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, 9 deletions

diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 212df0d9c2..dbd6f15923 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -23,20 +23,13 @@ endif()
 add_subdirectory(3rdparty)
 
 function(find_or_build_bootstrap_names)
-    # Move these into their own folder and move this code in the CMakeLists.txt file there!
-    set01(_build_tools "x${HOST_QT_TOOLS_DIRECTORY}" STREQUAL "x")
-
-    if (_build_tools)
+    if (QT_WILL_BUILD_TOOLS)
         add_subdirectory(tools/bootstrap)  # bootstrap library
     endif()
     add_subdirectory(tools/moc)
     add_subdirectory(tools/rcc)
     add_subdirectory(tools/qfloat16-tables)
     add_subdirectory(tools/tracegen)
-
-    if (_build_tools)
-        install(EXPORT "Qt${PROJECT_VERSION_MAJOR}ToolsTargets" NAMESPACE "${QT_CMAKE_EXPORT_NAMESPACE}::" DESTINATION "${INSTALL_LIBDIR}/cmake/Qt${PROJECT_VERSION_MAJOR}")
-    endif()
 endfunction()
 
 find_or_build_bootstrap_names()
@@ -54,10 +47,14 @@ endif()
 if (QT_FEATURE_xml)
     add_subdirectory(xml)
 endif()
+add_subdirectory(tools)
+
+# Need to build qmake and other Core tools before exporting them.
+qt_export_tools(Core)
+
 if (QT_FEATURE_dbus)
     add_subdirectory(dbus)
 endif()
-add_subdirectory(tools)
 if(QT_FEATURE_gui)
     add_subdirectory(gui)