CMake: Change the default of OUTPUT_DIRECTORY for qt6_add_qml_module()

The new default is now controlled via a new QT_QML_OUTPUT_DIRECTORY
variable. If that isn't set, the fallback assumes the source directory
structure follows the URI structure and uses
${CMAKE_CURRENT_BINARY_DIR} instead. This pattern means more projects
will have working import paths for qmllint and possibly other tools
out of the box. There should also be fewer cases where the
OUTPUT_DIRECTORY option needs to be used in calls to
qt6_add_qml_module(). The QT_QML_OUTPUT_DIRECTORY variable facilitates
the scenario where QML modules might be distributed across different
parts of the source directory hierarchy, but once collected under a
common base point defined by QT_QML_OUTPUT_DIRECTORY, they form a
coherent set of QML modules whose subdirectory structure below that
base point follows their TARGET_PATH.

Fixes: QTBUG-94164
Fixes: QTBUG-95081
Change-Id: I82864c361a2b34f7f1484cdbda0d9b64b34b9950
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
(cherry picked from commit 0c99c17761c89290d88e97367742122db5c9a46f)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

9 files changed, 40 insertions, 7 deletions

diff --git a/examples/qml/qmlextensionplugins/CMakeLists.txt b/examples/qml/qmlextensionplugins/CMakeLists.txt
index dcfde4a8ae..6ea73f83a4 100644
--- a/examples/qml/qmlextensionplugins/CMakeLists.txt
+++ b/examples/qml/qmlextensionplugins/CMakeLists.txt
@@ -14,6 +14,7 @@ if(NOT DEFINED INSTALL_EXAMPLESDIR)
 endif()
 
 set(INSTALL_EXAMPLEDIR "${INSTALL_EXAMPLESDIR}/qml/qmlextensionplugins/imports/TimeExample")
+set(QT_QML_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/examples/qml/qmlextensionplugins/imports)
 
 find_package(Qt6 COMPONENTS Core)
 find_package(Qt6 COMPONENTS Gui)
@@ -23,7 +24,6 @@ set_source_files_properties(imports/TimeExample/Clock.qml PROPERTIES
     QT_RESOURCE_ALIAS Clock.qml
 )
 qt6_add_qml_module(qmlqtimeexample
-    OUTPUT_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/imports/TimeExample"
     VERSION 1.0
     URI "TimeExample"
     SOURCES timemodel.cpp timemodel.h
diff --git a/examples/qml/tutorials/extending-qml/chapter6-plugins/CMakeLists.txt b/examples/qml/tutorials/extending-qml/chapter6-plugins/CMakeLists.txt
index 1c19c84caa..59ecdeae6b 100644
--- a/examples/qml/tutorials/extending-qml/chapter6-plugins/CMakeLists.txt
+++ b/examples/qml/tutorials/extending-qml/chapter6-plugins/CMakeLists.txt
@@ -14,6 +14,7 @@ if(NOT DEFINED INSTALL_EXAMPLESDIR)
 endif()
 
 set(INSTALL_EXAMPLEDIR "${INSTALL_EXAMPLESDIR}/qml/tutorials/extending-qml/chapter6-plugins")
+set(QT_QML_OUTPUT_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR})
 
 find_package(Qt6 COMPONENTS Qml)
 find_package(Qt6 COMPONENTS Quick)
diff --git a/examples/qml/tutorials/extending-qml/chapter6-plugins/import/CMakeLists.txt b/examples/qml/tutorials/extending-qml/chapter6-plugins/import/CMakeLists.txt
index f75028aa69..93ec5c5169 100644
--- a/examples/qml/tutorials/extending-qml/chapter6-plugins/import/CMakeLists.txt
+++ b/examples/qml/tutorials/extending-qml/chapter6-plugins/import/CMakeLists.txt
@@ -21,7 +21,6 @@ find_package(Qt6 COMPONENTS Qml)
 find_package(Qt6 COMPONENTS Quick)
 
 qt6_add_qml_module(chartsplugin
-    OUTPUT_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/../Charts"
     VERSION 1.0
     URI "Charts"
     PLUGIN_TARGET chartsplugin
diff --git a/examples/qmltest/qmltest/CMakeLists.txt b/examples/qmltest/qmltest/CMakeLists.txt
index c8a8361578..369e31fe7d 100644
--- a/examples/qmltest/qmltest/CMakeLists.txt
+++ b/examples/qmltest/qmltest/CMakeLists.txt
@@ -14,6 +14,7 @@ if(NOT DEFINED INSTALL_EXAMPLESDIR)
 endif()
 
 set(INSTALL_EXAMPLEDIR "${INSTALL_EXAMPLESDIR}")
+set(QT_QML_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/examples)
 
 find_package(Qt6 COMPONENTS Core)
 find_package(Qt6 COMPONENTS Gui)
diff --git a/examples/quick/customitems/painteditem/CMakeLists.txt b/examples/quick/customitems/painteditem/CMakeLists.txt
index fa964778d0..09f3424f15 100644
--- a/examples/quick/customitems/painteditem/CMakeLists.txt
+++ b/examples/quick/customitems/painteditem/CMakeLists.txt
@@ -14,6 +14,7 @@ if(NOT DEFINED INSTALL_EXAMPLESDIR)
 endif()
 
 set(INSTALL_EXAMPLEDIR "${INSTALL_EXAMPLESDIR}/quick/customitems/painteditem/TextBalloonPlugin")
+set(QT_QML_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/examples/quick/customitems/painteditem)
 
 find_package(Qt6 COMPONENTS Core)
 find_package(Qt6 COMPONENTS Gui)
@@ -21,7 +22,6 @@ find_package(Qt6 COMPONENTS Qml)
 find_package(Qt6 COMPONENTS Quick)
 
 qt6_add_qml_module(qmltextballoonplugin
-    OUTPUT_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/TextBalloonPlugin"
     VERSION 1.0
     URI "TextBalloonPlugin"
     PLUGIN_TARGET qmltextballoonplugin
diff --git a/examples/quick/imageprovider/CMakeLists.txt b/examples/quick/imageprovider/CMakeLists.txt
index 5a25a45deb..82e1bd2a51 100644
--- a/examples/quick/imageprovider/CMakeLists.txt
+++ b/examples/quick/imageprovider/CMakeLists.txt
@@ -14,6 +14,7 @@ if(NOT DEFINED INSTALL_EXAMPLESDIR)
 endif()
 
 set(INSTALL_EXAMPLEDIR "${INSTALL_EXAMPLESDIR}/quick/imageprovider/ImageProviderCore")
+set(QT_QML_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/examples/quick/imageprovider)
 
 find_package(Qt6 COMPONENTS Core)
 find_package(Qt6 COMPONENTS Gui)
@@ -21,7 +22,6 @@ find_package(Qt6 COMPONENTS Qml)
 find_package(Qt6 COMPONENTS Quick)
 
 qt6_add_qml_module(qmlimageproviderplugin
-    OUTPUT_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/ImageProviderCore"
     VERSION 1.0
     URI "ImageProviderCore"
     PLUGIN_TARGET qmlimageproviderplugin
diff --git a/examples/quick/imageresponseprovider/CMakeLists.txt b/examples/quick/imageresponseprovider/CMakeLists.txt
index 551ce01197..47dbab159d 100644
--- a/examples/quick/imageresponseprovider/CMakeLists.txt
+++ b/examples/quick/imageresponseprovider/CMakeLists.txt
@@ -14,6 +14,7 @@ if(NOT DEFINED INSTALL_EXAMPLESDIR)
 endif()
 
 set(INSTALL_EXAMPLEDIR "${INSTALL_EXAMPLESDIR}/quick/imageresponseprovider/ImageResponseProviderCore")
+set(QT_QML_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/examples/quick/imageresponseprovider)
 
 find_package(Qt6 COMPONENTS Core)
 find_package(Qt6 COMPONENTS Gui)
@@ -21,7 +22,6 @@ find_package(Qt6 COMPONENTS Qml)
 find_package(Qt6 COMPONENTS Quick)
 
 qt6_add_qml_module(qmlimageresponseproviderplugin
-    OUTPUT_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/ImageResponseProviderCore"
     VERSION 1.0
     URI "ImageResponseProviderCore"
     PLUGIN_TARGET qmlimageresponseproviderplugin
diff --git a/src/qml/Qt6QmlBuildInternals.cmake b/src/qml/Qt6QmlBuildInternals.cmake
index 3c1ecab69a..191fa690f5 100644
--- a/src/qml/Qt6QmlBuildInternals.cmake
+++ b/src/qml/Qt6QmlBuildInternals.cmake
@@ -105,11 +105,12 @@ function(qt_internal_add_qml_module target)
         ${ARGN}
     )
 
+    set(QT_QML_OUTPUT_DIRECTORY "${QT_BUILD_DIR}/${INSTALL_QMLDIR}")
     if(NOT arg_TARGET_PATH)
         string(REPLACE "." "/" arg_TARGET_PATH ${arg_URI})
     endif()
     if(NOT arg_OUTPUT_DIRECTORY)
-        set(arg_OUTPUT_DIRECTORY "${QT_BUILD_DIR}/${INSTALL_QMLDIR}/${arg_TARGET_PATH}")
+        set(arg_OUTPUT_DIRECTORY "${QT_QML_OUTPUT_DIRECTORY}/${arg_TARGET_PATH}")
     endif()
     if(NOT arg_INSTALL_DIRECTORY)
         set(arg_INSTALL_DIRECTORY "${INSTALL_QMLDIR}/${arg_TARGET_PATH}")
diff --git a/src/qml/Qt6QmlMacros.cmake b/src/qml/Qt6QmlMacros.cmake
index 24a88737ee..2ee1680993 100644
--- a/src/qml/Qt6QmlMacros.cmake
+++ b/src/qml/Qt6QmlMacros.cmake
@@ -281,7 +281,17 @@ function(qt6_add_qml_module target)
             ABSOLUTE BASE_DIR "${CMAKE_CURRENT_BINARY_DIR}"
         )
     else()
-        set(arg_OUTPUT_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR})
+        if("${QT_QML_OUTPUT_DIRECTORY}" STREQUAL "")
+            set(arg_OUTPUT_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR})
+        else()
+            if(NOT IS_ABSOLUTE "${QT_QML_OUTPUT_DIRECTORY}")
+                message(FATAL_ERROR
+                    "QT_QML_OUTPUT_DIRECTORY must be an absolute path, but given: "
+                    "${QT_QML_OUTPUT_DIRECTORY}"
+                )
+            endif()
+            set(arg_OUTPUT_DIRECTORY ${QT_QML_OUTPUT_DIRECTORY}/${arg_TARGET_PATH})
+        endif()
     endif()
 
     # TODO: Support for old keyword, remove once all repos no longer use CLASSNAME
@@ -595,6 +605,13 @@ function(_qt_internal_target_enable_qmllint target)
         _qt_generated_qrc_files "--resource$<SEMICOLON>" "$<SEMICOLON>"
     )
 
+    # Facilitate self-import so it can find the qmldir file
+    list(APPEND import_args -I "${CMAKE_CURRENT_BINARY_DIR}")
+
+    if(NOT "${QT_QML_OUTPUT_DIRECTORY}" STREQUAL "")
+        list(APPEND import_args -I "${QT_QML_OUTPUT_DIRECTORY}")
+    endif()
+
     set(cmd
         ${QT_TOOL_COMMAND_WRAPPER_PATH}
         ${QT_CMAKE_EXPORT_NAMESPACE}::qmllint
@@ -929,6 +946,10 @@ function(qt6_add_qml_plugin target)
     _qt_internal_get_escaped_uri("${arg_URI}" escaped_uri)
 
     if(TARGET ${target})
+        get_target_property(target_type ${target} TYPE)
+        if(target_type STREQUAL "EXECUTABLE")
+            message(FATAL_ERROR "Plugins cannot be executables (target: ${target})")
+        endif()
         foreach(arg IN ITEMS STATIC SHARED)
             if(arg_${arg})
                 message(FATAL_ERROR
@@ -1018,6 +1039,8 @@ function(qt6_add_qml_plugin target)
     endif()
 
     if(arg_OUTPUT_DIRECTORY)
+        # Plugin target must be in the output directory. The backing target,
+        # if it is different to the plugin target, can be anywhere.
         set_target_properties(${target} PROPERTIES
             RUNTIME_OUTPUT_DIRECTORY ${arg_OUTPUT_DIRECTORY}
             LIBRARY_OUTPUT_DIRECTORY ${arg_OUTPUT_DIRECTORY}
@@ -1789,10 +1812,18 @@ but this file does not exist.  Possible reasons include:
         -importPath "${qml_path}"
     )
     get_target_property(qml_import_path ${target} QT_QML_IMPORT_PATH)
+
     if (qml_import_path)
         list(APPEND cmd_args ${qml_import_path})
     endif()
 
+    # Facilitate self-import so we can find the qmldir file
+    list(APPEND cmd_args "${CMAKE_CURRENT_BINARY_DIR}")
+
+    if(NOT "${QT_QML_OUTPUT_DIRECTORY}" STREQUAL "" AND EXISTS "${QT_QML_OUTPUT_DIRECTORY}")
+        list(APPEND cmd_args "${QT_QML_OUTPUT_DIRECTORY}")
+    endif()
+
     get_target_property(qml_files ${target} QT_QML_MODULE_FILES)
     if (qml_files)
         list(APPEND cmd_args "-qmlFiles" ${qml_files})