In Rust, shadowing is when you "declare a new variable with the same name as a previous variable" [1] -- even in the same scope. It seems it "fell out" of how the original compiler was implemented, and there was more support to retain it than not. See: https://internals.rust-lang.org/t/history-of-shadowing-in-ru...

[1] The "Rust book" has a good explanation of shadowing, which contains a nearly identical example. See: https://doc.rust-lang.org/book/ch03-01-variables-and-mutabil...