C1XX -Zf


This option has no arguments. It is -Zf only.

This option is not recognised on the CL command line, but can be passed to C1XX through the CL /d1 option, giving Zf as its argument.


Under the -Zf option, the following identifiers become keywords:

Each tokenises indistinguishably from a corresponding keyword whose name differs only by having two leading underscores. As it happens, the specific tokenisation for all is that they are disabled, such that their use causes a warning (C4226) about being obsolete.

This behaviour is presumably intended for compatibility with earlier versions of the compiler. Indeed, since the list is so small, it seems likely that these keywords date from so long ago that Microsoft introduced them without caring for (or yet knowing of) any convention about leading underscores for implementation-specific keywords.

The behaviour of -Zf is also arranged by the /Ze option, but as one of many. With -Zf it is the sole action.