a4e990461d
2000-05-24 Phil Edwards <pme@sourceware.cygnus.com> * acinclude.m4 (GLIBCPP_CHECK_COMPILER_VERSION): If we can use -fdiagnostics-show-location=once, do so. Expand AC_LANG_* to enclose other tests in this macro, including future ones. * aclocal.m4: Regenerate. * configure: Regenerate. * docs/faq/index.html: Update location of libg++ FAQ. * docs/faq/index.txt: Regenerate. From-SVN: r34137
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HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0//EN">
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<HTML>
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<HEAD>
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<META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1">
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<META NAME="AUTHOR" CONTENT="pme@sourceware.cygnus.com (Phil Edwards)">
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<META NAME="KEYWORDS" CONTENT="libstdc++, libstdc++-v3, egcs, g++, libg++, STL">
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<META NAME="DESCRIPTION" CONTENT="FAQ for the GNU libstdc++ effort.">
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<META NAME="GENERATOR" CONTENT="vi and eight fingers">
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<TITLE>libstdc++-v3 FAQ</TITLE>
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<LINK REL="home" HREF="http://sourceware.cygnus.com/libstdc++/">
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<LINK REL=StyleSheet HREF="../lib3styles.css">
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<!--
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** Locations of "the most recent snapshot is the Nth" text are
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** answers 1_1, 1_4, 4_1, 5_6.
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-->
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<!-- $Id: index.html,v 1.2 2000/05/03 16:11:02 pme Exp $ -->
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</HEAD>
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<BODY>
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<H1 CLASS="centered">libstdc++ Frequently Asked Questions</H1>
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<P>The latest version of this document is always available at
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<A HREF="http://sourceware.cygnus.com/libstdc++/faq/index.html">
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http://sourceware.cygnus.com/libstdc++/faq/</A>.</P>
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<P>To the <A HREF="../index.html">libstdc++-v3 homepage</A>.
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<!-- ####################################################### -->
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<HR>
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<H1>Questions</H1>
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<OL>
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<LI><A HREF="#1_0">General Information</A>
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<!-- I suspect these will mostly be links to/into existing documents. -->
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<OL>
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<LI><A HREF="#1_1">What is libstdc++-v3?</A>
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<LI><A HREF="#1_2">Why should I use libstdc++?</A>
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<LI><A HREF="#1_3">Who's in charge of it?</A>
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<LI><A HREF="#1_4">How do I get libstdc++?</A>
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<LI><A HREF="#1_5">When is libstdc++ going to be finished?</A>
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<LI><A HREF="#1_6">How do I contribute to the effort?</A>
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<LI><A HREF="#1_7">What happened to libg++? I need that!</A>
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<LI><A HREF="#1_8">What if I have more questions?</A>
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</OL>
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<LI><A HREF="#2_0">Installation</A>
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<OL>
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<LI><A HREF="#2_1">How do I install libstdc++-v3?</A>
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<LI><A HREF="#2_2">Is this a drop-in replacement for the
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libstdc++ that's shipped with g++?</A>
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<LI><A HREF="#2_3">What is this CVS thing that you keep
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mentioning?</A>
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<LI><A HREF="#2_4">How do I know if it works?</A>
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</OL>
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<LI><A HREF="#3_0">Platform-Specific Issues</A>
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<OL>
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<LI><A HREF="#3_1">Can libstdc++-v3 be used with <my
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favorite compiler>?</A>
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<LI><A HREF="#3_2">Building under Cygwin hangs/explodes!?</A>
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</OL>
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<LI><A HREF="#4_0">Known Bugs and Non-Bugs</A>
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<OL>
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<LI><A HREF="#4_1">What works already?</A>
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<LI><A HREF="#4_2">Bugs in gcc/g++ (not libstdc++-v3)</A>
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<LI><A HREF="#4_3">Bugs in the C++ language/lib specification</A>
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<LI><A HREF="#4_4">Things in libstdc++ that look like bugs</A>
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<LI><A HREF="#4_5">Aw, that's easy to fix!</A>
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</OL>
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<LI><A HREF="#5_0">Miscellaneous</A>
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<OL>
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<LI><A HREF="#5_1">string::iterator is not char*;
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vector<T>::iterator is not T*</A>
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<LI><A HREF="#5_2">What's next after libstdc++-v3?</A>
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<LI><A HREF="#5_3">What about the STL from SGI?</A>
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<LI><A HREF="#5_4">Extensions and Backward Compatibility</A>
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<LI><A HREF="#5_5">Compiling with "-fnew-abi"</A>
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<LI><A HREF="#5_6">Is libstdc++-v3 thread-safe?</A>
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<LI><A HREF="#5_7">How do I get a copy of the ISO C++ Standard?</A>
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</OL>
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</OL>
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<HR>
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<!-- ####################################################### -->
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<H1><A NAME="1_0">1.0 General Information</A></H1>
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<!-- I suspect these will mostly be links to/into existing documents. -->
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<H2><A NAME="1_1">1.1 What is libstdc++-v3?</A></H2>
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<P>The GNU Standard C++ Library v3, or libstdc++-2.90.x, is an
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ongoing project to implement the ISO 14882 Standard C++ library
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as described in chapters 17 through 27 and annex D. As the
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library reaches stable plateaus, it is captured in a snapshot
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and released. The current release is <A
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HREF="ftp://sourceware.cygnus.com/pub/libstdc++/libstdc++-2.90.8.tar.gz">the
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ninth snapshot</A>. For those who want to see exactly how
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far the project has come, or just want the latest
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bleeding-edge code, the up-to-date source is available over
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anonymous CVS, and can even be browsed over the Web (see below).
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</P>
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<P>A more formal description of the V3 goals can be found in the
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official <A HREF="../17_intro/DESIGN">design document</A>.
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</P>
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<HR>
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<H2><A NAME="1_2">1.2 Why should I use libstdc++?</A></H2>
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<P>The completion of the ISO C++ standardization gave the
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C++ community a powerful set of reuseable tools in the form
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of the C++ Standard Library. However, all existing C++
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implementations are (as the Draft Standard used to say)
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"incomplet and incorrekt," and many suffer from
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limitations of the compilers that use them.
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</P>
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<P>The GNU C/C++/FORTRAN/<pick-a-language> compiler
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(<TT>gcc</TT>, <TT>g++</TT>, etc) is widely considered to be
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one of the leading compilers in the world. Its development
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has recently been taken over by the
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<A HREF="http://gcc.gnu.org/">GCC team</A>. All of
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the rapid development and near-legendary
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<A
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HREF="http://gcc.gnu.org/gcc-2.95/buildstat.html">portability</A>
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that are the hallmarks of an open-source project are being
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applied to libstdc++.
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</P>
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<P>That means that all of the Standard classes and functions
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(such as <TT>string</TT>, <TT>vector<></TT>, iostreams,
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and algorithms) will be freely available and fully compliant.
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Programmers will no longer need to "roll their own"
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nor be worried about platform-specific incompatabilities.
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</P>
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<HR>
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<H2><A NAME="1_3">1.3 Who's in charge of it?</A></H2>
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<P>The libstdc++ project is contributed to by several developers
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all over the world, in the same way as GCC (EGCS) or Linux.
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Benjamin Kosnik, Gabriel Dos Reis, Nathan Myers, and Ulrich
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Drepper are the lead maintainers of the CVS archive.
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</P>
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<P>Development and discussion is held on the libstdc++ mailing
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list. Subscribing to the list, or searching the list
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archives, is open to everyone. You can read instructions for
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doing so on the <A HREF="../index.html">homepage</A>. If you
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have questions, ideas, code, or are just curious, sign up!
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</P>
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<HR>
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<H2><A NAME="1_4">1.4 How do I get libstdc++?</A></H2>
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<P>The ninth (and latest) snapshot of libstdc++-v3 is <A
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HREF="ftp://sourceware.cygnus.com/pub/libstdc++/libstdc++-2.90.8.tar.gz">
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available via ftp</A>.
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</P>
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<P>The <A HREF="../index.html">homepage</A>
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has instructions for retrieving the latest CVS sources, and for
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browsing the CVS sources over the web.
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</P>
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<P>The subset commonly known as the Standard Template Library
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(chapters 23 through 25, mostly) is adapted from the SGI STL,
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which is also an ongoing work.<!-- Possibly a link to SGI's
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STL here. -->
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</P>
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<HR>
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<H2><A NAME="1_5">1.5 When is libstdc++ going to be finished?</A></H2>
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<P>Nathan Myers gave the best of all possible answers in <A
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HREF="http://www.deja.com/getdoc.xp?AN=469581698&fmt=text">a
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recent Usenet article</A>.</P>
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<HR>
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<H2><A NAME="1_6">1.6 How do I contribute to the effort?</A></H2>
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<P>Here is <A HREF="../17_intro/contribute.html">a
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page devoted to this topic</A>. Subscribing to the mailing
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list (see above, or the homepage) is a very good idea if you
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have something to contribute, or if you have spare time and
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want to help. Contributions don't have to be in the form of
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source code; anybody who is willing to help write
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documentation, for example, or has found a bug in code that
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we all thought was working, is more than welcome!
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</P>
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<HR>
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<H2><A NAME="1_7">1.7 What happened to libg++? I need that!</A></H2>
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<P>The most recent libg++ README states that libg++ is no longer
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being actively maintained. It should not be used for new
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projects, and is only being kicked along to support older code.
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</P>
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<P>The libg++ was designed and created when there was no Standard
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to provide guidance. Classes like linked lists are now provided
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for by <TT>list<T></TT> and do not need to be created by
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<TT>genclass</TT>. (For that matter, templates exist now and
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are well-supported, whereas genclass (mostly) predates them.)
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</P>
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<P>There are other classes in libg++ that are not specified in the
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ISO Standard (e.g., statistical analysis). While there are a
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lot of really useful things that are used by a lot of people
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(e.g., statistics :-), the Standards Committee couldn't include
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everything, and so a lot of those "obvious" classes
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didn't get included.
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</P>
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<P>Since libstdc++ is an implementation of the Standard Library, we
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have no plans at this time to include non-Standard utilities
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in the implementation, however handy they are. (The extensions
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provided in the SGI STL aren't maintained by us and don't get
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a lot of our attention, because they don't require a lot of our
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time.) It is entirely plausable that the "useful stuff"
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from libg++ might be extracted into an updated utilities library,
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but nobody has stated such a project yet.
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</P>
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<!-- The advertisement, so to speak, might have to go. Hmmmmm. -->
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<P>(The <A HREF="http://www.boost.org/">Boost</A> site houses free
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C++ libraries that do varying things, and happened to be started
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by members of the Standards Committee. Certain "useful
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stuff" classes will probably migrate there.)
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</P>
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<P>For the bold and/or desperate, the
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<A HREF="http://gcc.gnu.org/fom_serv/cache/33.html">GCC FAQ</A>
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describes where to find the last libg++ source.
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</P>
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<HR>
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<H2><A NAME="1_8">1.8 What if I have more questions?</A></H2>
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<P>If you have read the README and RELEASE-NOTES files, and your
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question remains unanswered, then just ask the mailing list.
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At present, you do not need to be subscribed to the list to
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send a message to it. More information is available on the
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homepage (including how to browse the list archives); to send
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to the list, use <A HREF="mailto:libstdc++@sourceware.cygnus.com">
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<TT>libstdc++@sourceware.cygnus.com</TT></A>.
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</P>
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<P>If you have a question that you think should be included here,
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or if you have a question <EM>about</EM> a question/answer here,
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contact <A HREF="mailto:pme@sourceware.cygnus.com">Phil Edwards</A>
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or <A HREF="mailto:gdr@egcs.cygnus.com">Gabriel Dos Reis</A>.
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</P>
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<HR>
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<H1><A NAME="2_0">2.0 Installation</A></H1>
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<H2><A NAME="2_1">2.1 How do I install libstdc++-v3?</A></H2>
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<P>Complete instructions are not given here (this is a FAQ, not
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an installation document), but the tools required are few:
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<UL>
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<LI> A release of libstdc++.
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<LI> A recent release of GCC (version 2.95 works). Note
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that building GCC is much easier and more automated
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than building the GCC 2.[78] series was.
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<LI> If you plan on hacking around with the makefiles, you
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will need the tools <A
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HREF="http://sourceware.cygnus.com/autoconf/">autoconf</A>and <A
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HREF="http://sourceware.cygnus.com/automake/">automake</A>.
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<LI> GNU Make is the only make that supports these makefiles.
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</UL>
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</P>
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<P>The file <A HREF="../documentation.html">documentation.html</A>
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provides a good overview of the steps necessary to build, install,
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and use the library. Instructions for configuring the library
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with new flags such as --enable-threads are there also.
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</P>
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<P>The top-level install.html and
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<A HREF="../17_intro/RELEASE-NOTES">RELEASE-NOTES</A> files contain
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the exact build and installation instructions. You may wish to
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browse those files over CVSweb ahead of time to get a feel for
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what's required. RELEASE-NOTES is located in the
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".../docs/17_intro/" directory of the distribution.
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</P>
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<HR>
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<H2><A NAME="2_2">2.2 Is this a drop-in replacement for the
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libstdc++ that's shipped with g++?</A></H2>
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<P>Yes, as of 2.90.8, it is intended as such.</P>
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<P>The installation instructions cover this in more detail, but
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replacing the older library requires rebuilding some of the
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code that comes with g++. You will need sources for the 2.95.2
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compiler in order to build this snapshot. Building the library
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on its own and then using -I/-L will no longer work.
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</P>
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<P>After the 2.90.8 snapshot, the library sources were integrated
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into the compiler sources. Future releases of the compiler will
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ship with libstdc++-v3.
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</P>
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<HR>
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<H2><A NAME="2_3">2.3 What is this CVS thing that you
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keep mentioning?</A></H2>
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<P>The <EM>Concurrent Versions System</EM> is one of several
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revision control packages. It was selected for GNU projects
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because it's free and very high quality. The <A
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HREF="http://www.gnu.org/software/cvs/cvs.html">CVS entry in
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the GNU software catalogue</A> has a better description as
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well as a <A HREF="http://www.cyclic.com/">link to the makers
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of CVS</A>.
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</P>
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<P>The "anonymous client checkout" feature of CVS is
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similar to anonymous FTP in that it allows anyone to retrieve
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the latest libstdc++ sources.
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</P>
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<P>After the first of April, American users will have a
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"/pharmacy" command-line option...
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<!-- wonder how long that'll live -->
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</P>
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<HR>
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<H2><A NAME="2_4">2.4 How do I know if it works?</A></H2>
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<P>libstdc++-v3 comes with its own testsuite. You do not need
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to actually install the library ("<TT>gmake
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install</TT>") to run the testsuite.
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</P>
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<P>To run the testsuite on the library after building it, use
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"gmake check" while in your build directory. To run
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the testsuite on the library after building and installing it,
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use "gmake check-install" instead.
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</P>
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<P>The testsuite subdirectory in your build directory will then
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contain three files of the form YYYYMMDD-mkcheck*.txt. One of
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them (-mkcheck.txt itself) contains the results of the tests;
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this can be mailed to the list. The other files (-mkchecklog.txt
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and -mkcheckfiles.txt) contain messages from the compiler while
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building the test programs, and a list of the tests to be run,
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respectively.
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</P>
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<P>If you are using the libgcc.a-rebuilding method to enable std::
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you might find that the testsuite starts dying with nasty linker
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errors. This is symptomatic of the rebuilt libgcc.a not being
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installed; the previous one is still in use.
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</P>
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<P>If you find bugs in the testsuite programs themselves, or if
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you think of a new test program that should be added to the
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suite, <B>please</B> write up your idea and send it to the list!
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</P>
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<HR>
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<H1><A NAME="3_0">3.0 Platform-Specific Issues</A></H1>
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<H2><A NAME="3_1">3.1 Can libstdc++-v3 be used with <my
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favorite compiler>?</A></H2>
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<P>Probably not. Yet.</P>
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<P>Because GCC advances so rapidly, development and testing of
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libstdc++ is being done almost entirely under that compiler.
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If you are curious about whether other, lesser compilers
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(*grin*) support libstdc++, you are more than welcome to try.
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Configuring and building the library (see above) will still
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require certain tools, however. Also keep in mind that
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<EM>building</EM> libstdc++ does not imply that your compiler
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will be able to <EM>use</EM> all of the features found in the
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C++ Standard Library.
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</P>
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<P>Since the goal of ISO Standardization is for all C++
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implementations to be able to share code, the final libstdc++
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should, in theory, be useable under any ISO-compliant
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compiler. It will still be targeted and optimized for
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GCC/g++, however.
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</P>
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<HR>
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<H2><A NAME="3_2">3.2 Building under Cygwin hangs/explodes!?</A></H2>
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<P>Sometimes, yes. You're probably in the middle of generating
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the <TT>numeric_limits</TT> specializations when it hangs,
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right? Thought so...
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</P>
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<P>The <TT><limits></TT> header and its associated library
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code are platform-specific. These files get generated from
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scratch during installation, and it is this generator that is
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hanging. More specifically, the only sure way to determine
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what the <TT>numeric_limits<T>::traps</TT> boolean
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should be is to actually divide by zero and see if it is
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trapped or not.
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</P>
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<P>Under NT, this will occasionally just hang. On those
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occasions when the test does not hang, the zero-division is
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in fact trapped. That doesn't prevent hanging elsewhere.
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</P>
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<P>You have two options.
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You can wait until the signal-handling in Cygwin is reworked
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and released; this is planned to take "a few weeks"
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and will result in a fix sometime in late December or early January.
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Or you can get a prebuilt set of bits/std_limits.h and
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src/limitsMEMBERS.cc files from Mumit Khan's
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<A HREF="http://www.xraylith.wisc.edu/~khan/software/gnu-win32/libstdc++-v3.html">Cygwin-related
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website</A>.
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</P>
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<HR>
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<H1><A NAME="4_0">4.0 Known Bugs and Non-Bugs</A></H1>
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<EM>Note that this section can get rapdily outdated -- such is the
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nature of an open-source project. For the latest information, join
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the mailing list or look through recent archives. The RELEASE-
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NOTES and BUGS files are generally kept up-to-date.</EM>
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<H2><A NAME="4_1">4.1 What works already?</A></H2>
|
|
<P>This is a verbatim clip from the "Status" section
|
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of the RELEASE-NOTES for the latest snapshot.
|
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</P>
|
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|
|
<!-- 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="/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.
|
|
</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://sourceware.cygnus.com/ml/libstdc++/1999/msg00080.html">This
|
|
question</A> about the next libstdc++ prompted some brief but
|
|
interesting <A
|
|
HREF="http://sourceware.cygnus.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 3.2 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>
|
|
|
|
<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="/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://sourceware.cygnus.com/libstdc++/17_intro/howto.html#3">Library
|
|
Introduction</A>. Threadsafe containers are covered in
|
|
more detail in
|
|
<A HREF="http://sourceware.cygnus.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@sourceware.cygnus.com">Phil Edwards</A> or
|
|
<A HREF="mailto:gdr@egcs.cygnus.com">Gabriel Dos Reis</A>.
|
|
<BR> $Id: index.html,v 1.2 2000/05/03 16:11:02 pme Exp $
|
|
</EM></P>
|
|
|
|
|
|
</BODY>
|
|
</HTML>
|