Fix clippy warning for enums that impl Copy

typify-impl/src/type_entry.rs

@@ -706,6 +706,26 @@ impl TypeEntry {
             )
         }
 
+        // If the enum derives Copy it should dereference instead of cloning
+        // when converting to itself from a reference.
+        let from_ref_self_impl = if derive_set.contains("Copy") {
+            Some(quote! {
+                impl From<&#type_name> for #type_name {
+                    fn from(value: &#type_name) -> Self {
+                        *value
+                    }
+                }
+            })
+        } else {
+            Some(quote! {
+                impl From<&#type_name> for #type_name {
+                    fn from(value: &#type_name) -> Self {
+                        value.clone()
+                    }
+                }
+            })
+        };
+
         // ToString and FromStr impls for enums that are made exclusively of
         // simple variants (and are not untagged).
         let simple_enum_impl = bespoke_impls
@@ -957,12 +977,7 @@ impl TypeEntry {
                 #(#variants_decl)*
             }
 
-            impl From<&#type_name> for #type_name {
-                fn from(value: &#type_name) -> Self {
-                    value.clone()
-                }
-            }
-
+            #from_ref_self_impl
             #simple_enum_impl
             #default_impl
             #untagged_newtype_from_string_impl

typify-impl/tests/generator.out

@@ -163,7 +163,7 @@ mod types {
     }
     impl From<&StringEnum> for StringEnum {
         fn from(value: &StringEnum) -> Self {
-            value.clone()
+            *value
         }
     }
     impl ToString for StringEnum {