Next: Understanding Bug Reporting Up: Bugs
When Is There a Bug
If Emacs executes an illegal instruction, or dies with an operating
system error message that indicates a problem in the program (as
opposed to something like "disk full"), then it is certainly a bug.
If Emacs updates the display in a way that does not correspond to
what is in the buffer, then it is certainly a bug. If a command seems
to do the wrong thing but the problem corrects itself if you type
`C-l', it is a case of incorrect display updating.
Taking forever to complete a command can be a bug, but you must make
certain that it was really Emacs's fault. Some commands simply take a
long time. Type `C-g' and then `C-h l' to see whether the input Emacs
received was what you intended to type; if the input was such that you
*know* it should have been processed quickly, report a bug. If you
don't know whether the command should take a long time, find out by
looking in the manual or by asking for assistance.
If a command you are familiar with causes an Emacs error message in a
case where its usual definition ought to be reasonable, it is probably a
If a command does the wrong thing, that is a bug. But be sure you
know for certain what it ought to have done. If you aren't familiar
with the command, or don't know for certain how the command is supposed
to work, then it might actually be working right. Rather than jumping
to conclusions, show the problem to someone who knows for certain.
Finally, a command's intended definition may not be best for editing
with. This is a very important sort of problem, but it is also a
matter of judgment. Also, it is easy to come to such a conclusion out
of ignorance of some of the existing features. It is probably best not
to complain about such a problem until you have checked the
documentation in the usual ways, feel confident that you understand it,
and know for certain that what you want is not available. If you are
not sure what the command is supposed to do after a careful reading of
the manual, check the index and glossary for any terms that may be
If you still do not understand, that indicates a bug in the manual,
which you should report. The manual's job is to make everything clear
to people who are not Emacs experts--including you. It is just as
important to report documentation bugs as program bugs.
If the on-line documentation string of a function or variable
disagrees with the manual, one of them must be wrong; that is a bug.
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