[FreezyLemon]

I'm sorry, but even if this exact example does not appear, this case is technically specified by the reference.

The page on identifiers (https://doc.rust-lang.org/reference/identifiers.html) calls out that a "single underscore character is not an identifier". If you then follow the trail (Search for "Underscore"), you will find that it is instead a wildcard pattern (https://doc.rust-lang.org/reference/patterns.html#wildcard-p...). It says that "[u]nlike identifier patterns, it [the wildcard pattern] does not copy, move or borrow the value it matches."

From this, it follows that the right-hand side ("value expression", roughly equal to an rvalue) is not moved into a place called _, but is effectively just a value matched against a wildcard pattern. This does nothing (the value is not moved into any other place), so it gets dropped.