Deserialization of Blobs using serde confuses types

[cevans-uk]

Consider:

use nbt::{Blob, Value}; 

fn main() {
    let mut blob = Blob::new();
    blob.insert("test", Value::Int(123)).unwrap();

    let mut bytes = Vec::new();
    nbt::to_writer(&mut bytes, &blob, None).unwrap();
    println!("{:?}", bytes);

    let de_blob: Blob = nbt::from_reader(&bytes[..]).unwrap();
    println!("{:?}", de_blob);
}

Output:

[10, 0, 0, 3, 0, 4, 116, 101, 115, 116, 0, 0, 0, 123, 0]
Blob { title: "", content: {"test": Byte(123)} }

Serialization seems to work -- that 3 in the 4th position is TAG_Int as you'd expect, but it gets deserialized into a Value::Byte (using larger values will give Shorts and then Ints).

Using Blob::from_reader works, and gives Blob { title: "", content: {"test": Int(123)} }.

I think this is caused by using serde(untagged) for the Value enum, but I really don't understand serde well enough to know how to fix this.

[atheriel]

I'm not sure why this is the case, either. There is a test for this exact behaviour that seems to pass.

[cevans-uk]

The test passes since none of the values used can be represented in one of the smaller (or rather, earlier in enum Value) types. This is sufficient for a failure:

--- a/src/tests.rs
+++ b/src/tests.rs
@@ -293,7 +293,7 @@ fn serde_blob() {
 
     let mut nbt = Blob::new();
     nbt.insert("name", "Herobrine").unwrap();
-    nbt.insert("health", 100i8).unwrap();
+    nbt.insert("health", 100i16).unwrap();
     nbt.insert("food", 20.0f32).unwrap();
     nbt.insert("emeralds", 12345i16).unwrap();
     nbt.insert("timestamp", 1424778774i32).unwrap();
@@ -306,10 +306,10 @@ fn serde_blob() {
                 0x6e, 0x61, 0x6d, 0x65,
                 0x00, 0x09,
                 0x48, 0x65, 0x72, 0x6f, 0x62, 0x72, 0x69, 0x6e, 0x65,
-            0x01,
+            0x02,
                 0x00, 0x06,
                 0x68, 0x65, 0x61, 0x6c, 0x74, 0x68,
-                0x64,
+                0x00, 0x64,
             0x05,
                 0x00, 0x04,
                 0x66, 0x6f, 0x6f, 0x64,

---- tests::serde_blob stdout ----
thread 'tests::serde_blob' panicked at 'assertion failed: `(left == right)`
  left: `Blob { title: "", content: {"food": Float(20.0), "emeralds": Short(12345), "name": String("Herobrine"), "timestamp": Int(1424778774), "health": Byte(100)} }`,
 right: `Blob { title: "", content: {"name": String("Herobrine"), "health": Short(100), "emeralds": Short(12345), "timestamp": Int(1424778774), "food": Float(20.0)} }`', src/tests.rs:332:5