Workaround incorrect location of generic protocol extensions. Closes #…

…648

CHANGELOG.md

@@ -10,7 +10,7 @@
 
 ##### Bug Fixes
 
-- None.
+- Fix retaining members of public generic protocol extensions with `--retain-public`.
 
 ## 2.15.1 (2023-09-17)
 

Sources/PeripheryKit/Syntax/DeclarationSyntaxVisitor.swift

@@ -103,6 +103,11 @@ final class DeclarationSyntaxVisitor: PeripherySyntaxVisitor {
 
         if let memberType = node.extendedType.as(MemberTypeSyntax.self) {
             position = memberType.name.positionAfterSkippingLeadingTrivia
+        } else if let genericArgumentClause = node.extendedType.as(IdentifierTypeSyntax.self)?.genericArgumentClause {
+            // Generic protocol extensions in the form `extension Foo<Type>` have incorrect locations in the index store.
+            // This results in syntax metadata not being applied to the declaration due to the location mismatch. To
+            // workaround this, parse this node with the incorrect location.
+            position = genericArgumentClause.rightAngle.positionAfterSkippingLeadingTrivia
         }
 
         parse(

Tests/Fixtures/RetentionFixtures/testRetainsGenericProtocolExtensionMembers.swift

@@ -0,0 +1,25 @@
+public protocol FixtureProtocol38<Value> {
+    associatedtype Value
+}
+
+public extension FixtureProtocol38<Int> {
+    func someFunc() {}
+}
+
+public protocol FixtureProtocol39<Value, Value2> {
+    associatedtype Value
+    associatedtype Value2
+}
+
+public extension FixtureProtocol39<Int, Int> {
+    func someFunc() {}
+}
+
+public protocol FixtureProtocol40<Value, Value2> {
+    associatedtype Value
+    associatedtype Value2
+}
+
+public extension FixtureProtocol40 where Value == Int, Value2 == Int {
+    func someFunc() {}
+}

Tests/PeripheryTests/RetentionTest.swift

@@ -476,6 +476,25 @@ final class RetentionTest: FixtureSourceGraphTestCase {
         }
     }
 
+    func testRetainsGenericProtocolExtensionMembers() {
+        analyze(retainPublic: true) {
+            assertReferenced(.protocol("FixtureProtocol38"))
+            assertReferenced(.extensionProtocol("FixtureProtocol38")) {
+                self.assertReferenced(.functionMethodInstance("someFunc()"))
+            }
+
+            assertReferenced(.protocol("FixtureProtocol39"))
+            assertReferenced(.extensionProtocol("FixtureProtocol39")) {
+                self.assertReferenced(.functionMethodInstance("someFunc()"))
+            }
+
+            assertReferenced(.protocol("FixtureProtocol40"))
+            assertReferenced(.extensionProtocol("FixtureProtocol40")) {
+                self.assertReferenced(.functionMethodInstance("someFunc()"))
+            }
+        }
+    }
+
     func testUnusedTypealias() {
         analyze() {
             assertNotReferenced(.typealias("UnusedAlias"))