663 lines
31 KiB
HTML
663 lines
31 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0//EN">
|
|
<HTML>
|
|
<HEAD>
|
|
<META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1">
|
|
<META NAME="AUTHOR" CONTENT="pme@sources.redhat.com (Phil Edwards)">
|
|
<META NAME="KEYWORDS" CONTENT="libstdc++, libstdc++-v3, GCC, g++, libg++, STL">
|
|
<META NAME="DESCRIPTION" CONTENT="FAQ for the GNU libstdc++ effort.">
|
|
<META NAME="GENERATOR" CONTENT="vi and eight fingers">
|
|
<TITLE>libstdc++-v3 FAQ</TITLE>
|
|
<LINK REL="home" HREF="http://sources.redhat.com/libstdc++/">
|
|
<LINK REL=StyleSheet HREF="../lib3styles.css">
|
|
<!--
|
|
** Locations of "the most recent snapshot is the Nth" text are
|
|
** answers 1_1, 1_4, 4_1, 5_6.
|
|
-->
|
|
<!-- $Id: index.html,v 1.7 2000/10/21 00:51:50 jsm28 Exp $ -->
|
|
</HEAD>
|
|
<BODY>
|
|
|
|
<H1 CLASS="centered">libstdc++ Frequently Asked Questions</H1>
|
|
|
|
<P>The latest version of this document is always available at
|
|
<A HREF="http://sources.redhat.com/libstdc++/faq/index.html">
|
|
http://sources.redhat.com/libstdc++/faq/</A>.</P>
|
|
|
|
<P>To the <A HREF="../index.html">libstdc++-v3 homepage</A>.
|
|
|
|
<!-- ####################################################### -->
|
|
<HR>
|
|
<H1>Questions</H1>
|
|
<OL>
|
|
<LI><A HREF="#1_0">General Information</A>
|
|
<!-- I suspect these will mostly be links to/into existing documents. -->
|
|
<OL>
|
|
<LI><A HREF="#1_1">What is libstdc++-v3?</A>
|
|
<LI><A HREF="#1_2">Why should I use libstdc++?</A>
|
|
<LI><A HREF="#1_3">Who's in charge of it?</A>
|
|
<LI><A HREF="#1_4">How do I get libstdc++?</A>
|
|
<LI><A HREF="#1_5">When is libstdc++ going to be finished?</A>
|
|
<LI><A HREF="#1_6">How do I contribute to the effort?</A>
|
|
<LI><A HREF="#1_7">What happened to libg++? I need that!</A>
|
|
<LI><A HREF="#1_8">What if I have more questions?</A>
|
|
</OL>
|
|
|
|
<LI><A HREF="#2_0">Installation</A>
|
|
<OL>
|
|
<LI><A HREF="#2_1">How do I install libstdc++-v3?</A>
|
|
<LI><A HREF="#2_2">Is this a drop-in replacement for the
|
|
libstdc++ that's shipped with g++?</A>
|
|
<LI><A HREF="#2_3">What is this CVS thing that you keep
|
|
mentioning?</A>
|
|
<LI><A HREF="#2_4">How do I know if it works?</A>
|
|
</OL>
|
|
|
|
<LI><A HREF="#3_0">Platform-Specific Issues</A>
|
|
<OL>
|
|
<LI><A HREF="#3_1">Can libstdc++-v3 be used with <my
|
|
favorite compiler>?</A>
|
|
<LI><A HREF="#3_2">Building under Cygwin hangs/explodes!?</A>
|
|
</OL>
|
|
|
|
<LI><A HREF="#4_0">Known Bugs and Non-Bugs</A>
|
|
<OL>
|
|
<LI><A HREF="#4_1">What works already?</A>
|
|
<LI><A HREF="#4_2">Bugs in gcc/g++ (not libstdc++-v3)</A>
|
|
<LI><A HREF="#4_3">Bugs in the C++ language/lib specification</A>
|
|
<LI><A HREF="#4_4">Things in libstdc++ that look like bugs</A>
|
|
<LI><A HREF="#4_5">Aw, that's easy to fix!</A>
|
|
</OL>
|
|
|
|
<LI><A HREF="#5_0">Miscellaneous</A>
|
|
<OL>
|
|
<LI><A HREF="#5_1">string::iterator is not char*;
|
|
vector<T>::iterator is not T*</A>
|
|
<LI><A HREF="#5_2">What's next after libstdc++-v3?</A>
|
|
<LI><A HREF="#5_3">What about the STL from SGI?</A>
|
|
<LI><A HREF="#5_4">Extensions and Backward Compatibility</A>
|
|
<LI><A HREF="#5_5">Compiling with "-fnew-abi"</A>
|
|
<LI><A HREF="#5_6">Is libstdc++-v3 thread-safe?</A>
|
|
<LI><A HREF="#5_7">How do I get a copy of the ISO C++ Standard?</A>
|
|
</OL>
|
|
|
|
</OL>
|
|
|
|
<HR>
|
|
|
|
<!-- ####################################################### -->
|
|
|
|
<H1><A NAME="1_0">1.0 General Information</A></H1>
|
|
<!-- I suspect these will mostly be links to/into existing documents. -->
|
|
<H2><A NAME="1_1">1.1 What is libstdc++-v3?</A></H2>
|
|
<P>The GNU Standard C++ Library v3, or libstdc++-2.90.x, is an
|
|
ongoing project to implement the ISO 14882 Standard C++ library
|
|
as described in chapters 17 through 27 and annex D. As the
|
|
library reaches stable plateaus, it is captured in a snapshot
|
|
and released. The current release is <A
|
|
HREF="ftp://sources.redhat.com/pub/libstdc++/libstdc++-2.90.8.tar.gz">the
|
|
ninth snapshot</A>. For those who want to see exactly how
|
|
far the project has come, or just want the latest
|
|
bleeding-edge code, the up-to-date source is available over
|
|
anonymous CVS, and can even be browsed over the Web (see below).
|
|
</P>
|
|
<P>A more formal description of the V3 goals can be found in the
|
|
official <A HREF="../17_intro/DESIGN">design document</A>.
|
|
</P>
|
|
|
|
<HR>
|
|
<H2><A NAME="1_2">1.2 Why should I use libstdc++?</A></H2>
|
|
<P>The completion of the ISO C++ standardization gave the
|
|
C++ community a powerful set of reuseable tools in the form
|
|
of the C++ Standard Library. However, all existing C++
|
|
implementations are (as the Draft Standard used to say)
|
|
"incomplet and incorrekt," and many suffer from
|
|
limitations of the compilers that use them.
|
|
</P>
|
|
<P>The GNU C/C++/FORTRAN/<pick-a-language> compiler
|
|
(<TT>gcc</TT>, <TT>g++</TT>, etc) is widely considered to be
|
|
one of the leading compilers in the world. Its development
|
|
has recently been taken over by the
|
|
<A HREF="http://gcc.gnu.org/">GCC team</A>. All of
|
|
the rapid development and near-legendary
|
|
<A
|
|
HREF="http://gcc.gnu.org/gcc-2.95/buildstat.html">portability</A>
|
|
that are the hallmarks of an open-source project are being
|
|
applied to libstdc++.
|
|
</P>
|
|
<P>That means that all of the Standard classes and functions
|
|
(such as <TT>string</TT>, <TT>vector<></TT>, iostreams,
|
|
and algorithms) will be freely available and fully compliant.
|
|
Programmers will no longer need to "roll their own"
|
|
nor be worried about platform-specific incompatabilities.
|
|
</P>
|
|
|
|
<HR>
|
|
<H2><A NAME="1_3">1.3 Who's in charge of it?</A></H2>
|
|
<P>The libstdc++ project is contributed to by several developers
|
|
all over the world, in the same way as GCC or Linux.
|
|
Benjamin Kosnik, Gabriel Dos Reis, Nathan Myers, and Ulrich
|
|
Drepper are the lead maintainers of the CVS archive.
|
|
</P>
|
|
<P>Development and discussion is held on the libstdc++ mailing
|
|
list. Subscribing to the list, or searching the list
|
|
archives, is open to everyone. You can read instructions for
|
|
doing so on the <A HREF="../index.html">homepage</A>. If you
|
|
have questions, ideas, code, or are just curious, sign up!
|
|
</P>
|
|
|
|
<HR>
|
|
<H2><A NAME="1_4">1.4 How do I get libstdc++?</A></H2>
|
|
<P>The ninth (and latest) snapshot of libstdc++-v3 is <A
|
|
HREF="ftp://sources.redhat.com/pub/libstdc++/libstdc++-2.90.8.tar.gz">
|
|
available via ftp</A>.
|
|
</P>
|
|
<P>The <A HREF="../index.html">homepage</A>
|
|
has instructions for retrieving the latest CVS sources, and for
|
|
browsing the CVS sources over the web.
|
|
</P>
|
|
<P>The subset commonly known as the Standard Template Library
|
|
(chapters 23 through 25, mostly) is adapted from the SGI STL,
|
|
which is also an ongoing work.<!-- Possibly a link to SGI's
|
|
STL here. -->
|
|
</P>
|
|
|
|
<HR>
|
|
<H2><A NAME="1_5">1.5 When is libstdc++ going to be finished?</A></H2>
|
|
<!-- <P>Nathan Myers gave the best of all possible answers in <A
|
|
HREF="http://www.deja.com/getdoc.xp?AN=469581698&fmt=text">a
|
|
Usenet article</A>.</P>
|
|
which is no longer available, thanks deja...-->
|
|
<P>Nathan Myers gave the best of all possible answers in a
|
|
Usenet article asking this question: Sooner, if you help.
|
|
</P>
|
|
|
|
|
|
<HR>
|
|
<H2><A NAME="1_6">1.6 How do I contribute to the effort?</A></H2>
|
|
<P>Here is <A HREF="../17_intro/contribute.html">a
|
|
page devoted to this topic</A>. Subscribing to the mailing
|
|
list (see above, or the homepage) is a very good idea if you
|
|
have something to contribute, or if you have spare time and
|
|
want to help. Contributions don't have to be in the form of
|
|
source code; anybody who is willing to help write
|
|
documentation, for example, or has found a bug in code that
|
|
we all thought was working, is more than welcome!
|
|
</P>
|
|
|
|
<HR>
|
|
<H2><A NAME="1_7">1.7 What happened to libg++? I need that!</A></H2>
|
|
<P>The most recent libg++ README states that libg++ is no longer
|
|
being actively maintained. It should not be used for new
|
|
projects, and is only being kicked along to support older code.
|
|
</P>
|
|
<P>The libg++ was designed and created when there was no Standard
|
|
to provide guidance. Classes like linked lists are now provided
|
|
for by <TT>list<T></TT> and do not need to be created by
|
|
<TT>genclass</TT>. (For that matter, templates exist now and
|
|
are well-supported, whereas genclass (mostly) predates them.)
|
|
</P>
|
|
<P>There are other classes in libg++ that are not specified in the
|
|
ISO Standard (e.g., statistical analysis). While there are a
|
|
lot of really useful things that are used by a lot of people
|
|
(e.g., statistics :-), the Standards Committee couldn't include
|
|
everything, and so a lot of those "obvious" classes
|
|
didn't get included.
|
|
</P>
|
|
<P>Since libstdc++ is an implementation of the Standard Library, we
|
|
have no plans at this time to include non-Standard utilities
|
|
in the implementation, however handy they are. (The extensions
|
|
provided in the SGI STL aren't maintained by us and don't get
|
|
a lot of our attention, because they don't require a lot of our
|
|
time.) It is entirely plausable that the "useful stuff"
|
|
from libg++ might be extracted into an updated utilities library,
|
|
but nobody has stated such a project yet.
|
|
</P>
|
|
<!-- The advertisement, so to speak, might have to go. Hmmmmm. -->
|
|
<P>(The <A HREF="http://www.boost.org/">Boost</A> site houses free
|
|
C++ libraries that do varying things, and happened to be started
|
|
by members of the Standards Committee. Certain "useful
|
|
stuff" classes will probably migrate there.)
|
|
</P>
|
|
<P>For the bold and/or desperate, the
|
|
<A HREF="http://gcc.gnu.org/fom_serv/cache/33.html">GCC FAQ</A>
|
|
describes where to find the last libg++ source.
|
|
</P>
|
|
|
|
<HR>
|
|
<H2><A NAME="1_8">1.8 What if I have more questions?</A></H2>
|
|
<P>If you have read the README and RELEASE-NOTES files, and your
|
|
question remains unanswered, then just ask the mailing list.
|
|
At present, you do not need to be subscribed to the list to
|
|
send a message to it. More information is available on the
|
|
homepage (including how to browse the list archives); to send
|
|
to the list, use <A HREF="mailto:libstdc++@sources.redhat.com">
|
|
<TT>libstdc++@sources.redhat.com</TT></A>.
|
|
</P>
|
|
<P>If you have a question that you think should be included here,
|
|
or if you have a question <EM>about</EM> a question/answer here,
|
|
contact <A HREF="mailto:pme@sources.redhat.com">Phil Edwards</A>
|
|
or <A HREF="mailto:gdr@gcc.gnu.org">Gabriel Dos Reis</A>.
|
|
</P>
|
|
|
|
<HR>
|
|
|
|
<H1><A NAME="2_0">2.0 Installation</A></H1>
|
|
<H2><A NAME="2_1">2.1 How do I install libstdc++-v3?</A></H2>
|
|
<P>Complete instructions are not given here (this is a FAQ, not
|
|
an installation document), but the tools required are few:
|
|
<UL>
|
|
<LI> A release of libstdc++.
|
|
<LI> A recent release of GCC (version 2.95 works). Note
|
|
that building GCC is much easier and more automated
|
|
than building the GCC 2.[78] series was.
|
|
<LI> If you plan on hacking around with the makefiles, you
|
|
will need the tools <A
|
|
HREF="http://sources.redhat.com/autoconf/">autoconf</A>and <A
|
|
HREF="http://sources.redhat.com/automake/">automake</A>.
|
|
<LI> GNU Make is the only make that supports these makefiles.
|
|
</UL>
|
|
</P>
|
|
<P>The file <A HREF="../documentation.html">documentation.html</A>
|
|
provides a good overview of the steps necessary to build, install,
|
|
and use the library. Instructions for configuring the library
|
|
with new flags such as --enable-threads are there also.
|
|
</P>
|
|
<P>The top-level install.html and
|
|
<A HREF="../17_intro/RELEASE-NOTES">RELEASE-NOTES</A> files contain
|
|
the exact build and installation instructions. You may wish to
|
|
browse those files over CVSweb ahead of time to get a feel for
|
|
what's required. RELEASE-NOTES is located in the
|
|
".../docs/17_intro/" directory of the distribution.
|
|
</P>
|
|
|
|
<HR>
|
|
<H2><A NAME="2_2">2.2 Is this a drop-in replacement for the
|
|
libstdc++ that's shipped with g++?</A></H2>
|
|
<P>Yes, as of 2.90.8, it is intended as such.</P>
|
|
<P>The installation instructions cover this in more detail, but
|
|
replacing the older library requires rebuilding some of the
|
|
code that comes with g++. You will need sources for the 2.95.2
|
|
compiler in order to build this snapshot. Building the library
|
|
on its own and then using -I/-L will no longer work.
|
|
</P>
|
|
<P>After the 2.90.8 snapshot, the library sources were integrated
|
|
into the compiler sources. Future releases of the compiler will
|
|
ship with libstdc++-v3.
|
|
</P>
|
|
|
|
<HR>
|
|
<H2><A NAME="2_3">2.3 What is this CVS thing that you
|
|
keep mentioning?</A></H2>
|
|
<P>The <EM>Concurrent Versions System</EM> is one of several revision
|
|
control packages. It was selected for GNU projects because it's
|
|
free (speech), free (beer), and very high quality. The <A
|
|
HREF="http://www.gnu.org/software/cvs/cvs.html">CVS entry in
|
|
the GNU software catalogue</A> has a better description as
|
|
well as a
|
|
<A HREF="http://www.cyclic.com/">link to the makers of CVS</A>.
|
|
</P>
|
|
<P>The "anonymous client checkout" feature of CVS is
|
|
similar to anonymous FTP in that it allows anyone to retrieve
|
|
the latest libstdc++ sources.
|
|
</P>
|
|
<P>After the first of April, American users will have a
|
|
"/pharmacy" command-line option...
|
|
<!-- wonder how long that'll live -->
|
|
</P>
|
|
|
|
<HR>
|
|
<H2><A NAME="2_4">2.4 How do I know if it works?</A></H2>
|
|
<P>libstdc++-v3 comes with its own testsuite. You do not need
|
|
to actually install the library ("<TT>gmake
|
|
install</TT>") to run the testsuite.
|
|
</P>
|
|
<P>To run the testsuite on the library after building it, use
|
|
"gmake check" while in your build directory. To run
|
|
the testsuite on the library after building and installing it,
|
|
use "gmake check-install" instead.
|
|
</P>
|
|
<P>The testsuite subdirectory in your build directory will then
|
|
contain three files of the form YYYYMMDD-mkcheck*.txt. One of
|
|
them (-mkcheck.txt itself) contains the results of the tests;
|
|
this can be mailed to the list. The other files (-mkchecklog.txt
|
|
and -mkcheckfiles.txt) contain messages from the compiler while
|
|
building the test programs, and a list of the tests to be run,
|
|
respectively.
|
|
</P>
|
|
<P>If you are using the libgcc.a-rebuilding method to enable std::
|
|
you might find that the testsuite starts dying with nasty linker
|
|
errors. This is symptomatic of the rebuilt libgcc.a not being
|
|
installed; the previous one is still in use.
|
|
</P>
|
|
<P>If you find bugs in the testsuite programs themselves, or if
|
|
you think of a new test program that should be added to the
|
|
suite, <B>please</B> write up your idea and send it to the list!
|
|
</P>
|
|
|
|
<HR>
|
|
<H1><A NAME="3_0">3.0 Platform-Specific Issues</A></H1>
|
|
<H2><A NAME="3_1">3.1 Can libstdc++-v3 be used with <my
|
|
favorite compiler>?</A></H2>
|
|
<P>Probably not. Yet.</P>
|
|
<P>Because GCC advances so rapidly, development and testing of
|
|
libstdc++ is being done almost entirely under that compiler.
|
|
If you are curious about whether other, lesser compilers
|
|
(*grin*) support libstdc++, you are more than welcome to try.
|
|
Configuring and building the library (see above) will still
|
|
require certain tools, however. Also keep in mind that
|
|
<EM>building</EM> libstdc++ does not imply that your compiler
|
|
will be able to <EM>use</EM> all of the features found in the
|
|
C++ Standard Library.
|
|
</P>
|
|
<P>Since the goal of ISO Standardization is for all C++
|
|
implementations to be able to share code, the final libstdc++
|
|
should, in theory, be useable under any ISO-compliant
|
|
compiler. It will still be targeted and optimized for
|
|
GCC/g++, however.
|
|
</P>
|
|
|
|
<HR>
|
|
<H2><A NAME="3_2">3.2 Building under Cygwin hangs/explodes!?</A></H2>
|
|
<P>Sometimes, yes. You're probably in the middle of generating
|
|
the <TT>numeric_limits</TT> specializations when it hangs,
|
|
right? Thought so...
|
|
</P>
|
|
<P>The <TT><limits></TT> header and its associated library
|
|
code are platform-specific. These files get generated from
|
|
scratch during installation, and it is this generator that is
|
|
hanging. More specifically, the only sure way to determine
|
|
what the <TT>numeric_limits<T>::traps</TT> boolean
|
|
should be is to actually divide by zero and see if it is
|
|
trapped or not.
|
|
</P>
|
|
<P>Under NT, this will occasionally just hang. On those
|
|
occasions when the test does not hang, the zero-division is
|
|
in fact trapped. That doesn't prevent hanging elsewhere.
|
|
</P>
|
|
<P>You have two options. You can get a newer cygwin1.dll (see the
|
|
Cygwin paragraph in the
|
|
<A HREF="../install.html">installation instructions</A>).
|
|
Or you can get a prebuilt set of bits/std_limits.h and
|
|
src/limitsMEMBERS.cc files from Mumit Khan's
|
|
<A HREF="http://www.xraylith.wisc.edu/~khan/software/gnu-win32/libstdc++-v3.html">Cygwin-related website</A>.
|
|
</P>
|
|
|
|
<HR>
|
|
<H1><A NAME="4_0">4.0 Known Bugs and Non-Bugs</A></H1>
|
|
<EM>Note that this section can get rapdily outdated -- such is the
|
|
nature of an open-source project. For the latest information, join
|
|
the mailing list or look through recent archives. The RELEASE-
|
|
NOTES and BUGS files are generally kept up-to-date.</EM>
|
|
|
|
<H2><A NAME="4_1">4.1 What works already?</A></H2>
|
|
<P>This is a verbatim clip from the "Status" section
|
|
of the RELEASE-NOTES for the latest snapshot.
|
|
</P>
|
|
|
|
<!-- Yeah, I meant that "verbatim clip" thing literally... :-) -->
|
|
|
|
<pre>
|
|
New:
|
|
---
|
|
- MT safe string. Supported CPUs are alpha, powerpc, x86, sparc32 and sparc64.
|
|
- Configure support for --enable-threads=posix, as well as initial IO
|
|
locking implementation.
|
|
- Support for native building on Solaris 2.5.1, Solaris 2.6, Solaris
|
|
2.7, cygwin, [alpha, powerpc, x86]-linux, and preliminary support for
|
|
Irix and Aix4.2, Aix 4.3 hosts.
|
|
- --enable-namespaces is on by default.
|
|
- Configure and Makefile support for "drop-in" replacement to
|
|
libstdc++-v2 completed. It is now possible to bootstrap g++, and
|
|
have g++ find libstdc++-v3 headers and libraries by default.
|
|
- Synched with CVS egcs libio.
|
|
- Cygwin native compiling supported.
|
|
- Cross compiling and embedded targets (newlib) with multilibs support added.
|
|
- SGI's strstream implementation has been added.
|
|
- Copyright on all sources assigned to the FSF.
|
|
- Configure, build and install documentation has been added.
|
|
- Support to enable long long has been added.
|
|
- More valarray improvements.
|
|
- Extractors and inserters for std::complex have been added.
|
|
- Extractors and inserters for void* have been fixed.
|
|
- autoconf macros are now in _GLIBCPP_ namespace.
|
|
- group checking for num_get implemented.
|
|
- Many, many bug fixes.
|
|
</pre>
|
|
|
|
|
|
<HR>
|
|
<H2><A NAME="4_2">4.2 Bugs in gcc/g++ (not libstdc++-v3)</A></H2>
|
|
<P>This is by no means meant to be complete nor exhaustive, but
|
|
mentions some problems that users may encounter when building
|
|
or using libstdc++. If you are experiencing one of these
|
|
problems, you can find more information on the libstdc++ and
|
|
the GCC mailing lists.
|
|
</P>
|
|
<UL>
|
|
<LI>When using associative containers (like <TT>map</TT>), and
|
|
compiling with <TT>-O3</TT> (or <TT>-finline-functions</TT>)
|
|
and <TT>-Winline</TT>, I get a zillion errors like:
|
|
<!-- Careful, the leading spaces in PRE show up directly. -->
|
|
<PRE>
|
|
.../include/g++/stl_tree.h: In function `int __black_count(struct __rb_tree_node_base *, struct __rb_tree_node_base *)':
|
|
.../include/g++/stl_tree.h:1045: warning: can't inline call to `int __black_count(struct __rb_tree_node_base *, struct __rb_tree_node_base *)'
|
|
.../include/g++/stl_tree.h:1053: warning: called from here
|
|
</PRE>
|
|
<P>This has been discussed a number of times; the problem
|
|
is that __black_count is marked inline but is also a
|
|
recursive function. As of 12 July 1999, it has been
|
|
rewritten into an optimized non-recursive form, so
|
|
fresh checkouts/releases should no longer see this warning.
|
|
(The compiler can usually figure out how to make that
|
|
transformation on its own.)
|
|
</P>
|
|
|
|
<LI>The reason that EGCS 1.1.2 cannot be used to build the
|
|
library is that lookups do not work properly, and so the
|
|
compiler will ICE when building the locale-related source
|
|
files. This has been fixed in GCC 2.95.
|
|
</UL>
|
|
|
|
<HR>
|
|
<H2><A NAME="4_3">4.3 Bugs in the C++ language/lib specification</A></H2>
|
|
<P>Yes, unfortunately, there are some. In a <A
|
|
HREF="http://sources.redhat.com/ml/libstdc++/1998/msg00006.html">message
|
|
to the list</A>, Nathan Myers announced that he has started a list of
|
|
problems in the ISO C++ Standard itself, especially with
|
|
regard to the chapters that concern the library. The list
|
|
itself is <A
|
|
HREF="http://www.cantrip.org/draft-bugs.txt">posted on his
|
|
website</A>. Developers who are having problems interpreting
|
|
the Standard may wish to consult his notes.
|
|
</P>
|
|
<P>For those people who are not part of the ISO Library Group
|
|
(i.e., nearly all of us needing to read this page in the first
|
|
place :-), a public list of the library defects is occasionally
|
|
published <A HREF="http://anubis.dkuug.dk/jtc1/sc22/wg21/">here</A>.
|
|
</P>
|
|
|
|
<HR>
|
|
<H2><A NAME="4_4">4.4 Things in libstdc++ that look like bugs</A></H2>
|
|
<P>There are things which are not bugs in the compiler (4.2) nor
|
|
the language specification (4.3), but aren't really bugs in
|
|
libstdc++, either. Really!
|
|
</P>
|
|
<P>The biggest of these is the quadzillions of warnings about the
|
|
library headers emitted when <TT>-Weffc++</TT> is used. Making
|
|
libstdc++ "-Weffc++-clean" is not a goal of the project,
|
|
for a few reasons. Mainly, that option tries to enforce
|
|
object-oriented programming, while the Standard Library isn't
|
|
necessarily trying to be OO. There are multiple solutions
|
|
under discussion.
|
|
</P>
|
|
|
|
<HR>
|
|
<H2><A NAME="4_5">4.5 Aw, that's easy to fix!</A></H2>
|
|
<P>If you have found a bug in the library and you think you have
|
|
a working fix, then send it in! The main GCC site has a page
|
|
on <A HREF="http://gcc.gnu.org/contribute.html">submitting
|
|
patches</A> that covers the procedure, but for libstdc++ you
|
|
should of course send the patch to our mailing list, not the
|
|
GCC mailing list. The libstdc++
|
|
<A HREF="../17_intro/contribute.html">contributors' page</A>
|
|
also talks about how to submit patches.
|
|
</P>
|
|
<P>In addition to the description, the patch, and the ChangeLog
|
|
entry, it is a Good Thing if you can additionally create a small
|
|
test program to test for the presence of the bug that your
|
|
patch fixes. Bugs have a way of being reintroduced; if an old
|
|
bug creeps back in, it will be caught immediately by the
|
|
<A HREF="#2_4">testsuite</A> -- but only if such a test exists.
|
|
</P>
|
|
|
|
<HR>
|
|
<H1><A NAME="5_0">5.0 Miscellaneous</A></H1>
|
|
<H2><A NAME="5_1">5.1 string::iterator is not char*;
|
|
vector<T>::iterator is not T*</A></H2>
|
|
<P>If you have code that depends on container<T> iterators
|
|
being implemented as pointer-to-T, your code is broken.
|
|
</P>
|
|
<P>While there are arguments for iterators to be implemented in
|
|
that manner, A) they aren't very good ones in the long term,
|
|
and B) they were never guaranteed by the Standard anyway. The
|
|
type-safety achieved by making iterators a real class rather
|
|
than a typedef for <TT>T*</TT> outweighs nearly all opposing
|
|
arguments.
|
|
</P>
|
|
|
|
<HR>
|
|
<H2><A NAME="5_2">5.2 What's next after libstdc++-v3?</A></H2>
|
|
<P>Hopefully, not much. The goal of libstdc++-v3 is to produce
|
|
a fully-compliant, fully-portable Standard Library. After that,
|
|
we're mostly done: there won't <EM>be</EM> any more compliance
|
|
work to do.
|
|
</P>
|
|
<P>The ISO Committee will meet periodically to review Defect Reports
|
|
in the C++ Standard. Undoubtably some of these will result in
|
|
changes to the Standard, which will be reflected in patches to
|
|
libstdc++. Some of that is already happening, see 4.2. Some of
|
|
those changes are being predicted by the library maintainers, and
|
|
we add code to the library based on what the current proposed
|
|
resolution specifies.
|
|
</P>
|
|
<P>The current libstdc++ contains extensions to the Library which
|
|
must be explicitly requested by client code (for example, the
|
|
hash tables from SGI). Other extensions may be added to
|
|
libstdc++-v3 if they seem to be "standard" enough.
|
|
(For example, the "long long" type from C99.)
|
|
Bugfixes and rewrites (to improve or fix thread safety, for
|
|
instance) will of course be a continuing task.
|
|
</P>
|
|
<P><A
|
|
HREF="http://sources.redhat.com/ml/libstdc++/1999/msg00080.html">This
|
|
question</A> about the next libstdc++ prompted some brief but
|
|
interesting <A
|
|
HREF="http://sources.redhat.com/ml/libstdc++/1999/msg00084.html">speculation</A>.
|
|
</P>
|
|
|
|
<HR>
|
|
<H2><A NAME="5_3">5.3 What about the STL from SGI?</A></H2>
|
|
<P>The <A HREF="http://www.sgi.com/Technology/STL/">STL from SGI</A>
|
|
is merged into libstdc++-v3 with changes as necessary.
|
|
Currently release 3.3 is being used. Changes in the STL
|
|
usually produce some weird bugs and lots of changes in the
|
|
rest of the libstd++ source as we scramble to keep up. :-)
|
|
</P>
|
|
<P>In particular, <TT>string</TT> is not from SGI and makes no
|
|
use of their "rope" class (which is included as an
|
|
optional extension), nor is <TT>valarray</TT> and some others.
|
|
Classes like <TT>vector<></TT> are, however.
|
|
</P>
|
|
<P>The FAQ for SGI's STL (one jump off of their main page) is
|
|
recommended reading.
|
|
</P>
|
|
|
|
<HR>
|
|
<H2><A NAME="5_4">5.4 Extensions and Backward Compatibility</A></H2>
|
|
<P>Although you can specify <TT>-I</TT> options to make the
|
|
preprocessor search the g++-v3/ext and /backward directories,
|
|
it is better to refer to files there by their path, as in:
|
|
<!-- Careful, the leading spaces in PRE show up directly. -->
|
|
<PRE>
|
|
#include <ext/hash_map>
|
|
</PRE>
|
|
</P>
|
|
<P>Extensions to the library have
|
|
<A HREF="../ext/howto.html">their own page</A>.
|
|
</P>
|
|
|
|
<HR>
|
|
<H2><A NAME="5_5">5.5 Compiling with "-fnew-abi"</A></H2>
|
|
<P>The library mostly works if you compile it (and programs you
|
|
link with it) using "-fnew-abi -fno-honor-std" on a
|
|
vanilla GCC compiler. However, some features, such as RTTI
|
|
and error handlers, might not link properly with a vanilla
|
|
libgcc built in GCC under the old ABI. If you rebuild libgcc
|
|
using the "-f" flags above, you can get both complete
|
|
language support and full benefits of -fnew-abi -- short
|
|
mangled symbol names, far more efficient exception handling,
|
|
and empty base optimization, to name a few. (Note that the
|
|
new ABI may change from one GCC snapshot to the next, so you
|
|
would have to rebuild all your libraries each time you get a
|
|
new compiler snapshot.)
|
|
</P>
|
|
<P>Towards the end of July 1999, this subject was brought up again
|
|
on the mailing list under a different name. The related
|
|
<A HREF="http://sources.redhat.com/ml/libstdc++/1999-q3/msg00066.html">thread</A>
|
|
(by the name HOWTO-honor-std) is very instructive. More info
|
|
is at the end of RELEASE-NOTES.
|
|
</P>
|
|
<P>This functionality is now automated and turned on by default.
|
|
</P>
|
|
|
|
<HR>
|
|
<H2><A NAME="5_6">5.6 Is libstdc++-v3 thread-safe?</A></H2>
|
|
<P>Quick answer: no, as of 2.90.8 (ninth snapshot), the
|
|
library is not appropriate for multithreaded access. The
|
|
string class is MT-safe.
|
|
</P>
|
|
<P>This is assuming that your idea of "multithreaded"
|
|
is the same as ours... The general question of multithreading
|
|
and libstdc++-v3 is addressed in the chapter-specific advice for
|
|
<A HREF="http://sources.redhat.com/libstdc++/17_intro/howto.html#3">Library
|
|
Introduction</A>. Threadsafe containers are covered in
|
|
more detail in
|
|
<A HREF="http://sources.redhat.com/libstdc++/23_containers/howto.html">the
|
|
Received Wisdom section on containers</A>.
|
|
<!-- I have successfully evaded the topic; my work here is
|
|
done- no, wait, I have to write those other sections... -->
|
|
</P>
|
|
|
|
<HR>
|
|
<H2><A NAME="5_7">5.7 How do I get a copy of the ISO C++ Standard?</A></H2>
|
|
<P>Copies of the full ISO 14882 standard are available on line
|
|
via the ISO mirror site for committee members. Non-members,
|
|
or those who have not paid for the privilege of sitting on
|
|
the committee and sustained their two-meeting commitment for
|
|
voting rights, may get a copy of the standard from their
|
|
respective national standards organization. In the USA,
|
|
this national standards organization is ANSI and their
|
|
website is right <A HREF="http://www.ansi.org">here</A>.
|
|
(And if you've already registered with them, clicking this
|
|
link will take you to directly to the place where you can
|
|
<A HREF="http://webstore.ansi.org/ansidocstore/product.asp?sku=ISO%2FIEC+14882%2D1998">buy
|
|
the standard on-line</A>.
|
|
</P>
|
|
<P>Who is your country's member body? Visit the
|
|
<A HREF="http://www.iso.ch/">ISO homepage</A> and find out!
|
|
</P>
|
|
|
|
<!-- ####################################################### -->
|
|
|
|
<HR>
|
|
<P CLASS="fineprint"><EM>
|
|
Comments and suggestions are welcome, and may be sent to
|
|
<A HREF="mailto:pme@sources.redhat.com">Phil Edwards</A> or
|
|
<A HREF="mailto:gdr@gcc.gnu.org">Gabriel Dos Reis</A>.
|
|
<BR> $Id: index.html,v 1.7 2000/10/21 00:51:50 jsm28 Exp $
|
|
</EM></P>
|
|
|
|
|
|
</BODY>
|
|
</HTML>
|