According to cppreference, most uses of the volatile keyword are to be deprecated in C++20. What is the disadvantage of volatile? And what is the alternative solution when not using volatile?
There's a good talk by the C++ committee language evolution chair on why.
Brief summary, the places that volatile is being removed from didn't have any well defined meaning in the standard and just caused confusion.
+= a single/atomic instruction? How about ++?compare_exchange? What if it fails?void foo(int volatile n) mean? or int volatile foo()?*vp; do a load? (This has changed twice in the standard.)Historically, people have used volatile to achieve thread safety in C and C++. In C++11, non-UB ways to create synchronization and shared state between threads were added. I recommend Back to Basics: Concurrency as a good introduction.