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How
to report bugs
A number
of companies and individuals offer support for GNU products. If you obtained
GDB from a support organization, we recommend you contact that organization
first.
You can find contact information
for many support companies and individuals in the file ‘etc/SERVICE’
in the GNU Emacs distribution.
In any event, we also recommend
that you send bug reports for GDB to one of these addresses:
bug-gdb@prep.ai.mit.edu
{ucbvax|mit-eddie|uunet}!prep.ai.mit.edu!bug-gdb
Do not send bug reports
to ‘info-gdb’,
or to ‘help-gdb’,
or to any newsgroups. Most users of GDB do not want to receive
bug reports. Those that do have arranged to receive ‘bug-gdb’.
The mailing list ‘bug-gdb’
has a newsgroup ‘gnu.gdb.bug’
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:
GNU Debugger Bugs
Free Software Foundation
Inc.
59 Temple Place
Suite 330
Boston, MA 02111-1307
USA
The fundamental principle
of reporting bugs usefully is this: 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
do not matter. Thus, you might assume that the name of the variable you
use in an example does not matter. Well, probably it does not, 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. 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 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 the following things.
-
The version of GDB. GDB announces
it if you start with no arguments; you can also print it at any time using
show version.
Without this, we will not
know whether there is any point in looking for the bug in the current version
of GDB.
The type of machine you
are using, and the operating system name and version number.
-
What compiler (and its version)
was used to compile GDB—e.g., “gcc–2.0”.
-
What compiler (and its version)
was used to compile the program you are debugging—e.g., “gcc–2.0”.
-
The command arguments you gave
the compiler to compile your example and observe the bug. For example,
did you use ‘-O’?
To guarantee you will not omit something important, list them all. A copy
of the Makefile (or the output from make) is sufficient.
If we were to try to guess
the arguments, we would probably guess wrong and then we might not encounter
the bug.
-
A complete input script, and
all necessary source files, that will reproduce the bug.
-
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 GDB 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. 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 GDB 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.
-
If you wish to suggest changes
to the GDB source, send us context diffs. If you even discuss something
in the GDB source, refer to it by context, not by line number.
The line numbers in our
development sources will not match those in your sources. Your line numbers
would convey no useful information to us.
The following describes some
things that are not necessary:
-
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 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, and so on.
However, simplification
is not vital; if you do not want to do this, report the bug anyway and
send us the entire test case you used.
-
A patch for the bug.
A patch for the bug does
help us if it is a good one. But do not 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 GDB it is very hard to construct an example that will
make the program follow a certain path through the code.
If you do not send us the
example, we will not be able to construct one, so we will not be able to
verify that the bug is fixed.
And if we cannot understand
what bug you are trying to fix, or why your patch should be an improvement,
we will not install it. A test case will help us to understand.
-
A guess about what the bug is
or what it depends on.
Such guesses are usually
wrong.
Even we cannot guess right
about such things without first using the debugger to find the facts.
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