This error indicates that the bindings in a match arm would require a value to be moved into more than one location, thus violating unique ownership. Code like the following is invalid as it requires the entire Option<String>
to be moved into a variable called op_string
while simultaneously requiring the inner String
to be moved into a variable called s
.
Erroneous code example:
let x = Some("s".to_string()); match x { op_string @ Some(s) => {}, // error: cannot bind by-move with sub-bindings None => {}, }
See also the error E0303.