swift-format bug formatting nested #if #else #endif nodes in switch statement

[dduan]

Swift format can’t properly format multiple ifconfig statements in switch statements. To reproduce, paste the following as a unit test in the swift-format unit tests:

  func testNestedPoundIfInSwitchStatement() {
    let input =
      """
      switch self {
      #if os(iOS) || os(tvOS) || os(watchOS)
      case .a:
        return 40
      #if os(iOS) || os(tvOS)
      case .e:
        return 30
      #endif
      #if os(iOS)
      case .g:
        return 2
      #endif
      #endif
      default:
        return nil
      }

      """
    var configuration = Configuration.forTesting
    configuration.indentConditionalCompilationBlocks = false
    assertPrettyPrintEqual(input: input, expected: input, linelength: 45, configuration: configuration)
  }

The test fails with:

failed - Pretty-printed result was not what was expected - Actual output (+) differed from expected output (-):
 switch self {
 #if os(iOS) || os(tvOS) || os(watchOS)
 case .a:
   return 40
 #if os(iOS) || os(tvOS)
 case .e:
   return 30
-#endif
-#if os(iOS)
+#endif#if os(iOS)
 case .g:
   return 2
 #endif
 #endif
 default:
   return nil
 }

[dduan]

rdar://132365692