Fix range crash

Sources/Formatter.swift

@@ -741,7 +741,7 @@ public extension Formatter {
         for i in range.reversed() {
             let token = tokens[i]
             switch token {
-            case .startOfScope(":") where scopeStack.last == .endOfScope("#endif"):
+            case .startOfScope(":") where [.endOfScope("#endif"), .endOfScope("}")].contains(scopeStack.last):
                 break
             case .startOfScope where scopeStack.last?.isEndOfScope(token) == true:
                 scopeStack.removeLast()
@@ -758,7 +758,7 @@ public extension Formatter {
             case .linebreak:
                 linebreakEncountered = true
             case .endOfScope("case"), .endOfScope("default"):
-                if scopeStack.last != .endOfScope("#endif") {
+                if ![.endOfScope("#endif"), .endOfScope("}")].contains(scopeStack.last) {
                     fallthrough
                 }
             case .endOfScope:

Sources/ParsingHelpers.swift

@@ -173,12 +173,14 @@ public extension Formatter {
                     $0.isEndOfScope(startToken) || $0 == .endOfScope("#endif")
                 })
             }
+            assert(endIndex ?? index >= index)
             return endIndex
         }
         while let endIndex = self.index(after: startIndex, where: {
             $0.isEndOfScope(startToken)
         }), let token = token(at: endIndex) {
             if token == .endOfScope("}") {
+                assert(endIndex >= index)
                 return endIndex
             }
             startIndex = endIndex

Tests/Rules/UnusedArgumentsTests.swift

@@ -1524,4 +1524,38 @@ final class UnusedArgumentsTests: XCTestCase {
 
         testFormatting(for: input, rule: .unusedArguments)
     }
+
+    func testIfdefCrash() {
+        let input = """
+        func test(unused: Int) {
+            foo {
+                if true {
+                    #if FOO
+                        switch 1 {
+                        default: ()
+                        }
+                    #endif
+                } else if true {
+                    ()
+                }
+            }
+        }
+        """
+        let output = """
+        func test(unused _: Int) {
+            foo {
+                if true {
+                    #if FOO
+                        switch 1 {
+                        default: ()
+                        }
+                    #endif
+                } else if true {
+                    ()
+                }
+            }
+        }
+        """
+        testFormatting(for: input, output, rule: .unusedArguments)
+    }
 }