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, 11 deletions

diff --git a/cmake/QtSetup.cmake b/cmake/QtSetup.cmake
index c7d6f50b73..7285c0c516 100644
--- a/cmake/QtSetup.cmake
+++ b/cmake/QtSetup.cmake
@@ -54,18 +54,10 @@ include(QtCompilerOptimization)
 include(QtCompilerFlags)
 
 ## Find host tools (if non native):
-set(HOST_QT_TOOLS_DIRECTORY "" CACHE PATH "Directory with Qt host tools.")
+set(QT_HOST_PATH "" CACHE PATH "Installed Qt host directory path, used for cross compiling.")
 
-if (CMAKE_CROSSCOMPILING AND "x${HOST_QT_TOOLS_DIRECTORY}" STREQUAL "x")
-    message(FATAL_ERROR "You need to set HOST_QT_TOOLS_DIRECTORY for a cross-complile.")
-endif()
-
-## Find syncqt in HOST TOOLS or locally:
-if("x${HOST_QT_TOOLS_DIRECTORY}" STREQUAL "x")
-    set(QT_SYNCQT "${PROJECT_SOURCE_DIR}/bin/syncqt.pl")
-    install(PROGRAMS "${QT_SYNCQT}" DESTINATION "${INSTALL_BINDIR}")
-else()
-    set(QT_SYNCQT "${HOST_QT_TOOLS_DIRECTORY}/syncqt.pl")
+if (CMAKE_CROSSCOMPILING AND NOT IS_DIRECTORY ${QT_HOST_PATH})
+    message(FATAL_ERROR "You need to set QT_HOST_PATH to cross compile Qt.")
 endif()
 
 ## Enable support for sanitizers: