April 2016 - ghc-tickets

[GHC] #11581: TypeError requires UndecidableInstances unnecessarily
by GHC 25 May '16

25 May '16

#11581: TypeError requires UndecidableInstances unnecessarily -------------------------------------+------------------------------------- Reporter: rwbarton | Owner: Type: feature | Status: new request | Priority: low | Milestone: Component: Compiler | Version: 8.0.1-rc2 (Type checker) | 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: -------------------------------------+------------------------------------- The example from the `TypeError` documentation {{{ type family ByteSize x where ByteSize Word16 = 2 ByteSize Word8 = 1 ByteSize a = TypeError (Text "The type " :<>: ShowType a :<>: Text " is not exportable.") }}} requires `UndecidableInstances`: {{{ BS.hs:11:5: error: • The type family application ‘(TypeError ...)’ is no smaller than the instance head (Use UndecidableInstances to permit this) • In the equations for closed type family ‘ByteSize’ In the type family declaration for ‘ByteSize’ }}} Obviously there's no real danger of undecidability here. I tried changing the declaration of `TypeError` to {{{ type family TypeError :: ErrorMessage -> b where }}} but it didn't help. Same error. Is that a bug? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11581> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11993: RFC, allow local bindings in pattern synonyms
by GHC 25 May '16

25 May '16

#11993: RFC, allow local bindings in pattern synonyms -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: Type: feature | Status: new request | Priority: normal | Milestone: Component: Compiler | Version: Keywords: | Operating System: Unknown/Multiple PatternSynonyms | Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Code from #11992, allow users to write something like {{{#!hs pattern Suc :: Int -> Int pattern Suc n <- (hasSuc -> Just n) where Suc n = n + 1 hasSuc :: Int -> Maybe Int hasSuc n = [ n - 1 | n > 0 ] }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11993> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9526: Add missing Generic instances in base
by GHC 25 May '16

25 May '16

#9526: Add missing Generic instances in base -------------------------------------+------------------------------------- Reporter: nh2 | Owner: Type: feature request | Status: new Priority: normal | Milestone: 7.10.1 Component: libraries/base | Version: 7.8.3 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Moderate (less | Type of failure: than a day) | None/Unknown Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Most primitive types (`Int`, `Char`, etc.) have a GHC.Generics.Generic instance, but some are missing, such as `Integer` and the various `Word*` data types. We should consistently have instances for all primitive types offered by base, since they are required if you want to derive a Generic instance for any type that contains them. I boldly set the milestone to 7.10 because I naively assume this should be straightforward. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9526> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10512: Generic instances missing for Int32, Word64 etc.
by GHC 25 May '16

25 May '16

#10512: Generic instances missing for Int32, Word64 etc. -------------------------------------+------------------------------------- Reporter: | Owner: ekmett andreas.abel | Status: new Type: feature | Milestone: request | Version: 7.10.1 Priority: normal | Operating System: Unknown/Multiple Component: Core | Type of failure: None/Unknown Libraries | Blocked By: Keywords: | Related Tickets: Architecture: | Unknown/Multiple | Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Some base types have Generic instances, like Integer, the machine-specific ones like Int32 have none. But these would be most useful when using generic Binary serialization. I think it makes sense to add Generic instances for *all* primitive types in base. I can define the instance myself, see https://github.com/agda/agda/commit/1d3710189989aced61be79c8e52945651fc94c0e {{{#!hs import GHC.Generics (Generic(..)) import qualified GHC.Generics as Gen data D_Int32 data C_Int32 instance Gen.Datatype D_Int32 where datatypeName _ = "Int32" moduleName _ = "GHC.Int32" -- packageName _ = "base" instance Gen.Constructor C_Int32 where conName _ = "" -- JPM: I'm not sure this is the right implementation... instance Generic Int32 where type Rep Int32 = Gen.D1 D_Int32 (Gen.C1 C_Int32 (Gen.S1 Gen.NoSelector (Gen.Rec0 Int32))) from x = Gen.M1 (Gen.M1 (Gen.M1 (Gen.K1 x))) to (Gen.M1 (Gen.M1 (Gen.M1 (Gen.K1 x)))) = x }}} However, as GHC.Generics is a moving target, and changes over the compiler versions, I'd rather not have to. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10512> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10623: Handling of ASCII encodings introduced in D898 breaks Unicode terminal detection
by GHC 24 May '16

24 May '16

#10623: Handling of ASCII encodings introduced in D898 breaks Unicode terminal detection -------------------------------------+------------------------------------- Reporter: bgamari | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.2-rc2 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Blocked By: Test Case: T8958a | Related Tickets: #10298, #7695 Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Phab:D898 was primarily intended to fix hangs in the event that `iconv` was unavailable (namely #10298 and #7695). In addition to this fix, it also introduced self-contained handling of ANSI terminals to allow compiled executables to run in minimal environments lacking iconv. However, the behavior that the patch introduced is highly suspicious. Specifically, it gives the user a UTF-8 encoding even if they requested ASCII. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10623> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11743: Add unicode support for special brackets (`{| |}` and `[| |]`)
by GHC 24 May '16

24 May '16

#11743: Add unicode support for special brackets (`{| |}` and `[| |]`) -------------------------------------+------------------------------------- Reporter: JoshPrice247 | Owner: JoshPrice247 Type: feature | Status: new request | Priority: low | Milestone: Component: Compiler | Version: 7.10.3 (Parser) | Keywords: unicode, | Operating System: Unknown/Multiple UnicodeSyntax | Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: 2878, 10162 Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- This has been mentioned before but didn't have it's own ticket. The following where mentioned in #2978, but the respective patch did not include them: * For TemplateHaskell: `⟦ ⟧` (MATHEMATICAL _ WHITE SQUARE BRACKET) can be used instead of `[| |]` * For Generics: `⦃ ⦄` (_ WHITE CURLY BRACKET) can be used instead of `{| |}` * For Arrows: `⦇ ⦈` (Z NOTATION _ IMAGE BRACKET) can be used instead of `(| |)` Banana brackets were then suggested in #10162 and implemented in Phab:D2012 (which has been accepted, but has not yet landed). -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11743> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11977: ghc doesn't agree with its own inferred pattern type
by GHC 24 May '16

24 May '16

#11977: ghc doesn't agree with its own inferred pattern type -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.1 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: -------------------------------------+------------------------------------- GHCi, version 8.1.20160419: {{{ pattern F a <- (($ 'a') -> a) }}} {{{ >>> :i F pattern F :: b -> Char -> b -- Defined at /tmp/tTaa.hs:24:1 }}} Putting them together: {{{ -- tTaa.hs:25:9: error: … -- • Pattern synonym ‘F’ has one argument -- but its type signature has two -- • In the declaration for pattern synonym ‘F’ Compilation failed. pattern F :: b -> Char -> b pattern F a <- (($ 'a') -> a) }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11977> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11967: Custom message when showing functions, comparing functions, ...
by GHC 23 May '16

23 May '16

#11967: Custom message when showing functions, comparing functions, ... -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: Type: feature | Status: new request | Priority: normal | Milestone: Component: Compiler | Version: 7.10.3 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: -------------------------------------+------------------------------------- One of the [https://ghc.haskell.org/trac/ghc/wiki/Proposal/CustomTypeErrors#Examples examples] of type errors: {{{#!hs instance TypeError (Text "Cannot 'Show' functions." :$$: Text "Perhaps there is a missing argument?") => Show (a -> b) where showsPrec = error "unreachable" }}} We already have [https://hackage.haskell.org/package/base-4.8.2.0/docs/src/Text.Show.Functio… Text.Show.Functions], is there a place in `base` for this along with `Ord (a -> b)` instances and co. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11967> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11034: ghc 7.10.2 testsuite: "T367(normal)" test compilation fails
by GHC 23 May '16

23 May '16

#11034: ghc 7.10.2 testsuite: "T367(normal)" test compilation fails ----------------------------------------+--------------------------------- Reporter: dtonhofer | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Test Suite | Version: 7.10.2 Keywords: | Operating System: Linux Architecture: Unknown/Multiple | Type of failure: None/Unknown Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: ----------------------------------------+--------------------------------- {{{ =====> T367(normal) 39 of 4142 [0, 1, 0] cd ./concurrent/should_run && "/usr/local/bin/ghc" -o T367 T367.hs -fforce-recomp -dcore-lint -dcmm-lint -dno-debug-output -no-user-package- db -rtsopts -fno-warn-tabs -fno-ghci-history -O2 -fno-omit-yields > T367.comp.stderr 2>&1 Compile failed (status 256) errors were: [1 of 1] Compiling Main ( T367.hs, T367.o ) *** Core Lint errors : in result of Simplifier *** <no location info>: Warning: In the expression: seq @ (Id Int) @ (# State# RealWorld, () #) (foldlM' @ Int @ Int @ Id @ Vector $fMonadId ($fNumInt_$c+ `cast` (<Int>_R -> <Int>_R -> Sym (NTCo:Id[0] <Int>_R) :: (Int -> Int -> Int) ~R# (Int -> Int -> Id Int))) z_a2UZ (enumFromTo_int @ Id @ Vector $fMonadId (I# 1) (I# 1000000000))) (# eta_B1, () #) Kinds don't match in type application: Type variable: b_13 :: * Arg type: (# State# RealWorld, () #) :: # xx # (.... offending program attached ...) *** End of Offense *** <no location info>: Compilation had errors *** unexpected failure for T367(normal) }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11034> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8990: Performance tests behave differently depending on presence of .hi file (even with -fforce-recomp)
by GHC 23 May '16

23 May '16

#8990: Performance tests behave differently depending on presence of .hi file (even with -fforce-recomp) ------------------------------------+------------------------------------- Reporter: ezyang | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Test Suite | Version: 7.9 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- Example: {{{ [ezyang@hs01 compiler]$ cat T6048.comp.stats /home/hs01/ezyang/ghc-compalloc/inplace/lib/bin/ghc-stage2 -B/home/hs01/ezyang/ghc-compalloc/inplace/lib -fforce-recomp -dno-debug- output -no-user-package-db -rtsopts -fno-ghci-history -c T6048.hs -O -fasm +RTS -V0 -tT6048.comp.stats --machine-readable [("bytes allocated", "119871672") ,("num_GCs", "100") ,("average_bytes_used", "4388904") ,("max_bytes_used", "12539576") ,("num_byte_usage_samples", "7") ,("peak_megabytes_allocated", "27") ,("init_cpu_seconds", "0.00") ,("init_wall_seconds", "0.00") ,("mutator_cpu_seconds", "0.09") ,("mutator_wall_seconds", "0.10") ,("GC_cpu_seconds", "0.15") ,("GC_wall_seconds", "0.15") ] [ezyang@hs01 compiler]$ rm T6048.hi [ezyang@hs01 compiler]$ '/home/hs01/ezyang/ghc-compalloc/inplace/bin/ghc- stage2' -fforce-recomp -dno-debug-output -no-user-package-db -rtsopts -fno-ghci-history -c T6048.hs -O -fasm +RTS -V0 -tT6048.comp.stats --machine-readable -RTS [ezyang@hs01 compiler]$ cat T6048.comp.stats /home/hs01/ezyang/ghc-compalloc/inplace/lib/bin/ghc-stage2 -B/home/hs01/ezyang/ghc-compalloc/inplace/lib -fforce-recomp -dno-debug- output -no-user-package-db -rtsopts -fno-ghci-history -c T6048.hs -O -fasm +RTS -V0 -tT6048.comp.stats --machine-readable [("bytes allocated", "121022912") ,("num_GCs", "100") ,("average_bytes_used", "4022069") ,("max_bytes_used", "11224944") ,("num_byte_usage_samples", "7") ,("peak_megabytes_allocated", "25") ,("init_cpu_seconds", "0.00") ,("init_wall_seconds", "0.00") ,("mutator_cpu_seconds", "0.09") ,("mutator_wall_seconds", "0.11") ,("GC_cpu_seconds", "0.15") ,("GC_wall_seconds", "0.14") ] }}} It's a slight but present difference: I noticed because one of the perf tests was failing on an initial run of the test suite, but passing when I re-ran it. There are two possible bugs here. One is that our implementation of `-fforce-recomp` is buggy and we shouldn't be reading in the hi file at all if `-fforce-recomp` is on; the other is that we should always clean up interface files before running one of these perf tests. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8990> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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