While Ada is a great and sadly underused language, if my memory serves, it's not out-of-the-box memory-safe by today's definitions. I seem to recall that it takes Spark to make it memory-safe.
I guess it is similar to Rust code that uses `unsafe {}` as the other poster mentioned (maybe `unsafe fn` for a closer analogy). My knowledge of Ada/SPARK is much greater than what I know about Rust, so I might be guessing wrong.
Unsafe functions mark that the caller is responsible for upholding the invariants necessary to avoid UB. In the 2021 and earlier editions, they also implicitly created an unsafe block in the body, but don't in 2024.
Or, in a more pithy tone: an unsafe block is the "hold my beer" block, while an unsafe function is a "put down your beer" function.
What are todoay's definitions? If Ada simply had more thorough rules but introduced an "unsafe {}" construct, then what would the practical difference actually be? Compiler defaults?