refactor(derive): Make Sp copyable

clap_derive/src/item.rs

@@ -949,11 +949,11 @@ impl Item {
     }
 
     pub fn casing(&self) -> Sp<CasingStyle> {
-        self.casing.clone()
+        self.casing
     }
 
     pub fn env_casing(&self) -> Sp<CasingStyle> {
-        self.env_casing.clone()
+        self.env_casing
     }
 
     pub fn has_explicit_methods(&self) -> bool {

clap_derive/src/utils/spanned.rs

@@ -5,7 +5,7 @@ use syn::LitStr;
 use std::ops::{Deref, DerefMut};
 
 /// An entity with a span attached.
-#[derive(Debug, Clone)]
+#[derive(Debug, Copy, Clone)]
 pub struct Sp<T> {
     val: T,
     span: Span,