/Zs switch
The /Zs switch indicates that the compiler only checks syntax and does not generate output files.
midl /Zs
midl /syntax_check
This switch has no parameters.
This switch overrides all other switches that specify information about output files.
You can also specify syntax-checking mode with the MIDL compiler switch /syntax_check.
midl /Zs filename.idl
midl /syntax_check filename.idl