libstdc++: Document removal of implicit allocator rebinding extensions

Traditionally libstdc++ allowed containers and strings to be
instantiated with allocator's that have the wrong value type, implicitly
rebinding the allocator to the container's value type. Since C++20 that
has been explicitly ill-formed, so the extension is no longer supported
in strict modes (e.g. -std=c++17) and in C++20 and later.

libstdc++-v3/ChangeLog:

	* doc/xml/manual/evolution.xml: Document removal of implicit
	allocator rebinding extensions in strict mode and for C++20.
	* doc/html/*: Regenerate.

1 files changed, 13 insertions, 0 deletions

diff --git a/libstdc++-v3/doc/html/manual/api.html b/libstdc++-v3/doc/html/manual/api.html
index 7d5f754..27c0d09 100644
--- a/libstdc++-v3/doc/html/manual/api.html
+++ b/libstdc++-v3/doc/html/manual/api.html
@@ -370,6 +370,11 @@ Calling a <code class="code">std::bind</code> result as volatile was deprecated
   For the non-default <code class="option">--enable-symvers=gnu-versioned-namespace</code>
   configuration, the shared library SONAME has been changed to
   <code class="filename">libstdc++.so.8</code>.
+</p><p>
+  The extension allowing containers to be instantiated with an allocator
+  that doesn't match the container's value type is no longer allowed in
+  strict (<code class="option">-std=c++NN</code>) modes, only in
+  <code class="option">-std=gnu++NN</code> modes.
 </p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="api.rel_91"></a><code class="constant">9</code></h3></div></div></div><p>
   C++17 header
   <code class="filename">&lt;memory_resource&gt;</code>
@@ -425,6 +430,10 @@ Calling a <code class="code">std::bind</code> result as volatile was deprecated
   and
   <code class="filename">&lt;stop_token&gt;</code>
   added.
+</p><p>
+  The extension allowing containers to be instantiated with an allocator
+  that doesn't match the container's value type is no longer allowed in
+  C++20 mode, even in non-strict <code class="option">-std=gnu++20</code> mode.
 </p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="api.rel_111"></a><code class="constant">11</code></h3></div></div></div><p>
   The <code class="option">--enable-cheaders=c_std</code> configuration
   was deprecated.
@@ -479,4 +488,8 @@ Tunables <span style="color: red">&lt;variable&gt;glibcxx.eh_pool.obj_count&lt;/
 </p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="api.rel_141"></a><code class="constant">14</code></h3></div></div></div><p>
 Deprecate the non-standard overload that allows <code class="code">std::setfill</code>
 to be used with <code class="code">std::basic_istream</code>.
+</p><p>
+  The extension allowing <code class="code">std::basic_string</code> to be instantiated
+  with an allocator that doesn't match the string's character type is no
+  longer allowed in C++20 mode.
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