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, 3 insertions, 3 deletions

diff --git a/cmake/QtPostProcess.cmake b/cmake/QtPostProcess.cmake
index 0d50d7fa47..e63bcc0538 100644
--- a/cmake/QtPostProcess.cmake
+++ b/cmake/QtPostProcess.cmake
@@ -13,8 +13,8 @@ function(qt_internal_write_depends_file target)
 endfunction()
 
 function(qt_internal_create_depends_files)
-    message("Generating depends files for ${KNOWN_QT_MODULES}...")
-    foreach (target ${KNOWN_QT_MODULES})
+    message("Generating depends files for ${QT_KNOWN_MODULES}...")
+    foreach (target ${QT_KNOWN_MODULES})
         get_target_property(depends "${target}" LINK_LIBRARIES)
         set(qtdeps "")
         foreach (dep ${depends})
@@ -26,7 +26,7 @@ function(qt_internal_create_depends_files)
                 set(dep "${CMAKE_MATCH_1}")
             endif()
 
-            list(FIND KNOWN_QT_MODULES "${dep}" _pos)
+            list(FIND QT_KNOWN_MODULES "${dep}" _pos)
             if (_pos GREATER -1)
                 list(APPEND qtdeps "${dep}")
             endif()