We want to get rid of the INSTALL_EXAMPLEDIR and INSTALL_EXAMPLESDIR
code in each example project.
This was an internal workaround to ensure examples are installed into
a relative path somewhere under $qt_prefix/examples and not in
$qt_prefix/bin or similar.
To achieve that we do two things.
First, deduce the install prefix for each example in the
implementation of qt_internal_add_example (our add_subdirectory
wrapper) and assign it to CMAKE_INSTALL_PREFIX before calling
add_subdirectory. We need to make sure to remove the default
value of CMAKE_INSTALL_PREFIX in the generated
cmake_install.cmake file.
Second, we set an internal variable called
QT_INTERNAL_SET_EXAMPLE_INSTALL_DIR_TO_DOT before the add_subdirectory
call, which will be checked whenever find_package(Qt6Core) is called
in an example project. If the variable is set, the
INSTALL_EXAMPLEDIR var is set to "." in the scope of where Qt6Core
is found.
This ensures that the hardcoded INSTALL_EXAMPLEDIR values in our
example projects are changed to ".".
With both changes, our example project install(TARGET DESTINATION)
calls will now install to
"${CMAKE_INSTALL_PREFIX}/examples/${example_relative_dir}/."
Once all repositories are updated to use qt_internal_add_example
instead of add_subdirectory, we can get rid of the
QT_INTERNAL_SET_EXAMPLE_INSTALL_DIR_TO_DOT workaround.
For repositories that still don't use qt_internal_add_example,
the install prefix rewriting will not happen, but the examples will
still be installed to the proper place because they use their own
hardcoded INSTALL_EXAMPLEDIR value.
Amends d97fd7af2b
Pick-to: 6.2 6.3
Task-number: QTBUG-96232
Task-number: QTBUG-98545
Change-Id: I78c118e10c41b519c570c7d87529afd15aeed900
Reviewed-by: Jörg Bornemann <joerg.bornemann@qt.io>
ac4a913f33