August 2015 - ghc-tickets

[GHC] #10296: Segfaults when using dynamic wrappers and concurrency
by GHC 25 Apr '18

25 Apr '18

#10296: Segfaults when using dynamic wrappers and concurrency -------------------------------------+------------------------------------- Reporter: bitonic | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.11 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Blocked By: Test Case: | Related Tickets: Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- I had a largish program that sometimes segfaulted, the segfault seemingly coming from the code that gets a C pointer from an Haskell function. After much sweat I've managed to produce a self-contained program that exhibits the same behavior: {{{ bitonic@clay /tmp/ptr-crash % uname -a Linux clay 3.13.0-48-generic #80-Ubuntu SMP Thu Mar 12 11:16:15 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux bitonic@clay /tmp/ptr-crash % cabal configure --disable-library-profiling -w ghc-7.11.20150411 Resolving dependencies... Configuring ptr-crash-0... bitonic@clay /tmp/ptr-crash % cabal build Building ptr-crash-0... Preprocessing executable 'ptr-crash' for ptr-crash-0... [1 of 1] Compiling Main ( Main.hs, dist/build/ptr-crash/ptr- crash-tmp/Main.o ) Linking dist/build/ptr-crash/ptr-crash ... bitonic@clay /tmp/ptr-crash % strace -f -r -o strace-out ./dist/build/ptr- crash/ptr-crash +RTS -N2 -RTS [1] 26612 segmentation fault (core dumped) strace -f -r -o strace-out ./dist/build/ptr-crash/ptr-crash +RTS -N2 -RTS }}} I'm running GHC HEAD on a Linux 64bit machine. In the larger program, I'm pretty sure the segfaults happened on GHC 7.8.4 too, but currently I can reproduce it only on 7.10 and later. More details (thanks to Sergei Trofimovich on #ghc for helping me in investigating this): * The segfault only happens when using `-N2` or more. * Curiously, the segfault seems to happen much more often when compiling the program with `-g`. * `strace`ing the program when segfaulting shows that all the threads crash together right after some calls to `mremap`. I've attached the end of the output of `strace`. * `gdb`ing the program and breaking on `mremap` shows that all the calls to `mremap` originate from `getStablePtr`. I've attached a run of `gdb` that shows this pattern. Sergei had a hunch that this had to do with thread-unsafe calls to `mremap`. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10296> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9678: Warning about __sync_fetch_and_nand semantics from gcc
by GHC 24 Apr '18

24 Apr '18

#9678: Warning about __sync_fetch_and_nand semantics from gcc -------------------------------------+------------------------------------- Reporter: gintas | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Build System | Version: 7.9 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Blocked By: | None/Unknown Related Tickets: | Test Case: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- When building ghc, I'm getting warnings about __sync_fetch_and_nand that the semantics have changed for gcc 4.4+. I'm building on Windows, but I don't think that matters. Is this an indication of a problem or does that warning just need to be silenced? I ran the build with gcc 4.8.3: $ inplace/mingw/bin/gcc -v Using built-in specs. COLLECT_GCC=C:\msys64\home\Gintas\ghc\inplace\mingw\bin\gcc.exe COLLECT_LTO_WRAPPER=C:/msys64/home/Gintas/ghc/inplace/mingw/bin/../libexec/gcc/x86_64-w64-mingw32/4.8.3 /lto-wrapper.exe Target: x86_64-w64-mingw32 Configured with: ../../../src/gcc-4.8.3/configure --host=x86_64-w64-mingw32 --build=x86_64-w64-mingw32 --target=x86_64-w64-mingw32 --prefix=/mingw64 --with- sysroot=/c/mingw483/x86_64-483-posix-seh-rt_v3-rev0/mingw64 --with-gxx- include-dir=/mingw64/x86_64-w64-mingw32/include/c++ --enable-shared --enable-static --disable-multilib --enable- languages=ada,c,c++,fortran,objc,obj-c++,lto --enable-libstdcxx-time=yes --enable-threads=posix --enable-libgomp --enable-lto --enable-graphite --enable-checking=release --enable-fully-dynamic-string --enable-version- specific-runtime-libs --disable-isl-version-check --disable-cloog-version- check --disable-libstdcxx-pch --disable-libstdcxx-debug --enable-bootstrap --disable-rpath --disable-win32-registry --disable-nls --disable-werror --disable-symvers --with-gnu-as --with-gnu-ld --with-arch=nocona --with- tune=core2 --with-libiconv --with-system-zlib --with- gmp=/c/mingw483/prerequisites/x86_64-w64-mingw32-static --with- mpfr=/c/mingw483/prerequisites/x86_64-w64-mingw32-static --with- mpc=/c/mingw483/prerequisites/x86_64-w64-mingw32-static --with- isl=/c/mingw483/prerequisites/x86_64-w64-mingw32-static --with- cloog=/c/mingw483/prerequisites/x86_64-w64-mingw32-static --enable-cloog- backend=isl --with-pkgversion='x86_64-posix-seh-rev0, Built by MinGW-W64 project' --with-bugurl=http://sourceforge.net/projects/mingw-w64 CFLAGS='-O2 -pipe -I/c/mingw483/x86_64-483-posix-seh- rt_v3-rev0/mingw64/opt/include -I/c/mingw483/prerequisites/x86_64-zlib- static/include -I/c/mingw483/prerequisites/x86_64-w64-mingw32-static/include' CXXFLAGS='-O2 -pipe -I/c/mingw483/x86_64-483-posix-seh- rt_v3-rev0/mingw64/opt/include -I/c/mingw483/prerequisites/x86_64-zlib- static/include -I/c/mingw483/prerequisites/x86_64-w64-mingw32-static/include' CPPFLAGS= LDFLAGS='-pipe -L/c/mingw483/x86_64-483-posix-seh- rt_v3-rev0/mingw64/opt/lib -L/c/mingw483/prerequisites/x86_64-zlib- static/lib -L/c/mingw483/prerequisites/x86_64-w64-mingw32-static/lib' Thread model: posix gcc version 4.8.3 (x86_64-posix-seh-rev0, Built by MinGW-W64 project) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9678> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10607: Auto derive from top to bottom
by GHC 22 Apr '18

22 Apr '18

#10607: Auto derive from top to bottom -------------------------------------+------------------------------------- Reporter: songzh | Owner: Type: feature | Status: new request | Milestone: Priority: normal | Version: 7.11 Component: Compiler | Operating System: Unknown/Multiple Keywords: deriving, | Type of failure: None/Unknown typeclass, auto | Blocked By: Architecture: | Related Tickets: Unknown/Multiple | Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- It is very good to see that Template Haskell types are now `Generic` and `DeriveAnyClass` have been implemented. I suppose that this auto-deriving thing can go even further. The problem is like the following: When we manipulate a complex composite JSON object, we need to define a dozen of data types for each of the dozen we may need to derive `Eq`, `Show`, `Generic` etc. Another situaition can be manipulating the AST of a language, there may be dozens of data type definitions, also, for each of them, we need to derive `Show`, `Eq`, `Generic`. Take the old Template Haskell types without `Generic` as an example, I want to make them instances of `Generic` type class, I wrote: {{{#!hs deriving instance Generic FixityDirection deriving instance Generic Inline deriving instance Generic RuleBndr deriving instance Generic Match deriving instance Generic Name deriving instance Generic RuleMatch deriving instance Generic Pred deriving instance Generic Phases deriving instance Generic Con deriving instance Generic Module deriving instance Generic AnnTarget deriving instance Generic Type deriving instance Generic TyVarBndr deriving instance Generic TyLit deriving instance Generic Exp deriving instance Generic Lit deriving instance Generic Pat deriving instance Generic Dec deriving instance Generic Clause deriving instance Generic FunDep deriving instance Generic Foreign deriving instance Generic Fixity deriving instance Generic Pragma deriving instance Generic FamFlavour ... }}} How can we use `Generic`? Say we want to serialize Template Haskell data type with `Binary` type class, Of course, by writing `Binary` empty instances or just derive it with `DeriveAnyClass` extension. However, the problem is that we still need to write deriving Binary dozens of times, as many as the trivial `Generic` deriving declaration above. What if GHC can attemp to derive the instance from the top of the tree down to the leaf in the data type declarations? For example: {{{#!hs data Person = Person Names Address | Student Names Address deriving Generic data Names = Names String deriving Generic data Address = Address Gate deriving Generic type Gate = (String,Int) deriving topdown Eq Person }}} It will generate `Eq` instances of `Person`, `Names` and `Address`, since it is in the Person data declaration tree. I tried to implement a prototype see https://github.com/HaskellZhangSong /derive-topdown It is rather an experiment tryout than a formal implementation. If you think this feature is attractive, I would like to discuss it. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10607> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10412: isAlphaNum includes mark characters, but neither isAlpha nor isNumber do
by GHC 20 Apr '18

20 Apr '18

#10412: isAlphaNum includes mark characters, but neither isAlpha nor isNumber do -------------------------------------+------------------------------------- Reporter: | Owner: Artyom.Kazak | Status: new Type: bug | Milestone: Priority: normal | Version: 7.10.1 Component: | Operating System: Unknown/Multiple libraries/base | Type of failure: None/Unknown Keywords: unicode | Blocked By: Architecture: | Related Tickets: Unknown/Multiple | Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- {{{#!hs > isMark '\768' True > isAlphaNum '\768' True > (isAlpha '\768', isNumber '\768') (False,False) }}} This behavior comes from this piece in WCsubst.c: {{{ unipred(u_iswalnum,(GENCAT_LT|GENCAT_LU|GENCAT_LL|GENCAT_LM|GENCAT_LO| GENCAT_MC|GENCAT_ME|GENCAT_MN| GENCAT_NO|GENCAT_ND|GENCAT_NL)) }}} I'm not sure what should be done here. Is it a bug with isAlpaNum? Or with isAlpha? How does it correspond to iswalnum's behavior in C++? (And if it's a feature and not a bug, then it should definitely be documented.) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10412> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10037: Several profiling tests give different results optimised vs. unoptimised
by GHC 19 Apr '18

19 Apr '18

#10037: Several profiling tests give different results optimised vs. unoptimised -------------------------------------+------------------------------------- Reporter: simonmar | Owner: Type: bug | Status: new Priority: normal | Milestone: 7.12.1 Component: Profiling | Version: 7.10.1-rc2 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Blocked By: Test Case: | Related Tickets: Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Most of the differences are relatively harmless (mostly CAF attribution), but it would be nice to get this right. In the meantime I'll mark them expect_broken and point to this ticket. The following tests in `tests/profiling/should_run` are affected: {{{ scc001 T2552 ioprof callstack001 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10037> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9074: GHC 7.8.2's ghci does not track missing symbols when loading non-Haskell object files
by GHC 17 Apr '18

17 Apr '18

#9074: GHC 7.8.2's ghci does not track missing symbols when loading non-Haskell object files ------------------------------------+------------------------------------- Reporter: massysett | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.2 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- I have a package that bundles in C library sources. I never had a problem with this when using GHC 7.6. In GHC 7.8, the order of the c-sources in the cabal file now matters. Sources must be listed earlier if they have symbols that subsequently loaded object files will need. If the c-sources are in the wrong order, when running "cabal repl" I get Loading object (static) dist/build/decnumber/src/decQuad.o ... ghc: panic! (the 'impossible' happened) (GHC version 7.8.2 for x86_64-unknown-linux): Loading temp shared object failed: /tmp/ghc14294_0/ghc14294_1.so: undefined symbol: DECSTICKYTAB Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug When using the same code and cabal file with GHC 7.6, "cabal repl" works fine: GHCi loads each static object (regardless of ordering in the cabal file), links up the necessary symbols, and launches successfully. Haskell Cafe discussion here: http://www.haskell.org/pipermail/haskell-cafe/2014-May/114041.html -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9074> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10631: Report of GHC Panic
by GHC 14 Apr '18

14 Apr '18

#10631: Report of GHC Panic -------------------------------------+------------------------------------- Reporter: seewalker | Owner: Type: bug | Status: new Priority: low | Milestone: Component: Compiler | Version: 7.10.1 Keywords: | Operating System: MacOS X Architecture: x86_64 | Type of failure: Compile-time (amd64) | crash Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- I'll just copy here the error message; I wouldn't say I have the judgement to interpret it: ''ghc: panic! (the 'impossible' happened) (GHC version 7.10.1 for x86_64-apple-darwin): Loading temp shared object failed: dlopen(/var/folders/84/5rj51n8x70g4km60lfh_ds1m0000gt/T/ghc22694_0/libghc22694_107.dylib, 5): Symbol not found: _AlexSzuELoZZpfyhWUk8IXGTl3Kiel_ModulesziDBTypes_zdfPersistFieldLinkTag_closure Referenced from: /var/folders/84/5rj51n8x70g4km60lfh_ds1m0000gt/T/ghc22694_0/libghc22694_107.dylib Expected in: flat namespace in /var/folders/84/5rj51n8x70g4km60lfh_ds1m0000gt/T/ghc22694_0/libghc22694_107.dylib Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug'' This occurred while interactively developing a website with "yesod devel". After the compiler crashed, I killed the program, invoked "yesod devel" again without changing anything in my source code. This next time, no error occurred. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10631> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9307: wave4main in nofib fails
by GHC 14 Apr '18

14 Apr '18

#9307: wave4main in nofib fails -------------------------------------+------------------------------------- Reporter: jrp | Owner: Type: bug | Status: new Priority: normal | Milestone: 7.10.1 Component: NoFib benchmark | Version: 7.8.3 suite | Operating System: MacOS X Keywords: wave4main | Type of failure: Incorrect result Architecture: x86_64 (amd64) | at runtime Difficulty: Unknown | Test Case: wave4main Blocked By: | Blocking: Related Tickets: | -------------------------------------+------------------------------------- Compiling HEAD with perf-llvm, (3.4.2) and running the nofib suite fails at the wave4main case. It is not clear to me whether wave4main should always produce the same output (and so the test fails because it does not do so) or whether the numbers generated depend on some feature of the build settings, or OS. {{{ HC = /Users/xxx/Projects/ghc/inplace/bin/ghc-stage2 HC_OPTS = -O2 -Rghc-timing -H32m -hisuf hi -cpp -fglasgow-exts -rtsopts RUNTEST_OPTS = -ghc-timing ==nofib== wave4main: size of wave4main follows... __TEXT __DATA __OBJC others dec hex 4091904 450560 0 4295947176 4300489640 1005443a8 ==nofib== wave4main: time to run wave4main follows... ../../../runstdtest/runstdtest ./wave4main -o1 wave4main.stdout -o1 wave4main.stdout2 -o1 wave4main.stdout3 -o1 wave4main.stdout -o1 wave4main.stdout2 -o1 wave4main.stdout3 -ghc-timing 4000; ../../../runstdtest/runstdtest ./wave4main -o1 wave4main.stdout -o1 wave4main.stdout2 -o1 wave4main.stdout3 -o1 wave4main.stdout -o1 wave4main.stdout2 -o1 wave4main.stdout3 -ghc-timing 4000; ../../../runstdtest/runstdtest ./wave4main -o1 wave4main.stdout -o1 wave4main.stdout2 -o1 wave4main.stdout3 -o1 wave4main.stdout -o1 wave4main.stdout2 -o1 wave4main.stdout3 -ghc-timing 4000; ../../../runstdtest/runstdtest ./wave4main -o1 wave4main.stdout -o1 wave4main.stdout2 -o1 wave4main.stdout3 -o1 wave4main.stdout -o1 wave4main.stdout2 -o1 wave4main.stdout3 -ghc-timing 4000; ../../../runstdtest/runstdtest ./wave4main -o1 wave4main.stdout -o1 wave4main.stdout2 -o1 wave4main.stdout3 -o1 wave4main.stdout -o1 wave4main.stdout2 -o1 wave4main.stdout3 -ghc-timing 4000; real 0m0.217s user 0m0.191s sys 0m0.011s ././wave4main 4000 < /dev/null expected stdout not matched by reality --- wave4main.stdout 2014-07-08 20:57:14.000000000 +0100 +++ /var/folders/d9/94xh7l810mz3_skcsfh68khh0000gn/T//runtest16932.1 2014-07-13 13:43:22.000000000 +0100 @@ -1 +1 @@ -69923/1465 +69096/1465 real 0m0.197s user 0m0.186s sys 0m0.008s ././wave4main 4000 < /dev/null expected stdout not matched by reality --- wave4main.stdout 2014-07-08 20:57:14.000000000 +0100 +++ /var/folders/d9/94xh7l810mz3_skcsfh68khh0000gn/T//runtest16961.1 2014-07-13 13:43:22.000000000 +0100 @@ -1 +1 @@ -69923/1465 +69096/1465 real 0m0.201s user 0m0.189s sys 0m0.009s ././wave4main 4000 < /dev/null expected stdout not matched by reality --- wave4main.stdout 2014-07-08 20:57:14.000000000 +0100 +++ /var/folders/d9/94xh7l810mz3_skcsfh68khh0000gn/T//runtest17011.1 2014-07-13 13:43:22.000000000 +0100 @@ -1 +1 @@ -69923/1465 +69096/1465 real 0m0.201s user 0m0.190s sys 0m0.008s ././wave4main 4000 < /dev/null expected stdout not matched by reality --- wave4main.stdout 2014-07-08 20:57:14.000000000 +0100 +++ /var/folders/d9/94xh7l810mz3_skcsfh68khh0000gn/T//runtest17051.1 2014-07-13 13:43:23.000000000 +0100 @@ -1 +1 @@ -69923/1465 +69096/1465 real 0m0.200s user 0m0.189s sys 0m0.009s ././wave4main 4000 < /dev/null expected stdout not matched by reality --- wave4main.stdout 2014-07-08 20:57:14.000000000 +0100 +++ /var/folders/d9/94xh7l810mz3_skcsfh68khh0000gn/T//runtest17080.1 2014-07-13 13:43:23.000000000 +0100 @@ -1 +1 @@ -69923/1465 +69096/1465 make: *** [runtests] Error 1 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9307> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10367: "ghc: panic! (the 'impossible' happened)"
by GHC 14 Apr '18

14 Apr '18

#10367: "ghc: panic! (the 'impossible' happened)" -------------------------------------+------------------------------------- Reporter: bgwines | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.1 Keywords: panic | Operating System: MacOS X Architecture: | Type of failure: Runtime crash Unknown/Multiple | Blocked By: Test Case: | Related Tickets: Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- When running tasty-hunit tests through `cabal repl`, I get the following error: {{{ ghc: panic! (the 'impossible' happened) (GHC version 7.8.3 for x86_64-apple-darwin): Loading temp shared object failed: dlopen(/var/folders/l6/v2vhn_3j6bb1yvp6k5sh2hv80000gp/T/ghc80357_0/ghc80357_61.dylib, 9): Symbol not found: __hpc_tickboxes_horsezmcontrolzm0zi1zi0zi0_HorseziCommands_hpc Referenced from: /var/folders/l6/v2vhn_3j6bb1yvp6k5sh2hv80000gp/T/ghc80357_0/ghc80357_61.dylib Expected in: flat namespace in /var/folders/l6/v2vhn_3j6bb1yvp6k5sh2hv80000gp/T/ghc80357_0/ghc80357_61.dylib Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} I have a hunch that it's because I enabled the following flags in my .cabal file, since I didn't get the exception before adding them: {{{ Test-Suite test-horse ... GHC-Options: -fhpc -hpcdir dist/hpc/horse-control-1.0 }}} When I run the tests via `cabal test`, I don't get the exception. I've created a branch that showcases the crash: https://github.com/bgwines /horse-control/tree/ghc-panic Repro steps: * clone repo * cd to repo * run `cabal repl` * run `:l Tests/test-horse.hs` * run `main` Reproducability: 100% Please feel free to contact me if there's information lacking, here! :) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10367> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8165: Use GeneralizedNewtypeDeriving to automatically create associated type families
by GHC 12 Apr '18

12 Apr '18

#8165: Use GeneralizedNewtypeDeriving to automatically create associated type families ------------------------------------+------------------------------------- Reporter: MikeIzbicki | 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: | ------------------------------------+------------------------------------- Here's a simple example: {{{ class C a where type T a instance C Int where type T Int = Bool newtype NT = NT Int deriving C }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8165> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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