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
People will be tempted to put things there for convenience, thereby
causing conflicts similar to
http://thread.gmane.org/gmane.comp.compilers.clang.devel/35162/focus=35169
where it is conceivable that the LLVM developers could put a flag on
a target for convenience, which would cause conflicts for some downstreams.
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.
The cmGeneratorExpression is used here, but the header for it is not
in the include heirarchy. This would be a compile error if the file
were compiled as a standalone translation unit, but it is instead
used in a mini-unity-build by inclusion in cmCommands.cxx. The header
for cmGeneratorExpression happens to be included first, so the
compilation works fine.
IDEs do not know this however, and flag the use as an error.
