How to specify one file for a library to be compiled with C++ 11 instead of 98?

I'm working on a project where most of it has to be compiled in C++ 98, however, I have exactly one file that needs to be compiled with C++ 11 instead.

Current example code:

set(SOURCES
   file1.cpp
   file2.cpp
   file3.cpp
)

add_library(examplelibraryname SHARED ${SOURCES})

I want to specify that file3.cpp needs to be compiled with CXX STANDARD 11.

I tried doing a set_target_properties(examplelibraryname PROPERTIES CXX_STANDARD 11) on the whole library, but unfortunately one of the other files can't compile with C++ 11.

I have tried specifying just the target file by using: set_property(SOURCE file3.cpp PROPERTY CXX_STANDARD 11)

but unfortunately I still get the errors associated with not compiling it with C++ 11 (presumably because this line is not affecting the add_library line).

Is there any way for me to specify that just that file for the library should use C++ 11?

I would go with what @Eljay suggested and create separate targets for the different standars.

project("Stackoverflow70610506")

set(USE_COMBINED 0)

# Build c++98 specific compilation units.
add_library(Cpp98 STATIC cpp98.cpp)
set_property(TARGET Cpp98 PROPERTY CXX_STANDARD 98)

# Build c++11 specific compilation units.
add_library(Cpp11 STATIC cpp11.cpp)
set_property(TARGET Cpp11 PROPERTY CXX_STANDARD 11)

# Create an c++98 executable.
add_executable(Stackoverflow70610506 main.cpp)
set_property(TARGET Stackoverflow70610506 PROPERTY CXX_STANDARD 98)

if(USE_COMBINED)
# Alternativly combine them into a common c++98 library.
add_library(Combined STATIC Cpp11 Cpp98)
set_property(TARGET Cpp11 PROPERTY CXX_STANDARD 98)
# And link the combined library.
target_link_libraries(Stackoverflow70610506 Combined)
else()
# Or link them both directly.
target_link_libraries(Stackoverflow70610506 Cpp98 Cpp11)
endif()

The downside is, that you might have to adjust the export / visibility behavior of the API in your compilation units / libraries.