Pushed to trunk. The first two changes will be backported too.
-- >8 --
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.
---
libstdc++-v3/doc/html/manual/api.html | 13 +++++++++++++
libstdc++-v3/doc/xml/manual/evolution.xml | 19 +++++++++++++++++++
2 files changed, 32 insertions(+)
diff --git a/libstdc++-v3/doc/xml/manual/evolution.xml
b/libstdc++-v3/doc/xml/manual/evolution.xml
index 4037a18d2df..db70f24f2f9 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>
@@ -1096,6 +1109,12 @@ Deprecate the non-standard overload that allows
<code>std::setfill</code>
to be used with <code>std::basic_istream</code>.
</para>
+<para>
+ The extension allowing <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.
+</para>
+
</section>
</section>
--
2.40.1
