The required argument consists of everything after the colon. It is taken in two parts, source and target, separated by an equals sign. It is a fatal error (LNK1146) if source begins with a comma. It is a fatal error (LNK1117) if there is no equals sign or if source is empty. It is a fatal error (LNK1146) if target is empty.

The /pchmap option is for the command line only. It is not valid as a directive in an object file.


Apart from the preceding quick check of syntax, the /pchmap option is just something to pass through to the back-end compiler should link-time code generation turn out to be required. Pending documentation of /pchmap as a compiler option, the following summary must suffice. The source and target both name PCH files. Wherever the back-end compiler encounters a reference to source, most notably in an object file, it should use target instead.