Change the -qpa configure argument logic

Parse the -qpa configure argument as list and translate it to the
QT_QPA_PLATFORMS cmake variable. This variable is new to the Qt build
procedure. The QT_QPA_DEFAULT_PLATFORM variable supposed to get
multiple values, but this didn't work at all, since the variable value
then was used in the compile definition that is expected to be a single
value QPA platfrom definition. This inconsistency forced to introduce
a new variable.

The QT_QPA_DEFAULT_PLATFORM variable now controls the first-choice QPA
plugin for the GUI applications. The new configure argument
-default-qpa is now translated to the QT_QPA_DEFAULT_PLATFORM variable
instead the of -qpa one. The -qpa configure argument is now translated
to the QT_QPA_PLATFORMS variable, which is new one as well. The
variable contains the list of QPA plugins that are "default" for this
Qt configuration. The meaning of the "default" plugins is related to
the DEFAULT_IF argument of qt_internal_add_plugin command. Plugins
that are listed in the QT_QPA_PLATFORMS variable will be treated as
default by the build system and will be deployed within user
applications when using deployment API or linked statically when using
static Qt.

The QT_QPA_DEFAULT_PLATFORM falls back to the QT_QPA_PLATFORMS first
value in the list if it's not set explicitly and either
'-DQT_QPA_PLATFORMS' or '-qpa' arguments are specified.

[ChangeLog][CMake] Added QT_QPA_PLATFORMS variable which controls the
list of QPA plugins that will be deployed within the applications by
default.
[ChangeLog][CMake] The '-qpa' configure argument now is mapped to the
QT_QPA_PLATFORMS variable and has different functionality. It doesn't
control the platform plugin that the GUI application is using by
default, but controls the list of QPA plugins that will be deployed
within the applications by default.
[ChangeLog][CMake] Added '-default-qpa' argument which replaces the
'-qpa' one. The argument is translated to the QT_DEFAULT_QPA_PLATFORM
CMake variable and selects the default platform that should be used
by GUI application if QT_QPA_PLATFORM environment variable is not set.

Task-number: QTBUG-124265
Task-number: QTBUG-87805
Task-number: QTBUG-124449
Change-Id: Ibcebaccc535aaed6374f15ccfeddb3e6128f5ce0
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>

cmake/QtPostProcessHelpers.cmake

@@ -653,13 +653,19 @@ set(__qt_internal_initial_qt_cmake_build_type \"${CMAKE_BUILD_TYPE}\")
         endif()
 
         # Save the default qpa platform.
-        # Used by qtwayland/src/plugins/platforms/qwayland-generic/CMakeLists.txt. Otherwise
-        # the DEFAULT_IF condition is evaluated incorrectly.
         if(DEFINED QT_QPA_DEFAULT_PLATFORM)
             string(APPEND QT_EXTRA_BUILD_INTERNALS_VARS
                 "set(QT_QPA_DEFAULT_PLATFORM \"${QT_QPA_DEFAULT_PLATFORM}\" CACHE STRING \"\")\n")
         endif()
 
+        # Save the list of default qpa platforms.
+        # Used by qtwayland/src/plugins/platforms/qwayland-generic/CMakeLists.txt. Otherwise
+        # the DEFAULT_IF condition is evaluated incorrectly.
+        if(DEFINED QT_QPA_PLATFORMS)
+            string(APPEND QT_EXTRA_BUILD_INTERNALS_VARS
+                "set(QT_QPA_PLATFORMS \"${QT_QPA_PLATFORMS}\" CACHE STRING \"\")\n")
+        endif()
+
         # Save minimum and policy-related CMake versions to ensure the same minimum is
         # checked for when building other downstream repos (qtsvg, etc) and the policy settings
         # will be consistent unless the downstream repos explicitly override them.

cmake/QtProcessConfigureArgs.cmake

@@ -943,6 +943,7 @@ translate_string_input(platform QT_QMAKE_TARGET_MKSPEC)
 translate_string_input(xplatform QT_QMAKE_TARGET_MKSPEC)
 guess_compiler_from_mkspec()
 translate_string_input(qpa_default_platform QT_QPA_DEFAULT_PLATFORM)
+translate_list_input(qpa_platforms QT_QPA_PLATFORMS)
 
 translate_path_input(android-sdk ANDROID_SDK_ROOT)
 translate_path_input(android-ndk ANDROID_NDK_ROOT)

cmake/configure-cmake-mapping.md

@@ -145,7 +145,8 @@ The following table describes the mapping of configure options to CMake argument
 | -opengl <api>                         | -DINPUT_opengl=<api>                              |                                                                 |
 | -opengles3                            | -DFEATURE_opengles3=ON                            |                                                                 |
 | -egl                                  | -DFEATURE_egl=ON                                  |                                                                 |
-| -qpa <name>                           | -DQT_QPA_DEFAULT_PLATFORM=<name>                  |                                                                 |
+| -qpa <name>;...;<name_n>              | -DQT_QPA_PLATFORMS=<name>;...;<name_n>            |                                                                 |
+| -default-qpa <name>                   | -DQT_QPA_DEFAULT_PLATFORM=<name>                  |                                                                 |
 | -xcb-xlib                             | -DFEATURE_xcb_xlib=ON                             |                                                                 |
 | -direct2d                             | -DFEATURE_direct2d=ON                             |                                                                 |
 | -directfb                             | -DFEATURE_directfb=ON                             |                                                                 |

config_help.txt

@@ -290,8 +290,10 @@ Gui, printing, widget options:
   -opengles3 ........... Enable OpenGL ES 3.x support instead of ES 2.x [auto]
   -egl ................. Enable EGL support [auto]
 
-  -qpa <name> .......... Select default QPA backend(s) (e.g., xcb, cocoa, windows)
+  -qpa <qpa1>[;<qpa2>] . Select supported QPA backend(s) (e.g., xcb, cocoa,
-                         A prioritized list separated by semi-colons.
+                         windows). A list separated by semi-colons.
+  -default-qpa <name> .. Select the default QPA backend (e.g., xcb, cocoa,
+                         windows).
   -xcb-xlib............. Enable Xcb-Xlib support [auto]
 
   Platform backends:

src/gui/CMakeLists.txt

@@ -7,7 +7,9 @@ qt_find_package(WrapPNG PROVIDED_TARGETS WrapPNG::WrapPNG)
 qt_find_package(WrapFreetype PROVIDED_TARGETS WrapFreetype::WrapFreetype)
 
 if (QT_FEATURE_gui)
-    if(WIN32)
+    if(QT_QPA_PLATFORMS)
+        list(GET QT_QPA_PLATFORMS 0 _default_platform)
+    elseif(WIN32)
         set(_default_platform "windows")
     elseif(ANDROID)
         set(_default_platform "android")
@@ -30,6 +32,11 @@ if (QT_FEATURE_gui)
     endif()
 
     set(QT_QPA_DEFAULT_PLATFORM "${_default_platform}" CACHE STRING "QPA default platform")
+    if(NOT "${QT_QPA_DEFAULT_PLATFORM}" IN_LIST QT_QPA_PLATFORMS)
+        list(APPEND QT_QPA_PLATFORMS "${QT_QPA_DEFAULT_PLATFORM}")
+        set(QT_QPA_PLATFORMS "${QT_QPA_PLATFORMS}" CACHE STRING
+            "QPA platforms deployed by default" FORCE)
+    endif()
 endif()
 
 # Silence warnings in 3rdparty code

src/gui/qt_cmdline.cmake

@@ -27,7 +27,8 @@ qt_commandline_option(opengl TYPE optionalString VALUES no yes desktop es2 dynam
 qt_commandline_option(opengl-es-2 TYPE void NAME opengl VALUE es2)
 qt_commandline_option(opengles3 TYPE boolean)
 qt_commandline_option(openvg TYPE boolean)
-qt_commandline_option(qpa TYPE string NAME qpa_default_platform)
+qt_commandline_option(qpa TYPE string NAME qpa_platforms)
+qt_commandline_option(default-qpa TYPE string NAME qpa_default_platform)
 qt_commandline_option(sm TYPE boolean NAME sessionmanager)
 qt_commandline_option(tslib TYPE boolean)
 qt_commandline_option(vulkan TYPE boolean)

src/plugins/platforms/android/CMakeLists.txt

@@ -9,7 +9,7 @@ qt_find_package(EGL)
 qt_internal_add_plugin(QAndroidIntegrationPlugin
     OUTPUT_NAME qtforandroid
     PLUGIN_TYPE platforms
-    DEFAULT_IF ${QT_QPA_DEFAULT_PLATFORM} MATCHES android
+    DEFAULT_IF "android" IN_LIST QT_QPA_PLATFORMS
     SOURCES
         androidcontentfileengine.cpp androidcontentfileengine.h
         androiddeadlockprotector.h

src/plugins/platforms/cocoa/CMakeLists.txt

@@ -7,7 +7,7 @@
 
 qt_internal_add_plugin(QCocoaIntegrationPlugin
     OUTPUT_NAME qcocoa
-    DEFAULT_IF ${QT_QPA_DEFAULT_PLATFORM} MATCHES cocoa
+    DEFAULT_IF "cocoa" IN_LIST QT_QPA_PLATFORMS
     PLUGIN_TYPE platforms
     SOURCES
         main.mm

src/plugins/platforms/eglfs/CMakeLists.txt

@@ -92,7 +92,7 @@ endif()
 qt_internal_add_plugin(QEglFSIntegrationPlugin
     OUTPUT_NAME qeglfs
     PLUGIN_TYPE platforms
-    DEFAULT_IF ${QT_QPA_DEFAULT_PLATFORM} MATCHES eglfs
+    DEFAULT_IF "eglfs" IN_LIST QT_QPA_PLATFORMS
     SOURCES
         qeglfsmain.cpp
     DEFINES

src/plugins/platforms/ios/CMakeLists.txt

@@ -21,7 +21,7 @@ endif()
 qt_internal_add_plugin(QIOSIntegrationPlugin
     OUTPUT_NAME qios
     STATIC # Force static, even in shared builds
-    DEFAULT_IF ${QT_QPA_DEFAULT_PLATFORM} MATCHES ios
+    DEFAULT_IF "ios" IN_LIST QT_QPA_PLATFORMS
     PLUGIN_TYPE platforms
     SOURCES
         plugin.mm

src/plugins/platforms/linuxfb/CMakeLists.txt

@@ -8,7 +8,7 @@
 qt_internal_add_plugin(QLinuxFbIntegrationPlugin
     OUTPUT_NAME qlinuxfb
     PLUGIN_TYPE platforms
-    DEFAULT_IF ${QT_QPA_DEFAULT_PLATFORM} MATCHES linuxfb
+    DEFAULT_IF "linuxfb" IN_LIST QT_QPA_PLATFORMS
     SOURCES
         main.cpp
         qlinuxfbintegration.cpp qlinuxfbintegration.h

src/plugins/platforms/minimal/CMakeLists.txt

@@ -10,7 +10,7 @@ qt_find_package(WrapFreetype PROVIDED_TARGETS WrapFreetype::WrapFreetype)
 qt_internal_add_plugin(QMinimalIntegrationPlugin
     OUTPUT_NAME qminimal
     PLUGIN_TYPE platforms
-    DEFAULT_IF ${QT_QPA_DEFAULT_PLATFORM} MATCHES minimal
+    DEFAULT_IF "minimal" IN_LIST QT_QPA_PLATFORMS
     SOURCES
         main.cpp
         qminimalbackingstore.cpp qminimalbackingstore.h

src/plugins/platforms/minimalegl/CMakeLists.txt

@@ -10,7 +10,7 @@ qt_find_package(EGL)
 qt_internal_add_plugin(QMinimalEglIntegrationPlugin
     OUTPUT_NAME qminimalegl
     PLUGIN_TYPE platforms
-    DEFAULT_IF ${QT_QPA_DEFAULT_PLATFORM} MATCHES minimalegl
+    DEFAULT_IF "minimalegl" IN_LIST QT_QPA_PLATFORMS
     SOURCES
         main.cpp
         qminimaleglintegration.cpp qminimaleglintegration.h

src/plugins/platforms/offscreen/CMakeLists.txt

@@ -8,7 +8,7 @@
 qt_internal_add_plugin(QOffscreenIntegrationPlugin
     OUTPUT_NAME qoffscreen
     PLUGIN_TYPE platforms
-    DEFAULT_IF ${QT_QPA_DEFAULT_PLATFORM} MATCHES offscreen
+    DEFAULT_IF "offscreen" IN_LIST QT_QPA_PLATFORMS
     SOURCES
         main.cpp
         qoffscreencommon.cpp qoffscreencommon.h

src/plugins/platforms/qnx/CMakeLists.txt

@@ -8,7 +8,7 @@
 qt_internal_add_plugin(QQnxIntegrationPlugin
     OUTPUT_NAME qqnx
     PLUGIN_TYPE platforms
-    DEFAULT_IF ${QT_QPA_DEFAULT_PLATFORM} MATCHES qnx
+    DEFAULT_IF "qnx" IN_LIST QT_QPA_PLATFORMS
     SOURCES
         main.cpp main.h
         qqnxabstractcover.h

src/plugins/platforms/vkkhrdisplay/CMakeLists.txt

@@ -6,7 +6,7 @@ qt_find_package(WrapFreetype PROVIDED_TARGETS WrapFreetype::WrapFreetype)
 qt_internal_add_plugin(QVkKhrDisplayIntegrationPlugin
     OUTPUT_NAME qvkkhrdisplay
     PLUGIN_TYPE platforms
-    DEFAULT_IF ${QT_QPA_DEFAULT_PLATFORM} MATCHES vkkhrdisplay
+    DEFAULT_IF "vkkhrdisplay" IN_LIST QT_QPA_PLATFORMS
     SOURCES
         main.cpp
         qvkkhrdisplayintegration.cpp qvkkhrdisplayintegration.h

src/plugins/platforms/vnc/CMakeLists.txt

@@ -8,7 +8,7 @@
 qt_internal_add_plugin(QVncIntegrationPlugin
     OUTPUT_NAME qvnc
     PLUGIN_TYPE platforms
-    DEFAULT_IF ${QT_QPA_DEFAULT_PLATFORM} MATCHES vnc
+    DEFAULT_IF "vnc" IN_LIST QT_QPA_PLATFORMS
     SOURCES
         main.cpp
         qvnc.cpp qvnc_p.h

src/plugins/platforms/wasm/CMakeLists.txt

@@ -7,7 +7,7 @@
 
 qt_internal_add_plugin(QWasmIntegrationPlugin
     OUTPUT_NAME qwasm
-    DEFAULT_IF ${QT_QPA_DEFAULT_PLATFORM} MATCHES wasm
+    DEFAULT_IF "wasm" IN_LIST QT_QPA_PLATFORMS
     PLUGIN_TYPE platforms
     SOURCES
         main.cpp

src/plugins/platforms/windows/CMakeLists.txt

@@ -8,7 +8,7 @@
 qt_internal_add_plugin(QWindowsIntegrationPlugin
     OUTPUT_NAME qwindows
     PLUGIN_TYPE platforms
-    DEFAULT_IF ${QT_QPA_DEFAULT_PLATFORM} MATCHES windows
+    DEFAULT_IF "windows" IN_LIST QT_QPA_PLATFORMS
     SOURCES
         main.cpp
         qtwindowsglobal.h

src/plugins/platforms/xcb/CMakeLists.txt

@@ -164,7 +164,7 @@ endif()
 qt_internal_add_plugin(QXcbIntegrationPlugin
     OUTPUT_NAME qxcb
     PLUGIN_TYPE platforms
-    DEFAULT_IF ${QT_QPA_DEFAULT_PLATFORM} MATCHES xcb
+    DEFAULT_IF "xcb" IN_LIST QT_QPA_PLATFORMS
     SOURCES
         qxcbmain.cpp
     DEFINES