Previously QT_CMAKE_EXPORT_NAMESPACE was set by calling
find_package(QtBuildInternals) at repo dir scope, even in a top-level
build.
Starting with ddcafa0a51c65d86f6b5481f06fce5faeb75920d in
qtdeclarative, we now have a deferred call of
_qt_internal_write_deferred_qmlls_build_ini_file in the
CMAKE_BINARY_DIR scope, which lacks the QT_CMAKE_EXPORT_NAMESPACE
variable.
This caused errors in a top-level standalone tests build:
Error evaluating generator expression $
No target "::qtpaths"
CMakeLists.txt:DEFERRED
To avoid the error we now set QT_CMAKE_EXPORT_NAMESPACE in the
top level scope.
To avoid duplicating the code into the QtBaseTopLevelHelpers,
we extract the qt_internal_top_level_setup_cmake_and_export_namespace
function into a new QtBuildInternalsHelpers.cmake file, which is
included by both QtBaseTopLevelHelpers.cmake and
QtBuildInternalsConfig.cmake.
We also copy and install that file.
This has less side effects than trying to call
find_package(QtBuildInternals) in the top-level scope.
Pick-to: 6.10
Change-Id: I8e54e21d3f07ee86860cad49d6e43e0fdefbcee3
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>
9b9a2398f3