[GHC] #10231: TMVar - fmap - orElse clashes in ghc 7.8.4

GHC ghc-devs at haskell.org
Thu Apr 2 21:05:13 UTC 2015 

#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>
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