Code shared from the Rust Playground

playground.rs

struct Assignment {}
enum CodeNode {
    Assignment(Assignment),
}
enum CodeNodeRef<'a> {
    Assignment(&'a Assignment),
}
impl<'a> From<&'a Assignment> for CodeNodeRef<'a> {
    fn from(x: &'a Assignment) -> Self {
        CodeNodeRef::Assignment(x)
    }
}
impl<'a> From<&'a CodeNode> for CodeNodeRef<'a> {
    fn from(x: &'a CodeNode) -> Self {
        match x {
            CodeNode::Assignment(y) => y.into(),
        }
    }
}
fn foo<'a>(x: impl Into<CodeNodeRef<'a>>) {
}