[strong] Implement static restrictions on switch statement

Implements the strong mode proposal's restrictions on the syntax of the
switch statement. Also fixes a minor bug with empty statements in strong
mode and improves StrongUndefinedArrow parser synch tests.

BUG=v8:3956
LOG=N

Review URL: https://codereview.chromium.org/1084983002

Cr-Commit-Position: refs/heads/master@{#27885}

src/messages.js

@@ -161,6 +161,7 @@ var kMessages = {
   strong_arguments:              ["In strong mode, 'arguments' is deprecated, use '...args' instead"],
   strong_undefined:              ["In strong mode, binding or assigning to 'undefined' is deprecated"],
   strong_direct_eval:            ["In strong mode, direct calls to eval are deprecated"],
+  strong_switch_fallthrough :    ["In strong mode, switch fall-through is deprecated, terminate each case with 'break', 'continue', 'return' or 'throw'"],
   strong_equal:                  ["In strong mode, '==' and '!=' are deprecated, use '===' and '!==' instead"],
   strong_delete:                 ["In strong mode, 'delete' is deprecated, use maps or sets instead"],
   strong_var:                    ["In strong mode, 'var' is deprecated, use 'let' or 'const' instead"],

src/parser.cc

@@ -1821,36 +1821,29 @@ Statement* Parser::ParseSubStatement(ZoneList<const AstRawString*>* labels,
       return ParseForStatement(labels, ok);
 
     case Token::CONTINUE:
-      return ParseContinueStatement(ok);
-
     case Token::BREAK:
-      return ParseBreakStatement(labels, ok);
-
     case Token::RETURN:
-      return ParseReturnStatement(ok);
-
-    case Token::WITH:
-      return ParseWithStatement(labels, ok);
-
-    case Token::SWITCH:
-      return ParseSwitchStatement(labels, ok);
-
     case Token::THROW:
-      return ParseThrowStatement(ok);
-
     case Token::TRY: {
-      // NOTE: It is somewhat complicated to have labels on
-      // try-statements. When breaking out of a try-finally statement,
-      // one must take great care not to treat it as a
-      // fall-through. It is much easier just to wrap the entire
-      // try-statement in a statement block and put the labels there
+      // These statements must have their labels preserved in an enclosing
+      // block
+      if (labels == NULL) {
+        return ParseStatementAsUnlabelled(labels, ok);
+      } else {
         Block* result =
             factory()->NewBlock(labels, 1, false, RelocInfo::kNoPosition);
         Target target(&this->target_stack_, result);
-      TryStatement* statement = ParseTryStatement(CHECK_OK);
+        Statement* statement = ParseStatementAsUnlabelled(labels, CHECK_OK);
         if (result) result->AddStatement(statement, zone());
         return result;
       }
+    }
+
+    case Token::WITH:
+      return ParseWithStatement(labels, ok);
+
+    case Token::SWITCH:
+      return ParseSwitchStatement(labels, ok);
 
     case Token::FUNCTION: {
       // FunctionDeclaration is only allowed in the context of SourceElements
@@ -1892,6 +1885,30 @@ Statement* Parser::ParseSubStatement(ZoneList<const AstRawString*>* labels,
   }
 }
 
+Statement* Parser::ParseStatementAsUnlabelled(
+    ZoneList<const AstRawString*>* labels, bool* ok) {
+  switch (peek()) {
+    case Token::CONTINUE:
+      return ParseContinueStatement(ok);
+
+    case Token::BREAK:
+      return ParseBreakStatement(labels, ok);
+
+    case Token::RETURN:
+      return ParseReturnStatement(ok);
+
+    case Token::THROW:
+      return ParseThrowStatement(ok);
+
+    case Token::TRY:
+      return ParseTryStatement(ok);
+
+    default:
+      UNREACHABLE();
+      return NULL;
+  }
+}
+
 
 VariableProxy* Parser::NewUnresolved(const AstRawString* name,
                                      VariableMode mode) {
@@ -2847,13 +2864,19 @@ CaseClause* Parser::ParseCaseClause(bool* default_seen_ptr, bool* ok) {
   int pos = position();
   ZoneList<Statement*>* statements =
       new(zone()) ZoneList<Statement*>(5, zone());
+  Statement* stat = NULL;
   while (peek() != Token::CASE &&
          peek() != Token::DEFAULT &&
          peek() != Token::RBRACE) {
-    Statement* stat = ParseStatementListItem(CHECK_OK);
+    stat = ParseStatementListItem(CHECK_OK);
     statements->Add(stat, zone());
   }
-
+  if (is_strong(language_mode()) && stat != NULL && !stat->IsJump() &&
+      peek() != Token::RBRACE) {
+    ReportMessageAt(scanner()->location(), "strong_switch_fallthrough");
+    *ok = false;
+    return NULL;
+  }
   return factory()->NewCaseClause(label, statements, pos);
 }
 
@@ -4470,7 +4493,6 @@ void Parser::CheckConflictingVarDeclarations(Scope* scope, bool* ok) {
 // ----------------------------------------------------------------------------
 // Parser support
 
-
 bool Parser::TargetStackContainsLabel(const AstRawString* label) {
   for (Target* t = target_stack_; t != NULL; t = t->previous()) {
     if (ContainsLabel(t->statement()->labels(), label)) return true;

src/parser.h

@@ -924,6 +924,8 @@ class Parser : public ParserBase<ParserTraits> {
   ZoneList<ImportDeclaration*>* ParseNamedImports(int pos, bool* ok);
   Statement* ParseStatement(ZoneList<const AstRawString*>* labels, bool* ok);
   Statement* ParseSubStatement(ZoneList<const AstRawString*>* labels, bool* ok);
+  Statement* ParseStatementAsUnlabelled(ZoneList<const AstRawString*>* labels,
+                                   bool* ok);
   Statement* ParseFunctionDeclaration(ZoneList<const AstRawString*>* names,
                                       bool* ok);
   Statement* ParseClassDeclaration(ZoneList<const AstRawString*>* names,

src/preparser.cc

@@ -235,6 +235,11 @@ PreParser::Statement PreParser::ParseStatement(bool* ok) {
   // Statement ::
   //   EmptyStatement
   //   ...
+
+  if (peek() == Token::SEMICOLON) {
+    Next();
+    return Statement::Default();
+  }
   return ParseSubStatement(ok);
 }
 
@@ -395,15 +400,16 @@ PreParser::Statement PreParser::ParseBlock(bool* ok) {
   // (ECMA-262, 3rd, 12.2)
   //
   Expect(Token::LBRACE, CHECK_OK);
+  Statement final = Statement::Default();
   while (peek() != Token::RBRACE) {
     if (is_strict(language_mode())) {
-      ParseStatementListItem(CHECK_OK);
+      final = ParseStatementListItem(CHECK_OK);
     } else {
-      ParseStatement(CHECK_OK);
+      final = ParseStatement(CHECK_OK);
     }
   }
   Expect(Token::RBRACE, ok);
-  return Statement::Default();
+  return final;
 }
 
 
@@ -545,7 +551,8 @@ PreParser::Statement PreParser::ParseExpressionOrLabelledStatement(bool* ok) {
     DCHECK(is_sloppy(language_mode()) ||
            !IsFutureStrictReserved(expr.AsIdentifier()));
     Consume(Token::COLON);
-    return ParseStatement(ok);
+    Statement statement = ParseStatement(ok);
+    return statement.IsJumpStatement() ? Statement::Default() : statement;
     // Preparsing is disabled for extensions (because the extension details
     // aren't passed to lazily compiled functions), so we don't
     // accept "native function" in the preparser.
@@ -571,12 +578,16 @@ PreParser::Statement PreParser::ParseIfStatement(bool* ok) {
   Expect(Token::LPAREN, CHECK_OK);
   ParseExpression(true, CHECK_OK);
   Expect(Token::RPAREN, CHECK_OK);
-  ParseSubStatement(CHECK_OK);
+  Statement stat = ParseSubStatement(CHECK_OK);
   if (peek() == Token::ELSE) {
     Next();
-    ParseSubStatement(CHECK_OK);
+    Statement else_stat = ParseSubStatement(CHECK_OK);
+    stat = (stat.IsJumpStatement() && else_stat.IsJumpStatement()) ?
+        Statement::Jump() : Statement::Default();
+  } else {
+    stat = Statement::Default();
   }
-  return Statement::Default();
+  return stat;
 }
 
 
@@ -594,7 +605,7 @@ PreParser::Statement PreParser::ParseContinueStatement(bool* ok) {
     ParseIdentifier(kAllowRestrictedIdentifiers, CHECK_OK);
   }
   ExpectSemicolon(CHECK_OK);
-  return Statement::Default();
+  return Statement::Jump();
 }
 
 
@@ -612,7 +623,7 @@ PreParser::Statement PreParser::ParseBreakStatement(bool* ok) {
     ParseIdentifier(kAllowRestrictedIdentifiers, CHECK_OK);
   }
   ExpectSemicolon(CHECK_OK);
-  return Statement::Default();
+  return Statement::Jump();
 }
 
 
@@ -647,7 +658,7 @@ PreParser::Statement PreParser::ParseReturnStatement(bool* ok) {
     ParseExpression(true, CHECK_OK);
   }
   ExpectSemicolon(CHECK_OK);
-  return Statement::Default();
+  return Statement::Jump();
 }
 
 
@@ -691,12 +702,19 @@ PreParser::Statement PreParser::ParseSwitchStatement(bool* ok) {
     }
     Expect(Token::COLON, CHECK_OK);
     token = peek();
+    Statement statement = Statement::Jump();
     while (token != Token::CASE &&
            token != Token::DEFAULT &&
            token != Token::RBRACE) {
-      ParseStatementListItem(CHECK_OK);
+      statement = ParseStatementListItem(CHECK_OK);
       token = peek();
     }
+    if (is_strong(language_mode()) && !statement.IsJumpStatement() &&
+        token != Token::RBRACE) {
+      ReportMessageAt(scanner()->location(), "strong_switch_fallthrough");
+      *ok = false;
+      return Statement::Default();
+    }
   }
   Expect(Token::RBRACE, ok);
   return Statement::Default();
@@ -827,7 +845,7 @@ PreParser::Statement PreParser::ParseThrowStatement(bool* ok) {
   }
   ParseExpression(true, CHECK_OK);
   ExpectSemicolon(ok);
-  return Statement::Default();
+  return Statement::Jump();
 }
 
 

src/preparser.h

@@ -1104,6 +1104,10 @@ class PreParserStatement {
     return PreParserStatement(kUnknownStatement);
   }
 
+  static PreParserStatement Jump() {
+    return PreParserStatement(kJumpStatement);
+  }
+
   static PreParserStatement FunctionDeclaration() {
     return PreParserStatement(kFunctionDeclaration);
   }
@@ -1139,9 +1143,14 @@ class PreParserStatement {
     return code_ == kFunctionDeclaration;
   }
 
+  bool IsJumpStatement() {
+    return code_ == kJumpStatement;
+  }
+
  private:
   enum Type {
     kUnknownStatement,
+    kJumpStatement,
     kStringLiteralExpressionStatement,
     kUseStrictExpressionStatement,
     kUseStrongExpressionStatement,

test/cctest/test-parsing.cc

@@ -5805,7 +5805,7 @@ TEST(StrongEmptySubStatements) {
   const char* strict_context_data[][2] = {{"'use strict';", ""}, {NULL}};
   const char* strong_context_data[][2] = {{"'use strong';", ""}, {NULL}};
 
-  const char* data[] = {
+  const char* data_error[] = {
       "if (1);",
       "if (1) {} else;",
       "while (1);",
@@ -5818,15 +5818,24 @@ TEST(StrongEmptySubStatements) {
       "for (const x of []);",
       NULL};
 
+  const char* data_success[] =  {
+      "if (1) {} else {}",
+      "switch(1) {}",
+      "1+1;;",
+      "1+1; ;",
+      NULL};
+
   static const ParserFlag always_flags[] = {
       kAllowStrongMode,
   };
-  RunParserSyncTest(sloppy_context_data, data, kSuccess, NULL, 0, always_flags,
-                    arraysize(always_flags));
-  RunParserSyncTest(strict_context_data, data, kSuccess, NULL, 0, always_flags,
-                    arraysize(always_flags));
-  RunParserSyncTest(strong_context_data, data, kError, NULL, 0, always_flags,
-                    arraysize(always_flags));
+  RunParserSyncTest(sloppy_context_data, data_error, kSuccess, NULL, 0,
+                    always_flags, arraysize(always_flags));
+  RunParserSyncTest(strict_context_data, data_error, kSuccess, NULL, 0,
+                    always_flags, arraysize(always_flags));
+  RunParserSyncTest(strong_context_data, data_error, kError, NULL, 0,
+                    always_flags, arraysize(always_flags));
+  RunParserSyncTest(strong_context_data, data_success, kSuccess, NULL, 0,
+                    always_flags, arraysize(always_flags));
 }
 
 
@@ -5975,31 +5984,93 @@ TEST(StrongUndefinedArrow) {
 
 
 TEST(StrongDirectEval) {
-  const char* context_data[][2] = {{"", ""}, {NULL}};
+  const char* sloppy_context_data[][2] = {{"", ""}, {NULL}};
+  const char* strong_context_data[][2] = {{"'use strong';", ""}, {NULL}};
 
   const char* error_data[] = {
-      "'use strong'; eval();",
-      "'use strong'; eval([]);",
-      "'use strong'; (eval)();",
-      "'use strong'; (((eval)))();",
-      "'use strong'; eval('function f() {}');",
-      "'use strong'; function f() {eval()}",
+      "eval();",
+      "eval([]);",
+      "(eval)();",
+      "(((eval)))();",
+      "eval('function f() {}');",
+      "function f() {eval()}",
       NULL};
 
   const char* success_data[] = {
-      "'use strong'; eval;",
-      "'use strong'; eval`foo`;",
-      "'use strong'; let foo = eval; foo();",
-      "'use strong'; (1, eval)();",
+      "eval;",
+      "eval`foo`;",
+      "let foo = eval; foo();",
+      "(1, eval)();",
       NULL};
 
   static const ParserFlag always_flags[] = {
       kAllowStrongMode
   };
 
-  RunParserSyncTest(context_data, error_data, kError, NULL, 0,
+  RunParserSyncTest(sloppy_context_data, error_data, kSuccess, NULL, 0,
                     always_flags, arraysize(always_flags));
-  RunParserSyncTest(context_data, success_data, kSuccess, NULL, 0,
+  RunParserSyncTest(strong_context_data, error_data, kError, NULL, 0,
+                    always_flags, arraysize(always_flags));
+  RunParserSyncTest(strong_context_data, success_data, kSuccess, NULL, 0,
+                    always_flags, arraysize(always_flags));
+}
+
+
+TEST(StrongSwitchFallthrough) {
+  const char* sloppy_context_data[][2] = {
+      {"function f() { foo:for(;;) { switch(1) {", "};}}"},
+      {NULL, NULL}
+  };
+  const char* strong_context_data[][2] = {
+      {"function f() { 'use strong'; foo:for(;;) { switch(1) {", "};}}"},
+      {NULL, NULL}
+  };
+
+  const char* data_success[] = {
+      "",
+      "case 1:",
+      "case 1: case 2:",
+      "case 1: break;",
+      "default: throw new TypeError();",
+      "case 1: case 2: null",
+      "case 1: case 2: default: 1+1",
+      "case 1: break; case 2: return; default:",
+      "case 1: break foo; case 2: return; default:",
+      "case 1: case 2: break; case 3: continue; case 4: default:",
+      "case 1: case 2: break; case 3: continue foo; case 4: default:",
+      "case 1: case 2: {{return;}} case 3: default:",
+      "case 1: case 2: case 3: default: {1+1;{continue;}}",
+      "case 1: case 2: {1+1;{1+1;{continue;}}} case 3: default:",
+      "case 1: if (1) break; else continue; case 2: case 3: default:",
+      "case 1: case 2: if (1) {{break;}} else break; case 3: default:",
+      "case 1: if (1) break; else {if (1) break; else break;} case 2: default:",
+      "case 1: if (1) {if (1) break; else break;} else break; case 2: default:",
+      NULL};
+
+  const char* data_error[] = {
+      "case 1: case 2: (function(){return}); default:",
+      "case 1: 1+1; case 2:",
+      "case 1: bar: break bar; case 2: break;",
+      "case 1: bar:return; case 2:",
+      "case 1: bar:{ continue;} case 2:",
+      "case 1: break; case 2: bar:{ throw new TypeError() } default:",
+      "case 1: case 2: { bar:{ { break;} } } default: break;",
+      "case 1: if (1) break; else {}; case 2: default:",
+      "case 1: case 2: if (1) break; default:",
+      "case 1: case 2: if (1) break; else 0; default:",
+      "case 1: case 2: if (1) 0; else break; default:",
+      "case 1: case 2: case 3: if (1) {} default:",
+      "case 1: bar:if (1) break; else continue; case 2: case 3: default:",
+      NULL};
+
+  static const ParserFlag always_flags[] = {
+      kAllowStrongMode
+  };
+  RunParserSyncTest(strong_context_data, data_success, kSuccess, NULL, 0,
+                    always_flags, arraysize(always_flags));
+  RunParserSyncTest(sloppy_context_data, data_error, kSuccess, NULL, 0,
+                    always_flags, arraysize(always_flags));
+  RunParserSyncTest(strong_context_data, data_error, kError, NULL, 0,
                     always_flags, arraysize(always_flags));
 }
 

test/mjsunit/strong/switch.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
+
+"use strict";
+
+function CheckSwitch() {
+  let jumpStatements = [
+    "break; ",
+    "continue; ",
+    "break foo; ",
+    "continue foo; ",
+    "return; ",
+    "throw new TypeError(); ",
+    "if(1) break; else continue; ",
+    "if(1) {1+1; {break;}} else continue; "
+  ]
+
+  let otherStatements = [
+    "null; ",
+    "1+1; ",
+    "{} ",
+    "for(;false;) {break;} ",
+    "for(;false;) {1+1; {throw new TypeError();}} ",
+    "(function(){return});",
+    "(function(){throw new TypeError();});",
+    "{break; 1+1;} ",
+    "if(1) break; ",
+    "if(1) break; else 1+1; ",
+    "if(1) 1+1; else break; ",
+  ]
+
+  let successContexts = [
+    ["switch(1) {case 1: ", "case 2: }"],
+    ["switch(1) {case 1: case 2: ", "default: }"],
+    ["switch(1) {case 1: case 2: ", "default: {}}"],
+    ["switch(1) {case 1: case 2: ", "default: 1+1}"],
+    ["switch(1) {case 1: break; case 2: ", "default: }"],
+    ["switch(1) {case 1: case 2: break; case 3: ", "case 4: default: }"],
+    ["switch(1) {case 1: if(1) break; else {", "} default: break;}"]
+  ]
+
+  let strongThrowContexts = [
+    ["switch(1) {case 1: 1+1; case 2: ", "}"],
+    ["switch(1) {case 1: bar: break foo; case 2: ", "}"],
+    ["switch(1) {case 1: bar:", " case 2: }"],
+    ["switch(1) {case 1: bar:{ ", "} case 2: }"],
+    ["switch(1) {case 1: bar:{ ", "} default: break;}"],
+    ["switch(1) {case 1: { bar:{ { ", "} } } default: break;}"],
+    ["switch(1) {case 1: { { { ", "} 1+1;} } default: break;}"],
+    ["switch(1) {case 1: if(1) {", "} default: break;}"],
+    ["switch(1) {case 1: bar:if(1) break; else {", "} default: break;}"]
+  ]
+
+  let sloppy_wrap = ["function f() { foo:for(;;) {", "}}"];
+  let strong_wrap = ["function f() { 'use strong'; foo:for(;;) {", "}}"];
+
+  for (let context of successContexts) {
+    let sloppy_prefix = sloppy_wrap[0] + context[0];
+    let sloppy_suffix = context[1] + sloppy_wrap[1];
+    let strong_prefix = strong_wrap[0] + context[0];
+    let strong_suffix = context[1] + strong_wrap[1];
+
+    for (let code of jumpStatements) {
+      assertDoesNotThrow(strong_wrap[0] + "switch(1) {case 1: " + code + "}}}");
+      assertDoesNotThrow(strong_prefix + code + strong_suffix);
+      assertDoesNotThrow(strong_prefix + "{ 1+1; " + code + "}" +
+                         strong_suffix);
+      assertDoesNotThrow(strong_prefix + "{ 1+1; { 1+1; " + code + "}}" +
+                         strong_suffix);
+      assertDoesNotThrow(strong_prefix + "if(1) " + code + "else break;" +
+                         strong_suffix);
+      assertDoesNotThrow(strong_prefix + "if(1) " + code +
+                         "else if (1) break; else " + code + strong_suffix);
+    }
+    for (let code of otherStatements) {
+        assertDoesNotThrow(sloppy_prefix + code + sloppy_suffix);
+        assertThrows(strong_prefix + code + strong_suffix, SyntaxError);
+    }
+  }
+
+  for (let context of strongThrowContexts) {
+    let sloppy_prefix = sloppy_wrap[0] + context[0];
+    let sloppy_suffix = context[1] + sloppy_wrap[1];
+    let strong_prefix = strong_wrap[0] + context[0];
+    let strong_suffix = context[1] + strong_wrap[1];
+
+    for (let code of jumpStatements.concat(otherStatements)) {
+      assertDoesNotThrow(sloppy_prefix + code + sloppy_suffix);
+      assertThrows(strong_prefix + code + strong_suffix, SyntaxError);
+    }
+  }
+
+  for (let code of otherStatements) {
+    assertDoesNotThrow("switch(1) {default: " + code + "}");
+    assertDoesNotThrow("switch(1) {case 1: " + code + "}");
+    assertDoesNotThrow("switch(1) {case 1: default: " + code + "}");
+    assertDoesNotThrow("switch(1) {case 1: break; default: " + code + "}");
+    assertDoesNotThrow("switch(1) {case 1: " + code + "break; default: }");
+  }
+}
+
+CheckSwitch();
+
+assertDoesNotThrow("'use strong'; switch(1) {}");
+assertDoesNotThrow("'use strong'; switch(1) {case 1:}");
+assertDoesNotThrow("'use strong'; switch(1) {default:}");
+assertDoesNotThrow("'use strong'; switch(1) {case 1: case 2: default:}");