Return references from Type::kind

src/types/mod.rs

@@ -253,12 +253,15 @@ macro_rules! make_postgres_type {
             }
 
             /// The kind of this type
-            pub fn kind(&self) -> Kind {
+            pub fn kind(&self) -> &Kind {
                 match *self {
                     $(
-                        Type::$variant => $kind,
+                        Type::$variant => {
+                            const V: &'static Kind = &$kind;
+                            V
+                        }
                     )+
-                    Type::Unknown(ref u) => u.kind().clone(),
+                    Type::Unknown(ref u) => u.kind(),
                 }
             }
         }

src/types/slice.rs

@@ -6,7 +6,7 @@ use {Type, ToSql, Result, Error, Kind};
 ///
 /// `Slice`'s `ToSql` implementation maps the slice to a one-dimensional
 /// Postgres array of the relevant type. This is particularly useful with the
-/// `ANY` operator to match a column against multiple values without having
+/// `ANY` function to match a column against multiple values without having
 /// to dynamically construct the query string.
 ///
 /// # Examples
@@ -27,7 +27,7 @@ pub struct Slice<'a, T: 'a + ToSql>(pub &'a [T]);
 impl<'a, T: 'a + ToSql> ToSql for Slice<'a, T> {
     fn to_sql(&self, ty: &Type) -> Result<Option<Vec<u8>>> {
         let member_type = match ty.kind() {
-            Kind::Array(member) => member,
+            &Kind::Array(ref member) => member,
             _ => return Err(Error::WrongType(ty.clone())),
         };