Impl SerJson for HashMap<&str, T> and other types

src/serde_json.rs

@@ -1380,3 +1380,12 @@ impl DeJson for std::time::SystemTime {
         }
     }
 }
+
+impl<T> SerJson for &T
+where
+    T: SerJson + ?Sized,
+{
+    fn ser_json(&self, d: usize, s: &mut SerJsonState) {
+        (**self).ser_json(d, s);
+    }
+}

tests/json.rs

@@ -588,6 +588,21 @@
     assert_eq!(foo.map["qwe"], 2);
 }
 
+#[cfg(feature = "std")]
+#[test]
+fn serialize_hashmap_with_str_keys() {
+    let mut hm: HashMap<&str, i32> = HashMap::new();
+    hm.insert("foo", 1);
+    hm.insert("bar", 2);
+
+    let json = SerJson::serialize_json(&hm);
+
+    let hm: HashMap<String, i32> = DeJson::deserialize_json(&json).unwrap();
+    assert_eq!(hm.len(), 2);
+    assert_eq!(hm["foo"], 1);
+    assert_eq!(hm["bar"], 2);
+}
+
 #[cfg(feature = "std")]
 #[test]
 fn serialize_hashmap_with_custom_hasher() {
@@ -1090,7 +1105,7 @@
     pub struct Test(i32, pub i32, pub(crate) String, f32);
 
     #[derive(DeJson, SerJson, PartialEq)]
     pub struct Vec2(pub(crate) f32, pub(crate) f32);
 
     let test = Test(0, 1, "asd".to_string(), 2.);
     let bytes = SerJson::serialize_json(&test);