Don’t fail rename if there are multiple index entries for the same USR

The test case that I’m adding right now is that we have a lingering index entry from a file that has been moved on disk. While the proper fix here would be to ignore such an entry from the index, we should also be more resilient and not fail rename altogether just because there are multiple entries for a USR – the chances are very high that they all translate to the same Swift and Objective-C name.

rdar://123937371

Author: ahoppen

Sources/SourceKitLSP/Rename.swift

@@ -554,12 +554,14 @@ extension SourceKitServer {
     index: IndexStoreDB
   ) async throws -> CrossLanguageName? {
     let definitions = index.occurrences(ofUSR: usr, roles: [.definition])
-    guard let definitionSymbol = definitions.only else {
-      if definitions.isEmpty {
-        logger.error("no definitions for \(usr) found")
-      } else {
-        logger.error("Multiple definitions for \(usr) found")
-      }
+    if definitions.count > 1 {
+      logger.log("Multiple definitions for \(usr) found")
+    }
+    // There might be multiple definitions of the same symbol eg. in different `#if` branches. In this case pick any of
+    // them because with very high likelihood they all translate to the same clang and Swift name. Sort the entries to
+    // ensure that we deterministically pick the same entry every time.
+    guard let definitionSymbol = definitions.sorted().first else {
+      logger.error("no definitions for \(usr) found")
       return nil
     }
     let definitionLanguage: Language =

Tests/SourceKitLSPTests/RenameTests.swift

@@ -1081,4 +1081,77 @@ final class RenameTests: XCTestCase {
         """
     )
   }
+
+  func testRenameAfterFileMove() async throws {
+    let ws = try await SwiftPMTestWorkspace(
+      files: [
+        "definition.swift": """
+        func 1️⃣foo2️⃣() {}
+        """,
+        "caller.swift": """
+        func test() {
+          3️⃣foo4️⃣()
+        }
+        """,
+      ],
+      build: true
+    )
+
+    let definitionUri = try ws.uri(for: "definition.swift")
+    let (callerUri, callerPositions) = try ws.openDocument("caller.swift")
+
+    // Validate that we get correct rename results before moving the definition file.
+    let resultBeforeFileMove = try await ws.testClient.send(
+      RenameRequest(textDocument: TextDocumentIdentifier(callerUri), position: callerPositions["3️⃣"], newName: "bar")
+    )
+    XCTAssertEqual(
+      resultBeforeFileMove,
+      WorkspaceEdit(
+        changes: [
+          definitionUri: [
+            TextEdit(
+              range: try ws.position(of: "1️⃣", in: "definition.swift")..<ws.position(of: "2️⃣", in: "definition.swift"),
+              newText: "bar"
+            )
+          ],
+          callerUri: [TextEdit(range: callerPositions["3️⃣"]..<callerPositions["4️⃣"], newText: "bar")],
+        ]
+      )
+    )
+
+    let movedDefinitionUri =
+      DocumentURI(
+        definitionUri.fileURL!
+          .deletingLastPathComponent()
+          .appendingPathComponent("movedDefinition.swift")
+      )
+
+    try FileManager.default.moveItem(at: XCTUnwrap(definitionUri.fileURL), to: XCTUnwrap(movedDefinitionUri.fileURL))
+
+    ws.testClient.send(
+      DidChangeWatchedFilesNotification(changes: [
+        FileEvent(uri: definitionUri, type: .deleted), FileEvent(uri: movedDefinitionUri, type: .created),
+      ])
+    )
+
+    try await SwiftPMTestWorkspace.build(at: ws.scratchDirectory)
+
+    let resultAfterFileMove = try await ws.testClient.send(
+      RenameRequest(textDocument: TextDocumentIdentifier(callerUri), position: callerPositions["3️⃣"], newName: "bar")
+    )
+    XCTAssertEqual(
+      resultAfterFileMove,
+      WorkspaceEdit(
+        changes: [
+          movedDefinitionUri: [
+            TextEdit(
+              range: try ws.position(of: "1️⃣", in: "definition.swift")..<ws.position(of: "2️⃣", in: "definition.swift"),
+              newText: "bar"
+            )
+          ],
+          callerUri: [TextEdit(range: callerPositions["3️⃣"]..<callerPositions["4️⃣"], newText: "bar")],
+        ]
+      )
+    )
+  }
 }