[Bug] Introspect not working with flatten and (possibly) serde_with

[Dzordzu]

Description

Structs with flattened argument are improperly introspected. Any introspection of such a struct results in the empty array. Cannot determine if serde_with causes unexpected behaviors, because it's dependent on the flatten

Unresolved issues

• flatten working as expected
• verify that serde_with prefix is working as expected

Example

ser.rs

// ser.rs

use serde::{Serialize, Deserialize};

serde_with::with_prefix!(my "my_)");

#[derive(Debug, Serialize, Deserialize)]
pub struct B {
    pub b: String,
    #[serde(rename="z")]
    pub b2: usize
}

#[derive(Debug, Serialize, Deserialize)]
pub struct A {
    pub a: usize,
    #[serde(flatten, with="my")]
    pub bx: B
}

#[derive(Debug, Serialize, Deserialize)]
pub struct A0 {
    pub a: usize,
    pub bx: B
}

#[derive(Debug, Serialize, Deserialize)]
pub struct A1 {
    #[serde(with="my")]
    pub a: usize
}

#[derive(Debug, Serialize, Deserialize)]
pub struct A2 {
    #[serde(flatten)]
    pub bx: B
}

#[derive(Debug, Serialize, Deserialize)]
pub struct A3 {
    #[serde(with="my")]
    pub bx: B
}

main.rs

// main.rs

use serde_aux::prelude::*;
mod ser;

fn main() {
    let b = ser::B {
        b: "AA".into(),
        b2: 22,
    };

    let a = ser::A {
        a: 2,
        bx: b.clone()
    };

    let a0 = ser::A0 {
        a: 2,
        bx: b.clone()
    };

    let _a1 = ser::A1 {
        a: 2,
    };

    let a2 = ser::A2 {
        bx: b.clone()
    };

    let a3 = ser::A3 {
        bx: b.clone()
    };

    println!("A = \t{}", serde_json::to_string_pretty(&a).unwrap());
    println!("A0 = \t{}", serde_json::to_string_pretty(&a0).unwrap());
    println!("A2 = \t{}", serde_json::to_string_pretty(&a2).unwrap());
    println!("A3 = \t{}", serde_json::to_string_pretty(&a3).unwrap());

    println!("A = \t{:?}", serde_introspect::<ser::A>());
    println!("A0 = \t{:?}", serde_introspect::<ser::A0>());
    println!("A1 = \t{:?}", serde_introspect::<ser::A1>());
    println!("A2 = \t{:?}", serde_introspect::<ser::A2>());
    println!("A3 = \t{:?}", serde_introspect::<ser::A3>());
}

stdout

# Output

A =     {
  "a": 2,
  "my_)b": "AA",
  "my_)z": 22
}
A0 =    {
  "a": 2,
  "bx": {
    "b": "AA",
    "z": 22
  }
}
A2 =    {
  "b": "AA",
  "z": 22
}
A3 =    {
  "bx": {
    "my_)b": "AA",
    "my_)z": 22
}

A =     []          # Wrong
A0 =    ["a", "bx"] # Control sample. This is always ok
A1 =                # Actually panics, my bad
A2 =    []          # Wrong
A3 =    ["bx"]      # Actually ok, my bad

[iddm]

Hi! Thank you for filing your issue! I am not aware of how it should work together (not usually use serde_with), can you please provide the examples with the expected results?

[Dzordzu]

Sure. Here you go. I've edited my bug report to include jsons

[Dzordzu]

So it MAY work with serde_with prefixing, but it certainly fails with the flattened structs

[iddm]

I have just noticed you use the serde_introspect crate, which is not a part of serde_aux. Also, I couldn't see any use of serde_aux here except for the use statements, which do not do anything independently. Perhaps you meant to file an issue in the serde_introspect crate instead?

[Dzordzu]

Que? There is no such a crate... Also https://github.com/iddm/serde-aux/blob/master/src/serde_introspection.rs#L35

I couldn't see any use of serde_aux here except for the use statements, which do not do anything independently

I literally took it from this repo. See docs

[iddm]

Que? There is no such a crate... Also https://github.com/iddm/serde-aux/blob/master/src/serde_introspection.rs#L35

I couldn't see any use of serde_aux here except for the use statements, which do not do anything independently

I literally took it from this repo. See docs

Oh, I apologise! It wasn't me who added it, and I had completely forgotten about its existence.

The serde attributes often mess up with everything else. It has been long known, and unfortunately, not many things can be fixed. From what I can tell right now, it seems that the problem is introduced by using the serde's flatten attribute. Additionally, the serde_with might be breaking things another way. It is going to require research, which I unfortunately have no time for. @lucatrv would you like to take a look at what might cause a problem here?

[Dzordzu]

It wasn't me who added it,

No worries, it's the beauty of the OS projects ;)

@lucatrv would you like to take a look at what might cause a problem here?

Thanks a lot!

And obviously, thanks for your effort in maintaining this project!