Export tool config and target files for each relevant module

CMake will now generate config and target files for each module that
provides tools. As a result, namespaced global targets such as
Qt5::moc or Qt5::rcc can be made available.

Third party projects that require just these tools, and not the Qt
modules themselves,  should specify CMAKE_PREFIX_PATH pointing to the
installed Qt location, and call find_package(Qt5CoreTools),
find_package(Qt5GuiTools), etc.

It is also possible to call
find_package(Qt5Tools REQUIRED Core Widgets) where the last option
is a list of modules whose tools should be imported.

Note that all the tools are in the Qt5::
namespace and not in the Qt5CoreTools:: or Qt5WidgetsTools::
namespace.

This commit also changes the behavior regarding when to build tools
while building Qt itself.

When cross compiling Qt (checked via CMAKE_CROSSCOMPILING) or when
-DQT_FORCE_FIND_TOOLS=TRUE is passed, tools added by add_qt_tool will
always be searched for and not built.
In this case the user has to specify the CMake variable QT_HOST_PATH
pointing to an installed host Qt location.

When not cross compiling, tools added by add_qt_tool are built from
source.

When building leaf modules (like qtsvg) that require some tool that was
built in qtbase (like moc), the module project should contain a
find_package(Qt5ToolsCore) call and specify an appropriate
CMAKE_PREFIX_PATH so that the tool package is found.

Note that because HOST_QT_TOOLS_DIRECTORY was replaced by QT_HOST_PATH,
the ensure syncqt code was changed to make it work properly with
both qtbase and qtsvg.

Here's a list of tools and their module associations:
qmake, moc, rcc, tracegen, qfloat16-tables, qlalr  -> CoreTools
qvkgen -> GuiTools
uic -> WidgetTools
dbus related tools -> DBusTools

Task-number: QTBUG-74134
Change-Id: Ie67d1e2f8de46102b48eca008f0b50caf4fbe3ed
Reviewed-by: Tobias Hunger <tobias.hunger@qt.io>

1 files changed, 35 insertions, 0 deletions

diff --git a/cmake/QtToolsConfig.cmake.in b/cmake/QtToolsConfig.cmake.in
new file mode 100644
index 0000000000..7b2fa1de74
--- /dev/null
+++ b/cmake/QtToolsConfig.cmake.in
@@ -0,0 +1,35 @@
+@PACKAGE_INIT@
+
+get_filename_component(_qt_tools_cmake_dir "${CMAKE_CURRENT_LIST_DIR}/.." ABSOLUTE)
+
+ if (NOT @INSTALL_CMAKE_NAMESPACE@Tools_FIND_COMPONENTS)
+     set(@INSTALL_CMAKE_NAMESPACE@Tools_NOT_FOUND_MESSAGE
+         "The Qt tools package requires at least one component.")
+     set(@INSTALL_CMAKE_NAMESPACE@Tools_FOUND False)
+     return()
+ endif()
+
+foreach(module ${@INSTALL_CMAKE_NAMESPACE@Tools_FIND_COMPONENTS})
+    find_package(@INSTALL_CMAKE_NAMESPACE@${module}Tools
+        ${_@INSTALL_CMAKE_NAMESPACE@Tools_FIND_PARTS_QUIET}
+        ${_@INSTALL_CMAKE_NAMESPACE@Tools_FIND_PARTS_REQUIRED}
+        PATHS ${_qt_tools_cmake_dir} NO_DEFAULT_PATH
+    )
+    if (NOT @INSTALL_CMAKE_NAMESPACE@${module}Tools_FOUND)
+        string(CONFIGURE ${_qt5_module_location_template} _expected_module_location @ONLY)
+
+        if (@INSTALL_CMAKE_NAMESPACE@_FIND_REQUIRED_${module})
+            set(_Qt_NOTFOUND_MESSAGE
+                "${_Qt_NOTFOUND_MESSAGE}Failed to find Qt component \"${module}\" config file.")
+        elseif(NOT Qt_FIND_QUIETLY)
+            message(WARNING "Failed to find Qt component \"${module}\" config file.")
+        endif()
+
+        unset(_expected_module_location)
+    endif()
+endforeach()
+
+if (_Qt_NOTFOUND_MESSAGE)
+    set(@INSTALL_CMAKE_NAMESPACE@Tools_NOT_FOUND_MESSAGE "${_Qt_NOTFOUND_MESSAGE}")
+    set(@INSTALL_CMAKE_NAMESPACE@Tools_FOUND False)
+endif()