#10231: TMVar - fmap - orElse clashes in ghc 7.8.4 -------------------------------------+------------------------------------- Reporter: ran | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: libraries | Version: 7.8.4 (other) | Operating System: Linux Keywords: | Type of failure: Incorrect result Architecture: x86_64 | at runtime (amd64) | Blocked By: Test Case: | Related Tickets: Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Attached is a tar archive with minimal reproducible example. The problem is that after orElse success I get wrong constructor: I should have timer tick but get reset instead. That is, expected output is {{{ timer thread timer tick timer thread timer tick ... }}} but I get {{{ timer thread reset timer thread reset ... }}} The strange thing is that the problem presents, first, only when the binary is built by cabal (checked only inside sandbox): {{{ $ cabal sandbox init ... $ cabal configure Resolving dependencies... Configuring mvk-0.1.0.0... cabal: At least the following dependencies are missing: stm ==2.4.4 $ cabal install --dependencies-only ... $ cabal build }}} When I run {{{ cabal exec -- ghc --make mvk.hs }}} the resulting binary doesn't show the problem. Also, problem disappears if I: * either comment start of the (long-sleeping) reset thread at all; * or change content type of one of TMVars to, say, Bool But if I change type of content for both to, say, Bool, the problem presents. Furthermore, if with Bool content type I put False in timer thread and True in reset thread (and derive Show and output received value) I get {{{ timer thread received Reset False reset ... }}} That is, underlying Bool is right, but fmapped constructor is wrong. The problem was absent in Debian Wheezy's ghc 7.4.1 (not sure about STM version). Reproduced both in * Debian Jessie on x86_64 with GHC 7.8.4 binary from official site and cabal-install 1.20.0.3 from deb.haskell.org * Debian Wheezy on x86 with GHC 7.8.3 binary from deb.haskell.org and cabal-install 1.20.0.3 built by GHC from dist. In all cases used cabal.config from Stackage's lts-1.4 (included in the attached archive) Output from cabal build -v: {{{ Skipping add-source deps check... Using a sandbox located at /.main/home/ran/src/transas/knei24/mvk.bug/.cabal-sandbox The sandbox was created after the package was already configured. Re-configuring with most recently used options. If this fails, please run configure manually. Using a sandbox located at /.main/home/ran/src/transas/knei24/mvk.bug/.cabal-sandbox '/opt/ghc/7.8.4/bin/ghc' '--numeric-version' looking for tool ghc-pkg near compiler in /opt/ghc/7.8.4/bin found ghc-pkg in /opt/ghc/7.8.4/bin/ghc-pkg '/opt/ghc/7.8.4/bin/ghc-pkg' '--version' '/opt/ghc/7.8.4/bin/ghc' '--supported-languages' '/opt/ghc/7.8.4/bin/ghc' '--info' Reading available packages... Reading available packages... Choosing modular solver. Resolving dependencies... Configuring mvk-0.1.0.0... Dependency base ==4.7.0.2: using base-4.7.0.2 Dependency stm ==2.4.4: using stm-2.4.4 Using Cabal-1.20.0.0 compiled by ghc-7.4 Using compiler: ghc-7.8.4 Using install prefix: /.main/home/ran/src/transas/knei24/mvk.bug/.cabal-sandbox Binaries installed in: /.main/home/ran/src/transas/knei24/mvk.bug/.cabal-sandbox/bin Libraries installed in: /.main/home/ran/src/transas/knei24/mvk.bug/.cabal-sandbox/lib/x86_64 -linux-ghc-7.8.4/mvk-0.1.0.0 Private binaries installed in: /.main/home/ran/src/transas/knei24/mvk.bug/.cabal-sandbox/libexec Data files installed in: /.main/home/ran/src/transas/knei24/mvk.bug/.cabal-sandbox/share/x86_64 -linux-ghc-7.8.4/mvk-0.1.0.0 Documentation installed in: /.main/home/ran/src/transas/knei24/mvk.bug/.cabal-sandbox/share/doc/x86_64 -linux-ghc-7.8.4/mvk-0.1.0.0 Configuration files installed in: /.main/home/ran/src/transas/knei24/mvk.bug/.cabal-sandbox/etc Using alex version 3.1.3 found on system at: /usr/bin/alex Using ar found on system at: /usr/bin/ar No c2hs found No cpphs found No ffihugs found Using gcc version 4.9.2 found on system at: /usr/bin/gcc Using ghc version 7.8.4 found on system at: /opt/ghc/7.8.4/bin/ghc Using ghc-pkg version 7.8.4 found on system at: /opt/ghc/7.8.4/bin/ghc-pkg No greencard found Using haddock version 2.14.3 found on system at: /opt/ghc/7.8.4/bin/haddock Using happy version 1.19.4 found on system at: /usr/bin/happy 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: /opt/ghc/7.8.4/bin/hpc Using hsc2hs version 0.67 found on system at: /opt/ghc/7.8.4/bin/hsc2hs Using hscolour version 1.20 found on system at: /usr/bin/HsColour No hugs found No jhc found Using ld found on system at: /usr/bin/ld No lhc found No lhc-pkg found No nhc98 found Using pkg-config version 0.28 found on system at: /usr/bin/pkg-config Using strip found on system at: /usr/bin/strip Using tar found on system at: /bin/tar No uhc found Component build order: executable 'mvk' creating dist/build creating dist/build/autogen Building mvk-0.1.0.0... Preprocessing executable 'mvk' for mvk-0.1.0.0... Building executable mvk... creating dist/build/mvk creating dist/build/mvk/mvk-tmp /opt/ghc/7.8.4/bin/ghc --make -no-link -fbuilding-cabal-package -O -j4 -static -outputdir dist/build/mvk/mvk-tmp -odir dist/build/mvk/mvk-tmp -hidir dist/build/mvk/mvk-tmp -stubdir dist/build/mvk/mvk-tmp -i -idist/build/mvk/mvk-tmp -i. -idist/build/autogen -Idist/build/autogen -Idist/build/mvk/mvk-tmp -optP-include -optPdist/build/autogen/cabal_macros.h -hide-all-packages -no-user- package-db -package-db /.main/home/ran/src/transas/knei24/mvk.bug/.cabal- sandbox/x86_64-linux-ghc-7.8.4-packages.conf.d -package-db dist/package.conf.inplace -package-id base-4.7.0.2-bfd89587617e381ae01b8dd7b6c7f1c1 -package-id stm-2.4.4-c36cb8072081a12d13d98a3b4449e55c -XHaskell98 ./mvk.hs -Wall Linking... /opt/ghc/7.8.4/bin/ghc --make -fbuilding-cabal-package -O -static -outputdir dist/build/mvk/mvk-tmp -odir dist/build/mvk/mvk-tmp -hidir dist/build/mvk/mvk-tmp -stubdir dist/build/mvk/mvk-tmp -i -idist/build/mvk /mvk-tmp -i. -idist/build/autogen -Idist/build/autogen -Idist/build/mvk /mvk-tmp -optP-include -optPdist/build/autogen/cabal_macros.h -hide-all- packages -no-user-package-db -package-db /.main/home/ran/src/transas/knei24/mvk.bug/.cabal-sandbox/x86_64-linux- ghc-7.8.4-packages.conf.d -package-db dist/package.conf.inplace -package- id base-4.7.0.2-bfd89587617e381ae01b8dd7b6c7f1c1 -package-id stm-2.4.4-c36cb8072081a12d13d98a3b4449e55c -XHaskell98 ./mvk.hs -o dist/build/mvk/mvk -Wall Linking dist/build/mvk/mvk ... }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10231> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler