Sometimes I wonder why these nifty data structures that someone already implemented in c++ don't immediately (or even 5+ years later) have ports to other languages. Especially languages that are closer to the metal than average (e.g. Rust, Go, ...)
The closest I can think of is Rust, but it does have ports of such things. Rust's HashMap is a Swiss Table - Abseil's flash_hash_map but ported to Rust (via HashBrown), Haphazard is a Rust port of the Folly library's hazard pointers (which might some day be C++ 26 or C++ 29 Hazard Pointers)
So you might not be able to replace the default Java hashmap with absl::flat_hash_map, but you can steal ideas and maybe do better in other ways where the C++ map would be constrained. However, doing that is work that someone has to pick up.
And releasing a (e.g.) Go library that breaks from the built in map semantics might not see much adoption in that community. C++ actually seems a bit unique in terms of how many widely used implementations there are of key data structures (e.g. strings, maps, trees, inline vectors). Not criticizing just making an observation.
What’s holding it back currently is coming up with a way to do incremental rehash, which Go’s current map provides.
I'm more concerned about missing security policies. Like collision counting.