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Merged
simonjbeaumont merged 2 commits into from
Jul 3, 2026
Merged

Stop boxing types that recurse only through an array or dictionary #910

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0bab8aa
Stop boxing types that recurse only through an array or dictionary
eyupcanakman Jun 1, 2026
20037e9
Add tests for types that recurse through a direct ref and a container
eyupcanakman Jul 2, 2026
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10 changes: 6 additions & 4 deletions Sources/_OpenAPIGeneratorCore/Translator/Recursion/DeclarationRecursionDetector.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -155,13 +155,15 @@ fileprivate extension Array where Element == String {

extension ExistingTypeDescription {

/// The name in the `Components.Schemas.` namespace, if the type can appear
/// there. Nil otherwise.
/// The name in the `Components.Schemas.` namespace this type references
/// without an intervening array or dictionary, if any. Nil otherwise.
var referencedSchemaComponentName: String? {
switch self {
case .member(let components): return components.nameIfTopLevelSchemaComponent
case .array(let desc), .dictionaryValue(let desc), .any(let desc), .optional(let desc):
return desc.referencedSchemaComponentName
case .any(let desc), .optional(let desc): return desc.referencedSchemaComponentName
// Arrays and dictionaries provide heap indirection, so a reference reached
// only through them cannot form a value-type cycle that needs boxing.
case .array, .dictionaryValue: return nil
case .generic: return nil
}
}
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234 changes: 234 additions & 0 deletions Tests/OpenAPIGeneratorReferenceTests/SnippetBasedReferenceTests.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -1617,6 +1617,240 @@ final class SnippetBasedReferenceTests: XCTestCase {
)
}

func testComponentsSchemasRecursive_throughArray() throws {
try self.assertSchemasTranslation(
"""
schemas:
Node:
type: object
properties:
children:
type: array
items:
$ref: '#/components/schemas/Node'
""",
"""
public enum Schemas {
public struct Node: Codable, Hashable, Sendable {
public var children: [Components.Schemas.Node]?
public init(children: [Components.Schemas.Node]? = nil) {
self.children = children
}
public enum CodingKeys: String, CodingKey {
case children
}
}
}
"""
)
}

func testComponentsSchemasRecursive_throughDictionary() throws {
try self.assertSchemasTranslation(
"""
schemas:
Node:
type: object
properties:
children:
type: object
additionalProperties:
$ref: '#/components/schemas/Node'
""",
"""
public enum Schemas {
public struct Node: Codable, Hashable, Sendable {
public struct childrenPayload: Codable, Hashable, Sendable {
public var additionalProperties: [String: Components.Schemas.Node]
public init(additionalProperties: [String: Components.Schemas.Node] = .init()) {
self.additionalProperties = additionalProperties
}
public init(from decoder: any Swift.Decoder) throws {
additionalProperties = try decoder.decodeAdditionalProperties(knownKeys: [])
}
public func encode(to encoder: any Swift.Encoder) throws {
try encoder.encodeAdditionalProperties(additionalProperties)
}
}
public var children: Components.Schemas.Node.childrenPayload?
public init(children: Components.Schemas.Node.childrenPayload? = nil) {
self.children = children
}
public enum CodingKeys: String, CodingKey {
case children
}
}
}
"""
)
}

func testComponentsSchemasRecursive_directAndThroughArray() throws {
try self.assertSchemasTranslation(
"""
schemas:
Node:
type: object
properties:
parent:
$ref: '#/components/schemas/Node'
children:
type: array
items:
$ref: '#/components/schemas/Node'
""",
"""
public enum Schemas {
public struct Node: Codable, Hashable, Sendable {
public var parent: Components.Schemas.Node? {
get {
self.storage.value.parent
}
_modify {
yield &self.storage.value.parent
}
}
public var children: [Components.Schemas.Node]? {
get {
self.storage.value.children
}
_modify {
yield &self.storage.value.children
}
}
public init(
parent: Components.Schemas.Node? = nil,
children: [Components.Schemas.Node]? = nil
) {
self.storage = .init(value: .init(
parent: parent,
children: children
))
}
public enum CodingKeys: String, CodingKey {
case parent
case children
}
public init(from decoder: any Swift.Decoder) throws {
self.storage = try .init(from: decoder)
}
public func encode(to encoder: any Swift.Encoder) throws {
try self.storage.encode(to: encoder)
}
private var storage: OpenAPIRuntime.CopyOnWriteBox<Storage>
private struct Storage: Codable, Hashable, Sendable {
var parent: Components.Schemas.Node?
var children: [Components.Schemas.Node]?
init(
parent: Components.Schemas.Node? = nil,
children: [Components.Schemas.Node]? = nil
) {
self.parent = parent
self.children = children
}
typealias CodingKeys = Components.Schemas.Node.CodingKeys
}
}
}
"""
)
}

func testComponentsSchemasRecursive_directAndThroughDictionary() throws {
try self.assertSchemasTranslation(
"""
schemas:
Node:
type: object
properties:
parent:
$ref: '#/components/schemas/Node'
children:
type: object
additionalProperties:
$ref: '#/components/schemas/Node'
""",
"""
public enum Schemas {
public struct Node: Codable, Hashable, Sendable {
public var parent: Components.Schemas.Node? {
get {
self.storage.value.parent
}
_modify {
yield &self.storage.value.parent
}
}
public struct childrenPayload: Codable, Hashable, Sendable {
public var additionalProperties: [String: Components.Schemas.Node]
public init(additionalProperties: [String: Components.Schemas.Node] = .init()) {
self.additionalProperties = additionalProperties
}
public init(from decoder: any Swift.Decoder) throws {
additionalProperties = try decoder.decodeAdditionalProperties(knownKeys: [])
}
public func encode(to encoder: any Swift.Encoder) throws {
try encoder.encodeAdditionalProperties(additionalProperties)
}
}
public var children: Components.Schemas.Node.childrenPayload? {
get {
self.storage.value.children
}
_modify {
yield &self.storage.value.children
}
}
public init(
parent: Components.Schemas.Node? = nil,
children: Components.Schemas.Node.childrenPayload? = nil
) {
self.storage = .init(value: .init(
parent: parent,
children: children
))
}
public enum CodingKeys: String, CodingKey {
case parent
case children
}
public init(from decoder: any Swift.Decoder) throws {
self.storage = try .init(from: decoder)
}
public func encode(to encoder: any Swift.Encoder) throws {
try self.storage.encode(to: encoder)
}
private var storage: OpenAPIRuntime.CopyOnWriteBox<Storage>
private struct Storage: Codable, Hashable, Sendable {
var parent: Components.Schemas.Node?
struct childrenPayload: Codable, Hashable, Sendable {
public var additionalProperties: [String: Components.Schemas.Node]
public init(additionalProperties: [String: Components.Schemas.Node] = .init()) {
self.additionalProperties = additionalProperties
}
public init(from decoder: any Swift.Decoder) throws {
additionalProperties = try decoder.decodeAdditionalProperties(knownKeys: [])
}
public func encode(to encoder: any Swift.Encoder) throws {
try encoder.encodeAdditionalProperties(additionalProperties)
}
}
var children: Components.Schemas.Node.childrenPayload?
init(
parent: Components.Schemas.Node? = nil,
children: Components.Schemas.Node.childrenPayload? = nil
) {
self.parent = parent
self.children = children
}
typealias CodingKeys = Components.Schemas.Node.CodingKeys
}
}
}
"""
)
}

func testComponentsSchemasRecursive_objectNested() throws {
try self.assertSchemasTranslation(
"""
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