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 77543bde (Convert CMake-language commands to lower case,
2012-08-13) the CMakeVersion.cmake file contains lower-case 'set'
commands. Teach CMakeVersion.bash to replace the lower-case name
instead of the old upper-case 'SET'.
Move the CMake version number components out of "CMakeLists.txt" into
dedicated file "Source/CMakeVersion.cmake". Set the TWEAK level to the
date explicitly. Add a "Source/CMakeVersion.bash" script to update the
date, thus replacing KWSys DateStamp for CMake. Teach the bootstrap
script to extract the version components from their new location.
