CMake: Provide a way to find all available Qt module packages

A project might want to find_package all available (installed) Qt CMake
packages that contain qt modules.

A use case might be a qml app that needs to link to all of Qt, and
support showing qml files that can load any Qt qml module.

Add a new Qt6 COMPONENT called ALL_QT_MODULES.

It can be used like this:
  find_package(Qt6 COMPONENTS ALL_QT_MODULES).

The implementation will find all installed Qt modules by globbing over
all json files installed in $qt/modules dir, and treat the file names
as package names.

It will then tell Qt6 to find_package each of those packages.

Pick-to: 6.8
Change-Id: I89242307438576a0cbb3cdca80a9cb72818b6035
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>
(cherry picked from commit c7027880aa746a01362ac12491910479d7fc67e3)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

cmake/QtConfig.cmake.in

@@ -128,7 +128,12 @@ if(QT_DISABLE_NO_DEFAULT_PATH_IN_QT_PACKAGES)
     set(__qt_use_no_default_path_for_qt_packages "")
 endif()
 
-foreach(module ${@INSTALL_CMAKE_NAMESPACE@_FIND_COMPONENTS})
+set(__qt_umbrella_find_components ${@INSTALL_CMAKE_NAMESPACE@_FIND_COMPONENTS})
+__qt_internal_handle_find_all_qt_module_packages(__qt_umbrella_find_components
+    COMPONENTS ${__qt_umbrella_find_components}
+)
+
+foreach(module ${__qt_umbrella_find_components})
     if(NOT "${QT_HOST_PATH}" STREQUAL ""
        AND "${module}" MATCHES "Tools$"
        AND NOT "${module}" MATCHES "UiTools$"

cmake/QtInstallPaths.cmake.in

@@ -14,3 +14,4 @@ set(QT@PROJECT_VERSION_MAJOR@_INSTALL_PLUGINS "@INSTALL_PLUGINSDIR@")
 set(QT@PROJECT_VERSION_MAJOR@_INSTALL_QML "@INSTALL_QMLDIR@")
 set(QT@PROJECT_VERSION_MAJOR@_INSTALL_TESTS "@INSTALL_TESTSDIR@")
 set(QT@PROJECT_VERSION_MAJOR@_INSTALL_TRANSLATIONS "@INSTALL_TRANSLATIONSDIR@")
+set(QT@PROJECT_VERSION_MAJOR@_INSTALL_DESCRIPTIONSDIR "@INSTALL_DESCRIPTIONSDIR@")

cmake/QtModuleHelpers.cmake

@@ -1343,7 +1343,12 @@ function(qt_describe_module target)
     qt_path_join(install_dir ${QT_INSTALL_DIR} ${path_suffix})
 
     set(descfile_in "${QT_CMAKE_DIR}/ModuleDescription.json.in")
+
+    # IMPORTANT: If you adjust the file name not to be the exact target name and thus the CMake
+    # package name, it needs to consider also the code in QtConfig.cmake.in that globs the json
+    # files.
     set(descfile_out "${build_dir}/${target}.json")
+
     string(TOLOWER "${PROJECT_NAME}" lower_case_project_name)
     set(extra_module_information "")
     set(platforms_information "")

cmake/QtPublicCMakeHelpers.cmake

@@ -597,6 +597,45 @@ function(_qt_internal_remove_args out_var)
     set(${out_var} "${result}" PARENT_SCOPE)
 endfunction()
 
+function(__qt_internal_handle_find_all_qt_module_packages out_var)
+    set(opt_args "")
+    set(single_args "")
+    set(multi_args
+        COMPONENTS
+    )
+    cmake_parse_arguments(PARSE_ARGV 1 arg "${opt_args}" "${single_args}" "${multi_args}")
+    _qt_internal_validate_all_args_are_parsed(arg)
+
+    if(NOT arg_COMPONENTS)
+        return()
+    endif()
+
+    set(components ${arg_COMPONENTS})
+
+    if("ALL_QT_MODULES" IN_LIST components)
+        list(FIND components "ALL_QT_MODULES" all_qt_modules_index)
+        list(REMOVE_AT components ${all_qt_modules_index})
+
+        # Find the path to dir with module.json files. # We consider each file name to be a
+        # Qt package (component) name that contains a target with the same name.
+        set(json_modules_path "${QT6_INSTALL_PREFIX}/${QT6_INSTALL_DESCRIPTIONSDIR}")
+        file(GLOB json_modules "${json_modules_path}/*.json")
+
+        set(all_qt_modules "")
+
+        foreach(json_module IN LISTS json_modules)
+            get_filename_component(module_name "${json_module}" NAME_WE)
+            list(APPEND all_qt_modules ${module_name})
+        endforeach()
+
+        if(all_qt_modules)
+            list(INSERT components "${all_qt_modules_index}" ${all_qt_modules})
+        endif()
+    endif()
+
+    set(${out_var} "${components}" PARENT_SCOPE)
+endfunction()
+
 # Append ${ARGN} to ${target}'s ${property_name} property, removing duplicates.
 function(_qt_internal_append_to_target_property_without_duplicates target property_name)
     get_target_property(property "${target}" "${property_name}")