Make static_vector<T, N>'s destructor trivial if T is trivial.

doc/container.qbk

@@ -1437,6 +1437,7 @@ use [*Boost.Container]? There are several reasons for that:
 [section:release_notes_boost_1_91_00 Boost 1.91 Release]
 
 * Implemented heterogeneous overloads from C++23 ([@http://wg21.link/p2077r3 P2077]) and C++26 ([@http://wg21.link/P2363 P2363]).
+* In C++20 compilers, `static_vector<T>`'s destructor is now trivial if `T` is trivial.
 * Fixed bugs/issues:
    * [@https://github.com/boostorg/container/issues/323 GitHub #323: ['"flat_tree::try_emplace UB"]].
 
@@ -1447,7 +1448,7 @@ use [*Boost.Container]? There are several reasons for that:
 * Reimplemented [classref boost::container::deque]. The original implementation was based on
    the SGI's original data structure (similar to libstdc++). Main changes:
    * `sizeof(deque)` was 10 words, now is 4 words. Probably the lightest implementation around.
-   * `sizeof(deque::iterator)` was 4 words, now is is 2 words (similar to libc++ and MSVC).)
+   * `sizeof(deque::iterator)` was 4 words, now is is 2 words (similar to libc++ and MSVC).
    * Several internal algorithms were reimplemented to speed up the segmented nature of deque.
    * Defaults were slightly changed, 64 bit platforms now use 1024 byte blocks by default
      instead of classic SGI 512 byte blocks.

include/boost/container/detail/workaround.hpp

@@ -242,4 +242,8 @@ namespace boost {
 #define BOOST_CONTAINER_GCC_COMPATIBLE_HAS_DIAGNOSTIC_IGNORED
 #endif
 
+#if defined(__cpp_concepts) && (__cpp_concepts >= 202002L)
+#  define BOOST_CONTAINER_CONCEPTS_BASED_OVERLOADING
+#endif
+
 #endif   //#ifndef BOOST_CONTAINER_DETAIL_WORKAROUND_HPP

include/boost/container/vector.hpp

@@ -1223,12 +1223,22 @@ private:
    //!
    //! <b>Complexity</b>: Linear to the number of elements.
    ~vector() BOOST_NOEXCEPT_OR_NOTHROW
+   #if defined(BOOST_INTRUSIVE_CONCEPTS_BASED_OVERLOADING)
+      requires (dtl::version<allocator_type>::value != 0 || !::boost::move_detail::is_trivially_destructible<T>::value)
+   #endif
    {
       boost::container::destroy_alloc_n
          (this->get_stored_allocator(), this->priv_raw_begin(), this->m_holder.m_size);
       //vector_alloc_holder deallocates the data
    }
 
+   #if !defined(BOOST_CONTAINER_DOXYGEN_INVOKED) && defined(BOOST_INTRUSIVE_CONCEPTS_BASED_OVERLOADING)
+   //Default destructor for normal links (allows conditional triviality)
+   ~vector()
+      requires (dtl::version<allocator_type>::value == 0 && ::boost::move_detail::is_trivially_destructible<T>::value)
+      = default;
+   #endif
+
    //! <b>Effects</b>: Makes *this contain the same elements as x.
    //!
    //! <b>Postcondition</b>: this->size() == x.size(). *this contains a copy

test/static_vector_test.cpp

@@ -671,6 +671,35 @@ bool default_init_test()//Test for default initialization
    return true;
 }
 
+#if defined(BOOST_INTRUSIVE_CONCEPTS_BASED_OVERLOADING)
+
+#include <type_traits>
+
+template<class T, bool Result>
+void static_vector_destructor_triviality_impl()
+{
+   typedef static_vector<T, 10> vector_t;
+   BOOST_CONTAINER_STATIC_ASSERT(( Result == std::is_trivially_destructible_v<vector_t> ));
+}
+
+struct non_trivial
+{
+   non_trivial(){}
+   ~non_trivial(){}
+};
+
+void static_vector_triviality()
+{
+   static_vector_destructor_triviality_impl<int, true>();
+   static_vector_destructor_triviality_impl<float, true>();
+   static_vector_destructor_triviality_impl<non_trivial, false>();
+}
+
+#else
+
+void static_vector_triviality(){}
+
+#endif   //BOOST_INTRUSIVE_CONCEPTS_BASED_OVERLOADING
 
 int main(int, char* [])
 {
@@ -787,6 +816,8 @@ int main(int, char* [])
       boost::intrusive::test::test_iterator_random< cont_int >(a);
    }
 
+   static_vector_triviality();
+
    return boost::report_errors();
 }