It was recently discussed on the cpplang Slack that Boost implements a lot of class types that are "Platonically trivially relocatable" without being known to the compiler to be trivially relocatable.
In P1144R9 my go-to example was boost::movelib::unique_ptr<int>; but in the above discussion it was pointed out that boost::container::static_vector<int,10> would be a less archaic example, so P1144R10 might switch to that.

Executive summary: Wouldn't it be cool if we could write—

static_assert(__is_trivially_relocatable(boost::container::static_vector<int,10>));
static_assert(!__is_trivially_relocatable(boost::container::static_vector<std::list<int>,10>));

The __is_trivially_relocatable is available only on Clang so far, and the necessary std::is_trivially_relocatable_v/[[trivially_relocatable]] trait/attribute are available only in my fork of Clang/libc++; but both levels of support are detectable via the preprocessor (see Godbolt).

I propose to add an #ifdef so that static_vector and perhaps other containers will be recognized as trivially relocatable whenever the compiler/STL support that notion.