cmake-gui: Suppress MSVC deprecation warnings from Qt headers

MSVC 14.38+ toolsets deprecate `stdext::checked_array_iterator`.
Support building with versions of Qt that have not been updated
to avoid the deprecated API.

Qt-Issue: https://bugreports.qt.io/browse/QTBUG-118993

Source/QtDialog/CMakeLists.txt

@@ -48,6 +48,11 @@ if(WIN32)
   endif()
 endif()
 
+if(MSVC)
+  # QTBUG-118993: Qt uses deprecated stdext::checked_array_iterator
+  add_compile_definitions(_SILENCE_STDEXT_ARR_ITERS_DEPRECATION_WARNING)
+endif()
+
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${Qt${INSTALLED_QT_VERSION}Widgets_EXECUTABLE_COMPILE_FLAGS}")
 
 if(CMake_QT_STATIC_QXcbIntegrationPlugin_LIBRARIES)

Tests/CMakeGUI/CMakeLists.txt

@@ -2,6 +2,11 @@ include(CMakeParseArguments)
 
 find_package(Qt5Test REQUIRED)
 
+if(MSVC)
+  # QTBUG-118993: Qt uses deprecated stdext::checked_array_iterator
+  add_compile_definitions(_SILENCE_STDEXT_ARR_ITERS_DEPRECATION_WARNING)
+endif()
+
 include_directories(
   ${CMake_SOURCE_DIR}/Source
   ${CMake_SOURCE_DIR}/Source/QtDialog