std::is_pod has been deprecated in C++20.
What's the reason for this choice? What should I use in place of std::is_pod to know if a type is actually a POD?
POD is being replaced with two categories that give more nuances. The c++ standard meeting in november 2017 had this to say about it:
Deprecating the notion of “plain old data” (POD). It has been replaced with two more nuanced categories of types, “trivial” and “standard-layout”. “POD” is equivalent to “trivial and standard layout”, but for many code patterns, a narrower restriction to just “trivial” or just “standard layout” is appropriate; to encourage such precision, the notion of “POD” was therefore deprecated. The library trait is_pod has also been deprecated correspondingly.
For simple data types use the is_standard_layout function, for trivial data types (such as simple structs) use the is_trivial function.