Make Display for Number produce the same representation as serializing

Author: dtolnay

src/number.rs

@@ -292,10 +292,9 @@ impl Display for Number {
     #[cfg(not(feature = "arbitrary_precision"))]
     fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
         match self.n {
-            N::PosInt(u) => Display::fmt(&u, formatter),
-            N::NegInt(i) => Display::fmt(&i, formatter),
-            // Preserve `.0` on integral values, which Display hides
-            N::Float(f) => Debug::fmt(&f, formatter),
+            N::PosInt(u) => formatter.write_str(itoa::Buffer::new().format(u)),
+            N::NegInt(i) => formatter.write_str(itoa::Buffer::new().format(i)),
+            N::Float(f) => formatter.write_str(ryu::Buffer::new().format_finite(f)),
         }
     }
 

tests/debug.rs

@@ -28,6 +28,7 @@ fn value_number() {
     assert_eq!(format!("{:?}", json!(-1)), "Number(-1)");
     assert_eq!(format!("{:?}", json!(1.0)), "Number(1.0)");
     assert_eq!(Number::from_f64(1.0).unwrap().to_string(), "1.0"); // not just "1"
+    assert_eq!(Number::from_f64(12e40).unwrap().to_string(), "1.2e41");
 }
 
 #[test]