Create a `CMAKE_XDGDATA_DIR` option and add a corresponding flag to the
`bootstrap` script. This is needed for multiarch layouts where the
prefix is `/usr/${host}` but where architecture-independent files (like
the XDG-specific ones) are installed to `/usr/share`.
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
Since commit c9a5f34b (Cleanup use of CMake version in install
destinations, 2013-09-26) we use the full CMake version in default
install destinations. For rapidly changing versions of the form
<major>.<minor>.<patch>.<date>-g<commit>[-dirty]
used by developers this is too granular. Instead use just
<major>.<minor>.<patch>
as the version for default install destinations. This will still
be granular enough for unique directories in releases.
On Cygwin continue to use the full ${CMake_VERSION} as was the case
prior to the above-mentioned commit.
Factor the CMAKE_DATA_DIR, CMAKE_DOC_DIR, and CMAKE_MAN_DIR selection
out of CMakeLists.txt and into a Source/CMakeInstallDestinations.cmake
script. Load the script from the original location of the code.
Cache the destination values as empty strings so we know if the user
sets them explicitly. If not, then compute defaults based on the
platform and full CMake version string. By not caching the versioned
defaults, we can change them in a single build tree as the version
changes.
Remove duplication of the install destination defaults from the
bootstrap script. Cache empty defaults there too. Parse from the CMake
code the default values to report in the help output. Keep the CMake
code in a structured format to make this reliable.
Niels Ole Salscheider
Brad King