path: root/gdb/doc/gdb.bugs-m4

_dnl__ Copyright (c) 1990 1991 Free Software Foundation, Inc.
_dnl__ This file is part of the source for the GDB manual.
@c M4 FRAGMENT: $Id$
@node _GDBN__ Bugs, Renamed Commands, Emacs, Top
@chapter Reporting Bugs in _GDBN__
@cindex Bugs in _GDBN__
@cindex Reporting Bugs in _GDBN__

Your bug reports play an essential role in making _GDBN__ reliable.

Reporting a bug may help you by bringing a solution to your problem, or it
may not.  But in any case the principal function of a bug report is to help
the entire community by making the next version of _GDBN__ work better.  Bug
reports are your contribution to the maintenance of _GDBN__.

In order for a bug report to serve its purpose, you must include the
information that enables us to fix the bug.

@menu
* Bug Criteria::		Have You Found a Bug?
* Bug Reporting::		How to Report Bugs
@end menu

@node Bug Criteria, Bug Reporting, _GDBN__ Bugs, _GDBN__ Bugs
@section Have You Found a Bug?
@cindex Bug Criteria

If you are not sure whether you have found a bug, here are some guidelines:

@itemize @bullet
@item
@cindex Fatal Signal
@cindex Core Dump
If the debugger gets a fatal signal, for any input whatever, that is a
_GDBN__ bug.  Reliable debuggers never crash.

@item
@cindex error on Valid Input
If _GDBN__ produces an error message for valid input, that is a bug.

@item
@cindex Invalid Input
If _GDBN__ does not produce an error message for invalid input,
that is a bug.  However, you should note that your idea of
``invalid input'' might be our idea of ``an extension'' or ``support
for traditional practice''.

@item
If you are an experienced user of debugging tools, your suggestions
for improvement of _GDBN__ are welcome in any case.
@end itemize

@node Bug Reporting,  , Bug Criteria, _GDBN__ Bugs
@section How to Report Bugs
@cindex Bug Reports
@cindex Compiler Bugs, Reporting

A number of companies and individuals offer support for GNU products.
If you obtained _GDBN__ from a support organization, we recommend you
contact that organization first. 

Contact information for many support companies and individuals is
available in the file @file{etc/SERVICE} in the GNU Emacs distribution.

In any event, we also recommend that you send bug reports for _GDBN__ to one
of these addresses:

@example
bug-gdb@@prep.ai.mit.edu
@{ucbvax|mit-eddie|uunet@}!prep.ai.mit.edu!bug-gdb
@end example

@strong{Do not send bug reports to @samp{info-gdb}, or to
@samp{help-gdb}, or to any newsgroups.} Most users of _GDBN__ do not want to
receive bug reports.  Those that do, have arranged to receive @samp{bug-gdb}.

The mailing list @samp{bug-gdb} has a newsgroup which serves as a
repeater.  The mailing list and the newsgroup carry exactly the same
messages.  Often people think of posting bug reports to the newsgroup
instead of mailing them.  This appears to work, but it has one problem
which can be crucial: a newsgroup posting often lacks a mail path
back to the sender.  Thus, if we need to ask for more information, we
may be unable to reach you.  For this reason, it is better to send bug
reports to the mailing list.

As a last resort, send bug reports on paper to:

@example
GNU Debugger Bugs
545 Tech Square
Cambridge, MA 02139
@end example

The fundamental principle of reporting bugs usefully is this:
@strong{report all the facts}.  If you are not sure whether to state a
fact or leave it out, state it!

Often people omit facts because they think they know what causes the
problem and assume that some details don't matter.  Thus, you might
assume that the name of the variable you use in an example does not matter.
Well, probably it doesn't, but one cannot be sure.  Perhaps the bug is a
stray memory reference which happens to fetch from the location where that
name is stored in memory; perhaps, if the name were different, the contents
of that location would fool the debugger into doing the right thing despite
the bug.  Play it safe and give a specific, complete example.  That is the
easiest thing for you to do, and the most helpful.

Keep in mind that the purpose of a bug report is to enable us to fix
the bug if it is new to us.  It isn't as important what happens if
the bug is already known.  Therefore, always write your bug reports on
the assumption that the bug has not been reported previously.

Sometimes people give a few sketchy facts and ask, ``Does this ring a
bell?''  Those bug reports are useless, and we urge everyone to
@emph{refuse to respond to them} except to chide the sender to report
bugs properly.

To enable us to fix the bug, you should include all these things:

@itemize @bullet
@item
The version of _GDBN__.  _GDBN__ announces it if you start with no
arguments; you can also print it at any time using @code{show version}.

Without this, we won't know whether there is any point in looking for
the bug in the current version of _GDBN__.

@item
A complete input script, and all necessary source files, that will
reproduce the bug.  

@item
What compiler (and its version) was used to compile _GDBN__---e.g.
``_GCC__-1.37.1''.

@item
The command arguments you gave the compiler to compile your example and
observe the bug.  For example, did you use @samp{-O}?  To guarantee
you won't omit something important, list them all.

If we were to try to guess the arguments, we would probably guess wrong
and then we might not encounter the bug.

@item
The type of machine you are using, and the operating system name and
version number.

@item
A description of what behavior you observe that you believe is
incorrect.  For example, ``It gets a fatal signal.''

Of course, if the bug is that _GDBN__ gets a fatal signal, then we will
certainly notice it.  But if the bug is incorrect output, we might not
notice unless it is glaringly wrong.  We are human, after all.  You
might as well not give us a chance to make a mistake.

Even if the problem you experience is a fatal signal, you should still
say so explicitly.  Suppose something strange is going on, such as,
your copy of _GDBN__ is out of synch, or you have encountered a
bug in the C library on your system.  (This has happened!)  Your copy
might crash and ours would not.  If you told us to expect a crash,
then when ours fails to crash, we would know that the bug was not
happening for us.  If you had not told us to expect a crash, then we
would not be able to draw any conclusion from our observations.

@item
If you wish to suggest changes to the _GDBN__ source, send us context
diffs.  If you even discuss something in the _GDBN__ source, refer to
it by context, not by line number.

The line numbers in our development sources won't match those in your
sources.  Your line numbers would convey no useful information to us.

@end itemize

Here are some things that are not necessary:

@itemize @bullet
@item
A description of the envelope of the bug.

Often people who encounter a bug spend a lot of time investigating
which changes to the input file will make the bug go away and which
changes will not affect it.

This is often time consuming and not very useful, because the way we
will find the bug is by running a single example under the debugger
with breakpoints, not by pure deduction from a series of examples.
We recommend that you save your time for something else.

Of course, if you can find a simpler example to report @emph{instead}
of the original one, that is a convenience for us.  Errors in the
output will be easier to spot, running under the debugger will take
less time, etc. 

However, simplification is not vital; if you don't want to do this,
report the bug anyway and send us the entire test case you used.

@item
A patch for the bug.

A patch for the bug does help us if it is a good one.  But don't omit
the necessary information, such as the test case, on the assumption that
a patch is all we need.  We might see problems with your patch and decide
to fix the problem another way, or we might not understand it at all.

Sometimes with a program as complicated as _GDBN__ it is very hard to
construct an example that will make the program follow a certain path
through the code.  If you don't send us the example, we won't be able
to construct one, so we won't be able to verify that the bug is fixed.

And if we can't understand what bug you are trying to fix, or why your
patch should be an improvement, we won't install it.  A test case will
help us to understand.

@item
A guess about what the bug is or what it depends on.

Such guesses are usually wrong.  Even we can't guess right about such
things without first using the debugger to find the facts.
@end itemize