@c Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
|
@c Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
|
@c 1999, 2000, 2001, 2003, 2004, 2007 Free Software Foundation, Inc.
|
@c 1999, 2000, 2001, 2003, 2004, 2007 Free Software Foundation, Inc.
|
@c This is part of the GCC manual.
|
@c This is part of the GCC manual.
|
@c For copying conditions, see the file gcc.texi.
|
@c For copying conditions, see the file gcc.texi.
|
|
|
@node Bugs
|
@node Bugs
|
@chapter Reporting Bugs
|
@chapter Reporting Bugs
|
@cindex bugs
|
@cindex bugs
|
@cindex reporting bugs
|
@cindex reporting bugs
|
|
|
Your bug reports play an essential role in making GCC reliable.
|
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
|
When you encounter a problem, the first thing to do is to see if it is
|
already known. @xref{Trouble}. If it isn't known, then you should
|
already known. @xref{Trouble}. If it isn't known, then you should
|
report the problem.
|
report the problem.
|
|
|
@menu
|
@menu
|
* Criteria: Bug Criteria. Have you really found a bug?
|
* Criteria: Bug Criteria. Have you really found a bug?
|
* Reporting: Bug Reporting. How to report a bug effectively.
|
* Reporting: Bug Reporting. How to report a bug effectively.
|
* Known: Trouble. Known problems.
|
* Known: Trouble. Known problems.
|
* Help: Service. Where to ask for help.
|
* Help: Service. Where to ask for help.
|
@end menu
|
@end menu
|
|
|
@node Bug Criteria,Bug Reporting,,Bugs
|
@node Bug Criteria,Bug Reporting,,Bugs
|
@section Have You Found a Bug?
|
@section Have You Found a Bug?
|
@cindex bug criteria
|
@cindex bug criteria
|
|
|
If you are not sure whether you have found a bug, here are some guidelines:
|
If you are not sure whether you have found a bug, here are some guidelines:
|
|
|
@itemize @bullet
|
@itemize @bullet
|
@cindex fatal signal
|
@cindex fatal signal
|
@cindex core dump
|
@cindex core dump
|
@item
|
@item
|
If the compiler gets a fatal signal, for any input whatever, that is a
|
If the compiler gets a fatal signal, for any input whatever, that is a
|
compiler bug. Reliable compilers never crash.
|
compiler bug. Reliable compilers never crash.
|
|
|
@cindex invalid assembly code
|
@cindex invalid assembly code
|
@cindex assembly code, invalid
|
@cindex assembly code, invalid
|
@item
|
@item
|
If the compiler produces invalid assembly code, for any input whatever
|
If the compiler produces invalid assembly code, for any input whatever
|
(except an @code{asm} statement), that is a compiler bug, unless the
|
(except an @code{asm} statement), that is a compiler bug, unless the
|
compiler reports errors (not just warnings) which would ordinarily
|
compiler reports errors (not just warnings) which would ordinarily
|
prevent the assembler from being run.
|
prevent the assembler from being run.
|
|
|
@cindex undefined behavior
|
@cindex undefined behavior
|
@cindex undefined function value
|
@cindex undefined function value
|
@cindex increment operators
|
@cindex increment operators
|
@item
|
@item
|
If the compiler produces valid assembly code that does not correctly
|
If the compiler produces valid assembly code that does not correctly
|
execute the input source code, that is a compiler bug.
|
execute the input source code, that is a compiler bug.
|
|
|
However, you must double-check to make sure, because you may have a
|
However, you must double-check to make sure, because you may have a
|
program whose behavior is undefined, which happened by chance to give
|
program whose behavior is undefined, which happened by chance to give
|
the desired results with another C or C++ compiler.
|
the desired results with another C or C++ compiler.
|
|
|
For example, in many nonoptimizing compilers, you can write @samp{x;}
|
For example, in many nonoptimizing compilers, you can write @samp{x;}
|
at the end of a function instead of @samp{return x;}, with the same
|
at the end of a function instead of @samp{return x;}, with the same
|
results. But the value of the function is undefined if @code{return}
|
results. But the value of the function is undefined if @code{return}
|
is omitted; it is not a bug when GCC produces different results.
|
is omitted; it is not a bug when GCC produces different results.
|
|
|
Problems often result from expressions with two increment operators,
|
Problems often result from expressions with two increment operators,
|
as in @code{f (*p++, *p++)}. Your previous compiler might have
|
as in @code{f (*p++, *p++)}. Your previous compiler might have
|
interpreted that expression the way you intended; GCC might
|
interpreted that expression the way you intended; GCC might
|
interpret it another way. Neither compiler is wrong. The bug is
|
interpret it another way. Neither compiler is wrong. The bug is
|
in your code.
|
in your code.
|
|
|
After you have localized the error to a single source line, it should
|
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
|
be easy to check for these things. If your program is correct and
|
well defined, you have found a compiler bug.
|
well defined, you have found a compiler bug.
|
|
|
@item
|
@item
|
If the compiler produces an error message for valid input, that is a
|
If the compiler produces an error message for valid input, that is a
|
compiler bug.
|
compiler bug.
|
|
|
@cindex invalid input
|
@cindex invalid input
|
@item
|
@item
|
If the compiler does not produce an error message for invalid input,
|
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
|
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
|
``invalid input'' might be someone else's idea of ``an extension'' or
|
``support for traditional practice''.
|
``support for traditional practice''.
|
|
|
@item
|
@item
|
If you are an experienced user of one of the languages GCC supports, your
|
If you are an experienced user of one of the languages GCC supports, your
|
suggestions for improvement of GCC are welcome in any case.
|
suggestions for improvement of GCC are welcome in any case.
|
@end itemize
|
@end itemize
|
|
|
@node Bug Reporting,,Bug Criteria,Bugs
|
@node Bug Reporting,,Bug Criteria,Bugs
|
@section How and where to Report Bugs
|
@section How and where to Report Bugs
|
@cindex compiler bugs, reporting
|
@cindex compiler bugs, reporting
|
|
|
Bugs should be reported to the bug database at @value{BUGURL}.
|
Bugs should be reported to the bug database at @value{BUGURL}.
|
|
|
