This is about visual studio, but this is also about how the deprecated mechanisms work.

C++17 Feature Removals And Deprecations

by Stephan T. Lavavej

From the article:

Technology advances by inventing new ways of doing things and by discarding old ways. The C++ Standardization Committee is simultaneously adding new features and removing old features at a gradual pace, because we’ve discovered thoroughly better ways of writing code. While feature removals can be annoying, in the sense that programmers need to go change old codebases in order to make them conform to new Standards, they’re also important. Feature removals simplify the Core Language and Standard Library, avoiding the doom of accreting complexity forever. Additionally, removing old features makes it easier to read and write code. C++ will always be a language that offers programmers many ways to write something, but by taking away inferior techniques, it’s easier to choose one of the remaining techniques which are more modern...