Inconsistent behavior with serde rename_all

[neunenak]

Here's a simple reproduction of my issue:

Cargo.toml:

[package]
name = "kotlin-typeshare-repro"
version = "0.1.0"
edition = "2024"

[dependencies]
serde = "1.0.228"
serde_json = "1.0.149"
typeshare = "1.0.5"

src/lib.rs:

use serde::{Deserialize, Serialize};
use typeshare::typeshare;

#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "snake_case")]
#[typeshare]
pub enum DocumentType {
    PodcastEpisode,
    Podcast,
    PDF,
}

#[test]
fn test() {
    let v = DocumentType::PDF;
    assert_eq!(serde_json::to_string(&v).unwrap(), "\"p_d_f\"");
}

The test passes, you can see the (weird) "p_d_f" string that gets generated here.

However, if I run typeshare --lang kotlin --output-file Generated.kt . in the project, I get:

enum class DocumentType(val string: String) {
    @SerialName("podcast_episode")
    PodcastEpisode("podcast_episode"),
    @SerialName("podcast")
    Podcast("podcast"),
    @SerialName("pdf")
    PDF("pdf"),
}

Which has the serialization "pdf" not "p_d_f", which breaks compatibility between the rust and kotlin versions of this type.