Identify unused CodingKey enum cases

peripheryapp · Dec 29, 2023 · 11ebbc5 · 11ebbc5
1 parent 46d7a51
commit 11ebbc5
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Showing 6 changed files with 42 additions and 95 deletions.
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -8,6 +8,7 @@
 
 - Add experimental unused import analysis.
 - The option `--external-encodable-protocols` is deprecated, use `--external-codable-protocols` instead.
+- CodingKey enum case are now identified as unused if the corresponding property is also unused in the Codable type.
 
 ##### Bug Fixes
 

diff --git a/Sources/PeripheryKit/SourceGraph/Mutators/CodingKeyEnumReferenceBuilder.swift b/Sources/PeripheryKit/SourceGraph/Mutators/CodingKeyEnumReferenceBuilder.swift
@@ -26,12 +26,28 @@ final class CodingKeyEnumReferenceBuilder: SourceGraphMutator {
                 return [.protocol, .typealias].contains($0.kind) && codableTypes.contains(name)
             }
 
-            if isCodingKey && isParentCodable {
-                for usr in enumDeclaration.usrs {
-                    let newReference = Reference(kind: .enum, usr: usr, location: enumDeclaration.location)
-                    newReference.name = enumDeclaration.name
-                    newReference.parent = parent
-                    graph.add(newReference, from: parent)
+            guard isCodingKey, isParentCodable else { continue }
+
+            // Build a reference from the Codable type to the CodingKey enum.
+            for usr in enumDeclaration.usrs {
+                let newReference = Reference(kind: .enum, usr: usr, location: enumDeclaration.location)
+                newReference.name = enumDeclaration.name
+                newReference.parent = parent
+                graph.add(newReference, from: parent)
+            }
+
+            // For each property in the Codable type, build a reference to its corresponding
+            // CodingKey enum element.
+            for decl in parent.declarations {
+                guard decl.kind == .varInstance,
+                      let enumCase = enumDeclaration.declarations.first(where: { $0.kind == .enumelement && $0.name == decl.name })
+                else { continue }
+
+                for usr in enumCase.usrs {
+                    let newReference = Reference(kind: .enumelement, usr: usr, location: decl.location)
+                    newReference.name = enumCase.name
+                    newReference.parent = decl
+                    graph.add(newReference, from: decl)
                 }
             }
         }

diff --git a/Sources/PeripheryKit/SourceGraph/Mutators/EncodablePropertyRetainer.swift b/Sources/PeripheryKit/SourceGraph/Mutators/EncodablePropertyRetainer.swift
diff --git a/Sources/PeripheryKit/SourceGraph/SourceGraphMutatorRunner.swift b/Sources/PeripheryKit/SourceGraph/SourceGraphMutatorRunner.swift
@@ -38,7 +38,6 @@ public final class SourceGraphMutatorRunner {
         PubliclyAccessibleRetainer.self,
         XCTestRetainer.self,
         SwiftUIRetainer.self,
-        EncodablePropertyRetainer.self,
         StringInterpolationAppendInterpolationRetainer.self,
         PropertyWrapperRetainer.self,
         ResultBuilderRetainer.self,

diff --git a/Tests/Fixtures/RetentionFixtures/testCodingKeyEnum.swift b/Tests/Fixtures/RetentionFixtures/testCodingKeyEnum.swift
@@ -62,3 +62,13 @@ public struct FixtureClass218: CustomStringConvertible {
         case someVar
     }
 }
+
+public class FixtureClass220: Encodable {
+    public var someUsedVar: String?
+    var someUnusedVar: String?
+
+    enum CodingKeys: CodingKey {
+        case someUsedVar
+        case someUnusedVar
+    }
+}
diff --git a/Tests/PeripheryTests/RetentionTest.swift b/Tests/PeripheryTests/RetentionTest.swift
@@ -574,6 +574,15 @@ final class RetentionTest: FixtureSourceGraphTestCase {
             assertReferenced(.struct("FixtureClass218")) {
                 self.assertReferenced(.enum("CodingKeys"))
             }
+            assertReferenced(.class("FixtureClass220")) {
+                self.assertReferenced(.varInstance("someUsedVar"))
+                self.assertNotReferenced(.varInstance("someUnusedVar"))
+
+                self.assertReferenced(.enum("CodingKeys")) {
+                    self.assertReferenced(.enumelement("someUsedVar"))
+                    self.assertNotReferenced(.enumelement("someUnusedVar"))
+                }
+            }
         }
     }
 
@@ -951,43 +960,6 @@ final class RetentionTest: FixtureSourceGraphTestCase {
         }
     }
 
-    func testRetainsEncodableProperties() {
-        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.externalCodableProtocols = ["CustomStringConvertible"]
-
-        analyze(retainPublic: true) {
-            self.assertReferenced(.class("FixtureClass204")) {
-                self.assertReferenced(.varInstance("someVar"))
-            }
-
-            self.assertReferenced(.class("FixtureClass205")) {
-                self.assertReferenced(.varInstance("someVar"))
-            }
-
-            self.assertReferenced(.class("FixtureClass206")) {
-                self.assertReferenced(.varInstance("someVar"))
-            }
-
-            self.assertReferenced(.class("FixtureClass207")) {
-                self.assertReferenced(.varInstance("someVar"))
-            }
-
-            self.assertReferenced(.class("FixtureClass208")) {
-                self.assertReferenced(.varInstance("someVar"))
-            }
-
-            self.assertReferenced(.class("FixtureClass209")) {
-                self.assertReferenced(.varInstance("someVar"))
-            }
-
-            self.assertReferenced(.class("FixtureClass210")) {
-                self.assertReferenced(.varInstance("someVar"))
-            }
-        }
-    }
-
     func testCircularTypeInheritance() {
         analyze {
             // Intentionally blank.