mirror of git://gcc.gnu.org/git/gcc.git
966 lines
44 KiB
HTML
966 lines
44 KiB
HTML
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>Backwards Compatibility</title><meta name="generator" content="DocBook XSL-NS Stylesheets V1.78.1" /><meta name="keywords" content="ISO C++, backwards" /><meta name="keywords" content="ISO C++, library" /><meta name="keywords" content="ISO C++, runtime, library" /><link rel="home" href="../index.html" title="The GNU C++ Library" /><link rel="up" href="appendix_porting.html" title="Appendix B. Porting and Maintenance" /><link rel="prev" href="api.html" title="API Evolution and Deprecation History" /><link rel="next" href="appendix_free.html" title="Appendix C. Free Software Needs Free Documentation" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Backwards Compatibility</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="api.html">Prev</a> </td><th width="60%" align="center">Appendix B.
|
||
Porting and Maintenance
|
||
|
||
</th><td width="20%" align="right"> <a accesskey="n" href="appendix_free.html">Next</a></td></tr></table><hr /></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="manual.appendix.porting.backwards"></a>Backwards Compatibility</h2></div></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="backwards.first"></a>First</h3></div></div></div><p>The first generation GNU C++ library was called libg++. It was a
|
||
separate GNU project, although reliably paired with GCC. Rumors imply
|
||
that it had a working relationship with at least two kinds of
|
||
dinosaur.
|
||
</p><p>Some background: libg++ was designed and created when there was no
|
||
ISO standard to provide guidance. Classes like linked lists are now
|
||
provided for by <code class="classname">list<T></code> and do not need to be
|
||
created by <code class="function">genclass</code>. (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, the Standards
|
||
Committee couldn't include everything, and so a lot of those
|
||
<span class="quote">“<span class="quote">obvious</span>”</span> classes didn't get included.
|
||
</p><p>Known Issues include many of the limitations of its immediate ancestor.</p><p>Portability notes and known implementation limitations are as follows.</p><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="backwards.first.ios_base"></a>No <code class="code">ios_base</code></h4></div></div></div><p> At least some older implementations don't have <code class="code">std::ios_base</code>, so you should use <code class="code">std::ios::badbit</code>, <code class="code">std::ios::failbit</code> and <code class="code">std::ios::eofbit</code> and <code class="code">std::ios::goodbit</code>.
|
||
</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="backwards.first.cout_cin"></a>No <code class="code">cout</code> in <code class="filename"><ostream.h></code>, no <code class="code">cin</code> in <code class="filename"><istream.h></code></h4></div></div></div><p>
|
||
In earlier versions of the standard,
|
||
<code class="filename"><fstream.h></code>,
|
||
<code class="filename"><ostream.h></code>
|
||
and <code class="filename"><istream.h></code>
|
||
used to define
|
||
<code class="code">cout</code>, <code class="code">cin</code> and so on. ISO C++ specifies that one needs to include
|
||
<code class="filename"><iostream></code>
|
||
explicitly to get the required definitions.
|
||
</p><p> Some include adjustment may be required.</p><p>This project is no longer maintained or supported, and the sources
|
||
archived. For the desperate,
|
||
the <a class="link" href="http://gcc.gnu.org/extensions.html" target="_top">GCC extensions
|
||
page</a> describes where to find the last libg++ source. The code is
|
||
considered replaced and rewritten.
|
||
</p></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="backwards.second"></a>Second</h3></div></div></div><p>
|
||
The second generation GNU C++ library was called libstdc++, or
|
||
libstdc++-v2. It spans the time between libg++ and pre-ISO C++
|
||
standardization and is usually associated with the following GCC
|
||
releases: egcs 1.x, gcc 2.95, and gcc 2.96.
|
||
</p><p>
|
||
The STL portions of this library are based on SGI/HP STL release 3.11.
|
||
</p><p>
|
||
This project is no longer maintained or supported, and the sources
|
||
archived. The code is considered replaced and rewritten.
|
||
</p><p>
|
||
Portability notes and known implementation limitations are as follows.
|
||
</p><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="backwards.second.std"></a>Namespace <code class="code">std::</code> not supported</h4></div></div></div><p>
|
||
Some care is required to support C++ compiler and or library
|
||
implementation that do not have the standard library in
|
||
<code class="code">namespace std</code>.
|
||
</p><p>
|
||
The following sections list some possible solutions to support compilers
|
||
that cannot ignore <code class="code">std::</code>-qualified names.
|
||
</p><p>
|
||
First, see if the compiler has a flag for this. Namespace
|
||
back-portability-issues are generally not a problem for g++
|
||
compilers that do not have libstdc++ in <code class="code">std::</code>, as the
|
||
compilers use <code class="option">-fno-honor-std</code> (ignore
|
||
<code class="code">std::</code>, <code class="code">:: = std::</code>) by default. That is,
|
||
the responsibility for enabling or disabling <code class="code">std::</code> is
|
||
on the user; the maintainer does not have to care about it. This
|
||
probably applies to some other compilers as well.
|
||
</p><p>
|
||
Second, experiment with a variety of pre-processor tricks.
|
||
</p><p>
|
||
By defining <code class="code">std</code> as a macro, fully-qualified namespace
|
||
calls become global. Volia.
|
||
</p><pre class="programlisting">
|
||
#ifdef WICKEDLY_OLD_COMPILER
|
||
# define std
|
||
#endif
|
||
</pre><p>
|
||
Thanks to Juergen Heinzl who posted this solution on gnu.gcc.help.
|
||
</p><p>
|
||
Another pre-processor based approach is to define a macro
|
||
<code class="code">NAMESPACE_STD</code>, which is defined to either
|
||
<span class="quote">“<span class="quote"> </span>”</span> or <span class="quote">“<span class="quote">std</span>”</span> based on a compile-type
|
||
test. On GNU systems, this can be done with autotools by means of
|
||
an autoconf test (see below) for <code class="code">HAVE_NAMESPACE_STD</code>,
|
||
then using that to set a value for the <code class="code">NAMESPACE_STD</code>
|
||
macro. At that point, one is able to use
|
||
<code class="code">NAMESPACE_STD::string</code>, which will evaluate to
|
||
<code class="code">std::string</code> or <code class="code">::string</code> (i.e., in the
|
||
global namespace on systems that do not put <code class="code">string</code> in
|
||
<code class="code">std::</code>).
|
||
</p><pre class="programlisting">
|
||
dnl @synopsis AC_CXX_NAMESPACE_STD
|
||
dnl
|
||
dnl If the compiler supports namespace std, define
|
||
dnl HAVE_NAMESPACE_STD.
|
||
dnl
|
||
dnl @category Cxx
|
||
dnl @author Todd Veldhuizen
|
||
dnl @author Luc Maisonobe <luc@spaceroots.org>
|
||
dnl @version 2004-02-04
|
||
dnl @license AllPermissive
|
||
AC_DEFUN([AC_CXX_NAMESPACE_STD], [
|
||
AC_CACHE_CHECK(if g++ supports namespace std,
|
||
ac_cv_cxx_have_std_namespace,
|
||
[AC_LANG_SAVE
|
||
AC_LANG_CPLUSPLUS
|
||
AC_TRY_COMPILE([#include <iostream>
|
||
std::istream& is = std::cin;],,
|
||
ac_cv_cxx_have_std_namespace=yes, ac_cv_cxx_have_std_namespace=no)
|
||
AC_LANG_RESTORE
|
||
])
|
||
if test "$ac_cv_cxx_have_std_namespace" = yes; then
|
||
AC_DEFINE(HAVE_NAMESPACE_STD,,[Define if g++ supports namespace std. ])
|
||
fi
|
||
])
|
||
</pre></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="backwards.second.iterators"></a>Illegal iterator usage</h4></div></div></div><p>
|
||
The following illustrate implementation-allowed illegal iterator
|
||
use, and then correct use.
|
||
</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>
|
||
you cannot do <code class="code">ostream::operator<<(iterator)</code>
|
||
to print the address of the iterator => use
|
||
<code class="code">operator<< &*iterator</code> instead
|
||
</p></li><li class="listitem"><p>
|
||
you cannot clear an iterator's reference (<code class="code">iterator =
|
||
0</code>) => use <code class="code">iterator = iterator_type();</code>
|
||
</p></li><li class="listitem"><p>
|
||
<code class="code">if (iterator)</code> won't work any more => use
|
||
<code class="code">if (iterator != iterator_type())</code>
|
||
</p></li></ul></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="backwards.second.isspace"></a><code class="code">isspace</code> from <code class="filename"><cctype></code> is a macro
|
||
</h4></div></div></div><p>
|
||
Glibc 2.0.x and 2.1.x define <code class="filename"><ctype.h></code> functionality as macros
|
||
(isspace, isalpha etc.).
|
||
</p><p>
|
||
This implementations of libstdc++, however, keep these functions
|
||
as macros, and so it is not back-portable to use fully qualified
|
||
names. For example:
|
||
</p><pre class="programlisting">
|
||
#include <cctype>
|
||
int main() { std::isspace('X'); }
|
||
</pre><p>
|
||
Results in something like this:
|
||
</p><pre class="programlisting">
|
||
std:: (__ctype_b[(int) ( ( 'X' ) )] & (unsigned short int) _ISspace ) ;
|
||
</pre><p>
|
||
A solution is to modify a header-file so that the compiler tells
|
||
<code class="filename"><ctype.h></code> to define functions
|
||
instead of macros:
|
||
</p><pre class="programlisting">
|
||
// This keeps isalnum, et al from being propagated as macros.
|
||
#if __linux__
|
||
# define __NO_CTYPE 1
|
||
#endif
|
||
</pre><p>
|
||
Then, include <code class="filename"><ctype.h></code>
|
||
</p><p>
|
||
Another problem arises if you put a <code class="code">using namespace
|
||
std;</code> declaration at the top, and include
|
||
<code class="filename"><ctype.h></code>. This will
|
||
result in ambiguities between the definitions in the global namespace
|
||
(<code class="filename"><ctype.h></code>) and the
|
||
definitions in namespace <code class="code">std::</code>
|
||
(<code class="code"><cctype></code>).
|
||
</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="backwards.second.at"></a>No <code class="code">vector::at</code>, <code class="code">deque::at</code>, <code class="code">string::at</code></h4></div></div></div><p>
|
||
One solution is to add an autoconf-test for this:
|
||
</p><pre class="programlisting">
|
||
AC_MSG_CHECKING(for container::at)
|
||
AC_TRY_COMPILE(
|
||
[
|
||
#include <vector>
|
||
#include <deque>
|
||
#include <string>
|
||
|
||
using namespace std;
|
||
],
|
||
[
|
||
deque<int> test_deque(3);
|
||
test_deque.at(2);
|
||
vector<int> test_vector(2);
|
||
test_vector.at(1);
|
||
string test_string(<span class="quote">“<span class="quote">test_string</span>”</span>);
|
||
test_string.at(3);
|
||
],
|
||
[AC_MSG_RESULT(yes)
|
||
AC_DEFINE(HAVE_CONTAINER_AT)],
|
||
[AC_MSG_RESULT(no)])
|
||
</pre><p>
|
||
If you are using other (non-GNU) compilers it might be a good idea
|
||
to check for <code class="code">string::at</code> separately.
|
||
</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="backwards.second.eof"></a>No <code class="code">std::char_traits<char>::eof</code></h4></div></div></div><p>
|
||
Use some kind of autoconf test, plus this:
|
||
</p><pre class="programlisting">
|
||
#ifdef HAVE_CHAR_TRAITS
|
||
#define CPP_EOF std::char_traits<char>::eof()
|
||
#else
|
||
#define CPP_EOF EOF
|
||
#endif
|
||
</pre></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="backwards.second.stringclear"></a>No <code class="code">string::clear</code></h4></div></div></div><p>
|
||
There are two functions for deleting the contents of a string:
|
||
<code class="code">clear</code> and <code class="code">erase</code> (the latter returns the
|
||
string).
|
||
</p><pre class="programlisting">
|
||
void
|
||
clear() { _M_mutate(0, this->size(), 0); }
|
||
</pre><pre class="programlisting">
|
||
basic_string&
|
||
erase(size_type __pos = 0, size_type __n = npos)
|
||
{
|
||
return this->replace(_M_check(__pos), _M_fold(__pos, __n),
|
||
_M_data(), _M_data());
|
||
}
|
||
</pre><p>
|
||
Unfortunately, <code class="code">clear</code> is not implemented in this
|
||
version, so you should use <code class="code">erase</code> (which is probably
|
||
faster than <code class="code">operator=(charT*)</code>).
|
||
</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="backwards.second.ostreamform_istreamscan"></a>
|
||
Removal of <code class="code">ostream::form</code> and <code class="code">istream::scan</code>
|
||
extensions
|
||
</h4></div></div></div><p>
|
||
These are no longer supported. Please use stringstreams instead.
|
||
</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="backwards.second.stringstreams"></a>No <code class="code">basic_stringbuf</code>, <code class="code">basic_stringstream</code></h4></div></div></div><p>
|
||
Although the ISO standard <code class="code">i/ostringstream</code>-classes are
|
||
provided, (<code class="filename"><sstream></code>), for
|
||
compatibility with older implementations the pre-ISO
|
||
<code class="code">i/ostrstream</code> (<code class="filename"><strstream></code>) interface is also provided,
|
||
with these caveats:
|
||
</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>
|
||
<code class="code">strstream</code> is considered to be deprecated
|
||
</p></li><li class="listitem"><p>
|
||
<code class="code">strstream</code> is limited to <code class="code">char</code>
|
||
</p></li><li class="listitem"><p>
|
||
with <code class="code">ostringstream</code> you don't have to take care of
|
||
terminating the string or freeing its memory
|
||
</p></li><li class="listitem"><p>
|
||
<code class="code">istringstream</code> can be re-filled (clear();
|
||
str(input);)
|
||
</p></li></ul></div><p>
|
||
You can then use output-stringstreams like this:
|
||
</p><pre class="programlisting">
|
||
#ifdef HAVE_SSTREAM
|
||
# include <sstream>
|
||
#else
|
||
# include <strstream>
|
||
#endif
|
||
|
||
#ifdef HAVE_SSTREAM
|
||
std::ostringstream oss;
|
||
#else
|
||
std::ostrstream oss;
|
||
#endif
|
||
|
||
oss << "Name=" << m_name << ", number=" << m_number << std::endl;
|
||
...
|
||
#ifndef HAVE_SSTREAM
|
||
oss << std::ends; // terminate the char*-string
|
||
#endif
|
||
|
||
// str() returns char* for ostrstream and a string for ostringstream
|
||
// this also causes ostrstream to think that the buffer's memory
|
||
// is yours
|
||
m_label.set_text(oss.str());
|
||
#ifndef HAVE_SSTREAM
|
||
// let the ostrstream take care of freeing the memory
|
||
oss.freeze(false);
|
||
#endif
|
||
</pre><p>
|
||
Input-stringstreams can be used similarly:
|
||
</p><pre class="programlisting">
|
||
std::string input;
|
||
...
|
||
#ifdef HAVE_SSTREAM
|
||
std::istringstream iss(input);
|
||
#else
|
||
std::istrstream iss(input.c_str());
|
||
#endif
|
||
|
||
int i;
|
||
iss >> i;
|
||
</pre><p> One (the only?) restriction is that an istrstream cannot be re-filled:
|
||
</p><pre class="programlisting">
|
||
std::istringstream iss(numerator);
|
||
iss >> m_num;
|
||
// this is not possible with istrstream
|
||
iss.clear();
|
||
iss.str(denominator);
|
||
iss >> m_den;
|
||
</pre><p>
|
||
If you don't care about speed, you can put these conversions in
|
||
a template-function:
|
||
</p><pre class="programlisting">
|
||
template <class X>
|
||
void fromString(const string& input, X& any)
|
||
{
|
||
#ifdef HAVE_SSTREAM
|
||
std::istringstream iss(input);
|
||
#else
|
||
std::istrstream iss(input.c_str());
|
||
#endif
|
||
X temp;
|
||
iss >> temp;
|
||
if (iss.fail())
|
||
throw runtime_error(..)
|
||
any = temp;
|
||
}
|
||
</pre><p>
|
||
Another example of using stringstreams is in <a class="link" href="strings.html#strings.string.shrink" title="Shrink to Fit">this howto</a>.
|
||
</p><p> There is additional information in the libstdc++-v2 info files, in
|
||
particular <span class="quote">“<span class="quote">info iostream</span>”</span>.
|
||
</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="backwards.second.wchar"></a>Little or no wide character support</h4></div></div></div><p>
|
||
Classes <code class="classname">wstring</code> and
|
||
<code class="classname">char_traits<wchar_t></code> are
|
||
not supported.
|
||
</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="backwards.second.iostream_templates"></a>No templatized iostreams</h4></div></div></div><p>
|
||
Classes <code class="classname">wfilebuf</code> and
|
||
<code class="classname">wstringstream</code> are not supported.
|
||
</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="backwards.second.thread_safety"></a>Thread safety issues</h4></div></div></div><p>
|
||
Earlier GCC releases had a somewhat different approach to
|
||
threading configuration and proper compilation. Before GCC 3.0,
|
||
configuration of the threading model was dictated by compiler
|
||
command-line options and macros (both of which were somewhat
|
||
thread-implementation and port-specific). There were no
|
||
guarantees related to being able to link code compiled with one
|
||
set of options and macro setting with another set.
|
||
</p><p>
|
||
For GCC 3.0, configuration of the threading model used with
|
||
libraries and user-code is performed when GCC is configured and
|
||
built using the --enable-threads and --disable-threads options.
|
||
The ABI is stable for symbol name-mangling and limited functional
|
||
compatibility exists between code compiled under different
|
||
threading models.
|
||
</p><p>
|
||
The libstdc++ library has been designed so that it can be used in
|
||
multithreaded applications (with libstdc++-v2 this was only true
|
||
of the STL parts.) The first problem is finding a
|
||
<span class="emphasis"><em>fast</em></span> method of implementation portable to
|
||
all platforms. Due to historical reasons, some of the library is
|
||
written against per-CPU-architecture spinlocks and other parts
|
||
against the gthr.h abstraction layer which is provided by gcc. A
|
||
minor problem that pops up every so often is different
|
||
interpretations of what "thread-safe" means for a
|
||
library (not a general program). We currently use the <a class="link" href="http://www.sgi.com/tech/stl/thread_safety.html" target="_top">same
|
||
definition that SGI</a> uses for their STL subset. However,
|
||
the exception for read-only containers only applies to the STL
|
||
components. This definition is widely-used and something similar
|
||
will be used in the next version of the C++ standard library.
|
||
</p><p>
|
||
Here is a small link farm to threads (no pun) in the mail
|
||
archives that discuss the threading problem. Each link is to the
|
||
first relevant message in the thread; from there you can use
|
||
"Thread Next" to move down the thread. This farm is in
|
||
latest-to-oldest order.
|
||
</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>
|
||
Our threading expert Loren gives a breakdown of <a class="link" href="http://gcc.gnu.org/ml/libstdc++/2001-10/msg00024.html" target="_top">the
|
||
six situations involving threads</a> for the 3.0
|
||
release series.
|
||
</p></li><li class="listitem"><p>
|
||
<a class="link" href="http://gcc.gnu.org/ml/libstdc++/2001-05/msg00384.html" target="_top">
|
||
This message</a> inspired a recent updating of issues with
|
||
threading and the SGI STL library. It also contains some
|
||
example POSIX-multithreaded STL code.
|
||
</p></li></ul></div><p>
|
||
(A large selection of links to older messages has been removed;
|
||
many of the messages from 1999 were lost in a disk crash, and the
|
||
few people with access to the backup tapes have been too swamped
|
||
with work to restore them. Many of the points have been
|
||
superseded anyhow.)
|
||
</p></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="backwards.third"></a>Third</h3></div></div></div><p> The third generation GNU C++ library is called libstdc++, or
|
||
libstdc++-v3.
|
||
</p><p>The subset commonly known as the Standard Template Library
|
||
(clauses 23 through 25, mostly) is adapted from the final release
|
||
of the SGI STL (version 3.3), with extensive changes.
|
||
</p><p>A more formal description of the V3 goals can be found in the
|
||
official <a class="link" href="source_design_notes.html" title="Design Notes">design document</a>.
|
||
</p><p>Portability notes and known implementation limitations are as follows.</p><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="backwards.third.headers"></a>Pre-ISO headers moved to backwards or removed</h4></div></div></div><p> The pre-ISO C++ headers
|
||
(<code class="filename"><iostream.h></code>,
|
||
<code class="filename"><defalloc.h></code> etc.) are
|
||
available, unlike previous libstdc++ versions, but inclusion
|
||
generates a warning that you are using deprecated headers.
|
||
</p><p>This compatibility layer is constructed by including the
|
||
standard C++ headers, and injecting any items in
|
||
<code class="code">std::</code> into the global namespace.
|
||
</p><p>For those of you new to ISO C++ (welcome, time travelers!), no,
|
||
that isn't a typo. Yes, the headers really have new names.
|
||
Marshall Cline's C++ FAQ Lite has a good explanation in <a class="link" href="http://www.parashift.com/c++-faq-lite/std-headers.html" target="_top">What's
|
||
the difference between <xxx> and <xxx.h> headers?</a>.
|
||
</p><p> Some include adjustment may be required. What follows is an
|
||
autoconf test that defines <code class="code">PRE_STDCXX_HEADERS</code> when they
|
||
exist.</p><pre class="programlisting">
|
||
# AC_HEADER_PRE_STDCXX
|
||
AC_DEFUN([AC_HEADER_PRE_STDCXX], [
|
||
AC_CACHE_CHECK(for pre-ISO C++ include files,
|
||
ac_cv_cxx_pre_stdcxx,
|
||
[AC_LANG_SAVE
|
||
AC_LANG_CPLUSPLUS
|
||
ac_save_CXXFLAGS="$CXXFLAGS"
|
||
CXXFLAGS="$CXXFLAGS -Wno-deprecated"
|
||
|
||
# Omit defalloc.h, as compilation with newer compilers is problematic.
|
||
AC_TRY_COMPILE([
|
||
#include <new.h>
|
||
#include <iterator.h>
|
||
#include <alloc.h>
|
||
#include <set.h>
|
||
#include <hashtable.h>
|
||
#include <hash_set.h>
|
||
#include <fstream.h>
|
||
#include <tempbuf.h>
|
||
#include <istream.h>
|
||
#include <bvector.h>
|
||
#include <stack.h>
|
||
#include <rope.h>
|
||
#include <complex.h>
|
||
#include <ostream.h>
|
||
#include <heap.h>
|
||
#include <iostream.h>
|
||
#include <function.h>
|
||
#include <multimap.h>
|
||
#include <pair.h>
|
||
#include <stream.h>
|
||
#include <iomanip.h>
|
||
#include <slist.h>
|
||
#include <tree.h>
|
||
#include <vector.h>
|
||
#include <deque.h>
|
||
#include <multiset.h>
|
||
#include <list.h>
|
||
#include <map.h>
|
||
#include <algobase.h>
|
||
#include <hash_map.h>
|
||
#include <algo.h>
|
||
#include <queue.h>
|
||
#include <streambuf.h>
|
||
],,
|
||
ac_cv_cxx_pre_stdcxx=yes, ac_cv_cxx_pre_stdcxx=no)
|
||
CXXFLAGS="$ac_save_CXXFLAGS"
|
||
AC_LANG_RESTORE
|
||
])
|
||
if test "$ac_cv_cxx_pre_stdcxx" = yes; then
|
||
AC_DEFINE(PRE_STDCXX_HEADERS,,[Define if pre-ISO C++ header files are present. ])
|
||
fi
|
||
])
|
||
</pre><p>Porting between pre-ISO headers and ISO headers is simple: headers
|
||
like <code class="filename"><vector.h></code> can be replaced with <code class="filename"><vector></code> and a using
|
||
directive <code class="code">using namespace std;</code> can be put at the global
|
||
scope. This should be enough to get this code compiling, assuming the
|
||
other usage is correct.
|
||
</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="backwards.third.hash"></a>Extension headers hash_map, hash_set moved to ext or backwards</h4></div></div></div><p>At this time most of the features of the SGI STL extension have been
|
||
replaced by standardized libraries.
|
||
In particular, the <code class="classname">unordered_map</code> and
|
||
<code class="classname">unordered_set</code> containers of TR1 and C++ 2011
|
||
are suitable replacements for the non-standard
|
||
<code class="classname">hash_map</code> and <code class="classname">hash_set</code>
|
||
containers in the SGI STL.
|
||
</p><p> Header files <code class="filename"><hash_map></code> and <code class="filename"><hash_set></code> moved
|
||
to <code class="filename"><ext/hash_map></code> and <code class="filename"><ext/hash_set></code>,
|
||
respectively. At the same time, all types in these files are enclosed
|
||
in <code class="code">namespace __gnu_cxx</code>. Later versions deprecate
|
||
these files, and suggest using TR1's <code class="filename"><unordered_map></code>
|
||
and <code class="filename"><unordered_set></code> instead.
|
||
</p><p>The extensions are no longer in the global or <code class="code">std</code>
|
||
namespaces, instead they are declared in the <code class="code">__gnu_cxx</code>
|
||
namespace. For maximum portability, consider defining a namespace
|
||
alias to use to talk about extensions, e.g.:
|
||
</p><pre class="programlisting">
|
||
#ifdef __GNUC__
|
||
#if __GNUC__ < 3
|
||
#include <hash_map.h>
|
||
namespace extension { using ::hash_map; }; // inherit globals
|
||
#else
|
||
#include <backward/hash_map>
|
||
#if __GNUC__ == 3 && __GNUC_MINOR__ == 0
|
||
namespace extension = std; // GCC 3.0
|
||
#else
|
||
namespace extension = ::__gnu_cxx; // GCC 3.1 and later
|
||
#endif
|
||
#endif
|
||
#else // ... there are other compilers, right?
|
||
namespace extension = std;
|
||
#endif
|
||
|
||
extension::hash_map<int,int> my_map;
|
||
</pre><p>This is a bit cleaner than defining typedefs for all the
|
||
instantiations you might need.
|
||
</p><p>The following autoconf tests check for working HP/SGI hash containers.
|
||
</p><pre class="programlisting">
|
||
# AC_HEADER_EXT_HASH_MAP
|
||
AC_DEFUN([AC_HEADER_EXT_HASH_MAP], [
|
||
AC_CACHE_CHECK(for ext/hash_map,
|
||
ac_cv_cxx_ext_hash_map,
|
||
[AC_LANG_SAVE
|
||
AC_LANG_CPLUSPLUS
|
||
ac_save_CXXFLAGS="$CXXFLAGS"
|
||
CXXFLAGS="$CXXFLAGS -Werror"
|
||
AC_TRY_COMPILE([#include <ext/hash_map>], [using __gnu_cxx::hash_map;],
|
||
ac_cv_cxx_ext_hash_map=yes, ac_cv_cxx_ext_hash_map=no)
|
||
CXXFLAGS="$ac_save_CXXFLAGS"
|
||
AC_LANG_RESTORE
|
||
])
|
||
if test "$ac_cv_cxx_ext_hash_map" = yes; then
|
||
AC_DEFINE(HAVE_EXT_HASH_MAP,,[Define if ext/hash_map is present. ])
|
||
fi
|
||
])
|
||
</pre><pre class="programlisting">
|
||
# AC_HEADER_EXT_HASH_SET
|
||
AC_DEFUN([AC_HEADER_EXT_HASH_SET], [
|
||
AC_CACHE_CHECK(for ext/hash_set,
|
||
ac_cv_cxx_ext_hash_set,
|
||
[AC_LANG_SAVE
|
||
AC_LANG_CPLUSPLUS
|
||
ac_save_CXXFLAGS="$CXXFLAGS"
|
||
CXXFLAGS="$CXXFLAGS -Werror"
|
||
AC_TRY_COMPILE([#include <ext/hash_set>], [using __gnu_cxx::hash_set;],
|
||
ac_cv_cxx_ext_hash_set=yes, ac_cv_cxx_ext_hash_set=no)
|
||
CXXFLAGS="$ac_save_CXXFLAGS"
|
||
AC_LANG_RESTORE
|
||
])
|
||
if test "$ac_cv_cxx_ext_hash_set" = yes; then
|
||
AC_DEFINE(HAVE_EXT_HASH_SET,,[Define if ext/hash_set is present. ])
|
||
fi
|
||
])
|
||
</pre></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="backwards.third.nocreate_noreplace"></a>No <code class="code">ios::nocreate/ios::noreplace</code>.
|
||
</h4></div></div></div><p>Historically these flags were used with iostreams to control whether
|
||
new files are created or not when opening a file stream, similar to the
|
||
<code class="code">O_CREAT</code> and <code class="code">O_EXCL</code> flags for the
|
||
<code class="function">open(2)</code> system call. Because iostream modes correspond
|
||
to <code class="function">fopen(3)</code> modes these flags are not supported.
|
||
For input streams a new file will not be created anyway, so
|
||
<code class="code">ios::nocreate</code> is not needed.
|
||
For output streams, a new file will be created if it does not exist, which is
|
||
consistent with the behaviour of <code class="function">fopen</code>.
|
||
</p><p>When one of these flags is needed a possible alternative is to attempt
|
||
to open the file using <span class="type">std::ifstream</span> first to determine whether
|
||
the file already exists or not. This may not be reliable however, because
|
||
whether the file exists or not could change between opening the
|
||
<span class="type">std::istream</span> and re-opening with an output stream. If you need
|
||
to check for existence and open a file as a single operation then you will
|
||
need to use OS-specific facilities outside the C++ standard library, such
|
||
as <code class="function">open(2)</code>.
|
||
</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="backwards.third.streamattach"></a>
|
||
No <code class="code">stream::attach(int fd)</code>
|
||
</h4></div></div></div><p>
|
||
Phil Edwards writes: It was considered and rejected for the ISO
|
||
standard. Not all environments use file descriptors. Of those
|
||
that do, not all of them use integers to represent them.
|
||
</p><p>
|
||
For a portable solution (among systems which use
|
||
file descriptors), you need to implement a subclass of
|
||
<code class="code">std::streambuf</code> (or
|
||
<code class="code">std::basic_streambuf<..></code>) which opens a file
|
||
given a descriptor, and then pass an instance of this to the
|
||
stream-constructor.
|
||
</p><p>
|
||
An extension is available that implements this.
|
||
<code class="filename"><ext/stdio_filebuf.h></code> contains a derived class called
|
||
<a class="link" href="http://gcc.gnu.org/onlinedocs/libstdc++/latest-doxygen/a00074.html" target="_top"><code class="code">__gnu_cxx::stdio_filebuf</code></a>.
|
||
This class can be constructed from a C <code class="code">FILE*</code> or a file
|
||
descriptor, and provides the <code class="code">fd()</code> function.
|
||
</p><p>
|
||
For another example of this, refer to
|
||
<a class="link" href="http://www.josuttis.com/cppcode/fdstream.html" target="_top">fdstream example</a>
|
||
by Nicolai Josuttis.
|
||
</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="backwards.third.support_cxx98"></a>
|
||
Support for C++98 dialect.
|
||
</h4></div></div></div><p>Check for complete library coverage of the C++1998/2003 standard.
|
||
</p><pre class="programlisting">
|
||
# AC_HEADER_STDCXX_98
|
||
AC_DEFUN([AC_HEADER_STDCXX_98], [
|
||
AC_CACHE_CHECK(for ISO C++ 98 include files,
|
||
ac_cv_cxx_stdcxx_98,
|
||
[AC_LANG_SAVE
|
||
AC_LANG_CPLUSPLUS
|
||
AC_TRY_COMPILE([
|
||
#include <cassert>
|
||
#include <cctype>
|
||
#include <cerrno>
|
||
#include <cfloat>
|
||
#include <ciso646>
|
||
#include <climits>
|
||
#include <clocale>
|
||
#include <cmath>
|
||
#include <csetjmp>
|
||
#include <csignal>
|
||
#include <cstdarg>
|
||
#include <cstddef>
|
||
#include <cstdio>
|
||
#include <cstdlib>
|
||
#include <cstring>
|
||
#include <ctime>
|
||
|
||
#include <algorithm>
|
||
#include <bitset>
|
||
#include <complex>
|
||
#include <deque>
|
||
#include <exception>
|
||
#include <fstream>
|
||
#include <functional>
|
||
#include <iomanip>
|
||
#include <ios>
|
||
#include <iosfwd>
|
||
#include <iostream>
|
||
#include <istream>
|
||
#include <iterator>
|
||
#include <limits>
|
||
#include <list>
|
||
#include <locale>
|
||
#include <map>
|
||
#include <memory>
|
||
#include <new>
|
||
#include <numeric>
|
||
#include <ostream>
|
||
#include <queue>
|
||
#include <set>
|
||
#include <sstream>
|
||
#include <stack>
|
||
#include <stdexcept>
|
||
#include <streambuf>
|
||
#include <string>
|
||
#include <typeinfo>
|
||
#include <utility>
|
||
#include <valarray>
|
||
#include <vector>
|
||
],,
|
||
ac_cv_cxx_stdcxx_98=yes, ac_cv_cxx_stdcxx_98=no)
|
||
AC_LANG_RESTORE
|
||
])
|
||
if test "$ac_cv_cxx_stdcxx_98" = yes; then
|
||
AC_DEFINE(STDCXX_98_HEADERS,,[Define if ISO C++ 1998 header files are present. ])
|
||
fi
|
||
])
|
||
</pre></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="backwards.third.support_tr1"></a>
|
||
Support for C++TR1 dialect.
|
||
</h4></div></div></div><p>Check for library coverage of the TR1 standard.
|
||
</p><pre class="programlisting">
|
||
# AC_HEADER_STDCXX_TR1
|
||
AC_DEFUN([AC_HEADER_STDCXX_TR1], [
|
||
AC_CACHE_CHECK(for ISO C++ TR1 include files,
|
||
ac_cv_cxx_stdcxx_tr1,
|
||
[AC_LANG_SAVE
|
||
AC_LANG_CPLUSPLUS
|
||
AC_TRY_COMPILE([
|
||
#include <tr1/array>
|
||
#include <tr1/ccomplex>
|
||
#include <tr1/cctype>
|
||
#include <tr1/cfenv>
|
||
#include <tr1/cfloat>
|
||
#include <tr1/cinttypes>
|
||
#include <tr1/climits>
|
||
#include <tr1/cmath>
|
||
#include <tr1/complex>
|
||
#include <tr1/cstdarg>
|
||
#include <tr1/cstdbool>
|
||
#include <tr1/cstdint>
|
||
#include <tr1/cstdio>
|
||
#include <tr1/cstdlib>
|
||
#include <tr1/ctgmath>
|
||
#include <tr1/ctime>
|
||
#include <tr1/cwchar>
|
||
#include <tr1/cwctype>
|
||
#include <tr1/functional>
|
||
#include <tr1/memory>
|
||
#include <tr1/random>
|
||
#include <tr1/regex>
|
||
#include <tr1/tuple>
|
||
#include <tr1/type_traits>
|
||
#include <tr1/unordered_set>
|
||
#include <tr1/unordered_map>
|
||
#include <tr1/utility>
|
||
],,
|
||
ac_cv_cxx_stdcxx_tr1=yes, ac_cv_cxx_stdcxx_tr1=no)
|
||
AC_LANG_RESTORE
|
||
])
|
||
if test "$ac_cv_cxx_stdcxx_tr1" = yes; then
|
||
AC_DEFINE(STDCXX_TR1_HEADERS,,[Define if ISO C++ TR1 header files are present. ])
|
||
fi
|
||
])
|
||
</pre><p>An alternative is to check just for specific TR1 includes, such as <unordered_map> and <unordered_set>.
|
||
</p><pre class="programlisting">
|
||
# AC_HEADER_TR1_UNORDERED_MAP
|
||
AC_DEFUN([AC_HEADER_TR1_UNORDERED_MAP], [
|
||
AC_CACHE_CHECK(for tr1/unordered_map,
|
||
ac_cv_cxx_tr1_unordered_map,
|
||
[AC_LANG_SAVE
|
||
AC_LANG_CPLUSPLUS
|
||
AC_TRY_COMPILE([#include <tr1/unordered_map>], [using std::tr1::unordered_map;],
|
||
ac_cv_cxx_tr1_unordered_map=yes, ac_cv_cxx_tr1_unordered_map=no)
|
||
AC_LANG_RESTORE
|
||
])
|
||
if test "$ac_cv_cxx_tr1_unordered_map" = yes; then
|
||
AC_DEFINE(HAVE_TR1_UNORDERED_MAP,,[Define if tr1/unordered_map is present. ])
|
||
fi
|
||
])
|
||
</pre><pre class="programlisting">
|
||
# AC_HEADER_TR1_UNORDERED_SET
|
||
AC_DEFUN([AC_HEADER_TR1_UNORDERED_SET], [
|
||
AC_CACHE_CHECK(for tr1/unordered_set,
|
||
ac_cv_cxx_tr1_unordered_set,
|
||
[AC_LANG_SAVE
|
||
AC_LANG_CPLUSPLUS
|
||
AC_TRY_COMPILE([#include <tr1/unordered_set>], [using std::tr1::unordered_set;],
|
||
ac_cv_cxx_tr1_unordered_set=yes, ac_cv_cxx_tr1_unordered_set=no)
|
||
AC_LANG_RESTORE
|
||
])
|
||
if test "$ac_cv_cxx_tr1_unordered_set" = yes; then
|
||
AC_DEFINE(HAVE_TR1_UNORDERED_SET,,[Define if tr1/unordered_set is present. ])
|
||
fi
|
||
])
|
||
</pre></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="backwards.third.support_cxx11"></a>
|
||
Support for C++11 dialect.
|
||
</h4></div></div></div><p>Check for baseline language coverage in the compiler for the C++11 standard.
|
||
</p><pre class="programlisting">
|
||
# AC_COMPILE_STDCXX_11
|
||
AC_DEFUN([AC_COMPILE_STDCXX_11], [
|
||
AC_CACHE_CHECK(if g++ supports C++11 features without additional flags,
|
||
ac_cv_cxx_compile_cxx11_native,
|
||
[AC_LANG_SAVE
|
||
AC_LANG_CPLUSPLUS
|
||
AC_TRY_COMPILE([
|
||
template <typename T>
|
||
struct check final
|
||
{
|
||
static constexpr T value{ __cplusplus };
|
||
};
|
||
|
||
typedef check<check<bool>> right_angle_brackets;
|
||
|
||
int a;
|
||
decltype(a) b;
|
||
|
||
typedef check<int> check_type;
|
||
check_type c{};
|
||
check_type&& cr = static_cast<check_type&&>(c);
|
||
|
||
static_assert(check_type::value == 201103L, "C++11 compiler");],,
|
||
ac_cv_cxx_compile_cxx11_native=yes, ac_cv_cxx_compile_cxx11_native=no)
|
||
AC_LANG_RESTORE
|
||
])
|
||
|
||
AC_CACHE_CHECK(if g++ supports C++11 features with -std=c++11,
|
||
ac_cv_cxx_compile_cxx11_cxx,
|
||
[AC_LANG_SAVE
|
||
AC_LANG_CPLUSPLUS
|
||
ac_save_CXXFLAGS="$CXXFLAGS"
|
||
CXXFLAGS="$CXXFLAGS -std=c++11"
|
||
AC_TRY_COMPILE([
|
||
template <typename T>
|
||
struct check final
|
||
{
|
||
static constexpr T value{ __cplusplus };
|
||
};
|
||
|
||
typedef check<check<bool>> right_angle_brackets;
|
||
|
||
int a;
|
||
decltype(a) b;
|
||
|
||
typedef check<int> check_type;
|
||
check_type c{};
|
||
check_type&& cr = static_cast<check_type&&>(c);
|
||
|
||
static_assert(check_type::value == 201103L, "C++11 compiler");],,
|
||
ac_cv_cxx_compile_cxx11_cxx=yes, ac_cv_cxx_compile_cxx11_cxx=no)
|
||
CXXFLAGS="$ac_save_CXXFLAGS"
|
||
AC_LANG_RESTORE
|
||
])
|
||
|
||
AC_CACHE_CHECK(if g++ supports C++11 features with -std=gnu++11,
|
||
ac_cv_cxx_compile_cxx11_gxx,
|
||
[AC_LANG_SAVE
|
||
AC_LANG_CPLUSPLUS
|
||
ac_save_CXXFLAGS="$CXXFLAGS"
|
||
CXXFLAGS="$CXXFLAGS -std=gnu++11"
|
||
AC_TRY_COMPILE([
|
||
template <typename T>
|
||
struct check final
|
||
{
|
||
static constexpr T value{ __cplusplus };
|
||
};
|
||
|
||
typedef check<check<bool>> right_angle_brackets;
|
||
|
||
int a;
|
||
decltype(a) b;
|
||
|
||
typedef check<int> check_type;
|
||
check_type c{};
|
||
check_type&& cr = static_cast<check_type&&>(c);
|
||
|
||
static_assert(check_type::value == 201103L, "C++11 compiler");],,
|
||
ac_cv_cxx_compile_cxx11_gxx=yes, ac_cv_cxx_compile_cxx11_gxx=no)
|
||
CXXFLAGS="$ac_save_CXXFLAGS"
|
||
AC_LANG_RESTORE
|
||
])
|
||
|
||
if test "$ac_cv_cxx_compile_cxx11_native" = yes ||
|
||
test "$ac_cv_cxx_compile_cxx11_cxx" = yes ||
|
||
test "$ac_cv_cxx_compile_cxx11_gxx" = yes; then
|
||
AC_DEFINE(HAVE_STDCXX_11,,[Define if g++ supports C++11 features. ])
|
||
fi
|
||
])
|
||
</pre><p>Check for library coverage of the C++2011 standard.
|
||
(Some library headers are commented out in this check, they are
|
||
not currently provided by libstdc++).
|
||
</p><pre class="programlisting">
|
||
# AC_HEADER_STDCXX_11
|
||
AC_DEFUN([AC_HEADER_STDCXX_11], [
|
||
AC_CACHE_CHECK(for ISO C++11 include files,
|
||
ac_cv_cxx_stdcxx_11,
|
||
[AC_REQUIRE([AC_COMPILE_STDCXX_11])
|
||
AC_LANG_SAVE
|
||
AC_LANG_CPLUSPLUS
|
||
ac_save_CXXFLAGS="$CXXFLAGS"
|
||
CXXFLAGS="$CXXFLAGS -std=gnu++11"
|
||
|
||
AC_TRY_COMPILE([
|
||
#include <cassert>
|
||
#include <ccomplex>
|
||
#include <cctype>
|
||
#include <cerrno>
|
||
#include <cfenv>
|
||
#include <cfloat>
|
||
#include <cinttypes>
|
||
#include <ciso646>
|
||
#include <climits>
|
||
#include <clocale>
|
||
#include <cmath>
|
||
#include <csetjmp>
|
||
#include <csignal>
|
||
#include <cstdalign>
|
||
#include <cstdarg>
|
||
#include <cstdbool>
|
||
#include <cstddef>
|
||
#include <cstdint>
|
||
#include <cstdio>
|
||
#include <cstdlib>
|
||
#include <cstring>
|
||
#include <ctgmath>
|
||
#include <ctime>
|
||
// #include <cuchar>
|
||
#include <cwchar>
|
||
#include <cwctype>
|
||
|
||
#include <algorithm>
|
||
#include <array>
|
||
#include <atomic>
|
||
#include <bitset>
|
||
#include <chrono>
|
||
// #include <codecvt>
|
||
#include <complex>
|
||
#include <condition_variable>
|
||
#include <deque>
|
||
#include <exception>
|
||
#include <forward_list>
|
||
#include <fstream>
|
||
#include <functional>
|
||
#include <future>
|
||
#include <initializer_list>
|
||
#include <iomanip>
|
||
#include <ios>
|
||
#include <iosfwd>
|
||
#include <iostream>
|
||
#include <istream>
|
||
#include <iterator>
|
||
#include <limits>
|
||
#include <list>
|
||
#include <locale>
|
||
#include <map>
|
||
#include <memory>
|
||
#include <mutex>
|
||
#include <new>
|
||
#include <numeric>
|
||
#include <ostream>
|
||
#include <queue>
|
||
#include <random>
|
||
#include <ratio>
|
||
#include <regex>
|
||
#include <scoped_allocator>
|
||
#include <set>
|
||
#include <sstream>
|
||
#include <stack>
|
||
#include <stdexcept>
|
||
#include <streambuf>
|
||
#include <string>
|
||
#include <system_error>
|
||
#include <thread>
|
||
#include <tuple>
|
||
#include <typeindex>
|
||
#include <typeinfo>
|
||
#include <type_traits>
|
||
#include <unordered_map>
|
||
#include <unordered_set>
|
||
#include <utility>
|
||
#include <valarray>
|
||
#include <vector>
|
||
],,
|
||
ac_cv_cxx_stdcxx_11=yes, ac_cv_cxx_stdcxx_11=no)
|
||
AC_LANG_RESTORE
|
||
CXXFLAGS="$ac_save_CXXFLAGS"
|
||
])
|
||
if test "$ac_cv_cxx_stdcxx_11" = yes; then
|
||
AC_DEFINE(STDCXX_11_HEADERS,,[Define if ISO C++11 header files are present. ])
|
||
fi
|
||
])
|
||
</pre><p>As is the case for TR1 support, these autoconf macros can be made for a finer-grained, per-header-file check. For
|
||
<code class="filename"><unordered_map></code>
|
||
</p><pre class="programlisting">
|
||
# AC_HEADER_UNORDERED_MAP
|
||
AC_DEFUN([AC_HEADER_UNORDERED_MAP], [
|
||
AC_CACHE_CHECK(for unordered_map,
|
||
ac_cv_cxx_unordered_map,
|
||
[AC_REQUIRE([AC_COMPILE_STDCXX_11])
|
||
AC_LANG_SAVE
|
||
AC_LANG_CPLUSPLUS
|
||
ac_save_CXXFLAGS="$CXXFLAGS"
|
||
CXXFLAGS="$CXXFLAGS -std=gnu++11"
|
||
AC_TRY_COMPILE([#include <unordered_map>], [using std::unordered_map;],
|
||
ac_cv_cxx_unordered_map=yes, ac_cv_cxx_unordered_map=no)
|
||
CXXFLAGS="$ac_save_CXXFLAGS"
|
||
AC_LANG_RESTORE
|
||
])
|
||
if test "$ac_cv_cxx_unordered_map" = yes; then
|
||
AC_DEFINE(HAVE_UNORDERED_MAP,,[Define if unordered_map is present. ])
|
||
fi
|
||
])
|
||
</pre><pre class="programlisting">
|
||
# AC_HEADER_UNORDERED_SET
|
||
AC_DEFUN([AC_HEADER_UNORDERED_SET], [
|
||
AC_CACHE_CHECK(for unordered_set,
|
||
ac_cv_cxx_unordered_set,
|
||
[AC_REQUIRE([AC_COMPILE_STDCXX_11])
|
||
AC_LANG_SAVE
|
||
AC_LANG_CPLUSPLUS
|
||
ac_save_CXXFLAGS="$CXXFLAGS"
|
||
CXXFLAGS="$CXXFLAGS -std=gnu++11"
|
||
AC_TRY_COMPILE([#include <unordered_set>], [using std::unordered_set;],
|
||
ac_cv_cxx_unordered_set=yes, ac_cv_cxx_unordered_set=no)
|
||
CXXFLAGS="$ac_save_CXXFLAGS"
|
||
AC_LANG_RESTORE
|
||
])
|
||
if test "$ac_cv_cxx_unordered_set" = yes; then
|
||
AC_DEFINE(HAVE_UNORDERED_SET,,[Define if unordered_set is present. ])
|
||
fi
|
||
])
|
||
</pre><p>
|
||
Some C++11 features first appeared in GCC 4.3 and could be enabled by
|
||
<code class="option">-std=c++0x</code> and <code class="option">-std=gnu++0x</code> for GCC
|
||
releases which pre-date the 2011 standard. Those C++11 features and GCC's
|
||
support for them were still changing until the 2011 standard was finished,
|
||
but the autoconf checks above could be extended to test for incomplete
|
||
C++11 support with <code class="option">-std=c++0x</code> and
|
||
<code class="option">-std=gnu++0x</code>.
|
||
</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="backwards.third.iterator_type"></a>
|
||
<code class="code">Container::iterator_type</code> is not necessarily <code class="code">Container::value_type*</code>
|
||
</h4></div></div></div><p>
|
||
This is a change in behavior from older versions. Now, most
|
||
<span class="type">iterator_type</span> typedefs in container classes are POD
|
||
objects, not <span class="type">value_type</span> pointers.
|
||
</p></div></div><div class="bibliography"><div class="titlepage"><div><div><h3 class="title"><a id="backwards.biblio"></a>Bibliography</h3></div></div></div><div class="biblioentry"><a id="id-1.3.6.3.8.5.2"></a><p><span class="title"><em>
|
||
<a class="link" href="http://www.kegel.com/gcc/gcc4.html" target="_top">
|
||
Migrating to GCC 4.1
|
||
</a>
|
||
</em>. </span><span class="author"><span class="firstname">Dan</span> <span class="surname">Kegel</span>. </span></p></div><div class="biblioentry"><a id="id-1.3.6.3.8.5.3"></a><p><span class="title"><em>
|
||
<a class="link" href="https://lists.debian.org/debian-gcc/2006/03/msg00405.html" target="_top">
|
||
Building the Whole Debian Archive with GCC 4.1: A Summary
|
||
</a>
|
||
</em>. </span><span class="author"><span class="firstname">Martin</span> <span class="surname">Michlmayr</span>. </span></p></div><div class="biblioentry"><a id="id-1.3.6.3.8.5.4"></a><p><span class="title"><em>
|
||
<a class="link" href="http://annwm.lbl.gov/~leggett/Atlas/gcc-3.2.html" target="_top">
|
||
Migration guide for GCC-3.2
|
||
</a>
|
||
</em>. </span></p></div></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="api.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="appendix_porting.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="appendix_free.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">API Evolution and Deprecation History </td><td width="20%" align="center"><a accesskey="h" href="../index.html">Home</a></td><td width="40%" align="right" valign="top"> Appendix C.
|
||
Free Software Needs Free Documentation
|
||
|
||
</td></tr></table></div></body></html>
|