rcirc-log-filename-function

rcirc-log-filename-function is a variable defined in `rcirc.el'.
Its value is

rcirc-generate-log-filename

• This variable may be risky if used as a file-local variable.

Documentation:
A function to generate the filename used by rcirc's logging facility.

It is called with two arguments, PROCESS and TARGET (see
`rcirc-generate-new-buffer-name' for their meaning), and should
return the filename, or nil if no logging is desired for this
session.

If the returned filename is absolute (`file-name-absolute-p'
returns t), then it is used as-is, otherwise the resulting file
is put into `rcirc-log-directory'.

The filename is then cleaned using `convert-standard-filename' to
guarantee valid filenames for the current OS.

You can customize this variable.