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| CMake 2.6 implements a new approach to generating link lines for targets. | | {{CMake/Template/Moved}} |
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| Consider these libraries:
| | This page has moved [https://gitlab.kitware.com/cmake/community/wikis/doc/cmake/notes/2.6 here]. |
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| /path/to/libfoo.a
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| /path/to/libfoo.so
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| Previously if someone wrote
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| target_link_libraries(myexe /path/to/libfoo.a)
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| CMake would generate this code to link it:
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| ... -L/path/to -Wl,-Bstatic -lfoo -Wl,-Bdynamic ...
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| This worked most of the time, but some platforms (such as OS X) do not
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| support the -Bstatic or equivalent flag. This made it impossible to
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| link to the static version of a library without creating a symlink in
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| another directory and using that one instead.
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| Now CMake will generate this code:
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| ... /path/to/libfoo.a ...
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| This guarantees that the correct library is chosen. | |
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| There is a side-effect of this fix. Projects used to be able to write
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| this (wrong) code and it would work by accident:
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| add_executable(myexe myexe.c)
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| target_link_libraries(myexe /path/to/libA.so B)
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| where "B" is meant to link "/path/to/libB.so". This code is incorrect
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| because it asks CMake to link to B but does not provide the proper
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| linker search path for it. It used to work by accident because the
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| -L/path/to would get added as part of the implementation of linking to
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| A. The correct code would be
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| link_directories(/path/to)
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| add_executable(myexe myexe.c)
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| target_link_libraries(myexe /path/to/libA.so B)
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| or even better
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| add_executable(myexe myexe.c)
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| target_link_libraries(myexe /path/to/libA.so /path/to/libB.so)
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| In order to support projects that have this bug, we've added a
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| compatibility feature that adds the "-L/path/to" paths for all libraries
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| linked with full paths even though the linker will not need those paths
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| to find the main libraries. The compatibility mode is enabled when a
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| link line contains a non-full-path library (like B or -lB) and either
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| CMAKE_BACKWARDS_COMPATIBILITY is set to 2.4 or lower or
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| CMAKE_LINK_OLD_PATHS is set to true.
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