bug#50731: `progress-reporter-update' docstring and `backward-sexp' interaction

[Stefan Kangas <stefan@marxist.se>]

Severity: minor

The docstring of `progress-reporter-update' contains the following text:

    If REPORTER is a numerical progress reporter---i.e. if it was
     made using non-nil MIN-VALUE and MAX-VALUE arguments to
     `make-progress-reporter'---then VALUE should be a number between
     MIN-VALUE and MAX-VALUE.

If I place point on the space after "i.e." on the first row, and type
C-M-b (backward-sexp), point ends up before "reporter".  (This happens
in `emacs-lisp-mode', but not in `message-mode'; `message-mode' seems to
have no concept of an abbreviation and lands on the "e".)

This in turn leads to checkdoc flagging this as a mistake, and asks you
to put two spaces after dot.

I'm not sure which of these options is true:

A) We should support the above convention of using three dashes in
   `backward-sexp'.  (This is the rough ASCII equivalent of an em dash.)

B) We should just not use the above convention in
   `progress-reporter-update'.