gdb.info: Bug Reporting

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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 submit bug reports for GDB.
The prefered method is to submit them directly using GDB's Bugs web
page (http://www.gnu.org/software/gdb/bugs/).  Alternatively, the
e-mail gateway <bug-gdb@gnu.org> can be used.
   *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.
   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.  It may be that the bug has been reported previously, but
neither you nor we can know that unless your bug report is complete and
self-contained.
   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 these 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-2.8.1".
   * What compiler (and its version) was used to compile the program
     you are debugging--e.g.  "gcc-2.8.1", or "HP92453-01 A.10.32.03 HP
     C Compiler".  For GCC, you can say `gcc --version' to get this
     information; for other compilers, see the documentation for those
     compilers.
   * 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.
     To collect all this information, you can use a session recording
     program such as `script', which is available on many Unix systems.
     Just run your GDB session inside `script' and then include the
     `typescript' file with your bug report.
     Another way to record a GDB session is to run GDB inside Emacs and
     then save the entire buffer to a file.
   * 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.
   Here are 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.