mirror of
https://github.com/Detanup01/gbe_fork.git
synced 2024-11-28 13:44:02 +08:00
105 lines
3.5 KiB
ReStructuredText
105 lines
3.5 KiB
ReStructuredText
CMP0003
|
|
-------
|
|
|
|
Libraries linked via full path no longer produce linker search paths.
|
|
|
|
This policy affects how libraries whose full paths are NOT known are
|
|
found at link time, but was created due to a change in how CMake deals
|
|
with libraries whose full paths are known. Consider the code
|
|
|
|
::
|
|
|
|
target_link_libraries(myexe /path/to/libA.so)
|
|
|
|
CMake 2.4 and below implemented linking to libraries whose full paths
|
|
are known by splitting them on the link line into separate components
|
|
consisting of the linker search path and the library name. The
|
|
example code might have produced something like
|
|
|
|
::
|
|
|
|
... -L/path/to -lA ...
|
|
|
|
in order to link to library A. An analysis was performed to order
|
|
multiple link directories such that the linker would find library A in
|
|
the desired location, but there are cases in which this does not work.
|
|
CMake versions 2.6 and above use the more reliable approach of passing
|
|
the full path to libraries directly to the linker in most cases. The
|
|
example code now produces something like
|
|
|
|
::
|
|
|
|
... /path/to/libA.so ....
|
|
|
|
Unfortunately this change can break code like
|
|
|
|
::
|
|
|
|
target_link_libraries(myexe /path/to/libA.so B)
|
|
|
|
where ``B`` is meant to find ``/path/to/libB.so``. This code is wrong
|
|
because the user is asking the linker to find library B but has not
|
|
provided a linker search path (which may be added with the
|
|
link_directories command). However, with the old linking
|
|
implementation the code would work accidentally because the linker
|
|
search path added for library A allowed library B to be found.
|
|
|
|
In order to support projects depending on linker search paths added by
|
|
linking to libraries with known full paths, the ``OLD`` behavior for this
|
|
policy will add the linker search paths even though they are not
|
|
needed for their own libraries. When this policy is set to ``OLD``, CMake
|
|
will produce a link line such as
|
|
|
|
::
|
|
|
|
... -L/path/to /path/to/libA.so -lB ...
|
|
|
|
which will allow library B to be found as it was previously. When
|
|
this policy is set to NEW, CMake will produce a link line such as
|
|
|
|
::
|
|
|
|
... /path/to/libA.so -lB ...
|
|
|
|
which more accurately matches what the project specified.
|
|
|
|
The setting for this policy used when generating the link line is that
|
|
in effect when the target is created by an add_executable or
|
|
add_library command. For the example described above, the code
|
|
|
|
::
|
|
|
|
cmake_policy(SET CMP0003 OLD) # or cmake_policy(VERSION 2.4)
|
|
add_executable(myexe myexe.c)
|
|
target_link_libraries(myexe /path/to/libA.so B)
|
|
|
|
will work and suppress the warning for this policy. It may also be
|
|
updated to work with the corrected linking approach:
|
|
|
|
::
|
|
|
|
cmake_policy(SET CMP0003 NEW) # or cmake_policy(VERSION 2.6)
|
|
link_directories(/path/to) # needed to find library B
|
|
add_executable(myexe myexe.c)
|
|
target_link_libraries(myexe /path/to/libA.so B)
|
|
|
|
Even better, library B may be specified with a full path:
|
|
|
|
::
|
|
|
|
add_executable(myexe myexe.c)
|
|
target_link_libraries(myexe /path/to/libA.so /path/to/libB.so)
|
|
|
|
When all items on the link line have known paths CMake does not check
|
|
this policy so it has no effect.
|
|
|
|
Note that the warning for this policy will be issued for at most one
|
|
target. This avoids flooding users with messages for every target
|
|
when setting the policy once will probably fix all targets.
|
|
|
|
This policy was introduced in CMake version 2.6.0. CMake version
|
|
|release| warns when the policy is not set and uses ``OLD`` behavior. Use
|
|
the :command:`cmake_policy` command to set it to ``OLD`` or ``NEW`` explicitly.
|
|
|
|
.. include:: DEPRECATED.txt
|