Reland of Add errors for declarations which conflict with catch parameters.

test/mjsunit/es6/for-each-in-catch.js

+// 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.
+
+function checkIsRedeclarationError(code) {
+  try {
+    eval(`
+checkIsRedeclarationError : {
+  break checkIsRedeclarationError;
+${code}
+}
+`);
+    assertUnreachable();
+  } catch(e) {
+    assertInstanceof(e, SyntaxError );
+    assertTrue( e.toString().indexOf("has already been declared") >= 0 );
+  }
+}
+
+function checkIsNotRedeclarationError(code) {
+  assertDoesNotThrow(()=>eval(`
+checkIsNotRedeclarationError_label : {
+  break checkIsNotRedeclarationError_label;
+${code}
+}
+`));
+}
+
+
+let var_e = [
+  'var e',
+  'var {e}',
+  'var {f, e}',
+  'var [e]',
+  'var {f:e}',
+  'var [[[], e]]'
+];
+
+let not_var_e = [
+  'var f',
+  'var {}',
+  'var {e:f}',
+  'e',
+  '{e}',
+  'let e',
+  'const e',
+  'let {e}',
+  'const {e}',
+  'let [e]',
+  'const [e]',
+  'let {f:e}',
+  'const {f:e}'
+];
+
+// Check that `for (var ... of ...)` cannot redeclare a simple catch variable
+// but `for (var ... in ...)` can.
+for (let binding of var_e) {
+  checkIsRedeclarationError(`
+try {
+  throw 0;
+} catch(e) {
+  for (${binding} of []);
+}
+`);
+
+  checkIsNotRedeclarationError(`
+try {
+  throw 0;
+} catch(e) {
+  for (${binding} in []);
+}
+`);
+}
+
+// Check that the above error occurs even for nested catches.
+for (let binding of var_e) {
+  checkIsRedeclarationError(`
+try {
+  throw 0;
+} catch(e) {
+  try {
+    throw 1;
+  } catch(f) {
+    try {
+      throw 2;
+    } catch({}) {
+      for (${binding} of []);
+    }
+  }
+}
+`);
+
+  checkIsNotRedeclarationError(`
+try {
+  throw 0;
+} catch(e) {
+  try {
+    throw 1;
+  } catch(f) {
+    try {
+      throw 2;
+    } catch({}) {
+      for (${binding} in []);
+    }
+  }
+}
+`);
+}
+
+// Check that the above error does not occur if a declaration scope is between
+// the catch and the loop.
+for (let binding of var_e) {
+  checkIsNotRedeclarationError(`
+try {
+  throw 0;
+} catch(e) {
+  (()=>{for (${binding} of []);})();
+}
+`);
+
+  checkIsNotRedeclarationError(`
+try {
+  throw 0;
+} catch(e) {
+  (function(){for (${binding} of []);})();
+}
+`);
+}
+
+// Check that there is no error when not declaring a var named e.
+for (let binding of not_var_e) {
+  checkIsNotRedeclarationError(`
+try {
+  throw 0;
+} catch(e) {
+  for (${binding} of []);
+}
+`);
+}
+
+// Check that there is an error for both for-in and for-of when redeclaring
+// a non-simple catch parameter
+for (let binding of var_e) {
+  checkIsRedeclarationError(`
+try {
+  throw 0;
+} catch({e}) {
+  for (${binding} of []);
+}
+`);
+
+  checkIsRedeclarationError(`
+try {
+  throw 0;
+} catch({e}) {
+  for (${binding} in []);
+}
+`);
+}
+
+// Check that the above error occurs even for nested catches.
+for (let binding of var_e) {
+  checkIsRedeclarationError(`
+try {
+  throw 0;
+} catch({e}) {
+  try {
+    throw 1;
+  } catch(f) {
+    try {
+      throw 2;
+    } catch({}) {
+      for (${binding} of []);
+    }
+  }
+}
+`);
+
+  checkIsRedeclarationError(`
+try {
+  throw 0;
+} catch({e}) {
+  try {
+    throw 1;
+  } catch(f) {
+    try {
+      throw 2;
+    } catch({}) {
+      for (${binding} in []);
+    }
+  }
+}
+`);
+}