ok] in CoreUtils. }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/5129#comment:36> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #5129: "evaluate" optimized away
by GHC 20 Mar '18

20 Mar '18

#5129: "evaluate" optimized away -------------------------------------+------------------------------------- Reporter: dons | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.4.2 Component: Compiler | Version: 7.0.3 Resolution: | Keywords: seq, evaluate Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect result | Unknown/Multiple at runtime | Test Case: Blocked By: | Blocking: Related Tickets: #13930 | Differential Rev(s): Phab:D615, Wiki Page: | Phab:D4514 -------------------------------------+------------------------------------- Changes (by simonmar): * cc: simonmar (added) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/5129#comment:35> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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