[parser] Disallow Expression in for..of statements

Although the `for..in` statement allows Expressions to define the
iterator, only an AssignmentExpression may occupy this position in the
`for..of` statement.

BUG=v8:4692
LOG=N
R=adamk@chromium.org

Review URL: https://codereview.chromium.org/1602823003

Cr-Commit-Position: refs/heads/master@{#33420}

src/parsing/parser.cc

@@ -3676,7 +3676,15 @@ Statement* Parser::ParseForStatement(ZoneList<const AstRawString*>* labels,
             factory()->NewForEachStatement(mode, labels, stmt_pos);
         Target target(&this->target_stack_, loop);
 
-        Expression* enumerable = ParseExpression(true, CHECK_OK);
+        Expression* enumerable;
+        if (mode == ForEachStatement::ITERATE) {
+          ExpressionClassifier classifier;
+          enumerable = ParseAssignmentExpression(true, &classifier, CHECK_OK);
+          enumerable = ParserTraits::RewriteNonPattern(enumerable, &classifier,
+                                                       CHECK_OK);
+        } else {
+          enumerable = ParseExpression(true, CHECK_OK);
+        }
 
         Expect(Token::RPAREN, CHECK_OK);
 
@@ -3791,7 +3799,16 @@ Statement* Parser::ParseForStatement(ZoneList<const AstRawString*>* labels,
             factory()->NewForEachStatement(mode, labels, stmt_pos);
         Target target(&this->target_stack_, loop);
 
-        Expression* enumerable = ParseExpression(true, CHECK_OK);
+        Expression* enumerable;
+        if (mode == ForEachStatement::ITERATE) {
+          ExpressionClassifier classifier;
+          enumerable = ParseAssignmentExpression(true, &classifier, CHECK_OK);
+          enumerable = ParserTraits::RewriteNonPattern(enumerable, &classifier,
+                                                       CHECK_OK);
+        } else {
+          enumerable = ParseExpression(true, CHECK_OK);
+        }
+
         Expect(Token::RPAREN, CHECK_OK);
 
         // Make a block around the statement in case a lexical binding

src/parsing/preparser.cc

@@ -950,7 +950,16 @@ PreParser::Statement PreParser::ParseForStatement(bool* ok) {
           *ok = false;
           return Statement::Default();
         }
+
+        if (mode == ForEachStatement::ITERATE) {
+          ExpressionClassifier classifier;
+          Expression enumerable =
+              ParseAssignmentExpression(true, &classifier, CHECK_OK);
+          PreParserTraits::RewriteNonPattern(enumerable, &classifier, CHECK_OK);
+        } else {
           ParseExpression(true, CHECK_OK);
+        }
+
         Expect(Token::RPAREN, CHECK_OK);
         ParseSubStatement(CHECK_OK);
         return Statement::Default();
@@ -980,7 +989,16 @@ PreParser::Statement PreParser::ParseForStatement(bool* ok) {
               lhs, lhs_beg_pos, lhs_end_pos, MessageTemplate::kInvalidLhsInFor,
               kSyntaxError, CHECK_OK);
         }
+
+        if (mode == ForEachStatement::ITERATE) {
+          ExpressionClassifier classifier;
+          Expression enumerable =
+              ParseAssignmentExpression(true, &classifier, CHECK_OK);
+          PreParserTraits::RewriteNonPattern(enumerable, &classifier, CHECK_OK);
+        } else {
           ParseExpression(true, CHECK_OK);
+        }
+
         Expect(Token::RPAREN, CHECK_OK);
         ParseSubStatement(CHECK_OK);
         return Statement::Default();

test/cctest/test-parsing.cc

@@ -4925,6 +4925,23 @@ TEST(ConstParsingInForIn) {
 }
 
 
+TEST(StatementParsingInForIn) {
+  const char* context_data[][2] = {{"", ""},
+                                   {"'use strict';", ""},
+                                   {"function foo(){ 'use strict';", "}"},
+                                   {NULL, NULL}};
+
+  const char* data[] = {"for(x in {}, {}) {}", "for(var x in {}, {}) {}",
+                        "for(let x in {}, {}) {}", "for(const x in {}, {}) {}",
+                        NULL};
+
+  static const ParserFlag always_flags[] = {
+      kAllowHarmonySloppy, kAllowHarmonySloppyLet, kNoLegacyConst};
+  RunParserSyncTest(context_data, data, kSuccess, nullptr, 0, always_flags,
+                    arraysize(always_flags));
+}
+
+
 TEST(ConstParsingInForInError) {
   const char* context_data[][2] = {{"'use strict';", ""},
                                    {"function foo(){ 'use strict';", "}"},
@@ -5098,6 +5115,76 @@ TEST(ForOfNoDeclarationsError) {
 }
 
 
+TEST(ForOfInOperator) {
+  const char* context_data[][2] = {{"", ""},
+                                   {"'use strict';", ""},
+                                   {"function foo(){ 'use strict';", "}"},
+                                   {NULL, NULL}};
+
+  const char* data[] = {
+      "for(x of 'foo' in {}) {}", "for(var x of 'foo' in {}) {}",
+      "for(let x of 'foo' in {}) {}", "for(const x of 'foo' in {}) {}", NULL};
+
+  static const ParserFlag always_flags[] = {
+      kAllowHarmonySloppy, kAllowHarmonySloppyLet, kNoLegacyConst};
+  RunParserSyncTest(context_data, data, kSuccess, nullptr, 0, always_flags,
+                    arraysize(always_flags));
+}
+
+
+TEST(ForOfYieldIdentifier) {
+  const char* context_data[][2] = {{"", ""}, {NULL, NULL}};
+
+  const char* data[] = {"for(x of yield) {}", "for(var x of yield) {}",
+                        "for(let x of yield) {}", "for(const x of yield) {}",
+                        NULL};
+
+  static const ParserFlag always_flags[] = {
+      kAllowHarmonySloppy, kAllowHarmonySloppyLet, kNoLegacyConst};
+  RunParserSyncTest(context_data, data, kSuccess, nullptr, 0, always_flags,
+                    arraysize(always_flags));
+}
+
+
+TEST(ForOfYieldExpression) {
+  const char* context_data[][2] = {{"", ""},
+                                   {"'use strict';", ""},
+                                   {"function foo(){ 'use strict';", "}"},
+                                   {NULL, NULL}};
+
+  const char* data[] = {"function* g() { for(x of yield) {} }",
+                        "function* g() { for(var x of yield) {} }",
+                        "function* g() { for(let x of yield) {} }",
+                        "function* g() { for(const x of yield) {} }", NULL};
+
+  static const ParserFlag always_flags[] = {
+      kAllowHarmonySloppy, kAllowHarmonySloppyLet, kNoLegacyConst};
+  RunParserSyncTest(context_data, data, kSuccess, nullptr, 0, always_flags,
+                    arraysize(always_flags));
+}
+
+
+TEST(ForOfExpressionError) {
+  const char* context_data[][2] = {{"", ""},
+                                   {"'use strict';", ""},
+                                   {"function foo(){ 'use strict';", "}"},
+                                   {NULL, NULL}};
+
+  const char* data[] = {
+      "for(x of [], []) {}", "for(var x of [], []) {}",
+      "for(let x of [], []) {}", "for(const x of [], []) {}",
+
+      // AssignmentExpression should be validated statically:
+      "for(x of { y = 23 }) {}", "for(var x of { y = 23 }) {}",
+      "for(let x of { y = 23 }) {}", "for(const x of { y = 23 }) {}", NULL};
+
+  static const ParserFlag always_flags[] = {
+      kAllowHarmonySloppy, kAllowHarmonySloppyLet, kNoLegacyConst};
+  RunParserSyncTest(context_data, data, kError, nullptr, 0, always_flags,
+                    arraysize(always_flags));
+}
+
+
 TEST(InvalidUnicodeEscapes) {
   const char* context_data[][2] = {{"", ""},
                                    {"'use strict';", ""},