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 commit re-words the warning message produced for CMP0012 to avoid
the word 'you' since often the person reading the message is not the
author of the code. We also add an example of the bad OLD behavior to
the policy documentation.
These policies were originally developed during the 2.7.x series and
intended for 2.6.5. There was never a 2.6.5 release, so we should refer
to 2.8.0 instead.
CMake policies CMP0014 and CMP0015 were implemented in the development
series version 2.7.x but will be first released in 2.8.0. Now that the
development version number is higher than that (2.9.x) we can update
their version of introduction to the actual release number.
In CMake Policy documentation we specify the default behavior for the
current version of CMake. This commit fixes that version by reporting
the full version number instead of just major and minor.
The GNU compiler warns about possible operator precedence mistakes and
asks for explicit parentheses (-Wparentheses). We add the parentheses
to silence the warning. This also fixes one real logic error in the
find_package() implementation by correcting expression evaluation order.
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.
This fixes the CMP0012 description to have a one-line summary in the
'brief' section and the rest of the explanation in the 'full' section.
It makes the warning message shorter and improves formatting of the
policy documentation, especially in the HTML pages. The convention is
already used by all other policies.
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.
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.
- Message for missing cmake_minimum_required is not issued
until the end of processing the top CMakeLists.txt file
- During processing a cmake_policy command may set behavior
- OLD behavior is to silently ignore the problem
- NEW behavior is to issue an error instead of a warning
- In cmake_minimum_required do not set policy version if current
CMake is too old
- In cmPolicies::ApplyPolicyVersion report error if version is too
new or cannot be parsed
- Give example code to avoid the warning
- Make explanation more consise
- Explicitly state this is for compatibility
- Issue the warning for at most one target
- Update policy CMP0000 to require use of the command
cmake_minimum_required and not cmake_policy
so there is only one way to avoid it.
- Explicitly specify the line users should add.
- Reference policy CMP0000 only at the end.
- Fix policy CMP0000 documentation to not suggest
use of the cmake_policy command.
- 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
Brad King
Stephen Kelly
Andreas Mohr
Modestas Vainius
Alex Neundorf
Ken Martin
David Cole
Bill Hoffman