For people who are proficient in other languages but haven't touched C++ since CS036 in undergrad, some 15+ years ago, what would be the best way to learn what "modern C++", both the code and the dev stack, looks like?

Asking for a friend.

I'm a little 10 years out from writing C++ professionally and I found this cheat sheet[0] useful. Basically if you have an inkling of the concept you're looking for, just search on that cheat sheet to find the relevant new C++ thing. Specifically for me, we used Boost for smart pointers which are now part of the stdlib, and threads are now part of the stdlib as well.

[0] https://github.com/AnthonyCalandra/modern-cpp-features