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  23     "><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="test.html" title="Test"><link rel="next" href="api.html" title="API Evolution and Deprecation History"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">ABI Policy and Guidelines</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="test.html">Prev</a> </td><th width="60%" align="center">Appendix B.
  24   Porting and Maintenance
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  27 </p><div class="section" title="The C++ Interface"><div class="titlepage"><div><div><h3 class="title"><a name="abi.cxx_interface"></a>The C++ Interface</h3></div></div></div><p>
  28   C++ applications often depend on specific language support
  29   routines, say for throwing exceptions, or catching exceptions, and
  30   perhaps also depend on features in the C++ Standard Library.
  31 </p><p>
  32   The C++ Standard Library has many include files, types defined in
  33   those include files, specific named functions, and other
  34   behavior. The text of these behaviors, as written in source include
  35   files, is called the Application Programing Interface, or API.
  36 </p><p>
  37   Furthermore, C++ source that is compiled into object files is
  38   transformed by the compiler: it arranges objects with specific
  39   alignment and in a particular layout, mangling names according to a
  40   well-defined algorithm, has specific arrangements for the support of
  41   virtual functions, etc. These details are defined as the compiler
  42   Application Binary Interface, or ABI. The GNU C++ compiler uses an
  43   industry-standard C++ ABI starting with version 3. Details can be
  44   found in the <a class="link" href="http://www.codesourcery.com/public/cxx-abi/abi.html" target="_top">ABI
  45   specification</a>.
  46 </p><p>
  47  The GNU C++ compiler, g++, has a compiler command line option to
  48   switch between various different C++ ABIs. This explicit version
  49   switch is the flag <code class="code">-fabi-version</code>. In addition, some
  50   g++ command line options may change the ABI as a side-effect of
  51   use. Such flags include <code class="code">-fpack-struct</code> and
  52   <code class="code">-fno-exceptions</code>, but include others: see the complete
  53   list in the GCC manual under the heading <a class="link" href="http://gcc.gnu.org/onlinedocs/gcc/Code-Gen-Options.html#Code%20Gen%20Options" target="_top">Options
  54   for Code Generation Conventions</a>.
  55 </p><p>
  56   The configure options used when building a specific libstdc++
  57   version may also impact the resulting library ABI. The available
  58   configure options, and their impact on the library ABI, are
  59   documented
  60 <a class="link" href="configure.html" title="Configure">here</a>.
  61 </p><p> Putting all of these ideas together results in the C++ Standard
  62 library ABI, which is the compilation of a given library API by a
  63 given compiler ABI. In a nutshell:
  64 </p><p>
  65   <span class="quote">“<span class="quote">
  66     library API + compiler ABI = library ABI
  67   </span>”</span>
  68 </p><p>
  69  The library ABI is mostly of interest for end-users who have
  70  unresolved symbols and are linking dynamically to the C++ Standard
  71  library, and who thus must be careful to compile their application
  72  with a compiler that is compatible with the available C++ Standard
  73  library binary. In this case, compatible is defined with the equation
  74  above: given an application compiled with a given compiler ABI and
  75  library API, it will work correctly with a Standard C++ Library
  76  created with the same constraints.
  77 </p><p>
  78   To use a specific version of the C++ ABI, one must use a
  79   corresponding GNU C++ toolchain (i.e., g++ and libstdc++) that
  80   implements the C++ ABI in question.
  81 </p></div><div class="section" title="Versioning"><div class="titlepage"><div><div><h3 class="title"><a name="abi.versioning"></a>Versioning</h3></div></div></div><p> The C++ interface has evolved throughout the history of the GNU
  82 C++ toolchain. With each release, various details have been changed so
  83 as to give distinct versions to the C++ interface.
  84 </p><div class="section" title="Goals"><div class="titlepage"><div><div><h4 class="title"><a name="abi.versioning.goals"></a>Goals</h4></div></div></div><p>Extending existing, stable ABIs. Versioning gives subsequent
  85 releases of library binaries the ability to add new symbols and add
  86 functionality, all the while retaining compatibility with the previous
  87 releases in the series. Thus, program binaries linked with the initial
  88 release of a library binary will still run correctly if the library
  89 binary is replaced by carefully-managed subsequent library
  90 binaries. This is called forward compatibility.
  91 </p><p>
  92 The reverse (backwards compatibility) is not true. It is not possible
  93 to take program binaries linked with the latest version of a library
  94 binary in a release series (with additional symbols added), substitute
  95 in the initial release of the library binary, and remain link
  96 compatible.
  97 </p><p>Allows multiple, incompatible ABIs to coexist at the same time.
  98 </p></div><div class="section" title="History"><div class="titlepage"><div><div><h4 class="title"><a name="abi.versioning.history"></a>History</h4></div></div></div><p>
  99  How can this complexity be managed? What does C++ versioning mean?
 100   Because library and compiler changes often make binaries compiled
 101   with one version of the GNU tools incompatible with binaries
 102   compiled with other (either newer or older) versions of the same GNU
 103   tools, specific techniques are used to make managing this complexity
 104   easier.
 105 </p><p>
 106   The following techniques are used:
 107 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Release versioning on the libgcc_s.so binary. </p><p>This is implemented via file names and the ELF
 108     <code class="constant">DT_SONAME</code> mechanism (at least on ELF
 109     systems). It is versioned as follows:
 110     </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>GCC 3.x: libgcc_s.so.1</p></li><li class="listitem"><p>GCC 4.x: libgcc_s.so.1</p></li></ul></div><p>For m68k-linux the versions differ as follows: </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>GCC 3.4, GCC 4.x: libgcc_s.so.1
 111     when configuring <code class="code">--with-sjlj-exceptions</code>, or
 112     libgcc_s.so.2 </p></li></ul></div><p>For hppa-linux the versions differ as follows: </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>GCC 3.4, GCC 4.[0-1]: either libgcc_s.so.1
 113     when configuring <code class="code">--with-sjlj-exceptions</code>, or
 114     libgcc_s.so.2 </p></li><li class="listitem"><p>GCC 4.[2-7]: either libgcc_s.so.3 when configuring
 115     <code class="code">--with-sjlj-exceptions</code>) or libgcc_s.so.4
 116     </p></li></ul></div></li><li class="listitem"><p>Symbol versioning on the libgcc_s.so binary.</p><p>It is versioned with the following labels and version
 117    definitions, where the version definition is the maximum for a
 118    particular release. Labels are cumulative. If a particular release
 119    is not listed, it has the same version labels as the preceding
 120    release.</p><p>This corresponds to the mapfile: gcc/libgcc-std.ver</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>GCC 3.0.0: GCC_3.0</p></li><li class="listitem"><p>GCC 3.3.0: GCC_3.3</p></li><li class="listitem"><p>GCC 3.3.1: GCC_3.3.1</p></li><li class="listitem"><p>GCC 3.3.2: GCC_3.3.2</p></li><li class="listitem"><p>GCC 3.3.4: GCC_3.3.4</p></li><li class="listitem"><p>GCC 3.4.0: GCC_3.4</p></li><li class="listitem"><p>GCC 3.4.2: GCC_3.4.2</p></li><li class="listitem"><p>GCC 3.4.4: GCC_3.4.4</p></li><li class="listitem"><p>GCC 4.0.0: GCC_4.0.0</p></li><li class="listitem"><p>GCC 4.1.0: GCC_4.1.0</p></li><li class="listitem"><p>GCC 4.2.0: GCC_4.2.0</p></li><li class="listitem"><p>GCC 4.3.0: GCC_4.3.0</p></li><li class="listitem"><p>GCC 4.4.0: GCC_4.4.0</p></li><li class="listitem"><p>GCC 4.5.0: GCC_4.5.0</p></li><li class="listitem"><p>GCC 4.6.0: GCC_4.6.0</p></li><li class="listitem"><p>GCC 4.7.0: GCC_4.7.0</p></li></ul></div></li><li class="listitem"><p>
 121         Release versioning on the libstdc++.so binary, implemented in
 122         the same way as the libgcc_s.so binary above. Listed is the
 123         filename: <code class="constant">DT_SONAME</code> can be deduced from
 124         the filename by removing the last two period-delimited numbers. For
 125         example, filename <code class="filename">libstdc++.so.5.0.4</code>
 126         corresponds to a <code class="constant">DT_SONAME</code> of
 127         <code class="constant">libstdc++.so.5</code>. Binaries with equivalent
 128         <code class="constant">DT_SONAME</code>s are forward-compatibile: in
 129         the table below, releases incompatible with the previous
 130         one are explicitly noted.
 131         If a particular release is not listed, its libstdc++.so binary
 132         has the same filename and <code class="constant">DT_SONAME</code> as the
 133         preceding release.
 134       </p><p>It is versioned as follows:
 135     </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>GCC 3.0.0: libstdc++.so.3.0.0</p></li><li class="listitem"><p>GCC 3.0.1: libstdc++.so.3.0.1</p></li><li class="listitem"><p>GCC 3.0.2: libstdc++.so.3.0.2</p></li><li class="listitem"><p>GCC 3.0.3: libstdc++.so.3.0.2 (See Note 1)</p></li><li class="listitem"><p>GCC 3.0.4: libstdc++.so.3.0.4</p></li><li class="listitem"><p>GCC 3.1.0: libstdc++.so.4.0.0 <span class="emphasis"><em>(Incompatible with previous)</em></span></p></li><li class="listitem"><p>GCC 3.1.1: libstdc++.so.4.0.1</p></li><li class="listitem"><p>GCC 3.2.0: libstdc++.so.5.0.0 <span class="emphasis"><em>(Incompatible with previous)</em></span></p></li><li class="listitem"><p>GCC 3.2.1: libstdc++.so.5.0.1</p></li><li class="listitem"><p>GCC 3.2.2: libstdc++.so.5.0.2</p></li><li class="listitem"><p>GCC 3.2.3: libstdc++.so.5.0.3 (See Note 2)</p></li><li class="listitem"><p>GCC 3.3.0: libstdc++.so.5.0.4</p></li><li class="listitem"><p>GCC 3.3.1: libstdc++.so.5.0.5</p></li><li class="listitem"><p>GCC 3.4.0: libstdc++.so.6.0.0 <span class="emphasis"><em>(Incompatible with previous)</em></span></p></li><li class="listitem"><p>GCC 3.4.1: libstdc++.so.6.0.1</p></li><li class="listitem"><p>GCC 3.4.2: libstdc++.so.6.0.2</p></li><li class="listitem"><p>GCC 3.4.3: libstdc++.so.6.0.3</p></li><li class="listitem"><p>GCC 4.0.0: libstdc++.so.6.0.4</p></li><li class="listitem"><p>GCC 4.0.1: libstdc++.so.6.0.5</p></li><li class="listitem"><p>GCC 4.0.2: libstdc++.so.6.0.6</p></li><li class="listitem"><p>GCC 4.0.3: libstdc++.so.6.0.7</p></li><li class="listitem"><p>GCC 4.1.0: libstdc++.so.6.0.7</p></li><li class="listitem"><p>GCC 4.1.1: libstdc++.so.6.0.8</p></li><li class="listitem"><p>GCC 4.2.0: libstdc++.so.6.0.9</p></li><li class="listitem"><p>GCC 4.2.1: libstdc++.so.6.0.9 (See Note 3)</p></li><li class="listitem"><p>GCC 4.2.2: libstdc++.so.6.0.9</p></li><li class="listitem"><p>GCC 4.3.0: libstdc++.so.6.0.10</p></li><li class="listitem"><p>GCC 4.4.0: libstdc++.so.6.0.11</p></li><li class="listitem"><p>GCC 4.4.1: libstdc++.so.6.0.12</p></li><li class="listitem"><p>GCC 4.4.2: libstdc++.so.6.0.13</p></li><li class="listitem"><p>GCC 4.5.0: libstdc++.so.6.0.14</p></li><li class="listitem"><p>GCC 4.6.0: libstdc++.so.6.0.15</p></li><li class="listitem"><p>GCC 4.6.1: libstdc++.so.6.0.16</p></li></ul></div><p>
 136       Note 1: Error should be libstdc++.so.3.0.3.
 137     </p><p>
 138       Note 2: Not strictly required.
 139     </p><p>
 140       Note 3: This release (but not previous or subsequent) has one
 141       known incompatibility, see <a class="link" href="http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33678" target="_top">33678</a>
 142       in the GCC bug database.
 143     </p></li><li class="listitem"><p>Symbol versioning on the libstdc++.so binary.</p><p>mapfile: libstdc++-v3/config/abi/pre/gnu.ver</p><p>It is versioned with the following labels and version
 144    definitions, where the version definition is the maximum for a
 145    particular release. Note, only symbols which are newly introduced
 146    will use the maximum version definition. Thus, for release series
 147    with the same label, but incremented version definitions, the later
 148    release has both versions. (An example of this would be the
 149    GCC 3.2.1 release, which has GLIBCPP_3.2.1 for new symbols and
 150    GLIBCPP_3.2 for symbols that were introduced in the GCC 3.2.0
 151    release.) If a particular release is not listed, it has the same
 152    version labels as the preceding release.
 153    </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>GCC 3.0.0: (Error, not versioned)</p></li><li class="listitem"><p>GCC 3.0.1: (Error, not versioned)</p></li><li class="listitem"><p>GCC 3.0.2: (Error, not versioned)</p></li><li class="listitem"><p>GCC 3.0.3: (Error, not versioned)</p></li><li class="listitem"><p>GCC 3.0.4: (Error, not versioned)</p></li><li class="listitem"><p>GCC 3.1.0: GLIBCPP_3.1, CXXABI_1</p></li><li class="listitem"><p>GCC 3.1.1: GLIBCPP_3.1, CXXABI_1</p></li><li class="listitem"><p>GCC 3.2.0: GLIBCPP_3.2, CXXABI_1.2</p></li><li class="listitem"><p>GCC 3.2.1: GLIBCPP_3.2.1, CXXABI_1.2</p></li><li class="listitem"><p>GCC 3.2.2: GLIBCPP_3.2.2, CXXABI_1.2</p></li><li class="listitem"><p>GCC 3.2.3: GLIBCPP_3.2.2, CXXABI_1.2</p></li><li class="listitem"><p>GCC 3.3.0: GLIBCPP_3.2.2, CXXABI_1.2.1</p></li><li class="listitem"><p>GCC 3.3.1: GLIBCPP_3.2.3, CXXABI_1.2.1</p></li><li class="listitem"><p>GCC 3.3.2: GLIBCPP_3.2.3, CXXABI_1.2.1</p></li><li class="listitem"><p>GCC 3.3.3: GLIBCPP_3.2.3, CXXABI_1.2.1</p></li><li class="listitem"><p>GCC 3.4.0: GLIBCXX_3.4, CXXABI_1.3</p></li><li class="listitem"><p>GCC 3.4.1: GLIBCXX_3.4.1, CXXABI_1.3</p></li><li class="listitem"><p>GCC 3.4.2: GLIBCXX_3.4.2</p></li><li class="listitem"><p>GCC 3.4.3: GLIBCXX_3.4.3</p></li><li class="listitem"><p>GCC 4.0.0: GLIBCXX_3.4.4, CXXABI_1.3.1</p></li><li class="listitem"><p>GCC 4.0.1: GLIBCXX_3.4.5</p></li><li class="listitem"><p>GCC 4.0.2: GLIBCXX_3.4.6</p></li><li class="listitem"><p>GCC 4.0.3: GLIBCXX_3.4.7</p></li><li class="listitem"><p>GCC 4.1.1: GLIBCXX_3.4.8</p></li><li class="listitem"><p>GCC 4.2.0: GLIBCXX_3.4.9</p></li><li class="listitem"><p>GCC 4.3.0: GLIBCXX_3.4.10, CXXABI_1.3.2</p></li><li class="listitem"><p>GCC 4.4.0: GLIBCXX_3.4.11, CXXABI_1.3.3</p></li><li class="listitem"><p>GCC 4.4.1: GLIBCXX_3.4.12, CXXABI_1.3.3</p></li><li class="listitem"><p>GCC 4.4.2: GLIBCXX_3.4.13, CXXABI_1.3.3</p></li><li class="listitem"><p>GCC 4.5.0: GLIBCXX_3.4.14, CXXABI_1.3.4</p></li><li class="listitem"><p>GCC 4.6.0: GLIBCXX_3.4.15, CXXABI_1.3.5</p></li><li class="listitem"><p>GCC 4.6.1: GLIBCXX_3.4.16, CXXABI_1.3.5</p></li></ul></div></li><li class="listitem"><p>Incremental bumping of a compiler pre-defined macro,
 154     __GXX_ABI_VERSION. This macro is defined as the version of the
 155     compiler v3 ABI, with g++ 3.0 being version 100. This macro will
 156     be automatically defined whenever g++ is used (the curious can
 157     test this by invoking g++ with the '-v' flag.)
 158     </p><p>
 159     This macro was defined in the file "lang-specs.h" in the gcc/cp directory.
 160     Later versions defined it in "c-common.c" in the gcc directory, and from
 161     G++ 3.4 it is defined in c-cppbuiltin.c and its value determined by the
 162     '-fabi-version' command line option.
 163     </p><p>
 164     It is versioned as follows, where 'n' is given by '-fabi-version=n':
 165     </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>GCC 3.0: 100</p></li><li class="listitem"><p>GCC 3.1: 100 (Error, should be 101)</p></li><li class="listitem"><p>GCC 3.2: 102</p></li><li class="listitem"><p>GCC 3.3: 102</p></li><li class="listitem"><p>GCC 3.4, GCC 4.x: 102 (when n=1)</p></li><li class="listitem"><p>GCC 3.4, GCC 4.x: 1000 + n (when n&gt;1) </p></li><li class="listitem"><p>GCC 3.4, GCC 4.x: 999999 (when n=0)</p></li></ul></div><p></p></li><li class="listitem"><p>Changes to the default compiler option for
 166     <code class="code">-fabi-version</code>.
 167     </p><p>
 168     It is versioned as follows:
 169     </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>GCC 3.0: (Error, not versioned) </p></li><li class="listitem"><p>GCC 3.1: (Error, not versioned) </p></li><li class="listitem"><p>GCC 3.2: <code class="code">-fabi-version=1</code></p></li><li class="listitem"><p>GCC 3.3: <code class="code">-fabi-version=1</code></p></li><li class="listitem"><p>GCC 3.4, GCC 4.x: <code class="code">-fabi-version=2</code> <span class="emphasis"><em>(Incompatible with previous)</em></span></p></li></ul></div><p></p></li><li class="listitem"><p>Incremental bumping of a library pre-defined macro. For releases
 170     before 3.4.0, the macro is __GLIBCPP__. For later releases, it's
 171     __GLIBCXX__. (The libstdc++ project generously changed from CPP to
 172     CXX throughout its source to allow the "C" pre-processor the CPP
 173     macro namespace.) These macros are defined as the date the library
 174     was released, in compressed ISO date format, as an unsigned long.
 175     </p><p>
 176     This macro is defined in the file "c++config" in the
 177     "libstdc++-v3/include/bits" directory. (Up to GCC 4.1.0, it was
 178     changed every night by an automated script. Since GCC 4.1.0, it is
 179     the same value as gcc/DATESTAMP.)
 180     </p><p>
 181     It is versioned as follows:
 182     </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>GCC 3.0.0: 20010615</p></li><li class="listitem"><p>GCC 3.0.1: 20010819</p></li><li class="listitem"><p>GCC 3.0.2: 20011023</p></li><li class="listitem"><p>GCC 3.0.3: 20011220</p></li><li class="listitem"><p>GCC 3.0.4: 20020220</p></li><li class="listitem"><p>GCC 3.1.0: 20020514</p></li><li class="listitem"><p>GCC 3.1.1: 20020725</p></li><li class="listitem"><p>GCC 3.2.0: 20020814</p></li><li class="listitem"><p>GCC 3.2.1: 20021119</p></li><li class="listitem"><p>GCC 3.2.2: 20030205</p></li><li class="listitem"><p>GCC 3.2.3: 20030422</p></li><li class="listitem"><p>GCC 3.3.0: 20030513</p></li><li class="listitem"><p>GCC 3.3.1: 20030804</p></li><li class="listitem"><p>GCC 3.3.2: 20031016</p></li><li class="listitem"><p>GCC 3.3.3: 20040214</p></li><li class="listitem"><p>GCC 3.4.0: 20040419</p></li><li class="listitem"><p>GCC 3.4.1: 20040701</p></li><li class="listitem"><p>GCC 3.4.2: 20040906</p></li><li class="listitem"><p>GCC 3.4.3: 20041105</p></li><li class="listitem"><p>GCC 3.4.4: 20050519</p></li><li class="listitem"><p>GCC 3.4.5: 20051201</p></li><li class="listitem"><p>GCC 3.4.6: 20060306</p></li><li class="listitem"><p>GCC 4.0.0: 20050421</p></li><li class="listitem"><p>GCC 4.0.1: 20050707</p></li><li class="listitem"><p>GCC 4.0.2: 20050921</p></li><li class="listitem"><p>GCC 4.0.3: 20060309</p></li><li class="listitem"><p>GCC 4.1.0: 20060228</p></li><li class="listitem"><p>GCC 4.1.1: 20060524</p></li><li class="listitem"><p>GCC 4.1.2: 20070214</p></li><li class="listitem"><p>GCC 4.2.0: 20070514</p></li><li class="listitem"><p>GCC 4.2.1: 20070719</p></li><li class="listitem"><p>GCC 4.2.2: 20071007</p></li><li class="listitem"><p>GCC 4.2.3: 20080201</p></li><li class="listitem"><p>GCC 4.2.4: 20080519</p></li><li class="listitem"><p>GCC 4.3.0: 20080306</p></li><li class="listitem"><p>GCC 4.3.1: 20080606</p></li><li class="listitem"><p>GCC 4.3.2: 20080827</p></li><li class="listitem"><p>GCC 4.3.3: 20090124</p></li><li class="listitem"><p>GCC 4.3.4: 20090804</p></li><li class="listitem"><p>GCC 4.3.5: 20100522</p></li><li class="listitem"><p>GCC 4.3.6: 20110627</p></li><li class="listitem"><p>GCC 4.4.0: 20090421</p></li><li class="listitem"><p>GCC 4.4.1: 20090722</p></li><li class="listitem"><p>GCC 4.4.2: 20091015</p></li><li class="listitem"><p>GCC 4.4.3: 20100121</p></li><li class="listitem"><p>GCC 4.4.4: 20100429</p></li><li class="listitem"><p>GCC 4.4.5: 20101001</p></li><li class="listitem"><p>GCC 4.4.6: 20110416</p></li><li class="listitem"><p>GCC 4.5.0: 20100414</p></li><li class="listitem"><p>GCC 4.5.1: 20100731</p></li><li class="listitem"><p>GCC 4.5.2: 20101216</p></li><li class="listitem"><p>GCC 4.5.3: 20110428</p></li><li class="listitem"><p>GCC 4.6.0: 20110325</p></li><li class="listitem"><p>GCC 4.6.1: 20110627</p></li><li class="listitem"><p>GCC 4.6.2: 20111026</p></li></ul></div><p></p></li><li class="listitem"><p>
 183     Incremental bumping of a library pre-defined macro,
 184     _GLIBCPP_VERSION. This macro is defined as the released version of
 185     the library, as a string literal. This is only implemented in
 186     GCC 3.1.0 releases and higher, and is deprecated in 3.4 (where it
 187     is called _GLIBCXX_VERSION).
 188     </p><p>
 189     This macro is defined in the file "c++config" in the
 190     "libstdc++-v3/include/bits" directory and is generated
 191     automatically by autoconf as part of the configure-time generation
 192     of config.h.
 193     </p><p>
 194     It is versioned as follows:
 195     </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>GCC 3.0.0: "3.0.0"</p></li><li class="listitem"><p>GCC 3.0.1: "3.0.0" (Error, should be "3.0.1")</p></li><li class="listitem"><p>GCC 3.0.2: "3.0.0" (Error, should be "3.0.2")</p></li><li class="listitem"><p>GCC 3.0.3: "3.0.0" (Error, should be "3.0.3")</p></li><li class="listitem"><p>GCC 3.0.4: "3.0.0" (Error, should be "3.0.4")</p></li><li class="listitem"><p>GCC 3.1.0: "3.1.0"</p></li><li class="listitem"><p>GCC 3.1.1: "3.1.1"</p></li><li class="listitem"><p>GCC 3.2.0: "3.2"</p></li><li class="listitem"><p>GCC 3.2.1: "3.2.1"</p></li><li class="listitem"><p>GCC 3.2.2: "3.2.2"</p></li><li class="listitem"><p>GCC 3.2.3: "3.2.3"</p></li><li class="listitem"><p>GCC 3.3.0: "3.3"</p></li><li class="listitem"><p>GCC 3.3.1: "3.3.1"</p></li><li class="listitem"><p>GCC 3.3.2: "3.3.2"</p></li><li class="listitem"><p>GCC 3.3.3: "3.3.3"</p></li><li class="listitem"><p>GCC 3.4: "version-unused"</p></li><li class="listitem"><p>GCC 4.x: "version-unused"</p></li></ul></div><p></p></li><li class="listitem"><p>
 196     Matching each specific C++ compiler release to a specific set of
 197     C++ include files. This is only implemented in GCC 3.1.1 releases
 198     and higher.
 199     </p><p>
 200     All C++ includes are installed in
 201     <code class="filename">include/c++</code>, then nest in a
 202     directory hierarchy corresponding to the C++ compiler's released
 203     version. This version corresponds to the variable "gcc_version" in
 204     "libstdc++-v3/acinclude.m4," and more details can be found in that
 205     file's macro GLIBCXX_CONFIGURE (GLIBCPP_CONFIGURE before GCC 3.4.0).
 206     </p><p>
 207     C++ includes are versioned as follows:
 208     </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>GCC 3.0.0: include/g++-v3</p></li><li class="listitem"><p>GCC 3.0.1: include/g++-v3</p></li><li class="listitem"><p>GCC 3.0.2: include/g++-v3</p></li><li class="listitem"><p>GCC 3.0.3: include/g++-v3</p></li><li class="listitem"><p>GCC 3.0.4: include/g++-v3</p></li><li class="listitem"><p>GCC 3.1.0: include/g++-v3</p></li><li class="listitem"><p>GCC 3.1.1: include/c++/3.1.1</p></li><li class="listitem"><p>GCC 3.2.0: include/c++/3.2</p></li><li class="listitem"><p>GCC 3.2.1: include/c++/3.2.1</p></li><li class="listitem"><p>GCC 3.2.2: include/c++/3.2.2</p></li><li class="listitem"><p>GCC 3.2.3: include/c++/3.2.3</p></li><li class="listitem"><p>GCC 3.3.0: include/c++/3.3</p></li><li class="listitem"><p>GCC 3.3.1: include/c++/3.3.1</p></li><li class="listitem"><p>GCC 3.3.2: include/c++/3.3.2</p></li><li class="listitem"><p>GCC 3.3.3: include/c++/3.3.3</p></li><li class="listitem"><p>GCC 3.4.x: include/c++/3.4.x</p></li><li class="listitem"><p>GCC 4.x.y: include/c++/4.x.y</p></li></ul></div><p></p></li></ol></div><p>
 209   Taken together, these techniques can accurately specify interface
 210   and implementation changes in the GNU C++ tools themselves. Used
 211   properly, they allow both the GNU C++ tools implementation, and
 212   programs using them, an evolving yet controlled development that
 213   maintains backward compatibility.
 214 </p></div><div class="section" title="Prerequisites"><div class="titlepage"><div><div><h4 class="title"><a name="abi.versioning.prereq"></a>Prerequisites</h4></div></div></div><p>
 215       Minimum environment that supports a versioned ABI: A supported
 216       dynamic linker, a GNU linker of sufficient vintage to understand
 217       demangled C++ name globbing (ld) or the Sun linker, a shared
 218       executable compiled
 219       with g++, and shared libraries (libgcc_s, libstdc++) compiled by
 220       a compiler (g++) with a compatible ABI. Phew.
 221     </p><p>
 222       On top of all that, an additional constraint: libstdc++ did not
 223       attempt to version symbols (or age gracefully, really) until
 224       version 3.1.0.
 225     </p><p>
 226       Most modern GNU/Linux and BSD versions, particularly ones using
 227       GCC 3.1 and later, will meet the
 228       requirements above, as does Solaris 2.5 and up.
 229     </p></div><div class="section" title="Configuring"><div class="titlepage"><div><div><h4 class="title"><a name="abi.versioning.config"></a>Configuring</h4></div></div></div><p>
 230       It turns out that most of the configure options that change
 231       default behavior will impact the mangled names of exported
 232       symbols, and thus impact versioning and compatibility.
 233     </p><p>
 234       For more information on configure options, including ABI
 235       impacts, see:
 236       <a class="link" href="configure.html" title="Configure">here</a>
 237     </p><p>
 238       There is one flag that explicitly deals with symbol versioning:
 239       --enable-symvers.
 240     </p><p>
 241       In particular, libstdc++-v3/acinclude.m4 has a macro called
 242       GLIBCXX_ENABLE_SYMVERS that defaults to yes (or the argument
 243       passed in via --enable-symvers=foo). At that point, the macro
 244       attempts to make sure that all the requirement for symbol
 245       versioning are in place. For more information, please consult
 246       acinclude.m4.
 247     </p></div><div class="section" title="Checking Active"><div class="titlepage"><div><div><h4 class="title"><a name="abi.versioning.active"></a>Checking Active</h4></div></div></div><p>
 248       When the GNU C++ library is being built with symbol versioning
 249       on, you should see the following at configure time for
 250       libstdc++:
 251     </p><pre class="screen">
 252 <code class="computeroutput">
 253   checking versioning on shared library symbols... gnu
 254 </code>
 255 </pre><p>
 256   or another of the supported styles.
 257   If you don't see this line in the configure output, or if this line
 258   appears but the last word is 'no', then you are out of luck.
 259 </p><p>
 260   If the compiler is pre-installed, a quick way to test is to compile
 261   the following (or any) simple C++ file and link it to the shared
 262   libstdc++ library:
 263 </p><pre class="programlisting">
 264 #include &lt;iostream&gt;
 265
 266 int main()
 267 { std::cout &lt;&lt; "hello" &lt;&lt; std::endl; return 0; }
 268
 269 %g++ hello.cc -o hello.out
 270
 271 %ldd hello.out
 272         libstdc++.so.5 =&gt; /usr/lib/libstdc++.so.5 (0x00764000)
 273         libm.so.6 =&gt; /lib/tls/libm.so.6 (0x004a8000)
 274         libgcc_s.so.1 =&gt; /mnt/hd/bld/gcc/gcc/libgcc_s.so.1 (0x40016000)
 275         libc.so.6 =&gt; /lib/tls/libc.so.6 (0x0036d000)
 276         /lib/ld-linux.so.2 =&gt; /lib/ld-linux.so.2 (0x00355000)
 277
 278 %nm hello.out
 279 </pre><p>
 280 If you see symbols in the resulting output with "GLIBCXX_3" as part
 281 of the name, then the executable is versioned. Here's an example:
 282 </p><p>
 283    <code class="code">U _ZNSt8ios_base4InitC1Ev@@GLIBCXX_3.4</code>
 284 </p><p>
 285 On Solaris 2, you can use <code class="code">pvs -r</code> instead:
 286 </p><pre class="programlisting">
 287 %g++ hello.cc -o hello.out
 288
 289 %pvs -r hello.out
 290         libstdc++.so.6 (GLIBCXX_3.4, GLIBCXX_3.4.12);
 291         libgcc_s.so.1 (GCC_3.0);
 292         libc.so.1 (SUNWprivate_1.1, SYSVABI_1.3);
 293 </pre><p>
 294 <code class="code">ldd -v</code> works too, but is very verbose.
 295 </p></div></div><div class="section" title="Allowed Changes"><div class="titlepage"><div><div><h3 class="title"><a name="abi.changes_allowed"></a>Allowed Changes</h3></div></div></div><p>
 296 The following will cause the library minor version number to
 297 increase, say from "libstdc++.so.3.0.4" to "libstdc++.so.3.0.5".
 298 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Adding an exported global or static data member</p></li><li class="listitem"><p>Adding an exported function, static or non-virtual member function</p></li><li class="listitem"><p>Adding an exported symbol or symbols by additional instantiations</p></li></ol></div><p>
 299 Other allowed changes are possible.
 300 </p></div><div class="section" title="Prohibited Changes"><div class="titlepage"><div><div><h3 class="title"><a name="abi.changes_no"></a>Prohibited Changes</h3></div></div></div><p>
 301 The following non-exhaustive list will cause the library major version
 302 number to increase, say from "libstdc++.so.3.0.4" to
 303 "libstdc++.so.4.0.0".
 304 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Changes in the gcc/g++ compiler ABI</p></li><li class="listitem"><p>Changing size of an exported symbol</p></li><li class="listitem"><p>Changing alignment of an exported symbol</p></li><li class="listitem"><p>Changing the layout of an exported symbol</p></li><li class="listitem"><p>Changing mangling on an exported symbol</p></li><li class="listitem"><p>Deleting an exported symbol</p></li><li class="listitem"><p>Changing the inheritance properties of a type by adding or removing
 305     base classes</p></li><li class="listitem"><p>
 306   Changing the size, alignment, or layout of types
 307   specified in the C++ standard. These may not necessarily be
 308   instantiated or otherwise exported in the library binary, and
 309   include all the required locale facets, as well as things like
 310   std::basic_streambuf, et al.
 311 </p></li><li class="listitem"><p> Adding an explicit copy constructor or destructor to a
 312 class that would otherwise have implicit versions. This will change
 313 the way the compiler deals with this class in by-value return
 314 statements or parameters: instead of passing instances of this
 315 class in registers, the compiler will be forced to use memory. See the
 316 section on <a class="link" href="http://www.codesourcery.com/public/cxx-abi/abi.html#calls" target="_top">Function
 317 Calling Conventions and APIs</a>
 318  of the C++ ABI documentation for further details.
 319 </p></li></ol></div></div><div class="section" title="Implementation"><div class="titlepage"><div><div><h3 class="title"><a name="abi.impl"></a>Implementation</h3></div></div></div><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>
 320      Separation of interface and implementation
 321    </p><p>
 322      This is accomplished by two techniques that separate the API from
 323      the ABI: forcing undefined references to link against a library
 324      binary for definitions.
 325    </p><div class="variablelist"><dl><dt><span class="term">Include files have declarations, source files have defines</span></dt><dd><p>
 326         For non-templatized types, such as much of <code class="code">class
 327         locale</code>, the appropriate standard C++ include, say
 328         <code class="code">locale</code>, can contain full declarations, while
 329         various source files (say <code class="code"> locale.cc, locale_init.cc,
 330         localename.cc</code>) contain definitions.
 331       </p></dd><dt><span class="term">Extern template on required types</span></dt><dd><p>
 332        For parts of the standard that have an explicit list of
 333        required instantiations, the GNU extension syntax <code class="code"> extern
 334        template </code> can be used to control where template
 335        definitions reside. By marking required instantiations as
 336        <code class="code"> extern template </code> in include files, and providing
 337        explicit instantiations in the appropriate instantiation files,
 338        non-inlined template functions can be versioned. This technique
 339        is mostly used on parts of the standard that require <code class="code">
 340        char</code> and <code class="code"> wchar_t</code> instantiations, and
 341        includes <code class="code"> basic_string</code>, the locale facets, and the
 342        types in <code class="code"> iostreams</code>.
 343      </p></dd></dl></div><p>
 344    In addition, these techniques have the additional benefit that they
 345    reduce binary size, which can increase runtime performance.
 346  </p></li><li class="listitem"><p>
 347      Namespaces linking symbol definitions to export mapfiles
 348    </p><p>
 349      All symbols in the shared library binary are processed by a
 350      linker script at build time that either allows or disallows
 351      external linkage. Because of this, some symbols, regardless of
 352      normal C/C++ linkage, are not visible. Symbols that are internal
 353      have several appealing characteristics: by not exporting the
 354      symbols, there are no relocations when the shared library is
 355      started and thus this makes for faster runtime loading
 356      performance by the underlying dynamic loading mechanism. In
 357      addition, they have the possibility of changing without impacting
 358      ABI compatibility.
 359    </p><p>The following namespaces are transformed by the mapfile:</p><div class="variablelist"><dl><dt><span class="term"><code class="code">namespace std</code></span></dt><dd><p> Defaults to exporting all symbols in label
 360 <code class="code">GLIBCXX</code> that do not begin with an underscore, i.e.,
 361 <code class="code">__test_func</code> would not be exported by default. Select
 362 exceptional symbols are allowed to be visible.</p></dd><dt><span class="term"><code class="code">namespace __gnu_cxx</code></span></dt><dd><p> Defaults to not exporting any symbols in label
 363 <code class="code">GLIBCXX</code>, select items are allowed to be visible.</p></dd><dt><span class="term"><code class="code">namespace __gnu_internal</code></span></dt><dd><p> Defaults to not exported, no items are allowed to be visible.</p></dd><dt><span class="term"><code class="code">namespace __cxxabiv1</code>, aliased to <code class="code"> namespace abi</code></span></dt><dd><p> Defaults to not exporting any symbols in label
 364 <code class="code">CXXABI</code>, select items are allowed to be visible.</p></dd></dl></div><p>
 365 </p></li><li class="listitem"><p>Freezing the API</p><p>Disallowed changes, as above, are not made on a stable release
 366 branch. Enforcement tends to be less strict with GNU extensions that
 367 standard includes.</p></li></ol></div></div><div class="section" title="Testing"><div class="titlepage"><div><div><h3 class="title"><a name="abi.testing"></a>Testing</h3></div></div></div><div class="section" title="Single ABI Testing"><div class="titlepage"><div><div><h4 class="title"><a name="abi.testing.single"></a>Single ABI Testing</h4></div></div></div><p>
 368       Testing for GNU C++ ABI changes is composed of two distinct
 369       areas: testing the C++ compiler (g++) for compiler changes, and
 370       testing the C++ library (libstdc++) for library changes.
 371     </p><p>
 372       Testing the C++ compiler ABI can be done various ways.
 373     </p><p>
 374       One.  Intel ABI checker.
 375     </p><p>
 376 Two.
 377 The second is yet unreleased, but has been announced on the gcc
 378 mailing list. It is yet unspecified if these tools will be freely
 379 available, and able to be included in a GNU project. Please contact
 380 Mark Mitchell (mark@codesourcery.com) for more details, and current
 381 status.
 382 </p><p>
 383 Three.
 384 Involves using the vlad.consistency test framework. This has also been
 385 discussed on the gcc mailing lists.
 386 </p><p>
 387 Testing the C++ library ABI can also be done various ways.
 388 </p><p>
 389 One.
 390 (Brendan Kehoe, Jeff Law suggestion to run 'make check-c++' two ways,
 391 one with a new compiler and an old library, and the other with an old
 392 compiler and a new library, and look for testsuite regressions)
 393 </p><p>
 394 Details on how to set this kind of test up can be found here:
 395 http://gcc.gnu.org/ml/gcc/2002-08/msg00142.html
 396 </p><p>
 397 Two.
 398 Use the 'make check-abi' rule in the libstdc++ Makefile.
 399 </p><p>
 400 This is a proactive check of the library ABI. Currently, exported symbol
 401 names that are either weak or defined are checked against a last known
 402 good baseline. Currently, this baseline is keyed off of 3.4.0
 403 binaries, as this was the last time the .so number was incremented. In
 404 addition, all exported names are demangled, and the exported objects
 405 are checked to make sure they are the same size as the same object in
 406 the baseline.
 407
 408 Notice that each baseline is relative to a <span class="emphasis"><em>default</em></span>
 409 configured library and compiler: in particular, if options such as
 410 --enable-clocale, or --with-cpu, in case of multilibs, are used at
 411 configure time, the check may fail, either because of substantive
 412 differences or because of limitations of the current checking
 413 machinery.
 414 </p><p>
 415 This dataset is insufficient, yet a start. Also needed is a
 416 comprehensive check for all user-visible types part of the standard
 417 library for sizeof() and alignof() changes.
 418 </p><p>
 419 Verifying compatible layouts of objects is not even attempted.  It
 420 should be possible to use sizeof, alignof, and offsetof to compute
 421 offsets for each structure and type in the standard library, saving to
 422 another datafile. Then, compute this in a similar way for new
 423 binaries, and look for differences.
 424 </p><p>
 425 Another approach might be to use the -fdump-class-hierarchy flag to
 426 get information. However, currently this approach gives insufficient
 427 data for use in library testing, as class data members, their offsets,
 428 and other detailed data is not displayed with this flag.
 429 (See PR g++/7470 on how this was used to find bugs.)
 430 </p><p>
 431 Perhaps there are other C++ ABI checkers. If so, please notify
 432 us. We'd like to know about them!
 433 </p></div><div class="section" title="Multiple ABI Testing"><div class="titlepage"><div><div><h4 class="title"><a name="abi.testing.multi"></a>Multiple ABI Testing</h4></div></div></div><p>
 434 A "C" application, dynamically linked to two shared libraries, liba,
 435 libb. The dependent library liba is a C++ shared library compiled with
 436 GCC 3.3, and uses io, exceptions, locale, etc. The dependent library
 437 libb is a C++ shared library compiled with GCC 3.4, and also uses io,
 438 exceptions, locale, etc.
 439 </p><p> As above, libone is constructed as follows: </p><pre class="programlisting">
 440 %$bld/H-x86-gcc-3.4.0/bin/g++ -fPIC -DPIC -c a.cc
 441
 442 %$bld/H-x86-gcc-3.4.0/bin/g++ -shared -Wl,-soname -Wl,libone.so.1 -Wl,-O1 -Wl,-z,defs a.o -o libone.so.1.0.0
 443
 444 %ln -s libone.so.1.0.0 libone.so
 445
 446 %$bld/H-x86-gcc-3.4.0/bin/g++ -c a.cc
 447
 448 %ar cru libone.a a.o
 449 </pre><p> And, libtwo is constructed as follows: </p><pre class="programlisting">
 450 %$bld/H-x86-gcc-3.3.3/bin/g++ -fPIC -DPIC -c b.cc
 451
 452 %$bld/H-x86-gcc-3.3.3/bin/g++ -shared -Wl,-soname -Wl,libtwo.so.1 -Wl,-O1 -Wl,-z,defs b.o -o libtwo.so.1.0.0
 453
 454 %ln -s libtwo.so.1.0.0 libtwo.so
 455
 456 %$bld/H-x86-gcc-3.3.3/bin/g++ -c b.cc
 457
 458 %ar cru libtwo.a b.o
 459 </pre><p> ...with the resulting libraries looking like </p><pre class="screen">
 460 <code class="computeroutput">
 461 %ldd libone.so.1.0.0
 462         libstdc++.so.6 =&gt; /usr/lib/libstdc++.so.6 (0x40016000)
 463         libm.so.6 =&gt; /lib/tls/libm.so.6 (0x400fa000)
 464         libgcc_s.so.1 =&gt; /mnt/hd/bld/gcc/gcc/libgcc_s.so.1 (0x4011c000)
 465         libc.so.6 =&gt; /lib/tls/libc.so.6 (0x40125000)
 466         /lib/ld-linux.so.2 =&gt; /lib/ld-linux.so.2 (0x00355000)
 467
 468 %ldd libtwo.so.1.0.0
 469         libstdc++.so.5 =&gt; /usr/lib/libstdc++.so.5 (0x40027000)
 470         libm.so.6 =&gt; /lib/tls/libm.so.6 (0x400e1000)
 471         libgcc_s.so.1 =&gt; /mnt/hd/bld/gcc/gcc/libgcc_s.so.1 (0x40103000)
 472         libc.so.6 =&gt; /lib/tls/libc.so.6 (0x4010c000)
 473         /lib/ld-linux.so.2 =&gt; /lib/ld-linux.so.2 (0x00355000)
 474 </code>
 475 </pre><p>
 476   Then, the "C" compiler is used to compile a source file that uses
 477   functions from each library.
 478 </p><pre class="programlisting">
 479 gcc test.c -g -O2 -L. -lone -ltwo /usr/lib/libstdc++.so.5 /usr/lib/libstdc++.so.6
 480 </pre><p>
 481   Which gives the expected:
 482 </p><pre class="screen">
 483 <code class="computeroutput">
 484 %ldd a.out
 485         libstdc++.so.5 =&gt; /usr/lib/libstdc++.so.5 (0x00764000)
 486         libstdc++.so.6 =&gt; /usr/lib/libstdc++.so.6 (0x40015000)
 487         libc.so.6 =&gt; /lib/tls/libc.so.6 (0x0036d000)
 488         libm.so.6 =&gt; /lib/tls/libm.so.6 (0x004a8000)
 489         libgcc_s.so.1 =&gt; /mnt/hd/bld/gcc/gcc/libgcc_s.so.1 (0x400e5000)
 490         /lib/ld-linux.so.2 =&gt; /lib/ld-linux.so.2 (0x00355000)
 491 </code>
 492 </pre><p>
 493   This resulting binary, when executed, will be able to safely use
 494   code from both liba, and the dependent libstdc++.so.6, and libb,
 495   with the dependent libstdc++.so.5.
 496 </p></div></div><div class="section" title="Outstanding Issues"><div class="titlepage"><div><div><h3 class="title"><a name="abi.issues"></a>Outstanding Issues</h3></div></div></div><p>
 497   Some features in the C++ language make versioning especially
 498   difficult. In particular, compiler generated constructs such as
 499   implicit instantiations for templates, typeinfo information, and
 500   virtual tables all may cause ABI leakage across shared library
 501   boundaries. Because of this, mixing C++ ABIs is not recommended at
 502   this time.
 503 </p><p>
 504   For more background on this issue, see these bugzilla entries:
 505 </p><p>
 506 <a class="link" href="http://gcc.gnu.org/PR24660" target="_top">24660: versioning weak symbols in libstdc++</a>
 507 </p><p>
 508 <a class="link" href="http://gcc.gnu.org/PR19664" target="_top">19664: libstdc++ headers should have pop/push of the visibility around the declarations</a>
 509 </p></div><div class="bibliography" title="Bibliography"><div class="titlepage"><div><div><h3 class="title"><a name="abi.biblio"></a>Bibliography</h3></div></div></div><div class="biblioentry" title="ABIcheck"><a name="biblio.abicheck"></a><p>[biblio.abicheck] <span class="title"><i>
 510         <a class="link" href="http://abicheck.sourceforge.net" target="_top">
 511           ABIcheck
 512         </a>
 513       </i>. </span></p></div><div class="biblioentry" title="C++ ABI Summary"><a name="biblio.cxxabi"></a><p>[biblio.cxxabi] <span class="title"><i>
 514         <a class="link" href="http://www.codesourcery.com/public/cxx-abi" target="_top">
 515           C++ ABI Summary
 516         </a>
 517       </i>. </span></p></div><div class="biblioentry" title="Intel Compilers for Linux Compatibility with the GNU Compilers"><a name="id684275"></a><p><span class="title"><i>
 518         <a class="link" href="http://www.intel.com/cd/software/products/asmo-na/eng/284736.htm" target="_top">
 519         Intel Compilers for Linux Compatibility with the GNU Compilers
 520         </a>
 521       </i>. </span></p></div><div class="biblioentry" title="Linker and Libraries Guide (document 819-0690)"><a name="id684291"></a><p><span class="title"><i>
 522         <a class="link" href="http://download.oracle.com/docs/cd/E19963-01/html/819-0690/index.html" target="_top">
 523         Linker and Libraries Guide (document 819-0690)
 524         </a>
 525       </i>. </span></p></div><div class="biblioentry" title="Sun Studio 11: C++ Migration Guide (document 819-3689)"><a name="id684306"></a><p><span class="title"><i>
 526         <a class="link" href="http://download.oracle.com/docs/cd/E19422-01/819-3689/index.html" target="_top">
 527       Sun Studio 11: C++ Migration Guide (document 819-3689)
 528         </a>
 529       </i>. </span></p></div><div class="biblioentry" title="How to Write Shared Libraries"><a name="id684322"></a><p><span class="title"><i>
 530         <a class="link" href="http://www.akkadia.org/drepper/dsohowto.pdf" target="_top">
 531       How to Write Shared Libraries
 532         </a>
 533       </i>. </span><span class="author"><span class="firstname">Ulrich</span> <span class="surname">Drepper</span>. </span></p></div><div class="biblioentry" title="C++ ABI for the ARM Architecture"><a name="id684350"></a><p><span class="title"><i>
 534         <a class="link" href="http://www.arm.com/miscPDFs/8033.pdf" target="_top">
 535       C++ ABI for the ARM Architecture
 536         </a>
 537       </i>. </span></p></div><div class="biblioentry" title="Dynamic Shared Objects: Survey and Issues"><a name="id684365"></a><p><span class="title"><i>
 538         <a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2006/n1976.html" target="_top">
 539       Dynamic Shared Objects: Survey and Issues
 540         </a>
 541       </i>. </span><span class="subtitle">
 542       ISO C++ J16/06-0046
 543     . </span><span class="author"><span class="firstname">Benjamin</span> <span class="surname">Kosnik</span>. </span></p></div><div class="biblioentry" title="Versioning With Namespaces"><a name="id684393"></a><p><span class="title"><i>
 544         <a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2006/n2013.html" target="_top">
 545         Versioning With Namespaces
 546         </a>
 547       </i>. </span><span class="subtitle">
 548       ISO C++ J16/06-0083
 549     . </span><span class="author"><span class="firstname">Benjamin</span> <span class="surname">Kosnik</span>. </span></p></div><div class="biblioentry" title="Binary Compatibility of Shared Libraries Implemented in C++ on GNU/Linux Systems"><a name="id684420"></a><p><span class="title"><i>
 550         <a class="link" href="http://syrcose.ispras.ru/2009/files/SYRCoSE2009-CfP.pdf" target="_top">
 551       Binary Compatibility of Shared Libraries Implemented in C++
 552       on GNU/Linux Systems
 553         </a>
 554       </i>. </span><span class="subtitle">
 555       SYRCoSE 2009
 556     . </span><span class="author"><span class="firstname">Pavel</span> <span class="surname">Shved</span>. </span><span class="author"><span class="firstname">Denis</span> <span class="surname">Silakov</span>. </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="test.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="api.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Test </td><td width="20%" align="center"><a accesskey="h" href="../index.html">Home</a></td><td width="40%" align="right" valign="top"> API Evolution and Deprecation History</td></tr></table></div></body></html>