fix: support of oneOf

[dotkas]

No description provided.

[Copilot]

Pull request overview

This PR improves oneOf/anyOf support by making generated union enums more readable and safer: inline scalar members now get type-based variant names (e.g., String), x-rust-name can name inline union members, and unions that would contain the same lowered Rust type more than once are rejected with a targeted diagnostic.

Changes:

• Add union-variant naming rules (including x-rust-name on inline union members and scalar type-based variant names).
• Reject #[serde(untagged)] unions that contain the same lowered Rust type multiple times, with improved console hints.
• Extend docs and fixture-based coverage tests for the above behaviors.

Reviewed changes

Copilot reviewed 9 out of 11 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
docs/extensions.md	Documents x-rust-name behavior for inline union members and union variant naming rules.
docs/design.md	Adds design rationale around unions and updates x-rust-name guidance.
crates/oapi-codegen/tests/generated/recursive_schema.rs	Updates expected generated code for scalar union variant naming.
crates/oapi-codegen/tests/generated/oneof_variant_naming.rs	Adds a generated-code snapshot covering the new naming behavior.
crates/oapi-codegen/tests/generated.rs	Registers the new generated snapshot module.
crates/oapi-codegen/tests/fixtures/unsupported_duplicate_union_variant.yaml	Adds a fixture demonstrating duplicate lowered-type union rejection.
crates/oapi-codegen/tests/fixtures/oneof_variant_naming.yaml	Adds a fixture exercising scalar/object/ref/custom union member naming.
crates/oapi-codegen/tests/coverage.rs	Adds coverage entries and enables the new fixture-based test.
crates/oapi-codegen/src/lower/schema.rs	Implements variant naming tweaks and duplicate-lowered-type detection for unions.
crates/oapi-codegen/src/ir.rs	Adds RustType::label() for clearer diagnostics.
crates/oapi-codegen/src/console.rs	Adds a dedicated hint for the new “duplicate union type” unsupported-schema diagnostic.

Suppressed comments (1)

crates/oapi-codegen/src/lower/schema.rs:858

• The doc comment for extension_str is duplicated; it looks like the new example line was added without removing/updating the old one.

/// Extract a string-valued extension (for example `x-rust-type`) from schema data.
/// Extract a string-valued extension (for example `x-rust-name`) from schema data.

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[Copilot]

Pull request overview

Copilot reviewed 10 out of 12 changed files in this pull request and generated no new comments.

[alchemax-housekeeper]

🎉 This PR is included in version 1.0.0-dev.34 🎉

The release is available on GitHub release

Your semantic-release bot 📦🚀

[alchemax-housekeeper]

🎉 This PR is included in version 1.0.0 🎉

The release is available on GitHub release

Your semantic-release bot 📦🚀