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5 <META NAME="DESCRIPTION" CONTENT="FAQ for the GNU libstdc++ effort.">
6 <TITLE>libstdc++-v3 FAQ</TITLE>
7 <LINK REL=StyleSheet HREF="../lib3styles.css">
9 ** Locations of "the most recent snapshot is the Nth" text are
10 ** answers 1_1, 1_4, 4_1, 5_6.
12 <!-- $Id: index.html,v 1.6 2001/04/03 00:26:56 pme Exp $ -->
16 <H1 CLASS="centered">libstdc++ Frequently Asked Questions</H1>
18 <P>The latest version of this document is always available at
19 <A HREF="http://gcc.gnu.org/onlinedocs/libstdc++/faq/">
20 http://gcc.gnu.org/onlinedocs/libstdc++/faq/</A>.</P>
22 <P>To the <A HREF="http://gcc.gnu.org/libstdc++/">libstdc++-v3 homepage</A>.
24 <!-- ####################################################### -->
28 <LI><A HREF="#1_0">General Information</A>
29 <!-- I suspect these will mostly be links to/into existing documents. -->
31 <LI><A HREF="#1_1">What is libstdc++-v3?</A>
32 <LI><A HREF="#1_2">Why should I use libstdc++?</A>
33 <LI><A HREF="#1_3">Who's in charge of it?</A>
34 <LI><A HREF="#1_4">How do I get libstdc++?</A>
35 <LI><A HREF="#1_5">When is libstdc++ going to be finished?</A>
36 <LI><A HREF="#1_6">How do I contribute to the effort?</A>
37 <LI><A HREF="#1_7">What happened to libg++? I need that!</A>
38 <LI><A HREF="#1_8">What if I have more questions?</A>
41 <LI><A HREF="#2_0">Installation</A>
43 <LI><A HREF="#2_1">How do I install libstdc++-v3?</A>
44 <LI><A HREF="#2_2">Is this a drop-in replacement for the
45 libstdc++ that's shipped with g++?</A>
46 <LI><A HREF="#2_3">What is this CVS thing that you keep
48 <LI><A HREF="#2_4">How do I know if it works?</A>
51 <LI><A HREF="#3_0">Platform-Specific Issues</A>
53 <LI><A HREF="#3_1">Can libstdc++-v3 be used with <my
54 favorite compiler>?</A>
55 <LI><A HREF="#3_2">Building under Cygwin hangs/explodes!?</A>
56 <LI><A HREF="#3_3">Building under DEC OSF kills the assembler</A>
59 <LI><A HREF="#4_0">Known Bugs and Non-Bugs</A>
61 <LI><A HREF="#4_1">What works already?</A>
62 <LI><A HREF="#4_2">Bugs in gcc/g++ (not libstdc++-v3)</A>
63 <LI><A HREF="#4_3">Bugs in the C++ language/lib specification</A>
64 <LI><A HREF="#4_4">Things in libstdc++ that look like bugs</A>
66 <LI><A HREF="#4_4_Weff">-Weffc++ complains too much</A>
67 <LI><A HREF="#4_4_rel_ops">"ambiguous overloads"
68 after including an old-style header</A>
69 <LI><A HREF="#4_4_interface">The g++-3 headers are
70 <STRONG>not ours</STRONG></A>
71 <LI><A HREF="#4_4_glibc">compilation errors from streambuf.h</A>
72 <LI><A HREF="#4_4_checks">errors about <EM>*Cconcept</EM> and
73 <EM>constraints</EM> in the STL...</A>
75 <LI><A HREF="#4_5">Aw, that's easy to fix!</A>
78 <LI><A HREF="#5_0">Miscellaneous</A>
80 <LI><A HREF="#5_1">string::iterator is not char*;
81 vector<T>::iterator is not T*</A>
82 <LI><A HREF="#5_2">What's next after libstdc++-v3?</A>
83 <LI><A HREF="#5_3">What about the STL from SGI?</A>
84 <LI><A HREF="#5_4">Extensions and Backward Compatibility</A>
85 <LI><A HREF="#5_5">Compiling with "-fnew-abi"</A>
86 <LI><A HREF="#5_6">Is libstdc++-v3 thread-safe?</A>
87 <LI><A HREF="#5_7">How do I get a copy of the ISO C++ Standard?</A>
94 <!-- ####################################################### -->
96 <H1><A NAME="1_0">1.0 General Information</A></H1>
97 <!-- I suspect these will mostly be links to/into existing documents. -->
98 <H2><A NAME="1_1">1.1 What is libstdc++-v3?</A></H2>
99 <P>The GNU Standard C++ Library v3, or libstdc++-2.9x, is an
100 ongoing project to implement the ISO 14882 Standard C++ library
101 as described in chapters 17 through 27 and annex D. As the
102 library reaches stable plateaus, it is captured in a snapshot
103 and released. The current release is <A
104 HREF="ftp://gcc.gnu.org/pub/libstdc++/libstdc++-2.92.tar.gz">the
105 eleventh snapshot</A>. For those who want to see exactly how
106 far the project has come, or just want the latest
107 bleeding-edge code, the up-to-date source is available over
108 anonymous CVS, and can even be browsed over the Web (see below).
110 <P>A more formal description of the V3 goals can be found in the
111 official <A HREF="../17_intro/DESIGN">design document</A>.
115 <H2><A NAME="1_2">1.2 Why should I use libstdc++?</A></H2>
116 <P>The completion of the ISO C++ standardization gave the
117 C++ community a powerful set of reuseable tools in the form
118 of the C++ Standard Library. However, all existing C++
119 implementations are (as the Draft Standard used to say)
120 "incomplet and incorrekt," and many suffer from
121 limitations of the compilers that use them.
123 <P>The GNU C/C++/FORTRAN/<pick-a-language> compiler
124 (<TT>gcc</TT>, <TT>g++</TT>, etc) is widely considered to be
125 one of the leading compilers in the world. Its development
126 has recently been taken over by the
127 <A HREF="http://gcc.gnu.org/">GCC team</A>. All of
128 the rapid development and near-legendary
130 HREF="http://gcc.gnu.org/gcc-2.95/buildstat.html">portability</A>
131 that are the hallmarks of an open-source project are being
132 applied to libstdc++.
134 <P>That means that all of the Standard classes and functions
135 (such as <TT>string</TT>, <TT>vector<></TT>, iostreams,
136 and algorithms) will be freely available and fully compliant.
137 Programmers will no longer need to "roll their own"
138 nor be worried about platform-specific incompatabilities.
142 <H2><A NAME="1_3">1.3 Who's in charge of it?</A></H2>
143 <P>The libstdc++ project is contributed to by several developers
144 all over the world, in the same way as GCC or Linux.
145 Benjamin Kosnik, Gabriel Dos Reis, Phil Edwards, and Ulrich
146 Drepper are the lead maintainers of the CVS archive.
148 <P>Development and discussion is held on the libstdc++ mailing
149 list. Subscribing to the list, or searching the list
150 archives, is open to everyone. You can read instructions for
151 doing so on the <A HREF="http://gcc.gnu.org/libstdc++/">homepage</A>. If you
152 have questions, ideas, code, or are just curious, sign up!
156 <H2><A NAME="1_4">1.4 How do I get libstdc++?</A></H2>
157 <P>The eleventh (and latest) snapshot of libstdc++-v3 is <A
158 HREF="ftp://gcc.gnu.org/pub/libstdc++/libstdc++-2.92.tar.gz">
159 available via ftp</A>.
161 <P>The <A HREF="http://gcc.gnu.org/libstdc++/">homepage</A>
162 has instructions for retrieving the latest CVS sources, and for
163 browsing the CVS sources over the web.
165 <P>The subset commonly known as the Standard Template Library
166 (chapters 23 through 25, mostly) is adapted from the SGI STL,
167 which is also an ongoing work.<!-- Possibly a link to SGI's
172 <H2><A NAME="1_5">1.5 When is libstdc++ going to be finished?</A></H2>
173 <!-- <P>Nathan Myers gave the best of all possible answers in <A
174 HREF="http://www.deja.com/getdoc.xp?AN=469581698&fmt=text">a
175 Usenet article</A>.</P>
176 which is no longer available, thanks deja...-->
177 <P>Nathan Myers gave the best of all possible answers, responding
178 to a Usenet article asking this question: Sooner, if you help.
183 <H2><A NAME="1_6">1.6 How do I contribute to the effort?</A></H2>
184 <P>Here is <A HREF="../17_intro/contribute.html">a
185 page devoted to this topic</A>. Subscribing to the mailing
186 list (see above, or the homepage) is a very good idea if you
187 have something to contribute, or if you have spare time and
188 want to help. Contributions don't have to be in the form of
189 source code; anybody who is willing to help write
190 documentation, for example, or has found a bug in code that
191 we all thought was working, is more than welcome!
195 <H2><A NAME="1_7">1.7 What happened to libg++? I need that!</A></H2>
196 <P>The most recent libg++ README states that libg++ is no longer
197 being actively maintained. It should not be used for new
198 projects, and is only being kicked along to support older code.
200 <P>The libg++ was designed and created when there was no Standard
201 to provide guidance. Classes like linked lists are now provided
202 for by <TT>list<T></TT> and do not need to be created by
203 <TT>genclass</TT>. (For that matter, templates exist now and
204 are well-supported, whereas genclass (mostly) predates them.)
206 <P>There are other classes in libg++ that are not specified in the
207 ISO Standard (e.g., statistical analysis). While there are a
208 lot of really useful things that are used by a lot of people
209 (e.g., statistics :-), the Standards Committee couldn't include
210 everything, and so a lot of those "obvious" classes
213 <P>Since libstdc++ is an implementation of the Standard Library, we
214 have no plans at this time to include non-Standard utilities
215 in the implementation, however handy they are. (The extensions
216 provided in the SGI STL aren't maintained by us and don't get
217 a lot of our attention, because they don't require a lot of our
218 time.) It is entirely plausable that the "useful stuff"
219 from libg++ might be extracted into an updated utilities library,
220 but nobody has stated such a project yet.
222 <!-- The advertisement, so to speak, might have to go. Hmmmmm. -->
223 <P>(The <A HREF="http://www.boost.org/">Boost</A> site houses free
224 C++ libraries that do varying things, and happened to be started
225 by members of the Standards Committee. Certain "useful
226 stuff" classes will probably migrate there.)
228 <P>For the bold and/or desperate, the
229 <A HREF="http://gcc.gnu.org/fom_serv/cache/33.html">GCC FAQ</A>
230 describes where to find the last libg++ source.
234 <H2><A NAME="1_8">1.8 What if I have more questions?</A></H2>
235 <P>If you have read the README and RELEASE-NOTES files, and your
236 question remains unanswered, then just ask the mailing list.
237 At present, you do not need to be subscribed to the list to
238 send a message to it. More information is available on the
239 homepage (including how to browse the list archives); to send
240 to the list, use <A HREF="mailto:libstdc++@gcc.gnu.org">
241 <CODE>libstdc++@gcc.gnu.org</CODE></A>.
243 <P>If you have a question that you think should be included here,
244 or if you have a question <EM>about</EM> a question/answer here,
245 contact <A HREF="mailto:pme@sources.redhat.com">Phil Edwards</A>
246 or <A HREF="mailto:gdr@gcc.gnu.org">Gabriel Dos Reis</A>.
251 <H1><A NAME="2_0">2.0 Installation</A></H1>
252 <H2><A NAME="2_1">2.1 How do I install libstdc++-v3?</A></H2>
253 <P>Complete instructions are not given here (this is a FAQ, not
254 an installation document), but the tools required are few:
257 <LI> A release of libstdc++.
258 <LI> A recent release of GCC (version 2.95 works). Note
259 that building GCC is much easier and more automated
260 than building the GCC 2.[78] series was.
261 <LI> If you plan on hacking around with the makefiles, you
262 will need the tools <A
263 HREF="http://sources.redhat.com/autoconf/">autoconf</A>and <A
264 HREF="http://sources.redhat.com/automake/">automake</A>.
265 <LI> GNU Make is the only make that supports these makefiles.
267 <P>The file <A HREF="../documentation.html">documentation.html</A>
268 provides a good overview of the steps necessary to build, install,
269 and use the library. Instructions for configuring the library
270 with new flags such as --enable-threads are there also.
272 <P>The top-level install.html and
273 <A HREF="../17_intro/RELEASE-NOTES">RELEASE-NOTES</A> files contain
274 the exact build and installation instructions. You may wish to
275 browse those files over CVSweb ahead of time to get a feel for
276 what's required. RELEASE-NOTES is located in the
277 ".../docs/17_intro/" directory of the distribution.
281 <H2><A NAME="2_2">2.2 Is this a drop-in replacement for the
282 libstdc++ that's shipped with g++?</A></H2>
283 <P>Yes, as of 2.90.8, it is intended as such. And as of 2.91,
284 libstdc++-v3 <EM>is</EM> the library that's shipped with
285 g++, so much of this answer has become moot.
289 <H2><A NAME="2_3">2.3 What is this CVS thing that you
290 keep mentioning?</A></H2>
291 <P>The <EM>Concurrent Versions System</EM> is one of several revision
292 control packages. It was selected for GNU projects because it's
293 free (speech), free (beer), and very high quality. The <A
294 HREF="http://www.gnu.org/software/cvs/cvs.html">CVS entry in
295 the GNU software catalogue</A> has a better description as
297 <A HREF="http://www.cyclic.com/">link to the makers of CVS</A>.
299 <P>The "anonymous client checkout" feature of CVS is
300 similar to anonymous FTP in that it allows anyone to retrieve
301 the latest libstdc++ sources.
303 <P>After the first of April, American users will have a
304 "/pharmacy" command-line option...
305 <!-- wonder how long that'll live -->
309 <H2><A NAME="2_4">2.4 How do I know if it works?</A></H2>
310 <P>libstdc++-v3 comes with its own testsuite. You do not need
311 to actually install the library ("<TT>gmake
312 install</TT>") to run the testsuite. Note that 2.91 does
315 <P>To run the testsuite on the library after building it, use
316 "gmake check" while in your build directory. To run
317 the testsuite on the library after building and installing it,
318 use "gmake check-install" instead.
320 <P>The testsuite subdirectory in your build directory will then
321 contain three files of the form YYYYMMDD-mkcheck*.txt. One of
322 them (-mkcheck.txt itself) contains the results of the tests;
323 this can be mailed to the list. The other files (-mkchecklog.txt
324 and -mkcheckfiles.txt) contain messages from the compiler while
325 building the test programs, and a list of the tests to be run,
328 <P>If you find bugs in the testsuite programs themselves, or if
329 you think of a new test program that should be added to the
330 suite, <B>please</B> write up your idea and send it to the list!
334 <H1><A NAME="3_0">3.0 Platform-Specific Issues</A></H1>
335 <H2><A NAME="3_1">3.1 Can libstdc++-v3 be used with <my
336 favorite compiler>?</A></H2>
337 <P>Probably not. Yet.</P>
338 <P>Because GCC advances so rapidly, development and testing of
339 libstdc++ is being done almost entirely under that compiler.
340 If you are curious about whether other, lesser compilers
341 (*grin*) support libstdc++, you are more than welcome to try.
342 Configuring and building the library (see above) will still
343 require certain tools, however. Also keep in mind that
344 <EM>building</EM> libstdc++ does not imply that your compiler
345 will be able to <EM>use</EM> all of the features found in the
346 C++ Standard Library.
348 <P>Since the goal of ISO Standardization is for all C++
349 implementations to be able to share code, the final libstdc++
350 should, in theory, be useable under any ISO-compliant
351 compiler. It will still be targeted and optimized for
356 <H2><A NAME="3_2">3.2 Building under Cygwin hangs/explodes!?</A></H2>
357 <P>Sometimes, yes. You're probably in the middle of generating
358 the <TT>numeric_limits</TT> specializations when it hangs,
361 <P>The <TT><limits></TT> header and its associated library
362 code are platform-specific. These files get generated from
363 scratch during installation, and it is this generator that is
364 hanging. More specifically, the only sure way to determine
365 what the <TT>numeric_limits<T>::traps</TT> boolean
366 should be is to actually divide by zero and see if it is
369 <P>Under NT, this will occasionally just hang. On those
370 occasions when the test does not hang, the zero-division is
371 in fact trapped. That doesn't prevent hanging elsewhere.
373 <P>You have two options. You can get a newer cygwin1.dll (see the
374 Cygwin paragraph in the
375 <A HREF="../install.html">installation instructions</A>).
376 Or you can get a prebuilt set of bits/std_limits.h and
377 src/limitsMEMBERS.cc files from Mumit Khan's
378 <A HREF="http://www.xraylith.wisc.edu/~khan/software/gnu-win32/libstdc++-v3.html">Cygwin-related website</A>.
382 <H2><A NAME="3_3">3.3 Building DEC OSF kills the assembler</A></H2>
383 <P>The <TT>atomicity.h</TT> header for the Alpha processor
384 currently uses pseudo-operators which the DEC assembler
385 doesn't understand (in particular, .subsection and .previous).
386 The simple solution is to install GNU <TT>as</TT> and arrange
387 for the GCC build to use it (or merge the sources and build
388 it during the bootstrap).
391 <A HREF="http://gcc.gnu.org/ml/libstdc++/2000-12/msg00279.html">knows
392 the DEC assembler well enough</A> to provide the equivalent of
393 these two pseudos would win praise and accolades from many.
398 <H1><A NAME="4_0">4.0 Known Bugs and Non-Bugs</A></H1>
399 <EM>Note that this section can get rapdily outdated -- such is the
400 nature of an open-source project. For the latest information, join
401 the mailing list or look through recent archives. The RELEASE-
402 NOTES and BUGS files are generally kept up-to-date.</EM>
404 <H2><A NAME="4_1">4.1 What works already?</A></H2>
405 <P>This is a verbatim clip from the "Status" section
406 of the RELEASE-NOTES for the latest snapshot.
409 <!-- Yeah, I meant that "verbatim clip" thing literally... :-) -->
414 - preliminary doxygen documentation has been added. Running "make
415 doxygen" in the libstdc++-v3 build directory will generate HTML
416 documentation that can be used to cross-reference names and files in
418 - a dejagnu based testing framework has been added
419 - a new implementation of the concept checking code has been ported
420 from the boost libraries.
421 - support for -fno-exceptions has been added
422 - stdexcept was re-written
423 - using deprecated or antiquated headers now gives a warning
424 - the stdio interface to iostreams has been tweaked, and now works
425 with synchronized c/c++ io
426 - new libsupc++ routines implementing the IA-64 C++ ABI.
427 - HPUX configuration files
428 - support for AIX added
429 - a lot of bugs were fixed.
430 - preliminary named locales implemented
431 - portability improvements made to generation of <limits>
432 - speedups to improve configuration time.
433 - DJGPP support added.
434 - support for dlopening shared libstdc++
439 <H2><A NAME="4_2">4.2 Bugs in gcc/g++ (not libstdc++-v3)</A></H2>
440 <P>This is by no means meant to be complete nor exhaustive, but
441 mentions some problems that users may encounter when building
442 or using libstdc++. If you are experiencing one of these
443 problems, you can find more information on the libstdc++ and
444 the GCC mailing lists.
447 <LI>As of 2.91, these bugs have all been fixed. We look forward
448 to new ones, well, not exactly...
452 <H2><A NAME="4_3">4.3 Bugs in the C++ language/lib specification</A></H2>
453 <P>Yes, unfortunately, there are some. In a <A
454 HREF="http://gcc.gnu.org/ml/libstdc++/1998/msg00006.html">message
455 to the list</A>, Nathan Myers announced that he has started a list of
456 problems in the ISO C++ Standard itself, especially with
457 regard to the chapters that concern the library. The list
459 HREF="http://www.cantrip.org/draft-bugs.txt">posted on his
460 website</A>. Developers who are having problems interpreting
461 the Standard may wish to consult his notes.
463 <P>For those people who are not part of the ISO Library Group
464 (i.e., nearly all of us needing to read this page in the first
465 place :-), a public list of the library defects is occasionally
466 published <A HREF="http://anubis.dkuug.dk/jtc1/sc22/wg21/">here</A>.
470 <H2><A NAME="4_4">4.4 Things in libstdc++ that look like bugs</A></H2>
471 <P>There are things which are not bugs in the compiler (4.2) nor
472 the language specification (4.3), but aren't really bugs in
473 libstdc++, either. Really! Please do not report these as bugs.
476 <P>The biggest of these is the quadzillions of warnings about the
477 library headers emitted when <TT>-Weffc++</TT> is used. Making
478 libstdc++ "-Weffc++-clean" is not a goal of the project,
479 for a few reasons. Mainly, that option tries to enforce
480 object-oriented programming, while the Standard Library isn't
481 necessarily trying to be OO. There are multiple solutions
485 <A NAME="4_4_rel_ops">
486 <P>Another is the <TT>rel_ops</TT> namespace and the template
487 comparison operator functions contained therein. If they become
488 visible in the same namespace as other comparison functions
489 (e.g., '<TT>using</TT>' them and the <iterator> header),
490 then you will suddenly be faced with huge numbers of ambiguity
491 errors. This was discussed on the -v3 list; Nathan Myers
492 <A HREF="http://gcc.gnu.org/ml/libstdc++/2001-01/msg00247.html">sums
496 <A NAME="4_4_interface"><H3>The g++-3 headers are
497 <EM>not ours</EM></H3>
498 <P>If you have found an extremely broken header file which is
499 causing problems for you, look carefully before submitting a
500 "high" priority bug report (which you probably shouldn't
501 do anyhow; see the last paragraph of the page describing
502 <A HREF="http://gcc.gnu.org/gnatswrite.html">the GCC bug database</A>).
504 <P>If the headers are in <CODE>${prefix}/include/g++-3</CODE>, then
505 you are using the old libstdc++-v2 library, which is nonstandard
506 and unmaintained. Do not report problems with -v2 to the -v3
509 <P>Currently our header files are installed in
510 <CODE>${prefix}/include/g++-v3</CODE> (see the 'v'?). This may
511 change with the next release of GCC, as it may be too confusing,
512 but <A HREF="http://gcc.gnu.org/ml/gcc/2000-10/msg00732.html">the
513 question has not yet been decided</A>.
517 <P>If you're on a GNU/Linux system and have just upgraded to
518 glibc 2.2, but are still using gcc 2.95.2, then you should have
519 read the glibc FAQ, specifically 2.34:
521 2.34. When compiling C++ programs, I get a compilation error in streambuf.h.
523 {BH} You are using g++ 2.95.2? After upgrading to glibc 2.2, you need to
524 apply a patch to the include files in /usr/include/g++, because the fpos_t
525 type has changed in glibc 2.2. The patch is at
526 http://clisp.cons.org/~haible/gccinclude-glibc-2.2-compat.diff
528 Note that 2.95.x shipped with the
529 <A HREF="#4_4_interface">old v2 library</A> which is no longer
533 <A NAME="4_4_checks">
534 <P>If you see compilation errors containing messages about
535 <TT> <EM>foo</EM>Concept </TT>and a<TT> constraints </TT>
536 member function, then most
537 likely you have violated one of the requirements for types used
538 during instantiation of template containers. For example,
539 EqualityComparableConcept appears
540 if your types must be comparable with == and you have not
541 provided this capability (a typo, or wrong visibility, or you
542 just plain forgot, etc).
544 <P>More information, including how to optionally disable the checks,
545 is available <A HREF="../19_diagnostics/howto.html#3">here</A>.
550 <H2><A NAME="4_5">4.5 Aw, that's easy to fix!</A></H2>
551 <P>If you have found a bug in the library and you think you have
552 a working fix, then send it in! The main GCC site has a page
553 on <A HREF="http://gcc.gnu.org/contribute.html">submitting
554 patches</A> that covers the procedure, but for libstdc++ you
555 should also send the patch to our mailing list in addition to
556 the GCC patches mailing list. The libstdc++
557 <A HREF="../17_intro/contribute.html">contributors' page</A>
558 also talks about how to submit patches.
560 <P>In addition to the description, the patch, and the ChangeLog
561 entry, it is a Good Thing if you can additionally create a small
562 test program to test for the presence of the bug that your
563 patch fixes. Bugs have a way of being reintroduced; if an old
564 bug creeps back in, it will be caught immediately by the
565 <A HREF="#2_4">testsuite</A> -- but only if such a test exists.
569 <H1><A NAME="5_0">5.0 Miscellaneous</A></H1>
570 <H2><A NAME="5_1">5.1 string::iterator is not char*;
571 vector<T>::iterator is not T*</A></H2>
572 <P>If you have code that depends on container<T> iterators
573 being implemented as pointer-to-T, your code is broken.
575 <P>While there are arguments for iterators to be implemented in
576 that manner, A) they aren't very good ones in the long term,
577 and B) they were never guaranteed by the Standard anyway. The
578 type-safety achieved by making iterators a real class rather
579 than a typedef for <TT>T*</TT> outweighs nearly all opposing
584 <H2><A NAME="5_2">5.2 What's next after libstdc++-v3?</A></H2>
585 <P>Hopefully, not much. The goal of libstdc++-v3 is to produce
586 a fully-compliant, fully-portable Standard Library. After that,
587 we're mostly done: there won't <EM>be</EM> any more compliance
590 <P>The ISO Committee will meet periodically to review Defect Reports
591 in the C++ Standard. Undoubtably some of these will result in
592 changes to the Standard, which will be reflected in patches to
593 libstdc++. Some of that is already happening, see 4.2. Some of
594 those changes are being predicted by the library maintainers, and
595 we add code to the library based on what the current proposed
596 resolution specifies.
598 <P>The current libstdc++ contains extensions to the Library which
599 must be explicitly requested by client code (for example, the
600 hash tables from SGI). Other extensions may be added to
601 libstdc++-v3 if they seem to be "standard" enough.
602 (For example, the "long long" type from C99.)
603 Bugfixes and rewrites (to improve or fix thread safety, for
604 instance) will of course be a continuing task.
607 HREF="http://gcc.gnu.org/ml/libstdc++/1999/msg00080.html">This
608 question</A> about the next libstdc++ prompted some brief but
610 HREF="http://gcc.gnu.org/ml/libstdc++/1999/msg00084.html">speculation</A>.
614 <H2><A NAME="5_3">5.3 What about the STL from SGI?</A></H2>
615 <P>The <A HREF="http://www.sgi.com/Technology/STL/">STL from SGI</A>
616 is merged into libstdc++-v3 with changes as necessary.
617 Currently release 3.3 is being used. Changes in the STL
618 usually produce some weird bugs and lots of changes in the
619 rest of the libstdc++ source as we scramble to keep up. :-)
621 <P>In particular, <TT>string</TT> is not from SGI and makes no
622 use of their "rope" class (which is included as an
623 optional extension), nor is <TT>valarray</TT> and some others.
624 Classes like <TT>vector<></TT> are, however.
626 <P>The FAQ for SGI's STL (one jump off of their main page) is
631 <H2><A NAME="5_4">5.4 Extensions and Backward Compatibility</A></H2>
632 <P>Although you can specify <TT>-I</TT> options to make the
633 preprocessor search the g++-v3/ext and /backward directories,
634 it is better to refer to files there by their path, as in:
635 <!-- Careful, the leading spaces in PRE show up directly. -->
638 #include <ext/hash_map>
640 <P>Extensions to the library have
641 <A HREF="../ext/howto.html">their own page</A>.
645 <H2><A NAME="5_5">5.5 Compiling with "-fnew-abi"</A></H2>
646 <P>Towards the end of July 1999, this subject was brought up again
647 on the mailing list under a different name. The related
648 <A HREF="http://gcc.gnu.org/ml/libstdc++/1999-q3/msg00066.html">thread</A>
649 (by the name HOWTO-honor-std) is very instructive. More info
650 is at the end of RELEASE-NOTES.
652 <P>This functionality is now automated and turned on by default.
656 <H2><A NAME="5_6">5.6 Is libstdc++-v3 thread-safe?</A></H2>
657 <P>Quick answer: no, as of 2.92 (eleventh snapshot), the
658 library is not appropriate for multithreaded access. The
659 string class is MT-safe.
661 <P>This is assuming that your idea of "multithreaded"
662 is the same as ours... The general question of multithreading
663 and libstdc++-v3 is addressed in the chapter-specific advice for
664 <A HREF="http://gcc.gnu.org/onlinedocs/libstdc++/17_intro/howto.html#3">Library
665 Introduction</A>. Threadsafe containers are covered in
667 <A HREF="http://gcc.gnu.org/onlinedocs/libstdc++/23_containers/howto.html">the
668 Received Wisdom section on containers</A>.
669 <!-- I have successfully evaded the topic; my work here is
670 done- no, wait, I have to write those other sections... -->
674 <H2><A NAME="5_7">5.7 How do I get a copy of the ISO C++ Standard?</A></H2>
675 <P>Copies of the full ISO 14882 standard are available on line
676 via the ISO mirror site for committee members. Non-members,
677 or those who have not paid for the privilege of sitting on
678 the committee and sustained their two-meeting commitment for
679 voting rights, may get a copy of the standard from their
680 respective national standards organization. In the USA,
681 this national standards organization is ANSI and their
682 website is right <A HREF="http://www.ansi.org">here</A>.
683 (And if you've already registered with them, clicking this
684 link will take you to directly to the place where you can
685 <A HREF="http://webstore.ansi.org/ansidocstore/product.asp?sku=ISO%2FIEC+14882%2D1998">buy
686 the standard on-line</A>.
688 <P>Who is your country's member body? Visit the
689 <A HREF="http://www.iso.ch/">ISO homepage</A> and find out!
692 <!-- ####################################################### -->
695 <P CLASS="fineprint"><EM>
696 Comments and suggestions are welcome, and may be sent to
697 <A HREF="mailto:libstdc++@gcc.gnu.org">the mailing list</A>.
698 <BR> $Id: index.html,v 1.6 2001/04/03 00:26:56 pme Exp $