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Reporting Bugs

Your bug reports play an essential role in making GNU CC reliable.

When you encounter a problem, the first thing to do is to see if it is already known. See section Known Causes of Trouble with GNU CC. If it isn't known, then you should report the problem.

Reporting a bug may help you by bringing a solution to your problem, or it may not. (If it does not, look in the service directory; see section How To Get Help with GNU CC.) In any case, the principal function of a bug report is to help the entire community by making the next version of GNU CC work better. Bug reports are your contribution to the maintenance of GNU CC.

Since the maintainers are very overloaded, we cannot respond to every bug report. However, if the bug has not been fixed, we are likely to send you a patch and ask you to tell us whether it works.

In order for a bug report to serve its purpose, you must include the information that makes for fixing the bug.

Have You Found a Bug?

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

Where to Report Bugs

Send bug reports for GNU C to one of these addresses:

bug-gcc@prep.ai.mit.edu
{ucbvax|mit-eddie|uunet2!prep.ai.mit.edu!bug-gcc

Send bug reports for GNU C++ to one of these addresses:

bug-g++@prep.ai.mit.edu
{ucbvax|mit-eddie|uunet2!prep.ai.mit.edu!bug-g++

If your bug involves the C++ class library libg++, send mail to `bug-lib-g++@prep.ai.mit.edu'. If you're not sure, you can send the bug report to both lists.

Do not send bug reports to the mailing list `help-gcc', or to the newsgroup `gnu.gcc.help'. Most users of GNU CC do not want to receive bug reports. Those that do, have asked to be on `bug-gcc' and/or `bug-g++'.

The mailing lists `bug-gcc' and `bug-g++' both have newsgroups which serve as repeaters: `gnu.gcc.bug' and `gnu.g++.bug'. Each mailing list and its 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 does not contain a mail path back to the sender. Thus, if maintainers need more information, they may be unable to reach you. For this reason, you should always send bug reports by mail to the proper mailing list.

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

GNU Compiler Bugs
Free Software Foundation
675 Mass Ave
Cambridge, MA 02139

How to Report Bugs

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 they conclude 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 compiler 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 someone to fix the bug if it is not known. It isn't very important what happens if the bug is already known. Therefore, always write your bug reports on the assumption that the bug is not known.

Sometimes people give a few sketchy facts and ask, "Does this ring a bell?" This cannot help us fix a bug, so it is basically useless. We respond by asking for enough details to enable us to investigate. You might as well expedite matters by sending them to begin with.

Try to make your bug report self-contained. If we have to ask you for more information, it is best if you include all the previous information in your response, as well as the information that was missing.

To enable someone to investigate the bug, you should include all these things:

Here are some things that are not necessary:

Sending Patches for GNU CC

If you would like to write bug fixes or improvements for the GNU C compiler, that is very helpful. When you send your changes, please follow these guidelines to avoid causing extra work for us in studying the patches.

If you don't follow these guidelines, your information might still be useful, but using it will take extra work. Maintaining GNU C is a lot of work in the best of circumstances, and we can't keep up unless you do your best to help.

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