If you think you may have found a bug in GNU Emacs, please
read the Bugs section of the Emacs manual for advice on
(1) how to tell when to report a bug, and
(2) how to write a useful bug report and what information
it needs to have.

There are three ways to read the Bugs section.

(1) In a printed copy of the Emacs manual.
You can order one from the Free Software Foundation;
see the file etc/ORDERS.  But if you don't have a copy on
hand and you think you have found a bug, you shouldn't wait
to get a printed manual; you should read the section right away
as described below.

(2) With Info.  Start Emacs, do C-h i to enter Info,
then m Emacs RET to get to the Emacs manual, then m Bugs RET
to get to the section on bugs.  Or use standalone Info in
a like manner.  (Standalone Info is part of the Texinfo distribution,
not part of the Emacs distribution.)

(3) By hand.  Do
    cat info/emacs* | more "+/^File: emacs,  Node: Bugs,"

Please first check the file etc/PROBLEMS (e.g. with C-h C-p in Emacs) to
make sure it isn't a known issue.
