[aa_inplace_vector] Copying/moving an Alloc is not allowed to throw

The Standard specifies in [allocator.requirements.general] that copy
and move operations on allocators never throw, regardless of whether
they're marked noexcept or not. And in fact `boost::interprocess::allocator`
does not mark its SMFs as noexcept. So we shouldn't check the trait
here; instead we should assume that the operations are non-throwing.

include/sg14/aa_inplace_vector.h

@@ -293,6 +293,11 @@ struct ipv_alloc_holder {
 #endif
     explicit ipv_alloc_holder() = default;
     constexpr explicit ipv_alloc_holder(const Alloc& alloc) : alloc_(alloc) {}
+    ipv_alloc_holder(const ipv_alloc_holder&) noexcept = default;
+    ipv_alloc_holder(ipv_alloc_holder&&) noexcept = default;
+    ipv_alloc_holder& operator=(const ipv_alloc_holder&) noexcept = default;
+    ipv_alloc_holder& operator=(ipv_alloc_holder&&) noexcept = default;
+    ~ipv_alloc_holder() noexcept = default;
     constexpr const Alloc& get_allocator_() const { return alloc_; }
 };
 
@@ -397,13 +402,11 @@ struct SG14_INPLACE_VECTOR_TRIVIALLY_RELOCATABLE_IF((sg14::aaipv::be_trivially_r
     static constexpr bool CopyCtorIsNoexcept =
         ((std::is_nothrow_copy_constructible_v<T> &&
           sg14::aaipv::has_trivial_construct<Alloc, T, const T&>::value) || (N == 0)) &&
-        sg14::aaipv::propagate_on_container_copy_construction<Alloc>::value &&
-        std::is_nothrow_copy_constructible_v<sg14::ipv_alloc_holder<Alloc>>;
+        sg14::aaipv::propagate_on_container_copy_construction<Alloc>::value;
 
     static constexpr bool MoveCtorIsNoexcept =
         ((std::is_nothrow_move_constructible_v<T> &&
-          sg14::aaipv::has_trivial_construct<Alloc, T, T&&>::value) || (N == 0)) &&
-        std::is_nothrow_move_constructible_v<sg14::ipv_alloc_holder<Alloc>>;
+          sg14::aaipv::has_trivial_construct<Alloc, T, T&&>::value) || (N == 0));
 
     // Copy-assignment follows the Lakos Rule: if the precondition might be violated, then it's not noexcept.
     //

test/aa_inplace_vector_test.cpp

@@ -33,6 +33,23 @@ struct CountingAlloc {
     }
 };
 
+template<class T, bool B>
+struct NonNoexceptAlloc {
+    using value_type = T;
+    using propagate_on_container_copy_assignment = std::bool_constant<B>;
+    using propagate_on_container_move_assignment = std::bool_constant<B>;
+    using propagate_on_container_swap = std::bool_constant<B>;
+    using is_always_equal = std::false_type;
+    explicit NonNoexceptAlloc(int);
+    NonNoexceptAlloc(const NonNoexceptAlloc&); // non-throwing but not noexcept
+    NonNoexceptAlloc(NonNoexceptAlloc&&); // non-throwing but not noexcept
+    NonNoexceptAlloc& operator=(const NonNoexceptAlloc&); // non-throwing but not noexcept
+    NonNoexceptAlloc& operator=(NonNoexceptAlloc&&); // non-throwing but not noexcept
+    ~NonNoexceptAlloc() noexcept(false); // non-throwing but not noexcept
+    friend bool operator==(NonNoexceptAlloc, NonNoexceptAlloc); // non-throwing but not noexcept
+    int i_;
+};
+
 TEST(aa_inplace_vector, AllocExtendedCopyCtor)
 {
     using A = CountingAlloc<int>;
@@ -63,4 +80,24 @@ TEST(aa_inplace_vector, AllocExtendedMoveCtor)
     EXPECT_EQ(mr2.size(), 3u);
 }
 
+TEST(aa_inplace_vector, IgnoreNoexceptnessOfAllocator)
+{
+    {
+        using T = sg14::inplace_vector<int, 10, NonNoexceptAlloc<int, true>>;
+        static_assert(std::is_nothrow_copy_constructible_v<T>);
+        static_assert(std::is_nothrow_move_constructible_v<T>);
+        static_assert(std::is_nothrow_copy_assignable_v<T>);
+        static_assert(std::is_nothrow_move_assignable_v<T>);
+        static_assert(std::is_nothrow_destructible_v<T>);
+    }
+    {
+        using T = sg14::inplace_vector<int, 10, NonNoexceptAlloc<int, false>>;
+        static_assert(std::is_nothrow_copy_constructible_v<T>);
+        static_assert(std::is_nothrow_move_constructible_v<T>);
+        static_assert(std::is_nothrow_copy_assignable_v<T>);
+        static_assert(std::is_nothrow_move_assignable_v<T>);
+        static_assert(std::is_nothrow_destructible_v<T>);
+    }
+}
+
 #endif // __cplusplus >= 202002L