[gcc r12-9724] libstdc++: Document removal of implicit allocator rebinding extensions

[gcc r12-9724] libstdc++: Document removal of implicit allocator rebinding extensions

[Jonathan Wakely]

https://gcc.gnu.org/g:72ceed08d45137b0f1a9b4ea8ca533aa6489bc39

commit r12-9724-g72ceed08d45137b0f1a9b4ea8ca533aa6489bc39
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Mon May 15 21:41:56 2023 +0100

    libstdc++: Document removal of implicit allocator rebinding extensions
    
    Traditionally libstdc++ allowed containers 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.
    
    (cherry picked from commit 8cbaf679a3c1875c5475bd1cb0fb86fb9d03b2d4)

Diff:
---
 libstdc++-v3/doc/html/manual/api.html     |  9 +++++++++
 libstdc++-v3/doc/xml/manual/evolution.xml | 13 +++++++++++++
 2 files changed, 22 insertions(+)

diff --git a/libstdc++-v3/doc/html/manual/api.html b/libstdc++-v3/doc/html/manual/api.html
index 604380e0136..fd6420a9e2c 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.
diff --git a/libstdc++-v3/doc/xml/manual/evolution.xml b/libstdc++-v3/doc/xml/manual/evolution.xml
index 82936189179..9259c43fb19 100644
--- a/libstdc++-v3/doc/xml/manual/evolution.xml
+++ b/libstdc++-v3/doc/xml/manual/evolution.xml
@@ -915,6 +915,13 @@ Calling a <code>std::bind</code> result as volatile was deprecated for C++17.
   <filename>libstdc++.so.8</filename>.
 </para>
 
+<para>
+  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 (<option>-std=c++NN</option>) modes, only in
+  <option>-std=gnu++NN</option> modes.
+</para>
+
 </section>
 
 <section xml:id="api.rel_91"><info><title><constant>9</constant></title></info>
@@ -998,6 +1005,12 @@ Calling a <code>std::bind</code> result as volatile was deprecated for C++17.
   added.
 </para>
 
+<para>
+  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 <option>-std=gnu++20</option> mode.
+</para>
+
 </section>
 
 <section xml:id="api.rel_111"><info><title><constant>11</constant></title></info>