[CMake] Project dependencies do not work with Xcode on Mac OS X

[Tron Thomas]

I have a project configured by CMake that uses a macro to create an 
executable from a generated source file using code like the following:

macro(CreateProgram Name)
    set(SourceFile ${Name}.cpp)

    add_custom_command(OUTPUT ${SourceFile}
        COMMAND <Source code generation command>
        DEPENDS ${ARGN}
        WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR})

    add_executable(${Name} ${SourceFile} ${ARGN})
endmacro(CreateSourceFile)

ARGN is usually a list of header files the generated source code file 
will depend on.  This macro works fine for make files on Linux and 
Visual Studio on Windows.  However, with Xcode on Mac OS X, changes to 
the dependent header files will not cause the program to rebuild.

I suspect this is a bug with the way CMake is configuring the Xcode 
project.  I wanted to check to see if there was anything I'm missing 
that would make things work.

What do people know about why this might be failing on Xcode?