midl /no_cpp
midl /no_cpp filename.idl
The /no_cpp switch specifies that the MIDL compiler does not call the C preprocessor to preprocess the IDL file.
The /no_cpp switch takes precedence over the /cpp_cmd and /cpp_opt switches.
General MIDL Command-line Syntax, /cpp_cmd, /cpp_opt, /D, /I, /U