doc/html/boost_dll/limitations.html

   1 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
   2 <html>
   3 <head>
   4 <meta http-equiv="Content-Type" content="text/html; charset=US-ASCII">
   5 <title>Limitations</title>
   6 <link rel="stylesheet" href="../../../doc/src/boostbook.css" type="text/css">
   7 <meta name="generator" content="DocBook XSL Stylesheets V1.79.1">
   8 <link rel="home" href="../index.html" title="The Boost C++ Libraries BoostBook Documentation Subset">
   9 <link rel="up" href="../boost_dll.html" title="Chapter&#160;14.&#160;Boost.DLL">
  10 <link rel="prev" href="../boost/dll/experimental/import_mangled.html" title="Function import_mangled">
  11 <link rel="next" href="f_a_q_.html" title="F.A.Q.">
  12 </head>
  13 <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
  14 <table cellpadding="2" width="100%"><tr>
  15 <td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../boost.png"></td>
  16 <td align="center"><a href="../../../index.html">Home</a></td>
  17 <td align="center"><a href="../../../libs/libraries.htm">Libraries</a></td>
  18 <td align="center"><a href="http://www.boost.org/users/people.html">People</a></td>
  19 <td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td>
  20 <td align="center"><a href="../../../more/index.htm">More</a></td>
  21 </tr></table>
  22 <hr>
  23 <div class="spirit-nav">
  24 <a accesskey="p" href="../boost/dll/experimental/import_mangled.html"><img src="../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../boost_dll.html"><img src="../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="f_a_q_.html"><img src="../../../doc/src/images/next.png" alt="Next"></a>
  25 </div>
  26 <div class="section">
  27 <div class="titlepage"><div><div><h2 class="title" style="clear: both">
  28 <a name="boost_dll.limitations"></a><a class="link" href="limitations.html" title="Limitations">Limitations</a>
  29 </h2></div></div></div>
  30 <div class="toc"><dl class="toc">
  31 <dt><span class="section"><a href="limitations.html#boost_dll.limitations.exporting_weak_symbols__fails_on_mingw__android_">Exporting
  32       weak symbols (Fails on MinGW, Android)</a></span></dt>
  33 <dt><span class="section"><a href="limitations.html#boost_dll.limitations.user_defined_section_names__fails_on_sunos___oracle_solaris_studio_compilers_">User
  34       defined section names (Fails on SunOS + Oracle Solaris Studio Compilers)</a></span></dt>
  35 <dt><span class="section"><a href="limitations.html#boost_dll.limitations.multithread">Thread safe library
  36       loading (Fails on FreeBSD, MacOS, iOS and some other)</a></span></dt>
  37 <dt><span class="section"><a href="limitations.html#boost_dll.limitations.nested">Nested Function Definitions</a></span></dt>
  38 </dl></div>
  39 <p>
  40       Some platforms and compilers do not provide all the required functionality
  41       to have a fully functional Boost.DLL. Such compilers are mentioned in this
  42       section along with possible workarounds for those limitations.
  43     </p>
  44 <div class="section">
  45 <div class="titlepage"><div><div><h3 class="title">
  46 <a name="boost_dll.limitations.exporting_weak_symbols__fails_on_mingw__android_"></a><a class="link" href="limitations.html#boost_dll.limitations.exporting_weak_symbols__fails_on_mingw__android_" title="Exporting weak symbols (Fails on MinGW, Android)">Exporting
  47       weak symbols (Fails on MinGW, Android)</a>
  48 </h3></div></div></div>
  49 <p>
  50         Some versions of Android, <code class="computeroutput"><span class="identifier">MinGW</span></code>
  51         and <code class="computeroutput"><span class="identifier">ld</span></code> on Windows platform
  52         fail to mix <code class="computeroutput"><span class="identifier">__dllexport__</span></code>
  53         and <code class="computeroutput"><span class="identifier">weak</span></code> attributes. This
  54         leads us to situation, where we must explicitly specify translation unit
  55         in which <code class="computeroutput"><a class="link" href="../BOOST_DLL_ALIAS.html" title="Macro BOOST_DLL_ALIAS">BOOST_DLL_ALIAS</a></code> is
  56         instantiated, making all other <code class="computeroutput"><a class="link" href="../BOOST_DLL_ALIAS.html" title="Macro BOOST_DLL_ALIAS">BOOST_DLL_ALIAS</a></code>
  57         declarations with that alias name an <code class="computeroutput"><span class="keyword">extern</span></code>
  58         variable.
  59       </p>
  60 <p>
  61         Unit that must hold an instance of <code class="computeroutput"><a class="link" href="../BOOST_DLL_ALIAS.html" title="Macro BOOST_DLL_ALIAS">BOOST_DLL_ALIAS</a></code>
  62         must define <code class="computeroutput"><a class="link" href="../BOOST_DL_idm46262983596016.html" title="Macro BOOST_DLL_FORCE_ALIAS_INSTANTIATION">BOOST_DLL_FORCE_ALIAS_INSTANTIATION</a></code>
  63         before including any of the Boost.DLL library headers.
  64       </p>
  65 <p>
  66         You may explicitly disable export of weak symbols using <code class="computeroutput"><a class="link" href="../BOOST_DL_idm46262983594208.html" title="Macro BOOST_DLL_FORCE_NO_WEAK_EXPORTS">BOOST_DLL_FORCE_NO_WEAK_EXPORTS</a></code>.
  67         This may be useful for working around linker problems or to test your program
  68         for compatibility with linkers that do not support exporting weak symbols.
  69       </p>
  70 </div>
  71 <div class="section">
  72 <div class="titlepage"><div><div><h3 class="title">
  73 <a name="boost_dll.limitations.user_defined_section_names__fails_on_sunos___oracle_solaris_studio_compilers_"></a><a class="link" href="limitations.html#boost_dll.limitations.user_defined_section_names__fails_on_sunos___oracle_solaris_studio_compilers_" title="User defined section names (Fails on SunOS + Oracle Solaris Studio Compilers)">User
  74       defined section names (Fails on SunOS + Oracle Solaris Studio Compilers)</a>
  75 </h3></div></div></div>
  76 <p>
  77         Some platforms ignore section attributes, so that querying for a symbols
  78         in a specified section using <code class="computeroutput"><a class="link" href="../boost/dll/library_info.html" title="Class library_info">boost::dll::library_info</a></code>
  79         may return nothing.
  80       </p>
  81 </div>
  82 <div class="section">
  83 <div class="titlepage"><div><div><h3 class="title">
  84 <a name="boost_dll.limitations.multithread"></a><a class="link" href="limitations.html#boost_dll.limitations.multithread" title="Thread safe library loading (Fails on FreeBSD, MacOS, iOS and some other)">Thread safe library
  85       loading (Fails on FreeBSD, MacOS, iOS and some other)</a>
  86 </h3></div></div></div>
  87 <p>
  88         On some platforms <code class="computeroutput"><span class="identifier">dlopen</span></code>,<code class="computeroutput"><span class="identifier">dlclose</span></code> and some other functions assume
  89         that they won't be called concurrently.
  90       </p>
  91 <p>
  92         Platforms that certaly have that issue are FreeBSD, MacOS, iOS.
  93       </p>
  94 <p>
  95         Platforms that certaly do not have such issue are Windows, Linux+glibc, Android,
  96         QNX.
  97       </p>
  98 <p>
  99         Other platforms are under question. If you're using one of the platforms
 100         that are not listed (for example Linux+busybox), you may run the <code class="computeroutput"><span class="identifier">shared_library_concurrent_load_test</span></code> test
 101         to detect the issue:
 102 </p>
 103 <pre class="programlisting"><span class="identifier">cd</span> <span class="identifier">boost_folder</span><span class="special">/</span><span class="identifier">libs</span><span class="special">/</span><span class="identifier">dll</span><span class="special">/</span><span class="identifier">test</span>
 104 <span class="special">../../../</span><span class="identifier">b2</span> <span class="special">-</span><span class="identifier">a</span> <span class="identifier">shared_library_concurrent_load_test</span>
 105 </pre>
 106 <p>
 107       </p>
 108 </div>
 109 <div class="section">
 110 <div class="titlepage"><div><div><h3 class="title">
 111 <a name="boost_dll.limitations.nested"></a><a class="link" href="limitations.html#boost_dll.limitations.nested" title="Nested Function Definitions">Nested Function Definitions</a>
 112 </h3></div></div></div>
 113 <p>
 114         If a function is defined inside the class-definition it may be interpreted
 115         as always-inline which can lead to the function not being exported at all.
 116         This does however differ between between compilers.
 117       </p>
 118 </div>
 119 </div>
 120 <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
 121 <td align="left"></td>
 122 <td align="right"><div class="copyright-footer">Copyright &#169; 2014 Renato Tegon Forti, Antony Polukhin<br>Copyright &#169; 2015 Antony Polukhin<br>Copyright &#169; 2016 Antony Polukhin, Klemens Morgenstern<br>Copyright &#169; 2017-2019 Antony Polukhin<p>
 123         Distributed under the Boost Software License, Version 1.0. (See accompanying
 124         file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 125       </p>
 126 </div></td>
 127 </tr></table>
 128 <hr>
 129 <div class="spirit-nav">
 130 <a accesskey="p" href="../boost/dll/experimental/import_mangled.html"><img src="../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../boost_dll.html"><img src="../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="f_a_q_.html"><img src="../../../doc/src/images/next.png" alt="Next"></a>
 131 </div>
 132 </body>
 133 </html>