da928d30 Help: Add notes for topic 'Apple-compiler-selection'
1f085e11 OS X: Resolve compiler in /usr/bin to that reported by Xcode xcrun
85d31735 CMakeDetermineCompiler: Factor out xcrun invocation into a macro
dcd72a74 Help: Add notes for topic 'Xcode-clang-compile-features'
3ad893b5 Features: Record for historical Xcode clang versions.
98965fb1 Features: Record dialect flags for AppleClang 4.0+.
Revert commits:
2d738ce3 Help: Add notes for topic 'feature_record_msvc'
f73718c9 Features: Enable writing of MSVC compiler feature header.
64c30bdc Features: Record for MSVC C++ 2015 and MSVC C 2010-2015.
225c0ef8 Features: Record for MSVC 2010-2013.
This topic was merged to master prematurely, so remove it.
4035ef78 cmake -E tar: error out on multiple compression formats
d811d238 cmSystemTools: use an enumeration for compression formats
df16dcfb cmake -E tar: add support for .xz files with 'J'
b0a5d393 cmake -E tar: clean up flag documentation
2d738ce3 Help: Add notes for topic 'feature_record_msvc'
f73718c9 Features: Enable writing of MSVC compiler feature header.
64c30bdc Features: Record for MSVC C++ 2015 and MSVC C 2010-2015.
225c0ef8 Features: Record for MSVC 2010-2013.
AppleClang does not support the cxx_thread_local feature, even
though it is based on a Clang version which does support the
feature.
http://stackoverflow.com/a/23850891/2428389
A possible reason for that is that thread_local might be used as
a variable in existing Apple SDK headers.
Extend the WriteCompilerDetectionHeader module to generate a define
for that feature with portability fallbacks. For the avoidance of
making it easy to write code which looks correct but which has odd
runtime behavior, don't set the define symbol at all if no
equivalent keyword is known.
bb83cdaa Help: Add notes for topic 'AppleClang-5.1-features'
bd6b42c1 Features: Record for AppleClang 5.1
b341799e Tests: Fix RunCMake.CompileFeatures test NonValidTarget2 case
The change in commit v3.1.0-rc1~174^2 (Makefile: Handle '#' in
COMPILE_OPTIONS, 2014-08-12) was not compatible with code that
tries to workaround the original bug. Unfortunately there is no
good way to fix the bug in a compatible way. Add a release note
to call attention to the change.
On OS X, when CMAKE_USE_OPENSSL is OFF, use the OS implementation.
This will allow the OS-configured CA list to be trusted automatically.
This is supported on OS X 10.6 and above using AppleClang, Clang, and
GNU compilers.
Also add a 'CMAKE_ANDROID_API_MIN' variable to set the property
default. Teach the VS generator to write the MIN API value into
Nsight Tegra project files.
When install(EXPORT) is given an absolute destination we cannot compute
the install prefix relative to the installed export file location.
Previously we disallowed installation of targets in such exports with a
relative destination, but did not enforce this for target property
values besides the location of the main target file. This could lead to
broken installations when the EXPORT is installed to an absolute path
but usage requirements are specified relative to the install prefix.
Since an EXPORT installed to an absolute destination cannot be relocated
we can just hard-code the value of CMAKE_INSTALL_PREFIX as the base for
relative paths. This will allow absolute install(EXPORT) destinations
to work with relative destinations for targets and usage requirements.
Extend the ExportImport test with a case covering this behavior.
If this option is enabled, the test step is created with the
EXCLUDE_FROM_MAIN option, and if TEST_BEFORE_INSTALL is enabled, the
install step does not depend on the test step.
This means that the test step is never executed, unless the test target
is explicitly created by calling ExternalProject_Add_StepTarget, or by
passing it with the STEP_TARGETS option, or with the EP_STEP_TARGETS
directory property.
The FindXerces module was added in commit v3.1.0-rc1~155^2 (FindXerces:
New module to find Apache Xerces-C++, 2014-08-17). However, there are
two implementations of Xerces, one in C++:
http://xerces.apache.org/xerces-c/
and one in Java:
http://xerces.apache.org/xerces-j/
Rename FindXerces to FindXercesC to clarify that it is about the C++
implementation.
While at it, add the missing CMake 3.1 release note about this module.
Suggested-by: Erik Sjölund <erik.sjolund@gmail.com>
Copy CMAKE_EXE_LINKER_FLAGS into the test project generated by
try_compile, just like we already copy CMAKE_<LANG>_FLAGS.
Add CMake Policy CMP0056 to activate this behavior in a compatible way,
but do not warn by default when the policy is not set since it will
affect all try_compile calls.
Extend the RunCMake.try_compile test with a case covering this behavior
for each policy setting.
With PushScope and PopScope, keeping track of another bit of data for
each scope isn't easy. Instead, store it as another CMake variable so it
gets implicitly tracked along with everything else.
This works in a revert of commit
7d674b5f0b.
Add a VS_DEPLOYMENT_LOCATION source file property to specify where to
put files that are part of the package. For example:
set_property(SOURCE ${ASSET_FILES} PROPERTY VS_DEPLOYMENT_LOCATION "assets")
Without this, sources marked with VS_DEPLOYMENT_CONTENT cannot be
located properly.
Create properties VS_SHADER_ENTRYPOINT and VS_SHADER_MODEL. Without
these many .hlsl source files may not be possible to use. Extend the
VSWinStorePhone test project to cover them.
Revert the feature added by commit v3.1.0-rc1~420^2~2 (FindOpenGL:
Provide imported targets for GL and GLU, 2014-05-31). Unfortunately it
does not work on Windows because the full path to each library file is
not actually known. The IMPORTED_LOCATION of an imported target must be
a full path, but OPENGL_gl_LIBRARY is just 'opengl32' on Windows because
the actual library file is in some implicit link directory that we may
know know.
More infrastructure will be needed in CMake to allow a name-only
imported library. Until that exists, we will not be able to provide
imported targets in FindOpenGL.
In commit 079e8469ab (... OpenGL always needs X11 on Unix, 2002-09-05)
the FindOpenGL module was taught to search for X11 as a dependency of
the OpenGL library. This was done without a detailed explanation, and
the dependency should not be explicitly needed because OpenGL headers
should not expose applications to X11 APIs directly.
Unfortunately the only way to know if anything legitimately depends on
this behavior (perhaps in static library cases) is to simply remove it
and wait for issues to be reported. If so, then we can add some kind of
compatibility setting for this later. Add a release note to draw
attention to this change.
Reported-by: Dainius "GreatEmerald" Masiliūnas <pastas4@gmail.com>
Some applications only need the OpenSSL crypto library and want to avoid
linking against the SSL library. Set OPENSSL_CRYPTO_LIBRARY and
OPENSSL_SSL_LIBRARY in the code paths that do not need to find them
separately, and document them publicly. This allows applications to be
more specific when linking against OpenSSL.
2d75d7e5 Help: Add notes for topic 'console-pool'
f42d86f0 Ninja: Implement USES_TERMINAL using the console pool if available
f281ae01 Ninja: Remove unused declaration
d5eae556 Ninja: factor out the test for console pool support
4d1fedf4 Give the interactive cache editor the USES_TERMINAL property
fe5d6e8c Add USES_TERMINAL option for custom commands
ad6ee426 Rename doing_verbatim to doing_nothing
Now that we know the year component of this VS version we
can add it to the generator name. For convenience, map
the name without the year to the name with the year.
3c497f11 Help: Add notes for topic 'ExternalProject_UPDATE_DISCONNECTED'
aba5cec6 ExternalProject: Add unit tests for UPDATE_DISCONNECTED
3f606fa7 ExternalProject: Add UPDATE_DISCONNECTED option
c0b749cf ExternalProject: Always add a command to a step
The changes made by commit v3.1.0-rc1~46^2~1 (FindITK: Drop this ancient
compatibility module, 2014-10-02) and commit v3.1.0-rc1~46^2 (FindVTK:
Drop this ancient compatibility module, 2014-10-02) need to come with
release notes explaining that the modules were dropped. Also remove a
release not related to an update made to FindVTK that was never
released.
Add section headers similar to the 3.0 release notes and move each
individual bullet into an appropriate section. Highlight the new VS
generator capabilities for Windows Phone, Windows Store, and NVIDIA
Nsight Tegra with dedicated subsections.
Move all development release notes into a new version-specific document:
tail -q -n +3 Help/release/dev/* > Help/release/3.1.0.rst
git rm -- Help/release/dev/*
except the sample topic:
git checkout HEAD -- Help/release/dev/0-sample-topic.rst
Reference the new document from the release notes index document.
Add a title and intro sentence to the new document by hand.
631fadea Help: Add notes for topic 'fix-OSX-bundle-rpaths-and-Qt5'
50e261dd OSX: Warn when attempting to change runtime paths on OS X 10.5
9b98fd52 cmake-gui: Make sure we bundle Qt5 Cocoa platform plugin
83a06bb4 BundleUtilities: Framework codesign Resources/Info.plist & Current
f7df82ac BundleUtilities: Resolve & replace @rpath placeholders
14bc686f GetPrerequisites: Make sure dyld placeholders are prefixes
6c313797 BundleUtilities: Use find on UNIX for fast executable lookup
be6a555d Tests: Test setting a generator platform in a toolchain file
d506fee8 Tests: Use -A option to pass generator platform selection
11c9ddd6 ExternalProject: Use -A option to pass generator platform
29bd843e CTest: Use -A option to pass generator platform selection
eb7d8156 cmake: Add -A option to specify a generator platform
858d5a0b Fix if() checks of CMAKE_SYSTEM_NAME on Cygwin
e177e7af FPHSA: Avoid if() dereferencing of quoted variable
425acc52 cmcurl: Use if(DEFINED) to simplify conditions
cede5cbd libarchive: Avoid depending on if() to dereference a quoted variable
2d97178b FindGTK2: Avoid depending on if() to dereference a quoted variable
0b12815d Modules/Test*.cmake: Use if(DEFINED) to simplify conditions
188a1f23 If: Introduce policy CMP0054 - don't dereference quoted variables in if()
b900c1cc If: Extract cmConditionEvaluator from if() implementation
Define the 'cmake -A' option to set CMAKE_GENERATOR_PLATFORM
without having to spell out the whole variable name. We choose
the name '-A' for "platform" because '-P' is already taken, and
in the common use case the "platform" is actually an architecture
(e.g. x64).
Teach the RunCMake test infrastructure to use -A to pass the generator
platform. Extend the RunCMake.GeneratorPlatform test with a case to
verify that the -A option cannot be repeated.
For VS generator names that do not specify the platform name, read
CMAKE_GENERATOR_PLATFORM to get it.
Extend the RunCMake.GeneratorPlatform test with a case covering
use of the x64 platform when the test generator is a Visual Studio
generator whose name does not specify a platform.
39fefde2 VS: Add test case for Windows Phone and Windows Store
89da8465 MSVC: Define 'WIN32' for Windows Store and Windows Phone
ed7f085f Help: Add notes for topic 'vs-windows-apps'
dd11ae8f VS: Do not compile C sources as WinRT (#15100)
b8e40538 VS: Mark Windows Phone and Store targets as App Containers
0432f062 VS: Always ignore ole32 on Windows Phone 8.0
e6ff2f8b VS: Generate Windows Metadata for WinRT components
ee48f4c7 VS: Generate Windows Phone and Windows Store projects as Unicode
cb1aceed VS: Add VS_WINRT_COMPONENT property to enable CompileAsWinRT
401269e4 VS: Handle .pfx files explicitly in generator
23782171 VS: Handle AppxManifest sources explicitly in generator
bc373c6d VS: Set Window Phone/Store app type in CMake-generated targets
d89b2889 VS: Mark CMake-generated targets as Utility in .vcxproj files
03ad8f28 CMakeDetermineCompilerABI: Link with standard libraries on MSVC
cbd1d42b Help: Add notes for topic 'vs-masm'
0f8522a6 VS: Add MASM support to VS 8 and 9 (#8170, #14984)
a43f4400 VS: Move internal MasmEnabled member up to VS 7 generator
df3b007d VS: Add test for MASM support
e8727449 VS: Populate MASM tool build settings in .vcxproj files
0271a5f9 VS: Manually fix MASM flag table entries
1d662e48 VS: Generate MASM flag tables from MSBuild tool files
4f6940df VS: Fix ASM_MASM support in VS >= 10
d7866c52 ASM_MASM: Fix selection of ml64
0374abdb ASM_MASM: Add preprocessor definitions to compile lines
5b0a46e1 ASM_MASM: Do not require compiler to be a full path
802dbe52 cmLocalVisualStudio7Generator: Rename local 'lang' var
aa21001b Help: Add notes for topic 'vs-special-source-file-properties'
6fe770e1 VS: Add a source file property to set the hlsl shader type
9b4dc2ad VS: Add a source file property to mark content for Windows App deployment
f063a914 VS: Re-arrange WriteExtraSource to support tool configuration
Copy the CheckCSourceCompiles module and port it to Fortran.
Extend the FortranOnly test to try using the new module.
Suggested-by: Nicolas Bock <nicolasbock@gmail.com>
5d3d9a22 Help: Add notes for topic 'vs-windows-phone-and-store'
401a00d9 VS: Set WindowsPhone and WindowsStore min VS version required
709cebde VS: Generate WindowsPhone and WindowsStore application types
72395ab2 VS: Add .sln "Deploy" mark for WindowsPhone and WindowsStore binaries
2074f581 MSVC: Add system libs for WindowsPhone and WindowsStore
c72f0887 MSVC: Add default WindowsPhone and WindowsStore compile flags
1c94558a MSVC: Disable incremental linking for WindowsPhone and WindowsStore
592098e2 Define 'WINDOWS_PHONE' and 'WINDOWS_STORE' variables
aa42a78f Add WindowsPhone and WindowsStore platform information modules
b94ddf6c CMakeDetermineCompilerId: Recognize WindowsPhone and WindowsStore
d7938bff VS: Select WindowsPhone and WindowsStore default toolsets
3abd150c VS: Save WindowsPhone and WindowsStore system internally
2c470b77 add_library: Allow arbitrary non-linked sources in OBJECT libraries
de4f3e2c Tests: Fix broken dependency in ObjectLibrary test
54bf5858 Tests: Resolve TODO comment left in ObjectLibrary test
Loosen this restriction on OBJECT libraries to allow source files of any
name to be generated by custom commands or listed for reference in IDE
projects so long as they would not affect linking of a normal library.
Update the rejection message to be more specific about the looser
restriction.
Extend the ObjectLibrary test to cover a ".cmake" file generated by a
custom command in an OBJECT library.
f0e298ad Help: Add notes for topic 'vs14-generator'
5c105140 Tests: Simplify LoadCommand tests
b1cbd577 FindBoost: Add -vc140 mangling for VS 14
bdc7d9c8 VS14: Fix Cl and Link flag tables as previous versions
d96b3f68 VS14: Generate flag tables from MSBuild v140 tool files
65624c39 VS14: Add Visual Studio 14 generator (#14982)
8635ac23 Tests/Preprocess: Remove unnecessary VS version tests
Installing large directories, e.g., the output of a doxygen run, prints
one line per file resulting in too much noise in the build output. Add
an option to the install(DIRECTORY) command to not print anything upon
make install.
Extend the RunCMake.install test with cases covering MESSAGE_NEVER
behavior of the install(DIRECTORY) command.
Suggested-by: Stefan Eilemann <Stefan.Eilemann@epfl.ch>
Create a variable to allow users to control which installation
messages are printed. In particular, provide a "LAZY" setting
that prints "Installing" messages but not "Up-to-date" messages.
This is desirable for incremental re-installations.
Suggested-by: J Decker <d3ck0r@gmail.com>
Extend the cmake command-line interface to support
cmake -E env [--unset=NAME]... [NAME=VALUE]... COMMAND [ARG]...
This will be useful to run processes with modified environments
without using a shell or a full "cmake -P" script to wrap it.
Extend the RunCMake.CommandLine test to cover success and failure cases.
Inspired-by: Jonathan Bohren <jbo@jhu.edu>
Delay use of CMAKE_GENERATOR_TOOLSET until the CMakeSystem.cmake
file has been configured and loaded during the first project() or
enable_language() command. This gives the toolchain file named by
CMAKE_TOOLCHAIN_FILE a chance to set CMAKE_GENERATOR_TOOLSET. This
point is still early enough to set the generator toolset prior to
the initialization of any languages that might use the toolset.
The cmake::GeneratorToolset member variable remains an indication
of what was specified by the -T option or loaded from the cache.
It does not need to be updated based on the toolchain file setting.
The cmMakefile::TryCompile can still pass cmake::GeneratorToolset
into the inner instance because the try-compiled project will do
platform and language initialization using the CMakeSystem module
configured for the outer project.
Extend the RunCMake.GeneratorToolset test with cases that use a
toolchain file to set CMAKE_GENERATOR_TOOLSET.
The ALLOWED_UNKNOWN_VARIABLE_READ_ACCESS access type was switched on an
undocumented variable and its lookup caused an unnecessary performance
impact. Remove it.
Allow setting build properties based on the features available
for a target. The availability of features is determined at
generate-time by evaluating the link implementation.
Ensure that the <LANG>_STANDARD determined while evaluating
COMPILE_FEATURES in the link implementation is not lower than that
provided by the INTERFACE of the link implementation. This is
similar to handling of transitive properties such as
POSITION_INDEPENDENT_CODE.
Add source file properties to control Xcode file type attributes:
XCODE_EXPLICIT_FILE_TYPE => explicitFileType
XCODE_LAST_KNOWN_FILE_TYPE => lastKnownFileType
Add a RunCMake.XcodeProject test to verify generated project content.
Add properties and variables corresponding to CXX equivalents.
Add features for c_function_prototypes (C90), c_restrict (C99),
c_variadic_macros (C99) and c_static_assert (C11). This feature
set can be extended later.
Add a <PREFIX>_RESTRICT symbol define to WriteCompilerDetectionHeader
to conditionally represent the c_restrict feature.
Provide a function to write a portable header to detect compiler
features. Generate a preprocessor #error for unknown compilers
and compiler versions whose features are not yet recorded. This
error condition might be relaxed in the future, but for now it
is useful for verification of expectations.
ba387cb8 Help: Add notes for topic 'package-disable-registry'
be8ae960 Allow the Package Registry to be disabled (#14849)
d09fda5d Tests: Improve FindPackageTest for in-source builds
ac24a1c0 Tests: Improve FindPackageTest exported package version
Warn project developers at runtime that the module should not be used
anymore. Issue the diagnostic only when the project requires a new
enough CMake to use the alternative. Honor the
CMAKE_(ERROR|WARN)_DEPRECATED settings.
Allow directories in the source tree or build tree only if the
install tree is a subdirectory of the source tree or build tree,
as appropriate.
Re-use the test files in the RunCMake.include_directories test
to run in multiple scenarios. Bump the required CMake version
in the test to 3.0 to ensure that the new policy warnings are
emitted correctly.
This can be used to set the compiler features required by particular
targets. An error is issued at CMake time if the compiler does not
support the required feature. If a language dialect flag is required
by the features used, that will be added automatically.
Base the target_compile_features command on cmTargetPropCommandBase. This
gives us 'free' handling of IMPORTED, ALIAS, INTERFACE, non-compilable
and missing targets.
Use the contents of it to upgrade the CXX_STANDARD target property,
if appropriate. This will have the effect of adding the -std=c++11
compile flag or other language specification on GNU when that is
needed for the feature.
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.
Extend the cmGeneratorExpressionDAGChecker with an interface
returning the name of the top target. Use that to determine
when there is a DAG violation, as required by the RunCMake.Languages
tests.
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.
Not everything that isn't MSVC is GCC. I have support for LDC's depfile
format on its way upstream[1], but its future is uncertain. CMake should
at least support this for future depfile formats.
[1]https://github.com/martine/ninja/pull/721
Rely on evaluation in cmCustomCommandGenerator for the generators.
When tracing target dependencies, depend on the union of dependencies
for all configurations.
489b1c23 Windows: Use response files to specify link libraries for GNU tools
745caae6 Makefile: Rename linker response file boolean to be more specific
5e8e4d0f cmLocalGenerator: Add response file option to OutputLinkLibraries
b9aa5041 cmLocalGenerator: Simplify GetIncludeFlags output formatting
971653b7 cmLocalGenerator: Add format option to ConvertToLinkReference
0c0ef9e7 cmLocalGenerator: Add format option to ConvertToIncludeReference
02bebd60 cmLocalGenerator: Add format option to ConvertToOutputForExisting
c8751709 Makefile: Factor out some duplicate link libraries generation
Work around the command-line-length limit by using an @linklibs.rsp
response file to pass the flags for link libraries. This allows
very long lists of libraries to be used in addition to the existing
support for passing object files via response file.
Suggested-by: Peter Keuschnigg <peter.keuschnigg@pmu.ac.at>
Since commit v2.8.12~437^2~2 (VS: Separate compiler and linker PDB files
2013-04-05) we no longer set /Fd with the PDB_NAME or PDB_OUTPUT_DIRECTORY
properties. Those properties now exclusively handle linker PDB files.
Since STATIC libraries do not link their compiler PDB file becomes more
important. Add new target properties "COMPILE_PDB_NAME[_<CONFIG>]" and
"COMPILE_PDB_OUTPUT_DIRECTORY[_<CONFIG>]" to specify the compiler PDB
file location and pass the value to the MSVC /Fd option.
048be205 Help: Add release notes for the 'faster-parsers' topic
7c565d2f cmGeneratorExpression: Improve parsing in StripEmptyListElements
68eb1757 cmGeneratorExpressionLexer: Use a switch statement to parse
67253133 ExpandListArguments: Optimize the parser
6e89c8a5 install: Support generator expressions in FILES and PROGRAMS mode
f11f7b34 cmInstallFilesGenerator: Add reference to calling cmMakefile
e190236c Help: Format install() command documentation
Teach the install(FILES) and install(PROGRAMS) commands to evaluate
generator expressions in the list of files.
Extend the ExportImport test to cover installation cases involving
generator expressions.
Historically CMake used three version components for the feature level.
We released new features while incrementing only the third version
component. Since commit v2.8.2~105^2~4 (New version scheme to support
branchy workflow, 2010-04-23) we used the fourth version component for
bug-fix releases and the development date:
<major>.<minor>.<patch>[.<tweak>][-rc<n>] = Release
<major>.<minor>.<patch>.<date>[-<id>] = Development
This solidified use of three components for the feature level, and was
necessary to continue releasing 2.x versions because:
* Some existing projects performed floating-point comparisons of
${CMAKE_MAJOR_VERSION}.${CMAKE_MINOR_VERSION} to 2.x numbers
so ``x`` could never be higher than 9.
* Version 2.9.<date> was used briefly in post-2.8.0 development in
CVS prior to the transition to Git, so using it in releases may
have caused confusion.
Now that we are moving to 3.x versions, these two restrictions go away.
Therefore we now change to use only two components for the feature
level and use the scheme:
<major>.<minor>.<patch>[-rc<n>] = Release
<major>.<minor>.<date>[-<id>] = Development
When building boost with an alternate namespace the libraries generated
will have a different naming convention. This is often done to ensure
no symbol conflicts with external libraries built against a different
version of boost. If the namespace used is "myprivateboost::" instead
of "boost::" then the libraries built will be named myprivateboost_foo
instead of boost_foo. Add an option to specify a custom namespace used
to alter the library names that get searched for.
Manually read through version control history since the 2.8.12.2
release and write release notes for important user-facing changes.
Co-Author: Stephen Kelly <steveire@gmail.com>
Add a release/dev.txt file and include it from release/index.rst in
development versions. Add a "Changes Since Release" section with a
toctree that globs adjacent "dev/*" documents. Add a sample topic
document explaining how topic-specific release note documents work.
This approach will allow developers to write release notes for their
changes as they are made. The release manager may then consolidate and
organize the notes for a specific release version.
Add a release/index.rst document titled "CMake Release Notes" to hold
the toctree for release notes. Add a "Release Notes" section to the
top-level html document index to link to the new document.