fix: preserve allOf aliases and singleton maps

[dotkas]

No description provided.

[Copilot]

🟡 Changes recommended

Critical and moderate unresolved lowering issues block approval.

Get a fresh assessment by requesting another Copilot review.

Pull request overview

This PR improves allOf lowering for aliases, singleton maps, and closed empty objects, with added regression coverage and documentation.

Changes:

• Preserves map and equivalent composite aliases.
• Handles closed empty objects consistently.
• Adds fixtures, generated outputs, runtime tests, and coverage updates.

Review findings: Critical (2 votes): schema.rs can create duplicate definitions for inline map value schemas. Moderate (1 vote): all_of.rs does not preserve singleton wrapper aliases.

File summaries

File	Summary
docs/design.md	Documents updated allOf behavior.
crates/oapi-codegen/tests/generated/allof_merge.rs	Updates generated regression models.
crates/oapi-codegen/tests/generated.rs	Adds serialization and constraint tests.
crates/oapi-codegen/tests/fixtures/allof_merge.yaml	Adds map, alias, and closed-object fixtures.
crates/oapi-codegen/tests/coverage.rs	Accepts empty braced structs.
crates/oapi-codegen/src/lower/schema.rs	Lowers singleton maps and closed objects; contains the critical duplicate-definition issue.
crates/oapi-codegen/src/lower/paths.rs	Tests inline map body lowering.
crates/oapi-codegen/src/lower/all_of.rs	Reuses equivalent composites; contains the moderate singleton-alias issue.
crates/oapi-codegen/src/coverage.rs	Removes obsolete closed-map warnings.

Review details

Suppressed comments (1)

crates/oapi-codegen/src/lower/all_of.rs:189

• This guard only recognizes resolved composites with more than one allOf member. An alias declared as AliasA: { allOf: [{ $ref: Composite }] } resolves to a one-member wrapper, so two equivalent wrapper aliases skip this fast path; resolve() then unwraps into the multi-member Composite and errors with “overlapping composed properties”. Treat any equal resolved allOf schema as reusable (the equality already protects against differing metadata), so these aliases are preserved too.

    if matches!(&resolved_left.schema_kind, SchemaKind::AllOf { all_of } if all_of.len() > 1)
        && resolved_left == resolved_right

• Files reviewed: 8/9 changed files
• Comments generated: 1
• Review effort level: Lite

---

💡 Add a code-review agent skill or configure MCP servers for context-aware, tailored reviews. Learn more in the docs.

[Copilot]

🟡 Changes recommended

A critical unresolved allOf alias comparison issue can cause valid singleton-wrapper aliases to fail during resolution.

Get a fresh assessment by requesting another Copilot review.

Review details

• Files reviewed: 8/9 changed files
• Comments generated: 1
• Review effort level: Lite

[Copilot]

🔵 Needs a closer look

Closed-object lowering can accept unsatisfiable schemas, and the related documentation remains contradictory.

Review details

Suppressed comments (3)

crates/oapi-codegen/src/lower/schema.rs:244

• This new branch sends empty closed objects to object_to_struct, but that builder only iterates declared properties. A schema such as {type: object, additionalProperties: false, required: [missing]} therefore emits struct X {} and accepts {}, even though the closed schema requires an undeclared property and is unsatisfiable. Validate/reject undeclared required names before emitting this struct; the singleton allOf path already rejects non-empty required for the same reason.

        if obj.properties.is_empty() && !matches!(obj.additional_properties, Some(AdditionalProperties::Any(false))) {

crates/oapi-codegen/src/lower/schema.rs:822

• The analogous inline branch has the same correctness gap: empty closed objects with required names not present in properties are lowered to an empty struct, so {} deserializes even though the schema cannot be satisfied. Please apply the same undeclared-required validation here before object_to_struct is called.

        if obj.properties.is_empty() && !matches!(obj.additional_properties, Some(AdditionalProperties::Any(false))) {

docs/design.md:360

• This new statement leaves the later default-handling documentation at docs/design.md:688 contradictory: it still says an empty object is always represented as a map, while this change makes an empty closed object (additionalProperties: false) a struct. Please qualify that existing statement with the closed-object exception.

Empty closed objects remain structs and reject additional properties.

• Files reviewed: 8/9 changed files
• Comments generated: 0 new
• Review effort level: Lite

[alchemax-housekeeper]

🎉 This PR is included in version 1.4.0-dev.2 🎉

The release is available on GitHub release

Your semantic-release bot 📦🚀