moving c++20 standard specification to compiler flags section

CMakeLists.txt

@@ -166,7 +166,6 @@ if (WIN32)
     # "VCRUNTIME140.dll not found. Try reinstalling the app.", but give users
     # a choice to opt for the shared runtime if they want.
     option(USE_STATIC_CRT "Link against the static runtime libraries." ON)
-    set(CMAKE_CXX_STANDARD 20)
 
     # On Windows we need to instruct cmake to generate the .def in order to get the .lib required
     # when linking against dlls. CL.EXE will not generate .lib without .def file (or without pragma
@@ -283,11 +282,11 @@ endif()
 # ==================================================================================================
 set(CXX_STANDARD "-std=c++17")
 if (WIN32)
-    set(CXX_STANDARD "/std:c++17")
+    set(CXX_STANDARD "/std:c++20")
 endif()
 
 if (MSVC)
-    set(CXX_STANDARD "/std:c++latest")
+    set(CXX_STANDARD "/std:c++20")
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${CXX_STANDARD} /W0 /Zc:__cplusplus")
 else()
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${CXX_STANDARD} -fstrict-aliasing -Wno-unknown-pragmas -Wno-unused-function -Wno-deprecated-declarations")
@@ -453,7 +452,6 @@ endif()
 
 # By default, build with Vulkan support on desktop platforms, although clients must request to use
 # it at run time.
-# if (WIN32 OR WEBGL OR IOS)
 if (WEBGL OR IOS)
     option(FILAMENT_SUPPORTS_VULKAN "Include the Vulkan backend" OFF)
 else()