To get a picture, think about the case of referencing lines of code on github. View a source file on github, then place
y then it will change url into the tip of the tree commit (if we view it through the master/main branch). So when we share such url to others, specific lines won't be changed as might be affected from newer update of the Rust code.
So for example, if I view macros.rs - source at such specific line, do I have any option to make sure it reference to latest version in that time period of Rust so when others view it, specific lines won't change?