Don’t report no-op rename edits

When renaming `func test(foo: Int) {}` to `test2(foo:)`, rename used to report an edit from `foo` to `foo`, which clutters the refactor preview view. We shouldn’t report edits if no text is actually changed.

rdar://127291815

Author: ahoppen

Sources/SourceKitLSP/Rename.swift

@@ -817,6 +817,7 @@ extension SourceKitLSPServer {
             newName: newName
           )
         }
+        edits = edits.filter { !$0.isNoOp(in: snapshot) }
         return (uri, edits)
       }.compactMap { $0 }
     for (uri, editsForUri) in urisAndEdits {
@@ -1089,7 +1090,11 @@ extension SwiftLanguageService {
         )
       }
     }
+    edits = edits.filter { !$0.isNoOp(in: snapshot) }
 
+    if edits.isEmpty {
+      return (edits: WorkspaceEdit(changes: [:]), usr: usr)
+    }
     return (edits: WorkspaceEdit(changes: [snapshot.uri: edits]), usr: usr)
   }
 
@@ -1451,3 +1456,13 @@ fileprivate extension RelatedIdentifiersResponse {
     }
   }
 }
+
+fileprivate extension TextEdit {
+  /// Returns `true` the replaced text is the same as the new text
+  func isNoOp(in snapshot: DocumentSnapshot) -> Bool {
+    if snapshot.text[snapshot.indexRange(of: range)] == newText {
+      return true
+    }
+    return false
+  }
+}

Tests/SourceKitLSPTests/RenameTests.swift

@@ -1181,4 +1181,25 @@ final class RenameTests: XCTestCase {
       )
     )
   }
+
+  func testRenameDoesNotReportEditsIfNoActualChangeIsMade() async throws {
+    let project = try await SwiftPMTestProject(
+      files: [
+        "FileA.swift": """
+        func 1️⃣foo(x: Int) {}
+        """,
+        "FileB.swift": """
+        func test() {
+          foo(x: 1)
+        }
+        """,
+      ],
+      build: true
+    )
+    let (uri, positions) = try project.openDocument("FileA.swift")
+    let result = try await project.testClient.send(
+      RenameRequest(textDocument: TextDocumentIdentifier(uri), position: positions["1️⃣"], newName: "foo(x:)")
+    )
+    XCTAssertEqual(result?.changes, [:])
+  }
 }