Retain enums conforming to CodingKey when an external Codable protoco…

…l is specified. Closes #679

CHANGELOG.md

@@ -7,11 +7,13 @@
 ##### Enhancements
 
 - Add experimental unused import analysis.
+- The option `--external-encodable-protocols` is deprecated, use `--external-codable-protocols` instead.
 
 ##### Bug Fixes
 
 - Subscript functions required by `@dynamicMemberLookup` are now retained.
 - A newline is no longer printed before non-Xcode formatted results.
+- `--external-codable-protocols` now retains enums that conform to `CodingKey`.
 
 ## 2.17.1 (2023-12-04)
 

Sources/Frontend/Commands/ScanCommand.swift

@@ -63,9 +63,12 @@ struct ScanCommand: FrontendCommand {
     @Option(help: "Comma-separated list of property types to retain if the property is assigned, but never read", transform: split(by: ","))
     var retainAssignOnlyPropertyTypes: [String] = defaultConfiguration.$retainAssignOnlyPropertyTypes.defaultValue
 
-    @Option(help: "Comma-separated list of external protocols that inherit Encodable. Properties of types conforming to these protocols will be retained", transform: split(by: ","))
+    @Option(help: .private, transform: split(by: ","))
     var externalEncodableProtocols: [String] = defaultConfiguration.$externalEncodableProtocols.defaultValue
 
+    @Option(parsing: .upToNextOption, help: "Names of external protocols that inherit Codable. Properties and CodingKey enums of types conforming to these protocols will be retained")
+    var externalCodableProtocols: [String] = defaultConfiguration.$externalCodableProtocols.defaultValue
+
     @Option(parsing: .upToNextOption, help: "Names of XCTestCase subclasses that reside in external targets")
     var externalTestCaseClasses: [String] = defaultConfiguration.$externalTestCaseClasses.defaultValue
 
@@ -111,6 +114,10 @@ struct ScanCommand: FrontendCommand {
             try scanBehavior.setup(config).get()
         }
 
+        if !externalEncodableProtocols.isEmpty {
+            Logger().warn("The option '--external-encodable-protocols' is deprecated, use '--external-codable-protocols' instead.")
+        }
+
         let configuration = Configuration.shared
         configuration.guidedSetup = setup
         configuration.apply(\.$workspace, workspace)
@@ -132,6 +139,7 @@ struct ScanCommand: FrontendCommand {
         configuration.apply(\.$disableRedundantPublicAnalysis, disableRedundantPublicAnalysis)
         configuration.apply(\.$enableUnusedImportsAnalysis, enableUnusedImportAnalysis)
         configuration.apply(\.$externalEncodableProtocols, externalEncodableProtocols)
+        configuration.apply(\.$externalCodableProtocols, externalCodableProtocols)
         configuration.apply(\.$externalTestCaseClasses, externalTestCaseClasses)
         configuration.apply(\.$verbose, verbose)
         configuration.apply(\.$quiet, quiet)

Sources/PeripheryKit/SourceGraph/Mutators/CodingKeyEnumReferenceBuilder.swift

@@ -4,9 +4,11 @@ import Shared
 /// Builds a reference from a `Codable` conforming type to any child enum that conforms to `CodingKey`.
 final class CodingKeyEnumReferenceBuilder: SourceGraphMutator {
     private let graph: SourceGraph
+    private let configuration: Configuration
 
     required init(graph: SourceGraph, configuration: Configuration) {
         self.graph = graph
+        self.configuration = configuration
     }
 
     func mutate() {
@@ -17,8 +19,11 @@ final class CodingKeyEnumReferenceBuilder: SourceGraphMutator {
                 $0.kind == .protocol && $0.name == "CodingKey"
             }
 
+            let codableTypes = ["Codable", "Decodable", "Encodable"] + configuration.externalEncodableProtocols + configuration.externalCodableProtocols
+
             let isParentCodable = graph.inheritedTypeReferences(of: parent).contains {
-                [.protocol, .typealias].contains($0.kind) && ["Codable", "Decodable", "Encodable"].contains($0.name)
+                guard let name = $0.name else { return false }
+                return [.protocol, .typealias].contains($0.kind) && codableTypes.contains(name)
             }
 
             if isCodingKey && isParentCodable {

Sources/PeripheryKit/SourceGraph/Mutators/EncodablePropertyRetainer.swift

@@ -8,10 +8,12 @@ import Shared
 final class EncodablePropertyRetainer: SourceGraphMutator {
     private let graph: SourceGraph
     private let configuration: Configuration
+    private let externalCodableProtocols: [String]
 
     required init(graph: SourceGraph, configuration: Configuration) {
         self.graph = graph
         self.configuration = configuration
+        self.externalCodableProtocols = configuration.externalEncodableProtocols + configuration.externalCodableProtocols
     }
 
     func mutate() {
@@ -41,7 +43,7 @@ final class EncodablePropertyRetainer: SourceGraphMutator {
         }
 
         if let name = ref.name {
-            if graph.isExternal(ref), configuration.externalEncodableProtocols.contains(name) {
+            if graph.isExternal(ref), externalCodableProtocols.contains(name) {
                 return true
             }
         }

Sources/Shared/Configuration.swift

@@ -47,6 +47,9 @@ public final class Configuration {
     @Setting(key: "external_encodable_protocols", defaultValue: [])
     public var externalEncodableProtocols: [String]
 
+    @Setting(key: "external_codable_protocols", defaultValue: [])
+    public var externalCodableProtocols: [String]
+
     @Setting(key: "external_test_case_classes", defaultValue: [])
     public var externalTestCaseClasses: [String]
 
@@ -167,6 +170,10 @@ public final class Configuration {
             config[$externalEncodableProtocols.key] = externalEncodableProtocols
         }
 
+        if $externalCodableProtocols.hasNonDefaultValue {
+            config[$externalCodableProtocols.key] = externalCodableProtocols
+        }
+
         if $externalTestCaseClasses.hasNonDefaultValue {
             config[$externalTestCaseClasses.key] = externalTestCaseClasses
         }
@@ -264,7 +271,12 @@ public final class Configuration {
             case $retainAssignOnlyPropertyTypes.key:
                 $retainAssignOnlyPropertyTypes.assign(value)
             case $externalEncodableProtocols.key:
+                if !externalEncodableProtocols.isEmpty {
+                    logger.warn("The option '--external-encodable-protocols' is deprecated, use '--external-codable-protocols' instead.")
+                }
                 $externalEncodableProtocols.assign(value)
+            case $externalCodableProtocols.key:
+                $externalCodableProtocols.assign(value)
             case $externalTestCaseClasses.key:
                 $externalTestCaseClasses.assign(value)
             case $retainObjcAccessible.key:
@@ -323,6 +335,7 @@ public final class Configuration {
         $disableRedundantPublicAnalysis.reset()
         $enableUnusedImportsAnalysis.reset()
         $externalEncodableProtocols.reset()
+        $externalCodableProtocols.reset()
         $externalTestCaseClasses.reset()
         $verbose.reset()
         $quiet.reset()

Tests/Fixtures/RetentionFixtures/testCodingKeyEnum.swift

@@ -50,3 +50,15 @@ public struct FixtureClass120 {
 }
 
 extension FixtureClass120: Decodable {}
+
+// CustomStringConvertible doesn't actually inherit Codable, we're just using it because we don't have an external
+// module in which to declare our own type.
+public struct FixtureClass218: CustomStringConvertible {
+    public var description: String = ""
+
+    let someVar: String
+
+    enum CodingKeys: CodingKey {
+        case someVar
+    }
+}

Tests/PeripheryTests/RetentionTest.swift

@@ -556,6 +556,11 @@ final class RetentionTest: FixtureSourceGraphTestCase {
     }
 
     func testCodingKeyEnum() {
+        let configuration = Configuration.shared
+        // CustomStringConvertible doesn't actually inherit Codable, we're just using it because we don't have an
+        // external module in which to declare our own type.
+        configuration.externalCodableProtocols = ["CustomStringConvertible"]
+
         analyze(retainPublic: true) {
             assertReferenced(.class("FixtureClass74")) {
                 self.assertReferenced(.enum("CodingKeys"))
@@ -573,9 +578,12 @@ final class RetentionTest: FixtureSourceGraphTestCase {
                 // Not referenced because the enclosing class does not conform to Codable.
                 self.assertNotReferenced(.enum("CodingKeys"))
             }
-          assertReferenced(.struct("FixtureClass120")) {
-              self.assertReferenced(.enum("CodingKeys"))
-          }
+            assertReferenced(.struct("FixtureClass120")) {
+                self.assertReferenced(.enum("CodingKeys"))
+            }
+            assertReferenced(.struct("FixtureClass218")) {
+                self.assertReferenced(.enum("CodingKeys"))
+            }
         }
     }
 
@@ -960,7 +968,7 @@ final class RetentionTest: FixtureSourceGraphTestCase {
         let configuration = Configuration.shared
         // CustomStringConvertible doesn't actually inherit Encodable, we're just using it because we don't have an
         // external module in which to declare our own type.
-        configuration.externalEncodableProtocols = ["CustomStringConvertible"]
+        configuration.externalCodableProtocols = ["CustomStringConvertible"]
 
         analyze(retainPublic: true) {
             self.assertReferenced(.class("FixtureClass204")) {