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, 6 insertions, 5 deletions

diff --git a/src/corelib/CMakeLists.txt b/src/corelib/CMakeLists.txt
index eb11b1251e..37e89a3648 100644
--- a/src/corelib/CMakeLists.txt
+++ b/src/corelib/CMakeLists.txt
@@ -235,13 +235,14 @@ add_qt_module(Core
         Qt::Platform
     DISABLE_AUTOGEN_TOOLS # special case:
         uic
+    DISABLE_TOOLS_EXPORT # special case:
 )
 
 # special case:
-add_dependencies(Core Qt::moc)
-add_dependencies(Core Qt::rcc)
-add_dependencies(CorePrivate Qt::moc)
-add_dependencies(CorePrivate Qt::rcc)
+add_dependencies(Core ${QT_CMAKE_EXPORT_NAMESPACE}::moc)
+add_dependencies(Core ${QT_CMAKE_EXPORT_NAMESPACE}::rcc)
+add_dependencies(CorePrivate ${QT_CMAKE_EXPORT_NAMESPACE}::moc)
+add_dependencies(CorePrivate ${QT_CMAKE_EXPORT_NAMESPACE}::rcc)
 
 if (QT_NAMESPACE STREQUAL "")
 else()
@@ -1030,7 +1031,7 @@ endif()
 
 # special case:
 add_custom_command(OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/global/qfloat16tables.cpp"
-                   COMMAND qfloat16-tables
+                   COMMAND ${QT_CMAKE_EXPORT_NAMESPACE}::qfloat16-tables
                    ARGS "${CMAKE_CURRENT_BINARY_DIR}/global/qfloat16tables.cpp"
                    DEPENDS global/qfloat16.h
                    COMMENT qfloat16-tables