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<html><head><META http-equiv="Content-Type" content="text/html; charset=iso-8859-1"><title>STLport: Note for GCC users</title><link href="doc.css" type="text/css" rel="stylesheet"></head><body marginwidth="0" marginheight="0" leftmargin="0" topmargin="0" vlink="#314A30" link="#314A30" text="black" bgcolor="white"><table border="0" cellspacing="0" cellpadding="0"><tr valign="top" align="left"><td width="24"><img src="images/trans.gif" border="0" height="1" width="24"></td><td width="776"><img border="0" height="14" width="1" src="images/trans.gif"><br><a href="../index.html"><img src="images/stl_logo_doc.gif" border="0" height="80" width="80"></a><a href="http://www.stlport.com"><img border="0" height="80" width="461" src="images/t_doc2.gif"></a><br><img src="images/trans.gif" border="0" height="24" width="1"><br><img src="images/black.gif" border="0" height="1" width="776"><br><img src="images/trans.gif" border="0" height="24" width="1"></td></tr><tr valign="top" align="left"><td width="24"><img src="images/trans.gif" border="0" height="1" width="24"></td><td width="776"><img src="images/trans.gif" border="0" height="10" width="776"></td></tr><tr valign="top" align="left"><td width="24"><img src="images/trans.gif" border="0" height="1" width="24"></td><td width="776">
<span class="heading">Note for GCC users</span>
<hr>
<h3>GCC versions</h3>
STLport works with the following GCC flavours:
<p>gcc-3.0 Note : "wrapper mode" w/o STLport iostreams doesn't work with 3.0, as gcc 3.0 implements Koenig lookup properly, which leads to ambiguity errors when trying to wrap new-style gcc iostreams into STLport namespace.</p>
<p>gcc-2.95.x Note: on some platforms (HP, AIX) gcc-2.95 does not implement automatic instantiation of static template data members. Please refer to gcc-2.7 section below for workaround. </p>
<p><a href="http://www.cygnus.com/egcs">Cygnus "egcs":</a>
Based on gcc-2.8 development tree, it provides <b>better </b>template
support than in FSF gcc-2.8.1, and many modern commercial compilers. It
features full-blown default template parameters, namespaces, partial
template specialization and member template methods. EGCS also offers
greatly improved EH support.&nbsp; STLport works with egcs just fine.
Though it comes with SGI STL, <br>
you may still want to use STLport because of debug mode.</p>
<p>gcc-2.8.1: About the same as egcs. <br>
<i>( Note : you may encounter problems compiling with 2.8.1 due to bugs
in partial template specialization. Just #define _STLP_PARTIAL_SPECIALIZATION_BUG
then ) </i>.</p>
<p>If you use egcs or 2.8.1 or higher, you may stop reading here.</p>
<p>&nbsp;</p>
<hr width="100%">
<h3>GCC 2.7.x :</h3>
Althought it does work with STLport, it has poor template support
compared to other modern compilers. <br>
If you do generic programming, it's definitely time to upgrade.
<h3>Workaround strategy</h3>
To address GCC inability to auto-instantiate static template data
members, the following workaround introduced:
<p>Instantiations of required static data members provided in
corresponing headers under <i>#ifdef </i><tt>__PUT_STATIC_DATA_MEMBERS_HERE</tt>
( luckily, in this version of STL their amount doesn't depend on how
many different instantiations you have ). You should <tt>#define __PUT_STATIC_DATA_MEMBERS_HERE</tt><i>
</i>in <b>one</b> of your compilation unit ( or specify it in <i>CFLAGS </i>for
it ) <b>before </b>including any STL header. That should not affect
'good' compilers in any way.</p>
<p><b>Moreover,</b> <b>gcc on platforms that use ELF object file format
or GNU linker, will work without this hack</b>. gcc's <b><i>__attribute__((weak))__</i></b>
used instead as workaround. That makes gcc usable in portable way with
STL on many platforms ( Linux/Solaris/etc. ).</p>
<p>&nbsp;</p>
<hr>
<h2>Known problems</h2>
<h4>Compiling</h4>
See <a href="#Migration%20notes">Migration notes</a>.
<h4>Linking</h4>
When using <i>__attribute__((weak))__<b> </b></i>, you may run into
linker errors like : <b>'multiple definition of `global constructors
keyed to __malloc_alloc_template&lt;0&gt;::oom_handler'</b>. <br>
That indicates that you have defined some global objects in your source.
gcc then produce a bug treating weak symbol declared in header as real
global. <br>
The workaround is simple : just put some dummy global variable <b>before
</b>including STL headers. That worked for me. <br>
Another way is to <tt>#define _STLP_WEAK_ATTRIBUTE 0 </tt>in <b><i>stlconf.h</i></b>
and use <tt>__PUT_STATIC_DATA_MEMBERS_HERE</tt> scheme described above.
<p>On some non-ELF systems (<b>SunOS 4.x</b>) "configure" sets
<tt>_STLP_WEAK_ATTRIBUTE. </tt>Unfortunately, this won't work unless you
are using GNU linker. To justify this, <tt>#define _STLP_WEAK_ATTRIBUTE
0 </tt>in <b><i>stlconf.h</i></b> and use <tt>__PUT_STATIC_DATA_MEMBERS_HERE</tt>
scheme described above.</p>
<p>You may have troubles getting _linker_ errors compiling complex cases
without <i>-frepo</i>. If that problem occurs, try <i>-frepo</i> flag.
This flag is generally preferred unless you are compiling really short
examples. Be sure to supply -frepo switch on the link stage, too.</p>
<p>&nbsp;</p>
<hr>
<h2><a name="Migration%20notes"></a>Migration notes</h2>
You may have to define operators ==() and &lt;() on all classes you are
using with most containers, even if they are not really used. That is
the gcc bug. Another bug is that gcc won't find this operators defined
in base class, you have to redefine them. Don't define any of
!=(),&gt;(),&lt;=(),&gt;=;() operators for your classes - gcc have bugs
in resolution and report that as ambiguity with templates in <i>function.h.</i>
<p>If you use <tt>&lt;string&gt;</tt> from <tt>libg++</tt> the described
problem of the definition of <tt>!=, &gt;, &lt;=</tt> and <tt>&gt;=</tt>
occurs: something like: "<tt>ambiguous template instantiation in
sinst.h</tt>" The concrete solution is to disable the definitions
of those operators in <tt>g++-include/std/sinst.h (line 59):</tt></p>
<p><tt>__DOB (==)</tt> <br>
<tt>//__DOB (!=)</tt> <br>
<tt>__DOB (&gt;)</tt> <br>
<tt>//__DOB (&gt;)</tt> <br>
<tt>//__DOB (&lt;=)</tt> <br>
<tt>//__DOB (&lt;=)</tt> <br>
<tt>//__DOB (&gt;=)</tt></p>
<p>This would be a general fix due to gcc problems. The other possible
solution is to <tt>#include &lt;string&gt;</tt> after STL headers.</p>
</td></tr><tr valign="top" align="left"><td width="24"><img src="images/trans.gif" border="0" height="1" width="24"></td><td width="776"><img src="images/trans.gif" border="0" height="20" width="50"><br><a href="index.html">Table of Contents</a><br></td></tr><tr valign="top" align="left"><td width="24"><img src="images/trans.gif" border="0" height="1" width="24"></td><td width="776"><img src="images/trans.gif" border="0" height="40" width="80"><br><img src="images/black.gif" border="0" height="1" width="776"></td></tr><tr valign="top" align="left"><td width="24"><img src="images/trans.gif" border="0" height="1" width="24"></td><td width="776"><img src="images/black.gif" border="0" height="1" width="776"></td></tr><tr valign="top" align="left"><td width="24"><img src="images/trans.gif" border="0" height="1" width="24"></td><td width="776"><img src="images/trans.gif" border="0" height="5" width="50"><br><span class="copyright">Copyright 2001 by STLport</span><br><img src="images/trans.gif" border="0" height="50" width="80"></td></tr></table></body></html>