As with KDE 4.2, also for KDE 4.3 still CMake >= 2.6.2 is required, so no changes in this regard.
Again we had two changes, which are incompatible. But in both cases these changes are actually bug fixes, since what they did before was actually wrong or unnecessary.
failed if Perl could not be found. This was an internal, undocumented implementation detail and not necessary, since building software for KDE4 doesn't actually require Perl in general. With KDE 4.3 this has been changed. Now Perl is still searched, but if it is not found, the CMake-run doesn't fail, it just prints a warning message. This way one dependency less is necessary to build software for KDE4. Perl is still required to build kdelibs. So if you use Perl in your project, check properly for it:
find_package(Perl REQUIRED) # in case you didn't use the REQUIRED keyword: if (PERL_FOUND) ...
During the 4.3 cycle we introduced a commit policy for committing changes to kdelibs/cmake/modules, since commits there have the potential to break the build for everybody and can be part of the public interface of KDE: Policies/CMake_Commit_Policy
This option is only available under Windows, by default it is off. It enables support for generating uac manifest files (or something like that).
The macro MACRO_OPTIONAL_ADD_SUBDIRECTORY() from MacroOptionalAddSubDirectory.cmake now respects a new global CMake variable DISABLE_ALL_OPTIONAL_SUBDIRECTORIES. If the variable DISABLE_ALL_OPTIONAL_SUBDIRECTORIES is set to TRUE for the first CMake run on the project, all optional subdirectories will be disabled by default (but can of course be enabled via the respective options). E.g. the following will disable all optional subdirectories except the one named "kcalc":
$ cmake -DDISABLE_ALL_OPTIONAL_SUBDIRECTORIES=TRUE -DBUILD_kcalc=TRUE <srcdir>
In the RelWithDebInfo build type -DNDEBUG -DQT_NO_DEBUG have been added to the compiler flags.
In KDE 4.2 there were two variables KDE4_KNEPOMUK_LIBS and KDE4_KMETADATA_LIBS. This was a bug, they were always empty. They have been removed now (which is not incompatible, since they were empty). Instead a new and correct variable KDE4_NEPOMUK_LIBS has been added.
Some completely new modules have been added during this cycle: