Record the availability of this feature for GNU 4.8 on (UNIX AND
NOT APPLE) only. In the future, availability can be recorded for
earlier GNU, for other platforms and for other compilers. Initially
the affected configurations are as restricted as possible to allow
for easy testing while extending the features vector in only one
dimension.
The error message when using the set_property API directly is not
very good, but follow up commits will provide origin debugging of
the property and a target_compile_features command which will
provide a configure-time backtrace when possible.
This will allow decoupling the name of the test from the name and
location of the source file under test, which means one source
file can be used for multiple tests.
Rename the PARENT_SCOPE test in RunCMake.set to not use a keyword
of the if() command as a file name. As the filename is now used
with an if condition, this causes a conflict.
9407174b target_sources: New command to add sources to target.
81ad69e0 Make the SOURCES target property writable.
6e636f2e cmTarget: Make the SOURCES origin tracable.
3676fb49 cmTarget: Allow transitive evaluation of SOURCES property.
e6971df6 cmTarget: Make the source files depend on the config.
df753df9 cmGeneratorTarget: Don't add computed sources to the target.
869328aa cmComputeTargetDepends: Use valid config to compute target depends.
5de63265 Genex: Only evaluate TARGET_OBJECTS to determine target sources.
aa0a3562 cmGeneratorTarget: Compute target objects on demand
042c1c83 cmTarget: Compute languages from object libraries on demand.
fdcefe3c cmGeneratorTarget: Compute consumed object libraries on demand.
c355d108 cmComputeTargetDepends: Track object library depends.
e5da9e51 cmTarget: Allow any generator expression in SOURCES property.
5702e106 cmTarget: Include TARGET_OBJECTS genex in target SOURCES property.
857d30b5 cmGlobalGenerator: Add interface to call ForceLinkerLanguages
28e1d2f8 cmStringCommand: Add GENEX_STRIP subcommand.
bf98cc25 Genex: Evaluate TARGET_OBJECTS as a normal expression.
8cd113ad cmTarget: Store strings instead of cmSourceFile* to represent SOURCES.
4959f341 cmSourceFileLocation: Collapse full path for directory comparisons.
fcc92878 cmSourceFileLocation: Remove unused Update method.
59e8740a cmTarget: Remove AddSourceFile method
26d494ba cmTarget: Use string API to add sources to cmTarget objects.
d38423ec cmTarget: Add a method to obtain list of filenames for sources.
...
Disallow the use of config-specific source files with
the Visual Studio and Xcode generators. They don't have
any way to represent the condition currently.
Use the same common-config API in cmQtAutoGenerators. While
it accepts config-specific files, it doesn't have to support
multiple configurations yet.
Loop over the configs in cmTargetTraceDependencies
and cmGlobalGenerator::WriteSummary and consume all source
files.
Loop over the configs in cmComputeTargetDepends and compute the
object library dependencies for each config.
The output of this expression may contain macros for IDEs to replace
such as $(Configuration), $(CURRENT_ARCH) etc. To avoid generating
content which is not usable in other contexts, report an error if
there is an attempt to use it in other contexts.
This commit may be reverted in the future if a solution to the
above difference is implemented.
Remove use of UseObjectLibraries from Makefile and Ninja generators. It
is not needed now because those generators use GetExternalObjects
which already contains the objects from object libraries.
The VS10 generator calls both the UseObjectLibraries and the GetExternalObjects
methods. Ensure that duplicates are not created by skipping objects
from object libraries in handling of GetExternalObjects.
Similarly, fix VS6, VS7 and Xcode object handling by skipping
external objects from OBJECT_LIBRARY usage as appropriate.
The error message in the BadSourceExpression1 test is now reported
by the generator expression evaluator, so it has different text.
Use CMAKE_PREFIX_PATH, CMAKE_FRAMEWORK_PATH, and CMAKE_APPBUNDLE_PATH
cache and environment variables to extend PKG_CONFIG_PATH before calling
pkg-config.
In each of the path in these variables it searches for lib/pkgconfig.
Then, depending on the system, it searches for
lib/${CMAKE_LIBRARY_ARCHITECTURE}/pkgconfig (debian) or for
lib64/pkgconfig (other 64 bit unixes). If any of these path is found,
it is appended to the PKG_CONFIG_PATH enviromnent variable.
Add two new arguments to the pkg_check_module and pkg_search_module
macro, NO_CMAKE_PATH and NO_CMAKE_ENVIRONMENT_PATH. The new signature
are therefore:
pkg_check_modules(<PREFIX> [REQUIRED] [QUIET]
[NO_CMAKE_PATH] [NO_CMAKE_ENVIRONMENT_PATH]
<MODULE> [<MODULE>]*)
pkg_search_module(<PREFIX> [REQUIRED] [QUIET]
[NO_CMAKE_PATH] [NO_CMAKE_ENVIRONMENT_PATH]
<MODULE> [<MODULE>]*)
By default, if CMAKE_MINIMUM_REQUIRED_VERSION is 3.1 or later (in
order to keep compatibility with the previous behavior), or if
PKG_CONFIG_USE_CMAKE_PREFIX_PATH is set, the CMAKE_PREFIX_PATH,
CMAKE_FRAMEWORK_PATH, and CMAKE_APPBUNDLE_PATH cache and environment
variables will be added to pkgconfig search path.
The NO_CMAKE_PATH and NO_CMAKE_ENVIRONMENT_PATH arguments disable this
behavior for the cache variables and the environment variables,
respectively, similarly to the find_package() command.
Restore support for the undocumented <CONFIG>_LOCATION target property
removed by commit v3.0.0-rc1~175^2 (cmTarget: Remove support for
<CONFIG>_LOCATION property, 2013-12-30) as part of the CMP0026 OLD
behavior.
9608ef6f Tests: Optionally configure tests exclusively, with an external CMake
9f5bd180 Tests: Drop CMAKE_TEST_GENERATOR(|_TOOLSET) variables
76477267 Tests: Drop CMAKE_TEST_MAKEPROGRAM variable
a8a9fb7e Tests: Rename CMAKE_TEST_MAKEPROGRAM uses for explicit make program
40475573 Tests: Rename CMAKE_TEST_MAKEPROGRAM uses for nested test projects
f99734b2 Tests: Rename CMAKE_TEST_DEVENV -> CMake_TEST_DEVENV
3c01ee5a Tests: Drop CMAKE_TEST_MSVC and test MSVC directly
daf0a5fe Tests: Drop CMAKE_TEST_GENERATOR and CMAKE_TEST_MAKEPROGRAM options
e5096312 Tests: Drop kwsys test
On OS X we pass -DCMAKE_POLICY_DEFAULT_CMP0025=NEW to all tests.
Once tests start using cmake_minimum_required(VERSION 3.0) then
CMake will warn that CMAKE_POLICY_DEFAULT_CMP0025 is unused.
These warnings are not part of the expected test output and can
cause such tests to fail. Pass --no-warn-unused-cli to each test
cmake invocation to tell it not to produce these warnings.
f9d5b1fd Handle Mac OSX source flags for individual files lazily.
64d39841 cmGeneratorTarget: Classify sources on demand, not up front.
d3682d86 cmGeneratorTarget: Use a method to access the definition file.
5771f81d cmTarget: Add GetTransitiveTargetClosure method.
a6dd4990 cmTarget: Create a temporary cmTarget in checkInterfacePropertyCompatibility
b8b99cc1 cmTarget: Avoid computing languages when computing transitive targets.
01bca553 cmTarget: Move ComputeLinkInterface to the internal class.
d93e1af2 cmTarget: Extract a ComputeLinkInterfaceLibraries method.
3bcb197c cmTarget: Re-arrange the ComputeLinkInterface method.
326d07d2 cmTarget: Extract a ComputeLinkImplementationLanguages method.
21e91350 cmTarget: Change GetTransitivePropertyLinkLibraries to output targets.
f81eb49e cmTarget: Find source files on request.
84e5f5a0 cmTarget: Move SourceFileFlags to cmGeneratorTarget.
Replace calls to GetLinkInformation with calls to a method to get only
the target closure, not the link languages etc. The replaced calls
are used while evaluating generator expressions only. This makes
transitive generator expression evaluation independent from
the languages of a target. In a follow-up topic, it will be possible
to make the languages depend on generator expression evaluation, via
evaluation of the SOURCES and INTERFACE_SOURCES target properties.
Because the order of entries is not the same as the final link line,
the order of debug output is different in the RunCMake.CompatibleInterface
test, because the BOOL_PROP7 target property is evaluated first. Adjust
the test to account for that new order.
There are some corner cases in variable expansion which would be nice to
capture before going and rewriting the variable expansion code. The
majority of these are related to configuring files and strings with '@'
in them in conjunction with @ONLY being specified. Another is testing
for '(' usage inside of ENV variable references based on whether it is
quoted or not.
This has to be tested separately from the invalid_signature test because
target sources are evaluate at a later time, and earlier errors in the
invalid_signature test cause early exit.
Enable the C and CXX languages only in the test cases that really need
them. In the failure cases we do not get far enough to really use the
languages, so skip enabling them.
41d2f2c4 write_basic_package_version_file: use PROJECT_VERSION
7e142c5a project: Manage VERSION variables
16d040c9 project: Add optional LANGUAGES keyword
00007dcc Help: Format project command and variable documentation
Teach the project() command to set variables
{PROJECT,<PROJECT-NAME>}_VERSION{,_MAJOR,_MINOR,_PATCH,_TWEAK}
holding the project version number and its components. Add project()
command option "VERSION" to specify the version explicitly, and default
to the empty string when it is not given.
Since this clears variables when no VERSION is given, this may change
behavior for existing projects that set the version variables themselves
prior to calling project(). Add policy CMP0048 for compatibility.
Suggested-by: Alex Neundorf <neundorf@kde.org>
Teach the project() command to recognize an optional "LANGUAGES"
keyword after the project name and prior to the list of languages.
Do not allow multiple copies of the keyword. If the keyword is
specified and no languages are listed, imply NONE.
Set the minimum required version of CMake high enough to avoid the
warning for CMAKE_LEGACY_CYGWIN_WIN32. The warning appears on stderr
and breaks the expected output matching.
Define a new 'CMAKE_CONFIGURE_DEPENDS' directory property that projects
can use to specify input files to the CMake configuration process.
Extend the RunCMake.Configure test to verify that the build system
re-runs CMake when this input changes.
Extend the RunCMake.Configure with a case to verify that the CMake
configuration process does not immediately re-run the first time that
the generated build system is invoked.
The logic added by commit ffc0b5e4 (Overwrite the symlink if it already
exists, 2007-02-15) does not recognize and remove existing broken links
before replacing them. Improve the logic to remove any existing
destination file or link (but not directory). On failure, report an
error message explaining why the existing path could not be removed or
the new one could not be created.
Add a RunCMake.CommandLine test to cover 'cmake -E' cases. Start with
test cases covering 'cmake -E create_symlink' behavior on UNIX platforms.
Add a 'run_cmake_command' function that can be used by tests to run a
given command-line and check the results rather than always running a
CMake configuration process. This can be used in the future to test
'cmake -E' for example.
73e9340 get_target_property: Error on non-existent target.
ab9f58f FindQt4: Ensure target exists before calling get_target_property.
37ebeb9 FindQt4: Fix use of get_target_property to use actual target name.
6aabb6a Genex: Use case-sensitive comparison for COMPILER_ID.
5bb53f6 cmTarget: Deprecate COMPILE_DEFINITIONS_ properties with a policy.
This is consistent with other similar expressions such as PLATFORM_ID,
and makes the CONFIGURATION expression obsolete.
Fix an off-by-one error in
GeneratorExpressionContent::EvaluateParameters exposed by a unit test.
Remove the test for 'bad' nullary use of $<CONFIG>.
Add a unit test to verify that $<CONFIG> and $<CONFIGURATION> have
the same value.
As a new feature it does not need to participate in CMP0024.
Store cmExportBuildFileGenerator instances which correspond to the
export(EXPORT) signature in a second map which does not own the
pointers. This avoids the need to add cmExportBuildFileGenerator
and dependencies to the bootstrap system.
Test that it is an error to read a number-compatible property to
determine the link implementation. An alternative would be to
consider the value to be "0", however, that is too arbitrary
given the use-cases of this feature. Values from this feature may
be used in setting a define, where "0" may have special or invalid
meaning and should be explicit.
If the dependent target sets the property to boolean false, ensure
that that appears in the debug report. Previously, the report
output contained whether the property was consistent among dependencies,
displaying 'TRUE', instead of the content of the property, which may
be 'FALSE'.
Return a std::pair from the consistentProperty method. This makes
it possible to make the return value for string types easier to
reason about. The return value of consistentProperty was previously
set to an empty static string to emulate a 'true' value for the caller
in commit 816b4a8a (cmTarget: Make consistentProperty
return consistent content., 2013-10-22). The pair makes the
consistency result properly typed.
Don't refer to 'both', but a 'mixture'. List all compatible interface
property types possible.
Add another test for a mixture of three compatibilities.
Teach the export command to handle export sets defined by invocations
of install(TARGETS ... EXPORT foo). This makes maintenance of targets
exported to both the build tree and install tree trivial.
The INTERFACE_LIBRARY type does not have any LOCATION at all, so
return early from GetMappedConfig. GetMappedConfig is called from
two locations, one of which already pre-checks the INTERFACE_LIBRARY
case. Remove that pre-check and handle that case inside the method
instead.
Revert the origin-tracking infrastructure from commit 98093c45 (QtAutoUic:
Add INTERFACE_AUTOUIC_OPTIONS target property., 2013-11-20). Use the
compatibility-tracking for compatible strings instead.
If two different dependencies require different AUTOUIC_OPTIONS,
cmake will now appropriately issue an error.
Commit 66b290e7 (export(): Process the export() command at generate
time., 2012-10-06 ) refactored export() so that it could evaluate
strings at generate-time. This was intended for evaluating target
properties, but that commit also removed a check for target
existence at configure-time. Restore that check and add a test for
this case.
5838aba Export: Report error on relative include with genex.
7a3e45b Export: Prefix relative items with genexes in INSTALL_INTERFACE.
f088a32 Export: Process INSTALL_INTERFACE in INCLUDES DESTINATION.
9eedc85 Export: Process relative includes after genex evaluation.
80790f3 Export: Test existing behavior of exporting includes with genexes.
38afc82 target_include_directories: Allow relative path with genex
Diagnostics which check the sanity of exported include paths
previously skipped over any path containing a generator expression.
Introduce a policy to issue an error message in such cases.
The export files created in the OLD behavior are not usable, because
they contain relative paths or paths to the source or build location
which are not suitable for use on installation. CMake will report an
error on import.
In code such as
install(TARGETS ...
INCLUDES DESTINATION $<FOO>include
)
the generator expressions are evaluated at generate-time. Delay
determining whether each entry is a relative path until after
the generator expressions are evaluated. Such relative paths
are based relative to the CMAKE_INSTALL_PREFIX.
4cce44b Help: Document the CMAKE_MAKE_PROGRAM variable in more detail
558c74d VS: Switch to internal CMAKE_MAKE_PROGRAM lookup by generators
5229f2d Tests: Do not use an explicit make program for VS generators
72dd738 Tests: Fix MFC test heuristic for empty CMAKE_TEST_MAKEPROGRAM
fd6076d Tests: Pass CMAKE_MAKE_PROGRAM instead of --build-makeprogram
68031ab Tests: Configure SubProject-Stage2 test more robustly
003d10c Tests: Simplify VSExcludeFromDefaultBuild configuration
e47d934 Tests: Simplify VSProjectInSubdir configuration
e965cb1 Tests: Simplify CTest.BuildCommand.ProjectInSubdir configuration
72bf255 Tests: Pass --build-options to every test
4d1d772 ctest: Teach --build-options to allow zero options
96966b5 ctest: Make the --build-makeprogram optional for --build-and-test
91a0211 Simplify some calls to cmGlobalGenerator::Build
123a060 Teach GenerateBuildCommand to find its own make program
5f5c92b VS: Add internal APIs to find MSBuild, devenv/VCExpress, and msdev
4ac75fd Prefer CMAKE_MAKE_PROGRAM over CMAKE_BUILD_TOOL (#14548)
...
Teach add_custom_target to check the policy too. Extend the policy to
disallow reserved target names that we use for builtin targets like
"all".
Extend the RunCMake.CMP0037 test to cover these cases.
Historically these were both added for the Makefile and Visual Studio
generators, respectively. Later the VS generators started using the
CMAKE_MAKE_PROGRAM cache entry to find the IDE build tool, and the
CMAKE_BUILD_TOOL was simply set as an alias.
Fix the documentation to explain that CMAKE_MAKE_PROGRAM is the modern
variable and that CMAKE_BUILD_TOOL is the compatibility alias, not the
other way around. Replace uses of CMAKE_BUILD_TOOL with
CMAKE_MAKE_PROGRAM in CMake-provided modules. Nothing needs to lookup
CMAKE_BUILD_TOOL in the cache, so simply set it as a normal variable.
Re-implement the build_command() command to use "cmake --build" instead
of generating a native build tool invocation directly. This command
will internally invoke the proper native build tool.
This avoids requiring cmGlobalGenerator::GenerateBuildCommand to produce
a string so that it can be later refactored to produce a vector with no
quoting or escaping. It will also allow us to later teach CMake to
delay the decision about which build tool to invoke until after the
project build system is generated to disk. For example, on Visual
Studio 10 and above the preferred command-line tool is MSBuild, but we
need to fall back to devenv if the .sln has Intel Fortran .vfproj files.
bf755c7 set: Add unit tests for set/unset PARENT_SCOPE
bc280f1 set: Fix handling of empty value with PARENT_SCOPE
20afbd5 set: Handle value-less PARENT_SCOPE explicitly
Since commit 7d47c693 (Drop compatibility with CMake < 2.4, 2013-10-08)
we no longer need to use the configure_file IMMEDIATE option to support
compatibility modes less than 2.0.
Allow ExternalData_URL_TEMPLATES to be empty if a value for
ExternalData_OBJECT_STORES is provided. Assume in this use case that
the object stores will already contain all needed objects. Extend the
Module.ExternalData test to cover this case (all objects in stores).
Extend the RunCMake.ExternalData test to cover the non-failure message
case when stores are provided without URL templates.
Split the test cases covering spaces and colons into separate units.
Run the space cases everywhere. Disable the colon cases where they
are known to fail. This approach increases platform coverage for the
test and makes the known-failure logic as local as possible.
No Makefile generator on Windows can generate targets with ':'
in their name because the CMakeFiles/<target>.dir directory cannot
be created. Skip this part of the test on all Windows Make tools.
Commit 239b0c6b (Don't add invalid content to static lib
INTERFACE_LINK_LIBRARIES., 2013-10-20) extended a test which
excercised the logic of the LINK_ONLY generator expression.
Commit ef10b87c (CMP0022: Plain target_link_libraries must populate
link interface, 2013-11-02) removed the instance of LINK_ONLY which
was excercised by that test.
Add a new test which excercises the other instance of LINK_ONLY by
setting the CMP0022 policy to NEW and consuming the contents of the
INTERFACE_LINK_LIBRARIES target property.
Resolve conflict in Source/cmTarget.cxx by integrating the changes to
the internal copy constructor from both sides. Also resolve a logical
conflict by dropping the special case for INTERFACE_LIBRARY targets.
Since cmTarget::SetMakefile already forces CMP0022 to NEW for such
targets we need no special handling.
Resolve conflict in Source/cmTargetLinkLibrariesCommand.h by dropping
the documentation change. We will make the same change in the new
location of the same documentation in a separate commit.
Resolve conflicts in
Tests/RunCMake/CMP0022/CMP0022-WARN-empty-old-stderr.txt
Tests/RunCMake/CMP0022/RunCMakeTest.cmake
by taking the side from the 'policy-CMP0022-fixes' branch.
Since cmTarget::ComputeLinkInterface is called separately for each
"head" target that links a target, the warning we produce when
CMP0022 is not set could be repeated. Add explicit logic to allow
the warning to appear at most once. Multiple copies of the warning
for the same target are almost always identical and therefore
redundant. In the rare case that two copies of the warning are
different, the second can appear in a future run after the first
is fixed.
When cmExportFileGenerator::SetImportLinkInterface exports the old
LINK_INTERFACE_LIBRARIES property values it skips doing so for
non-linkable targets because target->GetLinkInterface returns NULL for
such targets.
Since cmExportFileGenerator::PopulateInterfaceLinkLibrariesProperty
looks at the INTERFACE_LINK_LIBRARIES property directly instead of using
the computed link interface, teach it to skip exporting the property if
target->IsLinkable returns false.
Extend the RunCMake.CMP0022 test with a case covering this. Simply
export an executable target that links to a library that is not
exported.
The CMP0022 NEW behavior is that the INTERFACE_LINK_LIBRARIES property
exactly defines the link interface. The plain target_link_libraries
signature says linking is transitive by default, so it should populate
the property.
Teach the target_link_libraries plain signature to populate the
INTERFACE_LINK_LIBRARIES regardless of the CMP0022 setting. Refactor
the cmTarget::ComputeLinkInterface checks that warn when the policy is
not set to compare the new property to either the explicitly set old
link interface properties or the link implementation fallback for all
linkable target types, not just static libraries.
This fixes a regression in 2.8.12.0 that caused target_link_libraries to
not implement transitive linking in the plain signature once the policy
CMP0022 is set to NEW.
Teach cmGlobalGenerator::CheckTargets to include OBJECT_LIBRARY targets
in the check for source file existence.
Extend the RunCMake.ObjectLibrary test to cover this case.
Teach the cmGeneratorExpressionEvaluator filesystem artifact logic
to reject OBJECT_LIBRARY targets since they have no main artifact.
Without the explicit rejection evaluation falls through to an
internal CMake error message in cmTarget::GetOutputInfo.
Extend the RunCMake.GeneratorExpression test to cover these cases.
In certain scenarios, it is preferable to keep a 'dirty' install prefix
than to clear it, and to expect that content will not be found there.
Add a CMAKE_FIND_NO_INSTALL_PREFIX variable that can be set to disable
searching the install prefix.
Bracket arguments recorded in command invocations inside foreach,
function, and macro blocks should not have any replacements done when
the arguments are replayed later. Teach the RunCMake.Syntax test to
cover these cases.
Add an Escape1 test case covering \-escape cases inside bracket, quoted,
and unquoted arguments. Also cover comments immediately after quoted
and unquoted arguments on lines containing \# escapes.
3e04946 Require CMAKE_<LANG>_COMPILER to be found as a full path
6007f7c CMakeDetermineCompilerId: Always use compiler detected from IDE
332771c CMakeDetermine*Compiler: Remove temporary cache entry
All generators now support detection of the full path to the compiler, so
require it to be so. This will allow CMake<LANG>Information.cmake and
other logic to assume the full path to the compiler tool is available.
The Makefile generators already rejected CMAKE_<LANG>_COMPILER values
that did not name an existing compiler. Extend this error message to
all generators, make it occur as early as possible, and improve the
message with advice about how to set the compiler. If the full path to
the compiler is not known, finish enabling languages with a fatal error
so configuration does not continue.
For now, allow the RC language compiler to not be a full path. Later we
will need to detect the full path to "rc" under the VS IDE.
Add a RunCMake.CompilerNotFound test to cover failure cases.
Fix the RunCMake.CompilerChange test EmptyCompiler case to work
when configuration does not continue past enable_language.
Only valid target names or generator expressions may appear in
the target field of a LINK_ONLY expression.
Other content like link flags should still be added to that property
(wrapped in config-specific generator expressions), but not wrapped
in LINK_ONLY. Otherwise undue warnings would be issued for the
policy CMP0022.
The LINK_ONLY expression only has an effect for actual target
names anyway, so there is no logical deficit.
Set the minimum required version of CMake high enough to avoid the
warning for CMAKE_LEGACY_CYGWIN_WIN32. The warning appears on stderr
and breaks the expected output matching.
It was a subtest of the RunCMake.ObjectLibrary test. However, we need
to test a build with ExternalProject after running CMake, which RunCMake tests
do not do.
Teach the CMake language lexer to treat the \-LF pair terminating a
line ending in an odd number of backslashes inside a quoted argument
as a continuation. Drop the pair from the returned quoted argument
token text. This will allow long lines inside quoted argument
strings to be divided across multiple lines in the source file.
It will also allow quoted argument text to start on the line after
the opening quote. For example, the code:
set(x "\
...")
sets variable "x" to the value "..." with no opening newline.
Previously an odd number of backslashes at the end of a line inside
a quoted argument would put a \-LF pair (or a \-CR pair) literally
in the argument. Then the command-argument evaluator would complain
that the \-escape sequence is invalid. Therefore this syntax is
available to use without changing behavior of valid existing code.
Teach the RunCMake.Syntax test to cover cases of quoted arguments
with lines ending in \, \\, and \\\. Odd counts are continuations.
Drop all behavior activated by setting CMAKE_BACKWARDS_COMPATIBILITY to
a value lower than 2.4, and generate an error when projects or the user
attempt to do so. In the error suggest using a CMake 2.8.x release.
Teach cmake_minimum_required to warn about projects that do not require
at least CMake 2.4. They are not supported by CMake >= 3.0.
Replace the documentation of CMAKE_BACKWARDS_COMPATIBILITY with a
reference to policy CMP0001.
Other warnings for the same policy already have similar output since
commit 81d2793e (Add differing target property content to policy CMP0022
warning, 2013-09-11).