rust-axum: Integer enums generate string-based serde(rename) instead of integer serialization

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?

Description

The rust-axum generator renders integer enums with string-based #[serde(rename = "0")] attributes instead of integer representations. This causes deserialization to fail when clients send spec-correct integer values (e.g., lib_type: 1 instead of "1").

OpenAPI declaration

LibType:
  type: integer
  description: TSS library/protocol type
  enum: [0, 1, 2]
  x-enum-varnames: [GG20, DKLS, KeyImport]

Expected generated code

An enum that serializes/deserializes as integers, e.g. using serde_repr:

#[repr(i32)]
#[derive(serde_repr::Serialize_repr, serde_repr::Deserialize_repr)]
pub enum LibType {
    GG20 = 0,
    DKLS = 1,
    KeyImport = 2,
}

Actual generated code

#[derive(serde::Serialize, serde::Deserialize)]
pub enum LibType {
    #[serde(rename = "0")]
    GG20,
    #[serde(rename = "1")]
    DKLS,
    #[serde(rename = "2")]
    KeyImport,
}

LibType::DKLS serializes as "1" (JSON string) instead of 1 (JSON number). Deserializing {"lib_type": 1} fails with a type mismatch error.

Generation details

• Generator: rust-axum
• Version: 7.20.0 (also reproducible on 7.21.0)
• Command: npx @openapitools/openapi-generator-cli generate -i spec.yaml -g rust-axum -o output/

Workaround

Post-generation script that regex-replaces the generated enum blocks with serde_repr-based versions. Fragile but functional.

Start with the provided OpenAPI enum and run the rust-axum generator using the documented command. Inspect the generated LibType enum and verify JSON serialization and deserialization for numeric values. Done means integer enums use integer representations rather than string-based serde renames, with the generated output accepting values such as 1.