Adding Default::default()

src/default.rs

@@ -0,0 +1,19 @@
+#[derive(Debug, Default, PartialEq)]
+struct Foo {
+    x: i32,
+    // d: chrono::Date<chrono::Utc>,
+        // If a field is no Default, Foo definition itself will cause error.
+        // err: the trait `Default` is not implemented for `Date<Utc>
+    s: String,
+    w: Option<bool>,
+    y: i32,
+}
+
+#[test]
+fn ex1() {
+    let foo = Foo { x: 42, y: 33, ..Default::default() };
+    assert_eq!(foo, Foo { x: 42, s: "".to_string(), w: None, y: 33 });
+
+    let foo: Foo = Default::default();
+    assert_eq!(foo, Foo { x: 0, s: "".to_string(), w: None, y: 0 });
+}

src/lib.rs

@@ -18,6 +18,7 @@ mod ctor_chain;
 mod compile_vs_runtime_read_env_and_file;
 mod concurrency;
 mod const_fn;
+mod default;
 mod drop_aka_dtor;
 mod r#enum;
 mod env_logger;