cmake-gui: Prefer local variable for Qt major version

QT_DEFAULT_MAJOR_VERSION was added in Qt 5.15 and CMake supports Qt versions >= 5.9

1 files changed, 27 insertions, 23 deletions

diff --git a/Source/QtDialog/CMakeLists.txt b/Source/QtDialog/CMakeLists.txt
index 81f9e70..ce55f51 100644
--- a/Source/QtDialog/CMakeLists.txt
+++ b/Source/QtDialog/CMakeLists.txt
@@ -9,30 +9,34 @@ set (QT_COMPONENTS
   Gui
 )
 # Look for Qt6 first
-find_package(Qt6
-  COMPONENTS ${QT_COMPONENTS}
-  QUIET
-)
-if (NOT Qt6Widgets_FOUND)
-  find_package(Qt5
+find_package(Qt6Widgets QUIET)
+set(INSTALLED_QT_VERSION 6)
+if(NOT Qt6Widgets_FOUND)
+  find_package(Qt5Widgets QUIET)
+  if(NOT Qt5Widgets_FOUND)
+    message(FATAL_ERROR "Could not find a valid Qt installation.")
+  endif()
+  set(INSTALLED_QT_VERSION 5)
+endif()
+
+find_package(Qt${INSTALLED_QT_VERSION}
     COMPONENTS ${QT_COMPONENTS}
     REQUIRED QUIET
-  )
-endif()
+)
 
 set(CMake_QT_EXTRA_LIBRARIES)
 
 # Try to find the package WinExtras for the task bar progress
 if(WIN32)
-  find_package(Qt${QT_DEFAULT_MAJOR_VERSION}WinExtras QUIET)
-  if (Qt${QT_DEFAULT_MAJOR_VERSION}WinExtras_FOUND)
+  find_package(Qt${INSTALLED_QT_VERSION}WinExtras QUIET)
+  if (Qt${INSTALLED_QT_VERSION}WinExtras_FOUND)
     add_definitions(-DQT_WINEXTRAS)
-    list(APPEND CMake_QT_EXTRA_LIBRARIES Qt${QT_DEFAULT_MAJOR_VERSION}::WinExtras)
+    list(APPEND CMake_QT_EXTRA_LIBRARIES Qt${INSTALLED_QT_VERSION}::WinExtras)
     list(APPEND QT_COMPONENTS WinExtras)
   endif()
 endif()
 
-set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${Qt${QT_DEFAULT_MAJOR_VERSION}Widgets_EXECUTABLE_COMPILE_FLAGS}")
+set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${Qt${INSTALLED_QT_VERSION}Widgets_EXECUTABLE_COMPILE_FLAGS}")
 
 if(CMake_QT_STATIC_QXcbIntegrationPlugin_LIBRARIES)
   list(APPEND CMake_QT_EXTRA_LIBRARIES ${CMake_QT_STATIC_QXcbIntegrationPlugin_LIBRARIES})
@@ -51,7 +55,7 @@ endif()
 # Qt5 support is missing there.
 if(CMake_INSTALL_DEPENDENCIES AND (APPLE OR WIN32))
   function(_qt_get_plugin_name_with_version target out_var)
-      string(REGEX REPLACE "^Qt::(.+)" "Qt${QT_DEFAULT_MAJOR_VERSION}::\\1"
+      string(REGEX REPLACE "^Qt::(.+)" "Qt${INSTALLED_QT_VERSION}::\\1"
              qt_plugin_with_version "${target}")
       if(TARGET "${qt_plugin_with_version}")
           set("${out_var}" "${qt_plugin_with_version}" PARENT_SCOPE)
@@ -87,16 +91,16 @@ if(CMake_INSTALL_DEPENDENCIES AND (APPLE OR WIN32))
   endmacro()
   macro(install_qt_plugins _comps _plugins_var)
     foreach(_qt_comp ${${_comps}})
-      if (QT_DEFAULT_MAJOR_VERSION VERSION_LESS 6)
-        set(_qt_module_plugins ${Qt${QT_DEFAULT_MAJOR_VERSION}${_qt_comp}_PLUGINS})
+      if (INSTALLED_QT_VERSION VERSION_LESS 6)
+        set(_qt_module_plugins ${Qt${INSTALLED_QT_VERSION}${_qt_comp}_PLUGINS})
       else()
-        get_target_property(_qt_module_plugins Qt${QT_DEFAULT_MAJOR_VERSION}::${_qt_comp} QT_PLUGINS)
+        get_target_property(_qt_module_plugins Qt${INSTALLED_QT_VERSION}::${_qt_comp} QT_PLUGINS)
       endif()
       foreach(_qt_plugin ${_qt_module_plugins})
-        if (QT_DEFAULT_MAJOR_VERSION VERSION_GREATER_EQUAL 6)
+        if (INSTALLED_QT_VERSION VERSION_GREATER_EQUAL 6)
           # Qt6 provides the plugins as individual packages that need to be found.
-          find_package(Qt${QT_DEFAULT_MAJOR_VERSION}${_qt_plugin} QUIET
-            PATHS ${Qt${QT_DEFAULT_MAJOR_VERSION}${_qt_comp}_DIR})
+          find_package(Qt${INSTALLED_QT_VERSION}${_qt_plugin} QUIET
+            PATHS ${Qt${INSTALLED_QT_VERSION}${_qt_comp}_DIR})
         endif()
         install_qt_plugin(${_qt_plugin} _plugins_var)
       endforeach()
@@ -118,7 +122,7 @@ if(CMake_INSTALL_DEPENDENCIES AND (APPLE OR WIN32))
   endif()
 endif()
 
-get_property(_Qt_Core_LOCATION TARGET Qt${QT_DEFAULT_MAJOR_VERSION}::Core PROPERTY LOCATION)
+get_property(_Qt_Core_LOCATION TARGET Qt${INSTALLED_QT_VERSION}::Core PROPERTY LOCATION)
 get_filename_component(Qt_BIN_DIR "${_Qt_Core_LOCATION}" PATH)
 if(APPLE)
   get_filename_component(Qt_BIN_DIR "${Qt_BIN_DIR}" PATH)
@@ -176,7 +180,7 @@ set(MOC_SRCS
   )
 set(QRC_SRCS CMakeSetup.qrc)
 
-if (QT_DEFAULT_MAJOR_VERSION VERSION_LESS 6)
+if (INSTALLED_QT_VERSION VERSION_LESS 6)
   qt5_wrap_ui(UI_BUILT_SRCS ${UI_SRCS})
   qt5_wrap_cpp(MOC_BUILT_SRCS ${MOC_SRCS})
   qt5_add_resources(QRC_BUILT_SRCS ${QRC_SRCS})
@@ -210,13 +214,13 @@ set(CMAKE_INCLUDE_CURRENT_DIR ON)
 add_library(CMakeGUILib STATIC ${SRCS})
 # CMake_QT_EXTRA_LIBRARIES have to come before the main libraries on the link line
 target_link_libraries(CMakeGUILib PUBLIC CMakeLib ${CMake_QT_EXTRA_LIBRARIES}
-  Qt${QT_DEFAULT_MAJOR_VERSION}::Core Qt${QT_DEFAULT_MAJOR_VERSION}::Widgets)
+  Qt${INSTALLED_QT_VERSION}::Core Qt${INSTALLED_QT_VERSION}::Widgets)
 
 add_library(CMakeGUIMainLib STATIC CMakeSetup.cxx)
 target_link_libraries(CMakeGUIMainLib PUBLIC CMakeGUILib)
 
 add_executable(cmake-gui WIN32 MACOSX_BUNDLE CMakeGUIExec.cxx ${MANIFEST_FILE})
-target_link_libraries(cmake-gui CMakeGUIMainLib Qt${QT_DEFAULT_MAJOR_VERSION}::Core)
+target_link_libraries(cmake-gui CMakeGUIMainLib Qt${INSTALLED_QT_VERSION}::Core)
 
 if(WIN32)
   target_sources(CMakeGUIMainLib INTERFACE $<TARGET_OBJECTS:CMakeVersion> CMakeSetup.rc)