erc-truncate-buffer-to-size
erc-truncate-buffer-to-size is an autoloaded Lisp function in `erc-truncate.el
'.
(erc-truncate-buffer-to-size SIZE &optional BUFFER)
Truncates the buffer to the size SIZE.
If BUFFER is not provided, the current buffer is assumed. The deleted
region is logged if `erc-logging-enabled' returns non-nil.