Prevent invalid enum deserialization

Fixes rust-num#220

json/src/de.rs

@@ -847,26 +847,26 @@ impl<'a, R: Read + 'a> de::VariantVisitor for UnitVariantVisitor<'a, R> {
         Ok(())
     }
 
-    fn visit_newtype_seed<T>(self, seed: T) -> Result<T::Value>
+    fn visit_newtype_seed<T>(self, _seed: T) -> Result<T::Value>
         where T: de::DeserializeSeed,
     {
-        seed.deserialize(self.de)
+        Err(self.de.error(ErrorCode::EOFWhileParsingValue))
     }
 
-    fn visit_tuple<V>(self, _len: usize, visitor: V) -> Result<V::Value>
+    fn visit_tuple<V>(self, _len: usize, _visitor: V) -> Result<V::Value>
         where V: de::Visitor,
     {
-        de::Deserializer::deserialize(self.de, visitor)
+        Err(self.de.error(ErrorCode::EOFWhileParsingValue))
     }
 
     fn visit_struct<V>(
         self,
         _fields: &'static [&'static str],
-        visitor: V
+        _visitor: V
     ) -> Result<V::Value>
         where V: de::Visitor,
     {
-        de::Deserializer::deserialize(self.de, visitor)
+        Err(self.de.error(ErrorCode::EOFWhileParsingValue))
     }
 }
 

json_tests/tests/test.rs

@@ -1133,6 +1133,8 @@ fn test_parse_enum_errors() {
             "trailing characters at line 1 column 9"),
         ("\"Frog\"",
             "EOF while parsing a value at line 1 column 6"),
+        ("\"Frog\" 0 ",
+            "EOF while parsing a value at line 1 column 6"),
         ("{\"Frog\":{}}",
             "invalid type: map, expected tuple variant Animal::Frog at line 1 column 10"),
         ("{\"Cat\":[]}",
@@ -1772,3 +1774,15 @@ fn test_json_macro() {
         (<Result<(), &str> as Clone>::clone(&Err("")).unwrap_err()): "err"
     });
 }
+
+#[test]
+fn issue_220() {
+    #[derive(Debug, PartialEq, Eq, Deserialize)]
+    enum E {
+        V(u8),
+    }
+
+    assert!(from_str::<E>(r#" "V"0 "#).is_err());
+
+    assert_eq!(from_str::<E>(r#"{"V": 0}"#).unwrap(), E::V(0));
+}