pw_containers: Add static_assert for Item type
Assert that the item type T is derived from IntrusiveList<T>::Item. The
assert must be in a function, since the class T is not fully defined
when IntrusiveList<T> is instantiated.
Change-Id: I802c6d2fe5872694098525933e522365c6ca86e1
diff --git a/pw_containers/public/pw_containers/intrusive_list.h b/pw_containers/public/pw_containers/intrusive_list.h
index cba6c8c..14be30f 100644
--- a/pw_containers/public/pw_containers/intrusive_list.h
+++ b/pw_containers/public/pw_containers/intrusive_list.h
@@ -64,18 +64,20 @@
using const_iterator =
intrusive_list_impl::Iterator<std::add_const_t<T>, const Item>;
- constexpr IntrusiveList() = default;
+ constexpr IntrusiveList() { CheckItemType(); }
// Constructs an IntrusiveList from an iterator over Items. The iterator may
// dereference as either Item& (e.g. from std::array<Item>) or Item* (e.g.
// from std::initializer_list<Item*>).
template <typename Iterator>
- IntrusiveList(Iterator first, Iterator last) : list_(first, last) {}
+ IntrusiveList(Iterator first, Iterator last) : list_(first, last) {
+ CheckItemType();
+ }
// Constructs an IntrusiveList from a std::initializer_list of pointers to
// items.
IntrusiveList(std::initializer_list<Item*> items)
- : list_(items.begin(), items.end()) {}
+ : IntrusiveList(items.begin(), items.end()) {}
template <typename Iterator>
void assign(Iterator first, Iterator last) {
@@ -144,6 +146,14 @@
const_iterator cend() const noexcept { return end(); }
private:
+ // Check that T is an Item in a function, since the class T will not be fully
+ // defined when the IntrusiveList<T> class is instantiated.
+ static constexpr void CheckItemType() {
+ static_assert(
+ std::is_base_of<Item, T>(),
+ "IntrusiveList items must be derived from IntrusiveList<T>::Item");
+ }
+
intrusive_list_impl::List list_;
};
