cmakepolicies(1)           OpenBSD Reference Manual           cmakepolicies(1)



NAME
       cmakepolicies - Reference of CMake policies.


DESCRIPTION
       The "cmake" executable is the CMake command-line interface.  It may be
       used to configure projects in scripts.  Project configuration settings
       may be specified on the command line with the -D option.  The -i option
       will cause cmake to interactively prompt for such settings.


       CMake is a cross-platform build system generator.  Projects specify
       their build process with platform-independent CMake listfiles included
       in each directory of a source tree with the name CMakeLists.txt. Users
       build a project by using CMake to generate a build system for a native
       tool on their platform.


POLICIES
       CMP0000
              A minimum required CMake version must be specified.

              CMake requires that projects specify the version of CMake to
              which they have been written.  This policy has been put in place
              so users trying to build the project may be told when they need
              to update their CMake.  Specifying a version also helps the
              project build with CMake versions newer than that specified.
              Use the cmake_minimum_required command at the top of your main
              CMakeLists.txt file:


                cmake_minimum_required(VERSION <major>.<minor>)

              where "<major>.<minor>" is the version of CMake you want to
              support (such as "2.6").  The command will ensure that at least
              the given version of CMake is running and help newer versions be
              compatible with the project.  See documentation of
              cmake_minimum_required for details.


              Note that the command invocation must appear in the
              CMakeLists.txt file itself; a call in an included file is not
              sufficient.  However, the cmake_policy command may be called to
              set policy CMP0000 to OLD or NEW behavior explicitly.  The OLD
              behavior is to silently ignore the missing invocation.  The NEW
              behavior is to issue an error instead of a warning.  An included
              file may set CMP0000 explicitly to affect how this policy is
              enforced for the main CMakeLists.txt file.


              This policy was introduced in CMake version 2.6.0.


       CMP0001
              CMAKE_BACKWARDS_COMPATIBILITY should no longer be used.

              The OLD behavior is to check CMAKE_BACKWARDS_COMPATIBILITY and
              present it to the user.  The NEW behavior is to ignore
              CMAKE_BACKWARDS_COMPATIBILITY completely.


              In CMake 2.4 and below the variable
              CMAKE_BACKWARDS_COMPATIBILITY was used to request compatibility
              with earlier versions of CMake.  In CMake 2.6 and above all
              compatibility issues are handled by policies and the
              cmake_policy command.  However, CMake must still check
              CMAKE_BACKWARDS_COMPATIBILITY for projects written for CMake 2.4
              and below.


              This policy was introduced in CMake version 2.6.0.  CMake
              version 2.8.7 warns when the policy is not set and uses OLD
              behavior.  Use the cmake_policy command to set it to OLD or NEW
              explicitly.


       CMP0002
              Logical target names must be globally unique.

              Targets names created with add_executable, add_library, or
              add_custom_target are logical build target names.  Logical
              target names must be globally unique because:


                - Unique names may be referenced unambiguously both in CMake
                  code and on make tool command lines.
                - Logical names are used by Xcode and VS IDE generators
                  to produce meaningful project names for the targets.

              The logical name of executable and library targets does not have
              to correspond to the physical file names built.  Consider using
              the OUTPUT_NAME target property to create two targets with the
              same physical name while keeping logical names distinct.  Custom
              targets must simply have globally unique names (unless one uses
              the global property ALLOW_DUPLICATE_CUSTOM_TARGETS with a
              Makefiles generator).


              This policy was introduced in CMake version 2.6.0.  CMake
              version 2.8.7 warns when the policy is not set and uses OLD
              behavior.  Use the cmake_policy command to set it to OLD or NEW
              explicitly.


       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 2.8.7 warns when the policy is not set and uses OLD
              behavior.  Use the cmake_policy command to set it to OLD or NEW
              explicitly.


       CMP0004
              Libraries linked may not have leading or trailing whitespace.

              CMake versions 2.4 and below silently removed leading and
              trailing whitespace from libraries linked with code like


                target_link_libraries(myexe " A ")

              This could lead to subtle errors in user projects.


              The OLD behavior for this policy is to silently remove leading
              and trailing whitespace.  The NEW behavior for this policy is to
              diagnose the existence of such whitespace as an error.  The
              setting for this policy used when checking the library names is
              that in effect when the target is created by an add_executable
              or add_library command.


              This policy was introduced in CMake version 2.6.0.  CMake
              version 2.8.7 warns when the policy is not set and uses OLD
              behavior.  Use the cmake_policy command to set it to OLD or NEW
              explicitly.


       CMP0005
              Preprocessor definition values are now escaped automatically.

              This policy determines whether or not CMake should generate
              escaped preprocessor definition values added via
              add_definitions.  CMake versions 2.4 and below assumed that only
              trivial values would be given for macros in add_definitions
              calls.  It did not attempt to escape non-trivial values such as
              string literals in generated build rules.  CMake versions 2.6
              and above support escaping of most values, but cannot assume the
              user has not added escapes already in an attempt to work around
              limitations in earlier versions.


              The OLD behavior for this policy is to place definition values
              given to add_definitions directly in the generated build rules
              without attempting to escape anything.  The NEW behavior for
              this policy is to generate correct escapes for all native build
              tools automatically.  See documentation of the
              COMPILE_DEFINITIONS target property for limitations of the
              escaping implementation.


              This policy was introduced in CMake version 2.6.0.  CMake
              version 2.8.7 warns when the policy is not set and uses OLD
              behavior.  Use the cmake_policy command to set it to OLD or NEW
              explicitly.


       CMP0006
              Installing MACOSX_BUNDLE targets requires a BUNDLE DESTINATION.

              This policy determines whether the install(TARGETS) command must
              be given a BUNDLE DESTINATION when asked to install a target
              with the MACOSX_BUNDLE property set.  CMake 2.4 and below did
              not distinguish application bundles from normal executables when
              installing targets.  CMake 2.6 provides a BUNDLE option to the
              install(TARGETS) command that specifies rules specific to
              application bundles on the Mac.  Projects should use this option
              when installing a target with the MACOSX_BUNDLE property set.


              The OLD behavior for this policy is to fall back to the RUNTIME
              DESTINATION if a BUNDLE DESTINATION is not given.  The NEW
              behavior for this policy is to produce an error if a bundle
              target is installed without a BUNDLE DESTINATION.


              This policy was introduced in CMake version 2.6.0.  CMake
              version 2.8.7 warns when the policy is not set and uses OLD
              behavior.  Use the cmake_policy command to set it to OLD or NEW
              explicitly.


       CMP0007
              list command no longer ignores empty elements.

              This policy determines whether the list command will ignore
              empty elements in the list. CMake 2.4 and below list commands
              ignored all empty elements in the list.  For example, a;b;;c
              would have length 3 and not 4. The OLD behavior for this policy
              is to ignore empty list elements. The NEW behavior for this
              policy is to correctly count empty elements in a list.


              This policy was introduced in CMake version 2.6.0.  CMake
              version 2.8.7 warns when the policy is not set and uses OLD
              behavior.  Use the cmake_policy command to set it to OLD or NEW
              explicitly.


       CMP0008
              Libraries linked by full-path must have a valid library file
              name.

              In CMake 2.4 and below it is possible to write code like


                target_link_libraries(myexe /full/path/to/somelib)

              where "somelib" is supposed to be a valid library file name such
              as "libsomelib.a" or "somelib.lib".  For Makefile generators
              this produces an error at build time because the dependency on
              the full path cannot be found.  For VS IDE and Xcode generators
              this used to work by accident because CMake would always split
              off the library directory and ask the linker to search for the
              library by name (-lsomelib or somelib.lib).  Despite the failure
              with Makefiles, some projects have code like this and build only
              with VS and/or Xcode.  This version of CMake prefers to pass the
              full path directly to the native build tool, which will fail in
              this case because it does not name a valid library file.


              This policy determines what to do with full paths that do not
              appear to name a valid library file.  The OLD behavior for this
              policy is to split the library name from the path and ask the
              linker to search for it.  The NEW behavior for this policy is to
              trust the given path and pass it directly to the native build
              tool unchanged.


              This policy was introduced in CMake version 2.6.1.  CMake
              version 2.8.7 warns when the policy is not set and uses OLD
              behavior.  Use the cmake_policy command to set it to OLD or NEW
              explicitly.


       CMP0009
              FILE GLOB_RECURSE calls should not follow symlinks by default.

              In CMake 2.6.1 and below, FILE GLOB_RECURSE calls would follow
              through symlinks, sometimes coming up with unexpectedly large
              result sets because of symlinks to top level directories that
              contain hundreds of thousands of files.


              This policy determines whether or not to follow symlinks
              encountered during a FILE GLOB_RECURSE call. The OLD behavior
              for this policy is to follow the symlinks. The NEW behavior for
              this policy is not to follow the symlinks by default, but only
              if FOLLOW_SYMLINKS is given as an additional argument to the
              FILE command.


              This policy was introduced in CMake version 2.6.2.  CMake
              version 2.8.7 warns when the policy is not set and uses OLD
              behavior.  Use the cmake_policy command to set it to OLD or NEW
              explicitly.


       CMP0010
              Bad variable reference syntax is an error.

              In CMake 2.6.2 and below, incorrect variable reference syntax
              such as a missing close-brace ("${FOO") was reported but did not
              stop processing of CMake code.  This policy determines whether a
              bad variable reference is an error.  The OLD behavior for this
              policy is to warn about the error, leave the string untouched,
              and continue. The NEW behavior for this policy is to report an
              error.


              This policy was introduced in CMake version 2.6.3.  CMake
              version 2.8.7 warns when the policy is not set and uses OLD
              behavior.  Use the cmake_policy command to set it to OLD or NEW
              explicitly.


       CMP0011
              Included scripts do automatic cmake_policy PUSH and POP.

              In CMake 2.6.2 and below, CMake Policy settings in scripts
              loaded by the include() and find_package() commands would affect
              the includer.  Explicit invocations of cmake_policy(PUSH) and
              cmake_policy(POP) were required to isolate policy changes and
              protect the includer.  While some scripts intend to affect the
              policies of their includer, most do not.  In CMake 2.6.3 and
              above, include() and find_package() by default PUSH and POP an
              entry on the policy stack around an included script, but provide
              a NO_POLICY_SCOPE option to disable it.  This policy determines
              whether or not to imply NO_POLICY_SCOPE for compatibility.  The
              OLD behavior for this policy is to imply NO_POLICY_SCOPE for
              include() and find_package() commands.  The NEW behavior for
              this policy is to allow the commands to do their default
              cmake_policy PUSH and POP.


              This policy was introduced in CMake version 2.6.3.  CMake
              version 2.8.7 warns when the policy is not set and uses OLD
              behavior.  Use the cmake_policy command to set it to OLD or NEW
              explicitly.


       CMP0012
              if() recognizes numbers and boolean constants.

              In CMake versions 2.6.4 and lower the if() command implicitly
              dereferenced arguments corresponding to variables, even those
              named like numbers or boolean constants, except for 0 and 1.
              Numbers and boolean constants such as true, false, yes, no, on,
              off, y, n, notfound, ignore (all case insensitive) were
              recognized in some cases but not all.  For example, the code
              "if(TRUE)" might have evaluated as false.  Numbers such as 2
              were recognized only in boolean expressions like "if(NOT 2)"
              (leading to false) but not as a single-argument like "if(2)"
              (also leading to false). Later versions of CMake prefer to treat
              numbers and boolean constants literally, so they should not be
              used as variable names.


              The OLD behavior for this policy is to implicitly dereference
              variables named like numbers and boolean constants. The NEW
              behavior for this policy is to recognize numbers and boolean
              constants without dereferencing variables with such names.


              This policy was introduced in CMake version 2.8.0.  CMake
              version 2.8.7 warns when the policy is not set and uses OLD
              behavior.  Use the cmake_policy command to set it to OLD or NEW
              explicitly.


       CMP0013
              Duplicate binary directories are not allowed.

              CMake 2.6.3 and below silently permitted add_subdirectory()
              calls to create the same binary directory multiple times.
              During build system generation files would be written and then
              overwritten in the build tree and could lead to strange
              behavior.  CMake 2.6.4 and above explicitly detect duplicate
              binary directories.  CMake 2.6.4 always considers this case an
              error.  In CMake 2.8.0 and above this policy determines whether
              or not the case is an error.  The OLD behavior for this policy
              is to allow duplicate binary directories.  The NEW behavior for
              this policy is to disallow duplicate binary directories with an
              error.


              This policy was introduced in CMake version 2.8.0.  CMake
              version 2.8.7 warns when the policy is not set and uses OLD
              behavior.  Use the cmake_policy command to set it to OLD or NEW
              explicitly.


       CMP0014
              Input directories must have CMakeLists.txt.

              CMake versions before 2.8 silently ignored missing
              CMakeLists.txt files in directories referenced by
              add_subdirectory() or subdirs(), treating them as if present but
              empty.  In CMake 2.8.0 and above this policy determines whether
              or not the case is an error.  The OLD behavior for this policy
              is to silently ignore the problem.  The NEW behavior for this
              policy is to report an error.


              This policy was introduced in CMake version 2.8.0.  CMake
              version 2.8.7 warns when the policy is not set and uses OLD
              behavior.  Use the cmake_policy command to set it to OLD or NEW
              explicitly.


       CMP0015
              link_directories() treats paths relative to the source dir.

              In CMake 2.8.0 and lower the link_directories() command passed
              relative paths unchanged to the linker.  In CMake 2.8.1 and
              above the link_directories() command prefers to interpret
              relative paths with respect to CMAKE_CURRENT_SOURCE_DIR, which
              is consistent with include_directories() and other commands.
              The OLD behavior for this policy is to use relative paths
              verbatim in the linker command.  The NEW behavior for this
              policy is to convert relative paths to absolute paths by
              appending the relative path to CMAKE_CURRENT_SOURCE_DIR.


              This policy was introduced in CMake version 2.8.1.  CMake
              version 2.8.7 warns when the policy is not set and uses OLD
              behavior.  Use the cmake_policy command to set it to OLD or NEW
              explicitly.


       CMP0016
              target_link_libraries() reports error if only argument is not a
              target.

              In CMake 2.8.2 and lower the target_link_libraries() command
              silently ignored if it was called with only one argument, and
              this argument wasn't a valid target. In CMake 2.8.3 and above it
              reports an error in this case.


              This policy was introduced in CMake version 2.8.3.  CMake
              version 2.8.7 warns when the policy is not set and uses OLD
              behavior.  Use the cmake_policy command to set it to OLD or NEW
              explicitly.


       CMP0017
              Prefer files from the CMake module directory when including from
              there.

              Starting with CMake 2.8.4, if a cmake-module shipped with CMake
              (i.e. located in the CMake module directory) calls include() or
              find_package(), the files located in the the CMake module
              directory are preferred over the files in CMAKE_MODULE_PATH.
              This makes sure that the modules belonging to CMake always get
              those files included which they expect, and against which they
              were developed and tested.  In call other cases, the files found
              in CMAKE_MODULE_PATH still take precedence over the ones in the
              CMake module directory.  The OLD behaviour is to always prefer
              files from CMAKE_MODULE_PATH over files from the CMake modules
              directory.


              This policy was introduced in CMake version 2.8.4.  CMake
              version 2.8.7 warns when the policy is not set and uses OLD
              behavior.  Use the cmake_policy command to set it to OLD or NEW
              explicitly.


COPYRIGHT
       Copyright 2000-2009 Kitware, Inc., Insight Software Consortium.  All
       rights reserved.


       Redistribution and use in source and binary forms, with or without
       modification, are permitted provided that the following conditions are
       met:


       Redistributions of source code must retain the above copyright notice,
       this list of conditions and the following disclaimer.


       Redistributions in binary form must reproduce the above copyright
       notice, this list of conditions and the following disclaimer in the
       documentation and/or other materials provided with the distribution.


       Neither the names of Kitware, Inc., the Insight Software Consortium,
       nor the names of their contributors may be used to endorse or promote
       products derived from this software without specific prior written
       permission.


       THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
       IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
       TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
       PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
       HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
       SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
       LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
       DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
       THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
       (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
       OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.


SEE ALSO
       ccmake(1), cpack(1), ctest(1), cmakecommands(1), cmakecompat(1),
       cmakemodules(1), cmakeprops(1), cmakevars(1)


       The following resources are available to get help using CMake:


       Home Page
              http://www.cmake.org

              The primary starting point for learning about CMake.


       Frequently Asked Questions
              http://www.cmake.org/Wiki/CMake_FAQ

              A Wiki is provided containing answers to frequently asked
              questions.


       Online Documentation
              http://www.cmake.org/HTML/Documentation.html

              Links to available documentation may be found on this web page.


       Mailing List
              http://www.cmake.org/HTML/MailingLists.html

              For help and discussion about using cmake, a mailing list is
              provided at cmake@cmake.org. The list is member-post-only but
              one may sign up on the CMake web page. Please first read the
              full documentation at http://www.cmake.org before posting
              questions to the list.


       Summary of helpful links:


         Home: http://www.cmake.org
         Docs: http://www.cmake.org/HTML/Documentation.html
         Mail: http://www.cmake.org/HTML/MailingLists.html
         FAQ:  http://www.cmake.org/Wiki/CMake_FAQ




cmake 2.8.7                    February 09, 2012              cmakepolicies(1)
