text: // Copyright 2016 the V8 project authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  
  // Flags: --opt
  
  Debug = debug.Debug
  
  var exception = null;
  
  function f() {
    let a = 0;
    function g() {
      let a = 1;
      {
        let a = 2;
        debugger;  // Breakpoint.
        if (a !== 3) {
          // We cannot change stack locals in optimized frames.
          assertEquals(2, a);
          assertOptimized(g);
        }
      }
      assertEquals(1, a);
    }
    g.call(1);
    if (a !== 4) {
      // We cannot change stack locals in optimized frames.
      assertEquals(0, a);
      assertOptimized(f);
    }
  }
  
  
  function listener(event, exec_state, event_data, data) {
    if (event != Debug.DebugEvent.Break) return;
    try {
      exec_state.frame(0).evaluate("a = 3");
      exec_state.frame(1).evaluate("a = 4");
      assertThrows(() => exec_state.frame(0).evaluate("this = 2"));
    } catch (e) {
      exception = e;
      print("Caught something. " + e + " " + e.stack);
    };
  };
  
  Debug.setListener(listener);
  
  f();
  
  Debug.setListener(null);
  assertNull(exception);
  