October 2018 - ghc-tickets

[GHC] #15444: 8.4.3 has an undocumented dependency on libnuma.
by GHC 11 Dec '18

11 Dec '18

#15444: 8.4.3 has an undocumented dependency on libnuma. -------------------------------------+------------------------------------- Reporter: AndreasK | Owner: (none) Type: bug | Status: new Priority: high | Milestone: 8.6.1 Component: Compiler | Version: 8.4.3 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: -------------------------------------+------------------------------------- See also https://github.com/haskell/network/issues/328 for some discussion. The issue seems to be that the rts "package" depends on libnuma. See below for build log and rts package info. {{{ The Glorious Glasgow Haskell Compilation System, version 8.4.3 cabal-install version 2.2.0.0 compiled using version 2.2.0.0 of the Cabal library - network-2.6.3.5 (lib:network) (requires build) }}} {{{ checking for netdb.h... yes checking netinet/in.h usability... yes checking netinet/in.h presence... yes checking for netinet/in.h... yes checking netinet/tcp.h usability... yes checking netinet/tcp.h presence... yes checking for netinet/tcp.h... yes checking sys/socket.h usability... yes checking sys/socket.h presence... yes checking for sys/socket.h... yes checking sys/uio.h usability... yes checking sys/uio.h presence... yes checking for sys/uio.h... yes checking sys/un.h usability... yes checking sys/un.h presence... yes checking for sys/un.h... yes checking linux/can.h usability... yes checking linux/can.h presence... yes checking for linux/can.h... yes checking linux/tcp.h usability... yes checking linux/tcp.h presence... yes checking for linux/tcp.h... yes checking net/if.h usability... yes checking net/if.h presence... yes checking for net/if.h... yes checking for readlink... yes checking for symlink... yes checking for if_nametoindex... yes checking for struct msghdr.msg_control... yes checking for struct msghdr.msg_accrights... no checking for struct sockaddr.sa_len... no checking for in_addr_t in netinet/in.h... yes checking for SO_PEERCRED and struct ucred in sys/socket.h... yes checking for getpeereid in unistd.h... checking for getpeereid... no checking for _head_libws2_32_a in -lws2_32... no checking for getaddrinfo... yes checking for gai_strerror... yes checking whether AI_ADDRCONFIG is declared... yes checking whether AI_ALL is declared... yes checking whether AI_NUMERICSERV is declared... yes checking whether AI_V4MAPPED is declared... yes checking whether IPV6_V6ONLY is declared... yes checking whether IPPROTO_IP is declared... yes checking whether IPPROTO_TCP is declared... yes checking whether IPPROTO_IPV6 is declared... yes checking for sendfile in sys/sendfile.h... yes checking for sendfile in sys/socket.h... no checking for gethostent... yes checking for accept4... yes configure: creating ./config.status config.status: creating network.buildinfo config.status: creating include/HsNetworkConfig.h configure: WARNING: unrecognized options: --with-compiler Preprocessing library for network-2.6.3.5.. /usr/bin/ld.gold: error: cannot find -lnuma collect2: error: ld returned 1 exit status linking dist/build/Network/BSD_hsc_make.o failed (exit code 1) command was: /usr/bin/gcc dist/build/Network/BSD_hsc_make.o dist/build/Network/BSD_hsc_utils.o -o dist/build/Network/BSD_hsc_make -fuse-ld=gold -fno-stack-protector -fuse-ld=gold -L/usr/local/lib/ghc-8.4.3/unix-2.7.2.2 -Wl,-R,/usr/local/lib/ghc-8.4.3/unix-2.7.2.2 -lrt -lutil -ldl -lpthread -L/usr/local/lib/ghc-8.4.3/time-1.8.0.2 -Wl,-R,/usr/local/lib/ghc-8.4.3/time-1.8.0.2 -L/usr/local/lib/ghc-8.4.3/bytestring-0.10.8.2 -Wl,-R,/usr/local/lib/ghc-8.4.3/bytestring-0.10.8.2 -L/usr/local/lib/ghc-8.4.3/deepseq-1.4.3.0 -Wl,-R,/usr/local/lib/ghc-8.4.3/deepseq-1.4.3.0 -L/usr/local/lib/ghc-8.4.3/array-0.5.2.0 -Wl,-R,/usr/local/lib/ghc-8.4.3/array-0.5.2.0 -L/usr/local/lib/ghc-8.4.3/base-4.11.1.0 -Wl,-R,/usr/local/lib/ghc-8.4.3/base-4.11.1.0 -L/usr/local/lib/ghc-8.4.3 /integer-gmp-1.0.2.0 -Wl,-R,/usr/local/lib/ghc-8.4.3/integer-gmp-1.0.2.0 -lgmp -L/usr/local/lib/ghc-8.4.3/ghc-prim-0.5.2.0 -Wl,-R,/usr/local/lib/ghc-8.4.3/ghc-prim-0.5.2.0 -L/usr/local/lib/ghc-8.4.3/rts -Wl,-R,/usr/local/lib/ghc-8.4.3/rts -lm -lrt -ldl -lnuma -lpthread cabal: Failed to build exe:hsc2hs from hsc2hs-0.68.3 (which is required by cabal-install-2.2.0.0). See the build log above for details. Failed to build network-2.6.3.5 (which is required by cabal- install-2.2.0.0). See the build log above for details. }}} {{{ name: rts version: 1.0 id: rts key: rts license: BSD-3-Clause maintainer: glasgow-haskell-users(a)haskell.org exposed: True library-dirs: /usr/local/lib/ghc-8.4.3/rts hs-libraries: HSrts Cffi extra-libraries: m rt dl numa pthread include-dirs: /usr/local/lib/ghc-8.4.3/include includes: Stg.h ld-options: "-Wl,-u,base_GHCziTopHandler_runIO_closure" "-Wl,-u,base_GHCziTopHandler_runNonIO_closure" "-Wl,-u,ghczmprim_GHCziTuple_Z0T_closure" "-Wl,-u,ghczmprim_GHCziTypes_True_closure" "-Wl,-u,ghczmprim_GHCziTypes_False_closure" "-Wl,-u,base_GHCziPack_unpackCString_closure" "-Wl,-u,base_GHCziWeak_runFinalizzerBatch_closure" "-Wl,-u,base_GHCziIOziException_stackOverflow_closure" "-Wl,-u,base_GHCziIOziException_heapOverflow_closure" "-Wl,-u,base_GHCziIOziException_allocationLimitExceeded_closure" "-Wl,-u,base_GHCziIOziException_blockedIndefinitelyOnMVar_closure" "-Wl,-u,base_GHCziIOziException_blockedIndefinitelyOnSTM_closure" "-Wl,-u,base_GHCziIOziException_cannotCompactFunction_closure" "-Wl,-u,base_GHCziIOziException_cannotCompactPinned_closure" "-Wl,-u,base_GHCziIOziException_cannotCompactMutable_closure" "-Wl,-u,base_ControlziExceptionziBase_absentSumFieldError_closure" "-Wl,-u,base_ControlziExceptionziBase_nonTermination_closure" "-Wl,-u,base_ControlziExceptionziBase_nestedAtomically_closure" "-Wl,-u,base_GHCziEventziThread_blockedOnBadFD_closure" "-Wl,-u,base_GHCziConcziSync_runSparks_closure" "-Wl,-u,base_GHCziConcziIO_ensureIOManagerIsRunning_closure" "-Wl,-u,base_GHCziConcziIO_ioManagerCapabilitiesChanged_closure" "-Wl,-u,base_GHCziConcziSignal_runHandlersPtr_closure" "-Wl,-u,base_GHCziTopHandler_flushStdHandles_closure" "-Wl,-u,base_GHCziTopHandler_runMainIO_closure" "-Wl,-u,ghczmprim_GHCziTypes_Czh_con_info" "-Wl,-u,ghczmprim_GHCziTypes_Izh_con_info" "-Wl,-u,ghczmprim_GHCziTypes_Fzh_con_info" "-Wl,-u,ghczmprim_GHCziTypes_Dzh_con_info" "-Wl,-u,ghczmprim_GHCziTypes_Wzh_con_info" "-Wl,-u,base_GHCziPtr_Ptr_con_info" "-Wl,-u,base_GHCziPtr_FunPtr_con_info" "-Wl,-u,base_GHCziInt_I8zh_con_info" "-Wl,-u,base_GHCziInt_I16zh_con_info" "-Wl,-u,base_GHCziInt_I32zh_con_info" "-Wl,-u,base_GHCziInt_I64zh_con_info" "-Wl,-u,base_GHCziWord_W8zh_con_info" "-Wl,-u,base_GHCziWord_W16zh_con_info" "-Wl,-u,base_GHCziWord_W32zh_con_info" "-Wl,-u,base_GHCziWord_W64zh_con_info" "-Wl,-u,base_GHCziStable_StablePtr_con_info" "-Wl,-u,hs_atomic_add8" "-Wl,-u,hs_atomic_add16" "-Wl,-u,hs_atomic_add32" "-Wl,-u,hs_atomic_add64" "-Wl,-u,hs_atomic_sub8" "-Wl,-u,hs_atomic_sub16" "-Wl,-u,hs_atomic_sub32" "-Wl,-u,hs_atomic_sub64" "-Wl,-u,hs_atomic_and8" "-Wl,-u,hs_atomic_and16" "-Wl,-u,hs_atomic_and32" "-Wl,-u,hs_atomic_and64" "-Wl,-u,hs_atomic_nand8" "-Wl,-u,hs_atomic_nand16" "-Wl,-u,hs_atomic_nand32" "-Wl,-u,hs_atomic_nand64" "-Wl,-u,hs_atomic_or8" "-Wl,-u,hs_atomic_or16" "-Wl,-u,hs_atomic_or32" "-Wl,-u,hs_atomic_or64" "-Wl,-u,hs_atomic_xor8" "-Wl,-u,hs_atomic_xor16" "-Wl,-u,hs_atomic_xor32" "-Wl,-u,hs_atomic_xor64" "-Wl,-u,hs_cmpxchg8" "-Wl,-u,hs_cmpxchg16" "-Wl,-u,hs_cmpxchg32" "-Wl,-u,hs_cmpxchg64" "-Wl,-u,hs_atomicread8" "-Wl,-u,hs_atomicread16" "-Wl,-u,hs_atomicread32" "-Wl,-u,hs_atomicread64" "-Wl,-u,hs_atomicwrite8" "-Wl,-u,hs_atomicwrite16" "-Wl,-u,hs_atomicwrite32" "-Wl,-u,hs_atomicwrite64" pkgroot: "/usr/local/lib/ghc-8.4.3" }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15444> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9718: Avoid TidyPgm predicting what CorePrep will do
by GHC 10 Dec '18

10 Dec '18

#9718: Avoid TidyPgm predicting what CorePrep will do -------------------------------------+------------------------------------- Reporter: simonpj | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.3 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Blocked By: | None/Unknown Related Tickets: | Test Case: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- At the moment the `TidyPgm` pass is forced to predict, accurately but unpleasantly, some aspects of what `CorePrep` and `Core2Stg` will do. Reason: * Each `Id` in the interface file records (among other things) the '''arity''' of the `Id`, and whether it has '''CAF references''' * We really only know these two things for sure after `CorePrep`. The conversion from Core to STG makes no structural changes. * However the result of `TidyPgm` (which preceded `CorePrep`) is used to generate the interface file. So it has to predict the arity and CAF-ref status of each `Id`. * This is not good. It restricts what `CorePrep` can do (notably, it must not change the arity of a top-level `Id`), and it leads to unsavoury code (e.g. look at the call to `CorePrep.cvtLitInteger` in `TidyPgm.cafRefsL`. It's also dangerous: an inconsistency could lead to a crash. This is a long-standing problem. My current thought for how to unravel it is this: * `TidyPgm` does not attach arity or CAF-ref info. * Instead, run `CorePrep` after `TidyPgm`, and generate accurate arity and CAF-ref info * Then use that auxiliary mapping during the conversion from tidied program to `ModIface`. I don't think this would be hard. It would mean that the tidied program and the core-prep'd program would have to exist in memory at the same time. An alternative would be to generate the `ModIface` from the tidied program ''sans'' arity and CAF-ref info, and then, after `CorePrep` run over it to add arity and CAF-ref info. (You'd have to do this before generating the fingerprints.) The advantage of this is that the `ModIface` can be a lot smaller than the code for the entire module. A long-standing wart which needs some careful attention. Simon -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9718> 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 09 Dec '18

09 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 09 Dec '18

09 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 09 Dec '18

09 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] #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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[GHC] #13165: Speed up the RTS hash table
by GHC 09 Dec '18

09 Dec '18

#13165: Speed up the RTS hash table -------------------------------------+------------------------------------- Reporter: dobenour | Owner: Type: bug | Status: new Priority: normal | Milestone: 8.2.1 Component: Runtime | Version: 8.1 System | 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 RTS hash table is rather slow. Every lookup involves at least one indirect call (to get a hash code). It also uses separate chaining, which is itself slow. Until recently, this didn't really matter, since the RTS hash table wasn't used for anything particularly performance critical other than `StablePtr` operations. However, it has since become the bottleneck when compacting with sharing, to the point that compacting without sharing is around 10x faster and is thus the default. Fortunately, there are easy ways to make the hash table faster. These include: - Use linear probing instead of separate chaining. - Specialize for the case of pointer keys - Don't use indirect calls for hashing - Use a fast, universal hash function for pointers. - Use SSE instructions where available to do fast searches. - Minimize the number of indirections in the use of the table. In both the case of the StablePtr table and that of compact regions, the keys of the table are not GC pointers, but the values are, so there needs to be a way to ensure that the GC handles the table correctly -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13165> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15794: shell.nix depends on build artifacts
by GHC 08 Dec '18

08 Dec '18

#15794: shell.nix depends on build artifacts -------------------------------------+------------------------------------- Reporter: int-index | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Build System | Version: 8.6.1 (Hadrian) | Keywords: | Operating System: Linux Architecture: | Type of failure: Building GHC Unknown/Multiple | failed Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Filed Mar 19, 2018, as https://github.com/snowleopard/hadrian/issues/532 **Steps to reproduce:** 1. `git clone --recursive git://git.haskell.org/ghc.git` 2. `cd ghc/hadrian` 3. `nix-shell --pure` **Expected result:** Successful build. **Actual result:** {{{ hadrian(master)$ nix-shell --pure these derivations will be built: /nix/store/lmpgkvswlkcgpcjdilbyh202vm8a5i5r-directory-1.3.1.5.drv /nix/store/rcg0mmq0bincjfjnzbabc8fq7307bylq-process-1.6.3.0.drv /nix/store/15alkpni823gkfp63c79962v032wxvjs-extra-1.6.4.drv /nix/store/1b54g6nv8rw0kq3i5xjpcbhy88jvdnbr-xml-1.3.14.drv /nix/store/89salv051l8yr2y2k52pzkqraw9lfib9-test-framework-0.8.1.1.drv /nix/store/iqq0xsvgf3hf551b3jj0x3lg661c5y4f-test-framework- hunit-0.3.0.2.drv /nix/store/cy7ynm7r9jb41kxb1gxbwdprhvl03ivk-parsec-3.1.13.0.drv /nix/store/rgnsvxfvmbhrkniy0c86v65jgvx8nsan-test-framework- quickcheck2-0.3.0.4.drv /nix/store/fyrj002axd2skdz370hi13fq6prjh5cz-network-uri-2.6.1.0.drv /nix/store/7qcfy5gy9sjcz7cijqghgj3cilm2pzps-HTTP-4000.3.8.drv /nix/store/gk0w3grh2hz008sp6ksy669zvl6pyznb-js-flot-0.8.3.drv /nix/store/h39chz7m8zvawlrzfjsz496vl2rbp921-hashable-1.2.6.1.drv /nix/store/zpv0xi25jq6p5kkpvbc11sq73dxi2g0a-unordered- containers-0.2.8.0.drv /nix/store/i7p5c3mv9p20z7kb2mrdlpx0fwmyz3f5-shake-0.16.2.drv /nix/store/pzfcvib6sbsaascsc7djzcfqzlw847gc-Cabal-2.3.0.0.drv /nix/store/j5w4i42pgfy03s7fjsj4dfkis26c3nnp-happy-1.19.8.drv /nix/store/pl2dxjvbqs36rh80q5i09zdhbh6hjl2r-alex-3.2.3.drv /nix/store/dck8p81zlij9qksglaw8hkp11msrm426-hadrian-0.1.0.0.drv building '/nix/store/lmpgkvswlkcgpcjdilbyh202vm8a5i5r- directory-1.3.1.5.drv'... building '/nix/store/1b54g6nv8rw0kq3i5xjpcbhy88jvdnbr-xml-1.3.14.drv'... setupCompilerEnvironmentPhase Build with /nix/store/d57p5gzyld7b3y4irzv70bfa3d8xxwgx-ghc-8.2.2. setupCompilerEnvironmentPhase Build with /nix/store/d57p5gzyld7b3y4irzv70bfa3d8xxwgx-ghc-8.2.2. unpacking sources unpacking source archive /nix/store/khjm3agcb1y91925r78h3chaq56w9fi7 -6wsbrbb60dzbfqf62c6sskwcijc3arjj-directory unpacking sources unpacking source archive /nix/store/dnx7hpl7wz81r3av4l09pqqhdqi4qpg6-xml-1.3.14.tar.gz source root is xml-1.3.14 source root is 6wsbrbb60dzbfqf62c6sskwcijc3arjj-directory setting SOURCE_DATE_EPOCH to timestamp 1424727750 of file xml-1.3.14/xml.cabal patching sources patching sources compileBuildDriverPhase compileBuildDriverPhase setupCompileFlags: -package-db=/tmp/nix-build- xml-1.3.14.drv-0/package.conf.d -j1 -threaded setupCompileFlags: -package-db=/tmp/nix-build- directory-1.3.1.5.drv-0/package.conf.d -j1 -threaded [1 of 1] Compiling Main ( Setup.hs, /tmp/nix-build- directory-1.3.1.5.drv-0/Main.o ) [1 of 1] Compiling Main ( Setup.hs, /tmp/nix-build- xml-1.3.14.drv-0/Main.o ) Linking Setup ... Linking Setup ... configuring configureFlags: --verbose --prefix=/nix/store /v3yazy78gy6kkpvrcn3schm8lc8y5dgl-xml-1.3.14 --libdir=$prefix/lib/$compiler --libsubdir=$pkgid --docdir=/nix/store /zdzgar7mwysym9dbai87fann20pbw75n-xml-1.3.14-doc/share/doc --with-gcc=gcc --package-db=/tmp/nix-build-xml-1.3.14.drv-0/package.conf.d --ghc- option=-optl=-Wl,-rpath=/nix/store/v3yazy78gy6kkpvrcn3schm8lc8y5dgl- xml-1.3.14/lib/ghc-8.2.2/xml-1.3.14 --ghc-option=-j1 --disable-split-objs --disable-library-profiling --disable-profiling --enable-shared --disable- coverage --enable-library-vanilla --enable-executable-dynamic --enable- tests --ghc-option=-split-sections configuring configureFlags: --verbose --prefix=/nix/store /59r1c7sfgph9j2xxsc1k3j6dwkm32ybk-directory-1.3.1.5 --libdir=$prefix/lib/$compiler --libsubdir=$pkgid --docdir=/nix/store /w0gkzrf5q6ng40vzyvdl5m8pvw9v9dxy-directory-1.3.1.5-doc/share/doc --with- gcc=gcc --package-db=/tmp/nix-build-directory-1.3.1.5.drv-0/package.conf.d --ghc-option=-optl=-Wl,-rpath=/nix/store/59r1c7sfgph9j2xxsc1k3j6dwkm32ybk- directory-1.3.1.5/lib/ghc-8.2.2/directory-1.3.1.5 --ghc-option=-j1 --disable-split-objs --disable-library-profiling --disable-profiling --enable-shared --disable-coverage --enable-library-vanilla --enable- executable-dynamic --enable-tests --ghc-option=-split-sections Configuring directory-1.3.1.5... Warning: The 'build-type' is 'Configure' but there is no 'configure' script. You probably need to run 'autoreconf -i' to generate it. Configuring xml-1.3.14... Dependency base >=3 && <5: using base-4.10.1.0 Dependency bytestring -any: using bytestring-0.10.8.2 Dependency text -any: using text-1.2.3.0 Dependency base >=4.5 && <4.12: using base-4.10.1.0 Dependency directory -any: using directory-1.3.1.5 Dependency filepath >=1.3 && <1.5: using filepath-1.4.2 Dependency time >=1.4 && <1.9: using time-1.8.0.2 Dependency unix >=2.5.1 && <2.8: using unix-2.7.2.2 Source component graph: component lib component test:test dependency lib Configured component graph: component directory-1.3.1.5-EFdDcGoPsV2JQnFPz1QOGK include base-4.10.1.0 include time-1.8.0.2 include filepath-1.4.2-DyDAQ5oOwBVDvLxMoNLDxx include unix-2.7.2.2 component directory-1.3.1.5-8aJ3UecsjNUIxs4bq1vU8T-test include base-4.10.1.0 include directory-1.3.1.5-EFdDcGoPsV2JQnFPz1QOGK include filepath-1.4.2-DyDAQ5oOwBVDvLxMoNLDxx include time-1.8.0.2 include unix-2.7.2.2 Linked component graph: unit directory-1.3.1.5-EFdDcGoPsV2JQnFPz1QOGK include base-4.10.1.0 include time-1.8.0.2 include filepath-1.4.2-DyDAQ5oOwBVDvLxMoNLDxx include unix-2.7.2.2 System.Directory=directory-1.3.1.5-EFdDcGoPsV2JQnFPz1QOGK:System.Directory,System.Directory.Internal=directory-1.3.1.5-EFdDcGoPsV2JQnFPz1QOGK:System.Directory.Internal,System.Directory.Internal.Prelude=directory-1.3.1.5-EFdDcGoPsV2JQnFPz1QOGK:System.Directory.Internal.Prelude unit directory-1.3.1.5-8aJ3UecsjNUIxs4bq1vU8T-test include base-4.10.1.0 include directory-1.3.1.5-EFdDcGoPsV2JQnFPz1QOGK include filepath-1.4.2-DyDAQ5oOwBVDvLxMoNLDxx include time-1.8.0.2 include unix-2.7.2.2 Ready component graph: definite directory-1.3.1.5-EFdDcGoPsV2JQnFPz1QOGK depends base-4.10.1.0 depends time-1.8.0.2 depends filepath-1.4.2-DyDAQ5oOwBVDvLxMoNLDxx depends unix-2.7.2.2 definite directory-1.3.1.5-8aJ3UecsjNUIxs4bq1vU8T-test depends base-4.10.1.0 depends directory-1.3.1.5-EFdDcGoPsV2JQnFPz1QOGK depends filepath-1.4.2-DyDAQ5oOwBVDvLxMoNLDxx depends time-1.8.0.2 depends unix-2.7.2.2 Using Cabal-2.0.1.0 compiled by ghc-8.2 Using compiler: ghc-8.2.2 Using install prefix: /nix/store/59r1c7sfgph9j2xxsc1k3j6dwkm32ybk-directory-1.3.1.5 Executables installed in: /nix/store/59r1c7sfgph9j2xxsc1k3j6dwkm32ybk-directory-1.3.1.5/bin Libraries installed in: /nix/store/59r1c7sfgph9j2xxsc1k3j6dwkm32ybk- directory-1.3.1.5/lib/ghc-8.2.2/directory-1.3.1.5 Dynamic Libraries installed in: /nix/store/59r1c7sfgph9j2xxsc1k3j6dwkm32ybk- directory-1.3.1.5/lib/ghc-8.2.2/x86_64-linux-ghc-8.2.2 Private executables installed in: /nix/store/59r1c7sfgph9j2xxsc1k3j6dwkm32ybk- directory-1.3.1.5/libexec/x86_64-linux-ghc-8.2.2/directory-1.3.1.5 Data files installed in: /nix/store/59r1c7sfgph9j2xxsc1k3j6dwkm32ybk-directory-1.3.1.5/share/x86_64 -linux-ghc-8.2.2/directory-1.3.1.5 Documentation installed in: /nix/store/w0gkzrf5q6ng40vzyvdl5m8pvw9v9dxy- directory-1.3.1.5-doc/share/doc Configuration files installed in: /nix/store/59r1c7sfgph9j2xxsc1k3j6dwkm32ybk-directory-1.3.1.5/etc No alex found Using ar found on system at: /nix/store/aplvnhqdm6s9wj9r0jh46r46wvh65j86-binutils-2.28.1/bin/ar No c2hs found No cpphs found No doctest found Using gcc version 6.4.0 given by user at: /nix/store/wriy1xis74fybcg3m1jnq5bd5myxvhm6-gcc-wrapper-6.4.0/bin/gcc Using ghc version 8.2.2 found on system at: /nix/store/d57p5gzyld7b3y4irzv70bfa3d8xxwgx-ghc-8.2.2/bin/ghc Using ghc-pkg version 8.2.2 found on system at: /nix/store/d57p5gzyld7b3y4irzv70bfa3d8xxwgx-ghc-8.2.2/bin/ghc-pkg No ghcjs found No ghcjs-pkg found No greencard found Using haddock version 2.18.1 found on system at: /nix/store/d57p5gzyld7b3y4irzv70bfa3d8xxwgx-ghc-8.2.2/bin/haddock No happy found Using haskell-suite found on system at: haskell-suite-dummy-location Using haskell-suite-pkg found on system at: haskell-suite-pkg-dummy- location No hmake found Using hpc version 0.67 found on system at: /nix/store/d57p5gzyld7b3y4irzv70bfa3d8xxwgx-ghc-8.2.2/bin/hpc Using hsc2hs version 0.68.2 found on system at: /nix/store/d57p5gzyld7b3y4irzv70bfa3d8xxwgx-ghc-8.2.2/bin/hsc2hs Using hscolour version 1.24 found on system at: /nix/store/yf0bs1q9ph388jms8xlgcd5vh99amjm4-hscolour-1.24.2/bin/HsColour No jhc found Using ld found on system at: /nix/store/wriy1xis74fybcg3m1jnq5bd5myxvhm6-gcc-wrapper-6.4.0/bin/ld No lhc found No lhc-pkg found No pkg-config found Using runghc version 8.2.2 found on system at: /nix/store/d57p5gzyld7b3y4irzv70bfa3d8xxwgx-ghc-8.2.2/bin/runghc Using strip version 2.28 found on system at: /nix/store/aplvnhqdm6s9wj9r0jh46r46wvh65j86-binutils-2.28.1/bin/strip Using tar found on system at: /nix/store/vvq16kzwgx9yhkf0fwwms5xzgg0rwdpl-gnutar-1.29/bin/tar No uhc found Setup: configure script not found. builder for '/nix/store/lmpgkvswlkcgpcjdilbyh202vm8a5i5r- directory-1.3.1.5.drv' failed with exit code 1 cannot build derivation '/nix/store/dck8p81zlij9qksglaw8hkp11msrm426-hadrian-0.1.0.0.drv': 1 dependencies couldn't be built error: build of '/nix/store/dck8p81zlij9qksglaw8hkp11msrm426-hadrian-0.1.0.0.drv' failed }}} Notice that the build fails for a library shipped with GHC. In `shell.nix` it's included as `localPackage`. **Workaround** First, we need to run `configurePhase` of the default Nix derivation for GHC HEAD: 1. `cd ghc` 2. `nix-shell '<nixpkgs>' -A haskell.compiler.ghcHEAD` 3. `configurePhase` 4. `exit` Now we can `cd` into `ghc/hadrian` and proceed normally, the build won't fail. The issue is that this step shouldn't be required, we must have a self- contained `shell.nix`. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15794> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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