Reporting Bugs
**************

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

When you encounter a problem, the first thing to do is to see if it is already known.  See Trouble.  If it isn't known, then you should report the problem.

Have You Found a Bug?
=====================

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

  * If the compiler gets a fatal signal, for any input whatever, that is a compiler bug.  Reliable compilers never crash.

  * If the compiler produces invalid assembly code, for any input whatever (except an asm statement), that is a compiler bug, unless the compiler reports errors (not just warnings) which would ordinarily prevent the assembler from being run.

  * If the compiler produces valid assembly code that does not correctly execute the input source code, that is a compiler bug.

     However, you must double-check to make sure, because you may have a program whose behavior is undefined, which happened by chance to give the desired results with another C or C++ compiler.

     For example, in many nonoptimizing compilers, you can write x; at the end of a function instead of return x;, with the same results.  But the value of the function is undefined if return is omitted; it is not a bug when GCC produces different results.

     Problems often result from expressions with two increment operators, as in f (*p++, *p++).  Your previous compiler might have interpreted that expression the way you intended; GCC might interpret it another way.  Neither compiler is wrong.  The bug is in your code.

     After you have localized the error to a single source line, it should be easy to check for these things.  If your program is correct and well defined, you have found a compiler bug.

  * If the compiler produces an error message for valid input, that is a compiler bug.

  * If the compiler does not produce an error message for invalid input, that is a compiler bug.  However, you should note that your idea of ``invalid input'' might be someone else's idea of ``an extension'' or ``support for traditional practice''.

  * If you are an experienced user of one of the languages GCC supports, your suggestions for improvement of GCC are welcome in any case.

How and where to Report Bugs
============================

Bugs should be reported to the GCC bug database.  Please refer to http://gcc.gnu.org/bugs.html for up-to-date instructions how to submit bug reports.  Copies of this file in HTML (bugs.html) and plain text (BUGS) are also part of GCC releases.