I plan to commit this to wwwdocs later today, it adds a caveat to the top of the file, with a link to a larger description in the libstdc++ section, which links to the new page I've just added to the manual.
It also clarifies that the deprecations apply to C++, so people who don't care about C++ can ignore that item.
Index: htdocs/gcc-5/changes.html =================================================================== RCS file: /cvs/gcc/wwwdocs/htdocs/gcc-5/changes.html,v retrieving revision 1.109 diff -u -r1.109 changes.html --- htdocs/gcc-5/changes.html 20 Apr 2015 08:22:35 -0000 1.109 +++ htdocs/gcc-5/changes.html 21 Apr 2015 11:45:51 -0000 @@ -16,15 +16,17 @@ <ul> <li>The default mode for C is now <code>-std=gnu11</code> instead of <code>-std=gnu89</code>.</li> + <li>The C++ runtime library (libstdc++) uses a new ABI by default + (see <a href="#libstdcxx">below</a>).</li> <li>The Graphite framework for loop optimizations no longer requires the CLooG library, only ISL version 0.14 (recommended) or 0.12.2. The installation manual contains more information about requirements to build GCC.</li> - <li>The non-standard type traits + <li>The non-standard C++0x type traits <code>has_trivial_default_constructor</code>, <code>has_trivial_copy_constructor</code> and <code>has_trivial_copy_assign</code> have been deprecated and will - be removed in a future version. The standard traits + be removed in a future version. The standard C++11 traits <code>is_trivially_default_constructible</code>, <code>is_trivially_copy_constructible</code> and <code>is_trivially_copy_assignable</code> should be used instead.</li> @@ -415,6 +417,11 @@ <h4 id="libstdcxx">Runtime Library (libstdc++)</h4> <ul> + <li>A <a href="/onlinedocs/libstdc++/manual/using_dual_abi.html">Dual + ABI</a> is provided by the library. A new ABI is enabled by default. + The old ABI is still supported and can be used by defining the macro + <code>_GLIBCXX_USE_CXX11_ABI</code> to </code>0</code> before + including any C++ standard library headers. </li> <li>A new implementation of <code>std::string</code> is enabled by default, using the <em>small string optimization</em> instead of <em>copy-on-write</em> reference counting.</li>