impl Hash for Value when "preserve_order" feature is not set

src/map.rs

@@ -368,6 +368,14 @@ impl PartialEq for Map<String, Value> {
 
 impl Eq for Map<String, Value> {}
 
+#[cfg(not(feature = "preserve_order"))]
+impl Hash for Map<String, Value> {
+    #[inline]
+    fn hash<H: core::hash::Hasher>(&self, state: &mut H) {
+        self.map.hash(state)
+    }
+}
+
 /// Access an element of this map. Panics if the given key is not present in the
 /// map.
 ///

src/value/mod.rs

@@ -113,6 +113,7 @@ pub use crate::raw::{to_raw_value, RawValue};
 ///
 /// See the [`serde_json::value` module documentation](self) for usage examples.
 #[derive(Clone, Eq, PartialEq)]
+#[cfg_attr(not(feature = "preserve_order"), derive(Hash))]
 pub enum Value {
     /// Represents a JSON null value.
     ///