Historically CMake has always expanded ${} variable references in the
values given to include_directories(), link_directories(), and
link_libraries(). This has been unnecessary since general ${}
evaluation syntax was added to the language a LONG time ago, but has
remained for compatibility with VERY early CMake versions.
For a long time the re-expansion was a lightweight operation because it
was only processed once at the directory level and the fast-path of
cmMakefile::ExpandVariablesInString was usually taken because values did
not have any '$' in them. Then commit d899eb71 (Call
ExpandVariablesInString for each target's INCLUDE_DIRECTORIES,
2012-02-22) made the operation a bit heavier because the expansion is
now needed on a per-target basis. In the future we will support
generator expressions in INCLUDE_DIRECTORIES with $<> syntax, so the
fast-path in cmMakefile::ExpandVariablesInString will no longer be taken
and re-expansion will be very expensive.
Add policy CMP0019 to skip the re-expansion altogether in NEW behavior.
In OLD behavior perform the expansion but improve the fast-path
heuristic to match ${} but not $<>. If the policy is not set then warn
if expansion actually does anything. We expect this to be encountered
very rarely in practice.
CMAKE_SHARED_LIBRARY_<lang>_FLAGS has flags on various platforms for a
variety of purposes that are correlated with shared libraries but not
exclusive to them. Refactor generation of these flags to use new
purpose-specific platform variables
CMAKE_<lang>_COMPILE_OPTIONS_DLL
CMAKE_<lang>_COMPILE_OPTIONS_PIC
CMAKE_<lang>_COMPILE_OPTIONS_PIE
Activate the DLL flags specifically for shared libraries. Add a new
POSITION_INDEPENDENT_CODE target property to activate PIC/PIE flags, and
default to true for shared libraries to preserve default behavior.
Initialize the new property from CMAKE_POSITION_INDEPENDENT_CODE to
allow easy global configuration in projects.
Although the default behavior is unchanged by this refactoring, the new
approach ignores CMAKE_SHARED_LIBRARY_<lang>_FLAGS completely. We must
leave it set in case projects reference the value. Furthermore, if a
project modifies CMAKE_SHARED_LIBRARY_<lang>_FLAGS it expects the new
value to be used. Add policy CMP0018 to handle compatibility with
projects that modify this platform variable.
Add a PositionIndependentCode test on platforms where we can get
meaningful results.
This patch makes include() and find_package() prefer cmake files
located in CMAKE_ROOT over those in CMAKE_MODULE_PATH.
This makes sure that the including file gets that file included
which it expects, i.e. the one from cmake with which it was tested.
It only changes behaviour when such an included file exists both
in CMAKE_MODULE_PATH and in CMAKE_ROOT.
This comes together with a new policy CMP0017, with default
behaviour it behaves as it always did, but warns.
With NEW behaviour it includes the file from CMAKE_ROOT
instead from CMAKE_MODULE_PATH. This fixes (if CMP0017 is set)
building KDE 4.5 with cmake >= 2.8.3.
Also a basic test for this policy in included.
Check CMAKE_POLICY_DEFAULT_CMP<NNNN> for a default when policy CMP<NNNN>
would otherwise be left unset. This allows users to set policies on the
command line when the project does not set them. One may do this to
quiet warnings or test whether a project will build with new behavior
without modifying code. There may also be cases when users want to
build an existing project release using new behavior for policies
unknown to the project at the time of the release.
When set to OLD, target_link_libraries() silently accepts if it is called
with only one argument and this one argument is not a target.
When set to NEW, this is an error. By default it is a warning now.
Alex
Add the [.tweak] version component throughout the policy implementation.
Document all components for the cmake_policy(VERSION) command. Record
the tweak level in which each policy was introduced (0 for all current
policies). In generated documentation we report the tweak level only if
it is not zero. This preserves existing documentation.
We create CMake Policy CMP0015 to make link_directories() treat relative
paths with respect to the source tree while retaining compatibility.
This makes it consistent with include_directories() and other commands.
Changes based on patch from Alex. See issue #9697.
The commit "modified the if command to address bug 9123 some" changed
the if() command behavior with respect to named boolean constants. It
introduced policy CMP0012 to provide compatibility. However, it also
changed behavior with respect to numbers (like '2') but did not cover
the change with the policy. Also, the behavior it created for numbers
is confusing ('2' is false).
This commit teaches if() to recognize numbers again, and treats them
like the C language does in terms of boolean conversion. We also fix
the CMP0012 check to trigger in all cases where the result of boolean
coersion differs from that produced by CMake 2.6.4.
We revert commit "Create CMake Policy CMP0015 to fix set(CACHE)" because
the NEW behavior of the policy breaks a valid use case:
# CMakeLists.txt
option(BUILD_SHARED_LIBS "..." ON)
add_library(mylib ...)
set(BUILD_SHARED_LIBS OFF) # we want only mylib to be shared
add_subdirectory(ThirdParty)
# ThirdParty/CMakeLists.txt
option(BUILD_SHARED_LIBS "..." ON)
# uh, oh, with NEW behavior this dir uses shared libs!!!
We'll re-introduce the policy later with a different change in behavior
to resolve the motivating case, which was more subtle but less common.
See issue #9008.
This converts the CMake license to a pure 3-clause OSI-approved BSD
License. We drop the previous license clause requiring modified
versions to be plainly marked. We also update the CMake copyright to
cover the full development time range.
The set(CACHE) and option() commands should always expose the cache
value. Previously we failed to expose the value when it was already set
if a local variable definition hid it. When set to NEW, this policy
tells the commands to always remove the local variable definition to
expose the cache value. See issue #9008.
Until now CMake accidentally accepted add_subdirectory() and subdirs()
calls referring to directories that do not contain a CMakeLists.txt
file. We introduce CMake Policy CMP0014 to make this case an error.
In CMake 2.6.3 and below we silently accepted duplicate build
directories whose build files would then conflict. At first this was
considured purely a bug that confused beginners but would not be used in
a real project. In CMake 2.6.4 we explicitly made it an error.
However, some real projects took advantage of this as a "feature" and
got lucky that the subtle build errors it can cause did not occur.
Therefore we need a policy to deal with the case more gracefully.
See issue #9173.
Isolation of policy changes inside scripts is important for protecting
the including context. This teaches include() and find_package() to
imply a cmake_policy(PUSH) and cmake_policy(POP) around the scripts they
load, with a NO_POLICY_SCOPE option to disable the behavior. This also
creates CMake Policy CMP0011 to provide compatibility. See issue #8192.
This defines PolicyMap as a public member of cmPolicies. Its previous
role as a policy stack entry is now called PolicyStackEntry and
represented as a class to which more information can be added later.
Previously error messages produced by parsing of command argument
variable references, such as bad $KEY{VAR} syntax or a bad escape
sequence, did not provide good context information. Errors parsing
arguments inside macro invocations gave no context at all. Furthermore,
some errors such as a missing close curly "${VAR" would be reported but
build files would still be generated.
These changes teach CMake to report errors with good context information
for all command argument parsing problems. Policy CMP0010 is introduced
so that existing projects that built despite such errors will continue
to work.
In the future some policies may be set to REQUIRED_IF_USED or
REQUIRED_ALWAYS. This change clarifies the error messages users receive
when violating the requirements.
This change introduces policy CMP0008 to decide how to treat full path
libraries that do not appear to be valid library file names. Such
libraries worked by accident in the VS IDE and Xcode generators with
CMake 2.4 and below. We support them in CMake 2.6 by introducing this
policy. See policy documentation added by this change for details.
- Policy is WARN by default so projects will build
as they did in 2.4 without user intervention
- Remove CMAKE_LINK_OLD_PATHS variable since it was
never in a release and the policy supercedes it
- Report target creation backtrace in warning message
since policy should be set by that point
- Remove CMP_0001 (no slash in target name) and restore
old CMAKE_BACKWARDS_COMPATIBILITY check for it
- Replace all checks of CMAKE_BACKWARDS_COMPATIBILITY
with cmLocalGenerator::NeedBackwardsCompatibility calls
- Create new CMP_0001 to determine whether or not
CMAKE_BACKWARDS_COMPATIBILITY is used.
(old = use, new = ignore)
- Show CMAKE_BACKWARDS_COMPATIBILITY in cache only when
CMP_0001 is set to OLD or WARN
- Update documentation of cmake_policy and cmake_minimum_required
to indicate their relationship and the 2.4 version boundary
- When no cmake policy version is set in top level makefile
implicitly call cmake_policy(VERSION 2.4) which restores
CMAKE_BACKWARDS_COMPATIBILITY and other 2.4 compatibility
- Fix tests MakeClean and Preprocess to call
cmake_policy(VERSION 2.6) because they depend on new policies
Stephen Kelly
Brad King
Yury G. Kudryashov
Alex Neundorf
Ken Martin
Bill Hoffman
David Cole