December 2018 - ghc-tickets

[GHC] #16016: Hadrian build fails on FreeBSD
by GHC 10 Dec '18

10 Dec '18

#16016: Hadrian build fails on FreeBSD -------------------------------------+------------------------------------- Reporter: bgamari | Owner: (none) Type: bug | Status: new Priority: high | Milestone: 8.10.1 Component: Build System | Version: 8.7 (Hadrian) | 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 plain hadrian build using `hadrian/build.cabal.sh` fails with {{{ /---------------------------------------------------------------------------------\ | Successfully built program 'ghc-pkg' (Stage0). | | Executable: _build/stage0/bin/ghc-pkg | | Program synopsis: A utility for querying and managing the GHC package database. | \---------------------------------------------------------------------------------/ hadrian: '/usr/home/ben/ghc/_build/stage0/bin/ghc' exited with an error: ghc: missing -B<dir> option shakeArgsWith 0.000s 0% Function shake 0.392s 0% Database read 0.000s 0% With database 0.000s 0% Running rules 1725.240s 99% ========================= Total 1725.633s 100% Error when running Shake build system: at src/Rules.hs:(32,19)-(45,17): at src/Rules.hs:45:5-17: * Depends on: _build/stage1/lib/bin/unlit at src/Development/Shake/Internal/Rules/Oracle.hs:157:43-68: * Depends on: OracleQ (PackageDataFile (Context {stage = Stage1, package = Package {pkgLanguage = Haskell, pkgType = Program, pkgName = "unlit", pkgPath = "utils/unlit"}, way = v})) at src/Hadrian/Haskell/Cabal/Parse.hs:200:5-36: * Depends on: _build/stage1/utils/unlit/setup-config * Raised the exception: ExitFailure 1 }}} on FreeBSD 11 on amd64. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16016> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15769: GHC 8.6 for macOS depends on homebrew
by GHC 10 Dec '18

10 Dec '18

#15769: GHC 8.6 for macOS depends on homebrew -------------------------------------+------------------------------------- Reporter: kazu-yamamoto | Owner: (none) Type: bug | Status: new Priority: highest | Milestone: 8.6.2 Component: Compiler | Version: 8.6.1 Keywords: | Operating System: MacOS X Architecture: | Type of failure: Installing GHC Unknown/Multiple | failed Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I guess the ghc-8.6.1-x86_64-apple-darwin.tar.xz is build with homebrew. So, it depends on homebrew's "libgmp". Since I'm using MacPorts, the following error occurs on installation: {{{ % sudo make install "utils/ghc-cabal/dist-install/build/tmp/ghc-cabal-bindist" copy libraries /ghc-prim dist-install "strip" '' '/usr/local/ghc-8.6.1' '/usr/local/ghc-8.6.1/lib/ghc-8.6.1' '/usr/local/ghc-8.6.1/share/doc/ghc-8.6.1/html/libraries' 'v p dyn' dyld: Library not loaded: /usr/local/opt/gmp/lib/libgmp.10.dylib Referenced from: /Users/kazu/Downloads/ghc-8.6.1/libraries/base/dist- install/build/libHSbase-4.12.0.0-ghc8.6.1.dylib Reason: image not found make[1]: *** [install_packages] Abort trap: 6 make: *** [install] Error 2 }}} After make a link from "/usr/local/opt/gmp/lib/libgmp.10.dylib" to "/opt/local/lib/libgmp.10.dylib" installed by MacPorts, the installation succeeds. But when using GHC 8.6.1, the following error occurs: {{{ [15 of 15] Compiling Network.DNS ( Network/DNS.hs, dist/build/Network/DNS.o ) ld: library not found for -lgmp clang: error: linker command failed with exit code 1 (use -v to see invocation) `gcc' failed in phase `Linker'. (Exit code: 1) cab: callCommand: cabal build (exit 1): failed }}} To fix this, the following is necessary: {{{ % export LIBRARY_PATH=/usr/lib:/opt/local/lib }}} - "/usr/lib" is for "libiconv" and should come first to hide "/opt/local/lib/libiconv" - "/opt/local/lib" is for "libgmp" -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15769> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14226: Common Block Elimination pass doesn't eliminate common blocks
by GHC 10 Dec '18

10 Dec '18

#14226: Common Block Elimination pass doesn't eliminate common blocks -------------------------------------+------------------------------------- Reporter: bgamari | Owner: (none) Type: bug | Status: new Priority: high | Milestone: 8.4.1 Component: Compiler | Version: 8.2.1 (CodeGen) | 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 #14222 it was noted that something appears to be broken in `CmmCommonBlockElim`. Consider the program from that ticket, {{{#!hs module T14221 where import Data.Text as T isNumeric :: Text -> Bool isNumeric t = T.all isNumeric' t && T.any isNumber t where isNumber c = '0' <= c && c <= '9' isNumeric' c = isNumber c || c == 'e' || c == 'E' || c == '.' || c == '-' || c == '+' }}} This program produces six copies of a block of the form, {{{#!c c6JT: R2 = I64[R1 + 7]; R1 = P64[Sp + 8]; Sp = Sp + 16; call $wloop_all_s6CQ_info(R2, R1) args: 8, res: 0, upd: 8; }}} in the `-ddump-opt-cmm` output, which are manifest in the assembler as, {{{#!asm block_c6JT_info: _c6JT: movq 7(%rbx),%r14 movq 8(%rbp),%rbx addq $16,%rbp jmp $wloop_all_s6CQ_info }}} CBE really ought to be catching these. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14226> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12893: Profiling defeats stream fusion when using vector library
by GHC 10 Dec '18

10 Dec '18

#12893: Profiling defeats stream fusion when using vector library -------------------------------------+------------------------------------- Reporter: newhoggy | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: stream-fusion | Operating System: MacOS X profiling | Architecture: x86_64 | Type of failure: Runtime (amd64) | performance bug Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I have this problem where enabling profiling in Haskell undoes stream fusion and I’d like to do my profiling with stream fusion intact. The following reproduces my problem: {{{ $ git clone git@github.com:haskell-works/hw-tutorial-performance.git $ cd hw-tutorial-performance/ $ stack init $ stack build --executable-profiling $ time $(find .stack-work/dist/ -type f -name hw-tutorial-performance- rwhe) 1e7 5000000.5 real 0m4.432s user 0m3.484s sys 0m0.936s $ rm -rf .stack-work/ $ stack build $ time $(find .stack-work/dist/ -type f -name hw-tutorial-performance- rwhe) 1e7 5000000.5 real 0m0.034s user 0m0.018s sys 0m0.013s With profiling, my program takes over 4 seconds to run. Without profiling, it only takes 0.034 seconds. }}} The problem has nothing to do with stack. {{{ (java-1.8.0 ghc-7.10.3) ✔ ~/wrk/haskell-works/hw-tutorial-performance/hw- tutorial-performance-rwhe [master|✚ 1] 08:12 $ ghc -fforce-recomp --make -O2 -funbox-strict-fields -rtsopts -optc-O2 Main.hs [1 of 1] Compiling Main ( Main.hs, Main.o ) Linking Main ... (java-1.8.0 ghc-7.10.3) ✔ ~/wrk/haskell-works/hw-tutorial-performance/hw- tutorial-performance-rwhe [master|✚ 1] 08:12 $ time ./Main +RTS -sstderr -RTS 1e7 5000000.5 115,888 bytes allocated in the heap 3,480 bytes copied during GC 44,384 bytes maximum residency (1 sample(s)) 17,056 bytes maximum slop 1 MB total memory in use (0 MB lost due to fragmentation) Tot time (elapsed) Avg pause Max pause Gen 0 0 colls, 0 par 0.000s 0.000s 0.0000s 0.0000s Gen 1 1 colls, 0 par 0.000s 0.005s 0.0049s 0.0049s INIT time 0.000s ( 0.002s elapsed) MUT time 0.010s ( 0.025s elapsed) GC time 0.000s ( 0.005s elapsed) EXIT time 0.000s ( 0.005s elapsed) Total time 0.012s ( 0.037s elapsed) %GC time 1.8% (13.1% elapsed) Alloc rate 11,904,262 bytes per MUT second Productivity 97.1% of total user, 31.2% of total elapsed real 0m0.057s user 0m0.012s sys 0m0.010s (java-1.8.0 ghc-7.10.3) ✔ ~/wrk/haskell-works/hw-tutorial-performance/hw- tutorial-performance-rwhe [master|✚ 1] 08:12 $ ghc -prof -fforce-recomp --make -O2 -funbox-strict-fields -rtsopts -optc-O2 Main.hs [1 of 1] Compiling Main ( Main.hs, Main.o ) Linking Main ... (java-1.8.0 ghc-7.10.3) ✔ ~/wrk/haskell-works/hw-tutorial-performance/hw- tutorial-performance-rwhe [master|✚ 1] 08:12 $ time ./Main +RTS -sstderr -RTS 1e7 5000000.5 3,012,099,000 bytes allocated in the heap 4,079,698,408 bytes copied during GC 1,162,199,352 bytes maximum residency (13 sample(s)) 19,313,368 bytes maximum slop 1990 MB total memory in use (0 MB lost due to fragmentation) Tot time (elapsed) Avg pause Max pause Gen 0 4869 colls, 0 par 1.046s 1.055s 0.0002s 0.0017s Gen 1 13 colls, 0 par 1.230s 1.960s 0.1508s 0.5764s INIT time 0.000s ( 0.004s elapsed) MUT time 0.963s ( 0.825s elapsed) GC time 2.276s ( 3.016s elapsed) RP time 0.000s ( 0.000s elapsed) PROF time 0.000s ( 0.000s elapsed) EXIT time 0.009s ( 0.185s elapsed) Total time 3.251s ( 4.029s elapsed) %GC time 70.0% (74.8% elapsed) Alloc rate 3,126,345,026 bytes per MUT second Productivity 30.0% of total user, 24.2% of total elapsed real 0m4.197s user 0m3.251s sys 0m0.883s }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12893> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13637: Printing type operators adds extraneous parenthesis
by GHC 10 Dec '18

10 Dec '18

#13637: Printing type operators adds extraneous parenthesis -------------------------------------+------------------------------------- Reporter: darchon | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.1-rc2 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: -------------------------------------+------------------------------------- Given the code: {{{ {-# LANGUAGE TypeOperators #-} type name ::: a = a f :: Int ::: Int -> Int f = id }}} In GHCi-8.0.2 I get: {{{ >>> :t f f :: Int ::: Int -> Int }}} But in GHCi-8.2.0.20170427 I get: {{{ >>> :t f f :: (Int ::: Int) -> Int }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13637> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #16018: Disabling core optimizations ignores code that would otherwise warn.
by GHC 10 Dec '18

10 Dec '18

#16018: Disabling core optimizations ignores code that would otherwise warn. -------------------------------------+------------------------------------- Reporter: dmjio | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.2 Component: Compiler | Version: 8.4.3 Keywords: core, | Operating System: Unknown/Multiple optimizations, Wall | Architecture: x86 | Type of failure: None/Unknown Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Given the below code snippet, {{{#!hs module Main where main :: IO () main = putStrLn "hey" data StopLight = Red | Green | Yellow deriving (Show, Eq) data Intersection = Intersection { light :: {-# UNPACK #-} !StopLight } deriving (Show, Eq) }}} The above code will warn with optimizations enabled (`ghc -Wall -O2 Main.hs`), message below: ''' Main.hs:13:5: warning: • Ignoring unusable UNPACK pragma on the first argument of ‘Intersection’ • In the definition of data constructor ‘Intersection’ In the data type declaration for ‘Intersection’ | 13 | = Intersection ''' Without optimizations, no warnings are emitted `ghc -Wall -O0 Main.hs`. The desired behavior should be a warning emitted in both cases. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16018> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #2550: Add an option to read file names from a file instead of the command line
by GHC 09 Dec '18

09 Dec '18

#2550: Add an option to read file names from a file instead of the command line -------------------------------------+------------------------------------- Reporter: YitzGale | Owner: (none) Type: feature request | Status: new Priority: lowest | Milestone: Component: Package system | Version: 6.9 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #2551 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by f-a): This would of course greatly mitigate the pain of Template Hakell stage restrictions, too. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/2550#comment:18> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #16021: Hadrian: remove/refactor package specific hacks
by GHC 09 Dec '18

09 Dec '18

#16021: Hadrian: remove/refactor package specific hacks -------------------------------------+------------------------------------- Reporter: davide | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.3 Component: Compiler | Version: 8.6.2 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: -------------------------------------+------------------------------------- Hadrian implements a number of package specific hacks (e.g. see #16020). Such hacks should be discussed in this ticket and ideally removed or refactored. Hacks: * libffi (#16020) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16021> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8109: Type family patterns should support as-patterns.
by GHC 09 Dec '18

09 Dec '18

#8109: Type family patterns should support as-patterns. ------------------------------------+------------------------------------- Reporter: carlhowells | 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: | ------------------------------------+------------------------------------- I recently wrote code similar to the following: {{{ {-# LANGUAGE DataKinds, ScopedTypeVariables, TypeOperators, TypeFamilies #-} {-# LANGUAGE PolyKinds, FlexibleInstances, FlexibleContexts #-} import GHC.TypeLits data P n = P fromNat :: forall (p :: Nat -> *) (n :: Nat). SingI n => p n -> Integer fromNat _ = fromSing (sing :: Sing n) class C (a :: [Nat]) where type T a :: * val :: p a -> T a instance SingI n => C '[n] where type T '[n] = Integer val _ = fromNat (P :: P n) instance (SingI n, C (n2 ': ns)) => C (n ': n2 ': ns) where type T (n ': n2 ': ns) = (Integer, T (n2 ': ns)) val _ = (fromNat (P :: P n), val (P :: P (n2 ': ns))) }}} There were semantic constraints in my case that made an empty list nonsensical, so it wasn't an appropriate base case. But the resulting effort in ensuring type family patterns didn't overlap got unwieldy. I would have much preferred to write that second instance more like this: {{{ instance (SingI n, C ns) => C (n ': ns@(_ ': _)) where type T (n ': ns) = (Integer, T ns) val _ = (fromNat (P :: P n), val (P :: P ns)) }}} The reasoning here is identical to as-patterns in value-level pattern matching. If you only want to match an expression when it has a particular sub-structure, it's way more convenient to do it with an as-pattern. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8109> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12126: Bad error messages for SPECIALIZE pragmas
by GHC 09 Dec '18

09 Dec '18

#12126: Bad error messages for SPECIALIZE pragmas -------------------------------------+------------------------------------- Reporter: antalsz | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: Specialize, | Operating System: Unknown/Multiple ErrorMessages | Architecture: | Type of failure: Incorrect Unknown/Multiple | warning at compile-time Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- When playing with SPECIALIZE pragmas, I've encountered one large problem with the error messages, and two minor ones. 1. Given a function with a `Num` constraint, applying `SPECIALIZE` at a non-function type triggers defaulting incorrectly; the code {{{#!hs f1 :: Num a => a -> a f1 x = x + x {-# SPECIALIZE f1 :: Bool #-} }}} produces the error {{{ …/Test1.hs:5:1: error: • Couldn't match expected type ‘Integer -> Integer’ with actual type ‘Bool’ • In the SPECIALISE pragma {-# SPECIALIZE f1 :: Bool #-} }}} (This is in the attached file `Test1.hs`.) 2. Given a function, applying `SPECIALIZE` at a well-formed type without the looked-for instance produces an error with some extra text (the first line ends with "a SPECIALISE pragma for ‘f2’", even though this is repeated on the next line); the code {{{#!hs f2 :: Num a => a -> a f2 x = x + x {-# SPECIALIZE f2 :: Bool -> Bool #-} }}} produces the error {{{ …/Test2.hs:5:1: error: • No instance for (Num Bool) a SPECIALISE pragma for ‘f2’ • In the SPECIALISE pragma {-# SPECIALIZE f2 :: Bool -> Bool #-} }}} (This is in the attached file `Test2.hs`.) 3. This is minor, but: both of these error messages talk about a `SPECIALISE` pragma when I wrote a `SPECIALIZE` pragma. Even more so, case is not preserved in the quoted pragma; if I provide a {{{#!hs {-# specialize … #-} }}} pragma, the error message ends with {{{ • In the SPECIALISE pragma {-# SPECIALIZE … #-}`. }}} even though that isn't what I wrote. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12126> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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