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IDProjectCategoryView StatusDate SubmittedLast Update
0011844CMakeCMakepublic2011-02-11 05:142011-11-11 10:45
ReporterMatthew Bentham 
Assigned ToBrad King 
PrioritynormalSeveritymajorReproducibilityalways
StatusclosedResolutionfixed 
PlatformApple MacOSOS XOS Version10.4.10
Product VersionCMake 2.8.3 
Target VersionCMake 2.8.5Fixed in VersionCMake 2.8.5 
Summary0011844: Xcode universal binary build interacts badly with Xcode depends helper
DescriptionCMake Xcode projects contain rules to delete out-of-date files during the build.

When building more than one architecture, the rules are incorrect and, depending on timing and number of Xcode processes, delete up-to-date files as well, which causes build failures as Xcode tries to use them as inputs into later build stages.

Xcode reports errors similar to this:

CreateUniversalBinary Debug/prog4 normal "i386 x86_64"
cd /Users/mjb67local/Documents/foo/xcode-depends-bug
/usr/bin/lipo -create /Users/mjb67local/Documents/foo/xcode-depends-bug/test_xcode_depends.build/Debug/prog4.build/Objects-normal/i386/prog4 /Users/mjb67local/Documents/foo/xcode-depends-bug/test_xcode_depends.build/Debug/prog4.build/Objects-normal/x86_64/prog4 -output /Users/mjb67local/Documents/foo/xcode-depends-bug/Debug/prog4

/usr/bin/lipo: can't open input file: /Users/mjb67local/Documents/foo/xcode-depends-bug/test_xcode_depends.build/Debug/prog4.build/Objects-normal/i386/prog4 (No such file or directory)
Command /usr/bin/lipo failed with exit code 1

It seems that the XCODE_DEPENDS_HELPER.make script contains rules like this:


/Users/mjb67local/Documents/foo/xcode-depends-bug/RelWithDebInfo/prog4:
    /bin/rm -f /Users/mjb67local/Documents/foo/xcode-depends-bug/RelWithDebInfo/prog4
    /bin/rm -f /Users/mjb67local/Documents/foo/xcode-depends-bug/test_xcode_depends.build/RelWithDebInfo/prog4.build/Objects-normal/i386/prog4
    /bin/rm -f /Users/mjb67local/Documents/foo/xcode-depends-bug/test_xcode_depends.build/RelWithDebInfo/prog4.build/Objects-normal/x86_64/prog4

Which will delete both architecture-specific files during an Xcode IDE build (or an xcodebuild -parllelizeTargets build) if lipo has not yet written to the universal binary file.
Steps To ReproduceThis CMakeLists file:

cmake_minimum_required(VERSION 2.8)
project("test_xcode_depends")
set(CMAKE_OSX_ARCHITECTURES "i386;x86_64")
add_executable("prog1" foo1.c)
add_executable("prog2" foo1.c)
add_executable("prog3" foo1.c)
add_executable("prog4" foo1.c)
add_executable("prog5" foo1.c)
add_executable("prog6" foo1.c)

With commands:

cmake -G Xcode
cmake --build . --clean-first -- -parallelizeTargets

Will produce the error pretty reliably. On machines with lots of cores a larger number of independent targets might be necessary. Basically the error occurs when the post-build steps of one of the targets gets run during the compilation steps of one of the other targets.
Additional InformationI suspect it would be fixed if XCODE_DEPENDS_HELPER.make looked something like this instead:

xcode-depends-bug/RelWithDebInfo/prog4: xcode-depends-bug/test_xcode_depends.build/RelWithDebInfo/prog4.build/Objects-normal/i386/prog4 xcode-depends-bug/test_xcode_depends.build/RelWithDebInfo/prog4.build/Objects-normal/x86_64/prog4
    /bin/rm -f xcode-depends-bug/RelWithDebInfo/prog4

xcode-depends-bug/test_xcode_depends.build/RelWithDebInfo/prog4.build/Objects-normal/i386/prog4:
    /bin/rm -f xcode-depends-bug/test_xcode_depends.build/RelWithDebInfo/prog4.build/Objects-normal/i386/prog4

xcode-depends-bug/test_xcode_depends.build/RelWithDebInfo/prog4.build/Objects-normal/x86_64/prog4:
    /bin/rm -f xcode-depends-bug/test_xcode_depends.build/RelWithDebInfo/prog4.build/Objects-normal/x86_64/prog4
TagsNo tags attached.
Attached Fileszip file icon xcode-depends-bug.zip [^] (750 bytes) 2011-02-11 05:14

 Relationships

  Notes
(0025389)
Johan Björk (reporter)
2011-02-11 06:31

 seen same issue. thanks for tracking down the cause, now hoping for a fix :)
(0026680)
Brad King (manager)
2011-06-06 16:19

 I do not think the proposed fix is enough. There is still a race condition. Between when the make tool determines that a file is out of date and when it actually removes the file a parallel build step may create it.

The XCODE_DEPEND_HELPER was written originally with the assumption that only one target builds at a time. It runs during a post-build phase after a target completes building with the goal of wiping out any files that depend on the target just completed. This can work in parallel if the set of targets considered during the depend helper phase of a given target is only those targets that depend on it (i.e. its dependents). The dependents cannot possibly be building because they cannot start until the original target finishes.

In order to fix this we need to generate a separate entry point into the XCODE_DEPEND_HELPER makefile for each target that simply lists its dependents. The post-build phase for a given target must use the corresponding entry point. With this approach there is no need to evaluate each architecture separately.
(0026681)
Brad King (manager)
2011-06-06 18:06

 This should do it:

  http://cmake.org/gitweb?p=cmake.git;a=commitdiff;h=44cdae92 [^]
(0027763)
David Cole (manager)
2011-11-11 10:45

 Closing resolved issues that have not been updated in more than 4 months.

 Issue History
Date Modified Username Field Change
2011-02-11 05:14 Matthew Bentham New Issue
2011-02-11 05:14 Matthew Bentham File Added: xcode-depends-bug.zip
2011-02-11 06:31 Johan Björk Note Added: 0025389
2011-04-14 14:38 David Cole Assigned To => David Cole
2011-04-14 14:38 David Cole Status new => assigned
2011-04-14 14:38 David Cole Target Version => CMake 2.8.5
2011-06-06 16:19 Brad King Note Added: 0026680
2011-06-06 18:06 Brad King Assigned To David Cole => Brad King
2011-06-06 18:06 Brad King Note Added: 0026681
2011-06-07 08:20 Brad King Status assigned => resolved
2011-06-07 08:20 Brad King Fixed in Version => CMake 2.8.5
2011-06-07 08:20 Brad King Resolution open => fixed
2011-11-11 10:45 David Cole Note Added: 0027763
2011-11-11 10:45 David Cole Status resolved => closed

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