v8/test/mjsunit/strong/declaration-after-use.js

// Copyright 2015 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: --strong-mode --harmony_rest_parameters --harmony_arrow_functions --harmony_classes --harmony_computed-property_names --harmony_templates

// Note that it's essential for these tests that the reference is inside dead
// code (because we already produce ReferenceErrors for run-time unresolved
// variables and don't want to confuse those with strong mode errors). But the
// errors should *not* be inside lazy, unexecuted functions, since lazy parsing
// doesn't produce strong mode scoping errors).

// In addition, assertThrows will call eval and that changes variable binding
// types (see e.g., UNBOUND_EVAL_SHADOWED). We can avoid unwanted side effects
// by wrapping the code to be tested inside an outer function.
function assertThrowsHelper(code) {
  "use strict";
  let prologue = "(function outer() { if (false) { ";
  let epilogue = " } })();";

  assertThrows("'use strong'; " + prologue + code + epilogue, ReferenceError);

  // Make sure the error happens only in strong mode (note that we need strict
  // mode here because of let).
  assertDoesNotThrow("'use strict'; " + prologue + code + epilogue);
}

(function DeclarationAfterUse() {
  // Note that these tests only test cases where the declaration is found but is
  // after the use. In particular, we cannot yet detect cases where the use can
  // possibly bind to a global variable.
  assertThrowsHelper("x; let x = 0;");
  assertThrowsHelper("function f() { x; let x = 0; }");
  assertThrowsHelper("function f() { x; } let x = 0;");

  // These tests needs to be done a bit more manually, since var is not allowed
  // in strong mode:
  assertThrows(
      `(function outer() {
        function f() { 'use strong'; if (false) { x; } } var x = 0; f();
      })()`,
      ReferenceError);
  assertDoesNotThrow(
      "(function outer() {\n" +
      "  function f() { if (false) { x; } } var x = 0; f(); \n" +
      "})()");

  assertThrows(
      "(function outer() {\n" +
      "  function f() { 'use strong'; if (false) { x; } } var x; f(); \n" +
      "})()",
      ReferenceError);
  assertDoesNotThrow(
      "(function outer() {\n" +
      "  function f() { if (false) { x; } } var x; f(); \n" +
      "})()");

  // Errors are also detected when the declaration and the use are in the same
  // eval scope.
  assertThrows("'use strong'; eval('if (false) { x; let x = 0;}')",
               ReferenceError);
  assertDoesNotThrow("'use strict'; eval('if (false) { x; let x = 0; }')");

  // Use occurring in the initializer of the declaration:
  assertThrowsHelper("let x = x + 1;");
  assertThrowsHelper("let x = x;");
  assertThrowsHelper("let x = y, y = 4;");
  assertThrowsHelper("let x = function() { x; }");
  assertThrowsHelper("let x = a => { x; }");
  assertThrowsHelper("function f(x) { return x; }; let x = f(x);");
  assertThrowsHelper("const x = x;");
  assertThrowsHelper("const x = function() { x; }");
  assertThrowsHelper("const x = a => { x; }");
  assertThrowsHelper("function f(x) {return x}; const x = f(x);");

  assertThrowsHelper("for (let x = x; ; ) { }");
  assertThrowsHelper("for (const x = x; ; ) { }");
  assertThrowsHelper("for (let x = y, y; ; ) { }");
  assertThrowsHelper("for (const x = y, y = 0; ; ) { }");

  // Computed property names
  assertThrowsHelper("let o = { 'a': 'b', [o.a]: 'c'};");
})();


(function DeclarationAfterUseInClasses() {
  assertThrowsHelper("class C extends C { }");
  assertThrowsHelper("let C = class C2 extends C { }");
  assertThrowsHelper("let C = class C2 extends C2 { }");

  assertThrowsHelper("let C = class C2 { constructor() { C; } }");
  assertThrowsHelper("let C = class C2 { method() { C; } }");
  assertThrowsHelper("let C = class C2 { *generator_method() { C; } }");

  assertThrowsHelper(
      `let C = class C2 {
        static a() { return 'A'; }
        [C.a()]() { return 'B'; }
      };`);

  assertThrowsHelper(
      `let C = class C2 {
        static a() { return 'A'; }
        [C2.a()]() { return 'B'; }
      };`);

  assertThrowsHelper(
      `let C = class C2 {
        [(function() { C; return 'A';})()]() { return 'B'; }
      };`);

  // The reference to C or C2 is inside a function, but not a method.
  assertThrowsHelper(
      `let C = class C2 {
        [(function() { C2; return 'A';})()]() { return 'B'; }
      };`);

  assertThrowsHelper(
      `let C = class C2 {
        [(function() { C; return 'A';})()]() { return 'B'; }
      };`);

  // The reference to C or C2 is inside a method, but it's not a method of the
  // relevant class (C2).
  assertThrowsHelper(
      `let C = class C2 {
        [(new (class D { m() { C2; return 'A'; } })).m()]() {
          return 'B';
        }
      }`);

  assertThrowsHelper(
      `let C = class C2 {
        [(new (class D { m() { C; return 'A'; } })).m()]() {
          return 'B';
        }
      }`);

  assertThrowsHelper(
      `let C = class C2 {
        [({m() { C2; return 'A'; }}).m()]() { return 'B'; }
      }`);

  assertThrowsHelper(
      `let C = class C2 {
        [({m() { C; return 'A'; }}).m()]() { return 'B'; }
      }`);

  assertThrowsHelper(
      `class COuter {
        m() {
          class CInner {
            [({ m() { CInner; return 'A'; } }).m()]() {
                return 'B';
            }
          }
        }
      }`);
})();


(function UsesWhichAreFine() {
  "use strong";

  let var1 = 0;
  var1;

  let var2a = 0, var2b = var2a + 1, var2c = 2 + var2b;

  for (let var3 = 0; var3 < 1; var3++) {
    var3;
  }

  for (let var4a = 0, var4b = var4a; var4a + var4b < 4; var4a++, var4b++) {
    var4a;
    var4b;
  }

  let var5 = 5;
  for (; var5 < 10; ++var5) { }

  let arr = [1, 2];
  for (let i of arr) {
    i;
  }

  let var6 = [1, 2];
  // The second var6 resolves to outside (not to the first var6).
  for (let var6 of var6) { var6; }

  try {
    throw "error";
  } catch (e) {
    e;
  }

  function func1() { func1; this; }
  func1();
  func1;

  function * func2() { func2; this; }
  func2();
  func2;

  function func4(p, ...rest) { p; rest; this; func2; }
  func4();

  let func5 = (p1, p2) => { p1; p2; };
  func5();

  function func6() {
    var1, var2a, var2b, var2c;
  }

  (function eval1() {
    let var7 = 0; // Declaration position will be something large.
    // But use position will be something small, however, this is not an error,
    // since the use is inside an eval scope.
    eval("var7;");
  })();


  class C1 { constructor() { C1; } }; new C1();
  let C2 = class C3 { constructor() { C3; } }; new C2();

  class C4 { method() { C4; } *generator_method() { C4; } }; new C4();
  let C5 = class C6 { method() { C6; } *generator_method() { C6; } }; new C5();

  class C7 { static method() { C7; } }; new C7();
  let C8 = class C9 { static method() { C9; } }; new C8();

  class C10 { get x() { C10; } }; new C10();
  let C11 = class C12 { get x() { C12; } }; new C11();

  // Regression test for unnamed classes.
  let C13 = class { m() { var1; } };

  class COuter {
    m() {
      class CInner {
        // Here we can refer to COuter but not to CInner (see corresponding
        // assertion test):
        [({ m() { COuter; return 'A'; } }).m()]() { return 'B'; }
        // And here we can refer to both:
        n() { COuter; CInner; }
      }
      return new CInner();
    }
  }
  (new COuter()).m().n();

  // Making sure the check which is supposed to prevent "object literal inside
  // computed property name references the class name" is not too generic:
  class C14 { m() { let obj = { n() { C14 } }; obj.n(); } }; (new C14()).m();
})();