CL Command-Line Warning D4030

Message Text

operation is incompatible with multiprocessing; ignoring /MP switch

In general, this warning message is written to whatever file or device was given to CL as standard output. However, if CL is given the /E, /EP, /P or /Zg option, the message is written to whatever file or device was given to CL as standard error and is not subject to simple redirection from the Command Prompt, e.g., for capture to a file.

Circumstances

For this warning to occur, the /MP option has an argument greater than 1 and there are two or more input files. Otherwise, the /MP is ignored anyway (and without warning).

The message text is perhaps unhelpful in leaving the user to wonder what is this “operation” that is incompatible. It may be one of two. One is preprocessing to standard output, as enabled by the /E and /EP options. The other is creating a precompiled header file, as enabled by the /Yc option.

Other incompatibilities with /MP are checked as syntactic relations and reported as error D2016. The applicable options are /FD, /Gm, /YX and /Zi.