Document boost::core::launder

doc/changes.qbk

@@ -16,6 +16,7 @@
   or C++ standard library type traits instead.
 * Marked `boost::ref` member functions and associated methods with `noexcept`.
 * Marked `boost::swap` function with `noexcept`, depending on whether the type supports a non-throwing swap operation.
+* Added `boost::core::launder`, a portable implementation of `std::launder`.
 
 [endsect]
 

doc/core.qbk

@@ -55,6 +55,7 @@ criteria for inclusion is that the utility component be:
 [include first_scalar.qbk]
 [include ignore_unused.qbk]
 [include is_same.qbk]
+[include launder.qbk]
 [include lightweight_test.qbk]
 [include no_exceptions_support.qbk]
 [include noinit_adaptor.qbk]

doc/launder.qbk

@@ -0,0 +1,39 @@
+[/
+  Copyright 2023 Peter Dimov
+  Distributed under the Boost Software License, Version 1.0.
+  https://boost.org/LICENSE_1_0.txt
+]
+
+[section:launder launder]
+
+[simplesect Authors]
+
+* Peter Dimov
+
+[endsimplesect]
+
+[section Header <boost/core/launder.hpp>]
+
+The header `<boost/core/launder.hpp>` defines the function
+`void boost::core::launder()`, a portable implementation of
+`std::launder`.
+
+[section Synopsis]
+
+``
+namespace boost
+{
+namespace core
+{
+
+template<class T> T* launder( T* p );
+
+} // namespace core
+} // namespace boost
+``
+
+[endsect]
+
+[endsect]
+
+[endsect]