A lifetime was declared more than once in the same scope.
Erroneous code example:
fn foo<'a, 'b, 'a>(x: &'a str, y: &'b str, z: &'a str) { // error!
}Two lifetimes cannot have the same name. To fix this example, change
the second 'a lifetime into something else ('c for example):
fn foo<'a, 'b, 'c>(x: &'a str, y: &'b str, z: &'c str) { // ok!
}