Add validation for single statement lexical declarations (#3326)

This patch fixes #3275 and fixes #3276.

JerryScript-DCO-1.0-Signed-off-by: Robert Fancsik frobert@inf.u-szeged.hu

jerry-core/parser/js/js-parser-statm.c

@@ -477,6 +477,21 @@ parser_pop_block_context (parser_context_t *context_p) /**< context */
   parser_stack_iterator_init (context_p, &context_p->last_statement);
 } /* parser_pop_block_context */
 
+/**
+ * Validate lexical context for a declaration.
+ */
+static void
+parser_validate_lexical_context (parser_context_t *context_p) /**< context */
+{
+  JERRY_ASSERT (context_p->token.type == LEXER_KEYW_LET
+                || context_p->token.type == LEXER_KEYW_CONST
+                || context_p->token.type == LEXER_KEYW_CLASS);
+
+  if (parser_statement_flags[context_p->stack_top_uint8] & PARSER_STATM_SINGLE_STATM)
+  {
+    parser_raise_error (context_p, PARSER_ERR_LEXICAL_SINGLE_STATEMENT);
+  }
+} /* parser_validate_lexical_context */
 #endif /* ENABLED (JERRY_ES2015) */
 
 /**
@@ -491,6 +506,11 @@ parser_parse_var_statement (parser_context_t *context_p) /**< context */
 
 #if ENABLED (JERRY_ES2015)
   uint8_t declaration_type = context_p->token.type;
+
+  if (declaration_type != LEXER_KEYW_VAR)
+  {
+    parser_validate_lexical_context (context_p);
+  }
 #endif /* ENABLED (JERRY_ES2015) */
 
   while (true)
@@ -612,6 +632,15 @@ parser_parse_function_statement (parser_context_t *context_p) /**< context */
 
   JERRY_ASSERT (context_p->token.type == LEXER_KEYW_FUNCTION);
 
+#if ENABLED (JERRY_ES2015)
+  if ((parser_statement_flags[context_p->stack_top_uint8] & PARSER_STATM_SINGLE_STATM)
+      && !(context_p->stack_top_uint8 == PARSER_STATEMENT_IF
+           || context_p->stack_top_uint8 == PARSER_STATEMENT_ELSE))
+  {
+    parser_raise_error (context_p, PARSER_ERR_LEXICAL_SINGLE_STATEMENT);
+  }
+#endif /* ENABLED (JERRY_ES2015) */
+
 #if ENABLED (JERRY_DEBUGGER)
   parser_line_counter_t debugger_line = context_p->token.line;
   parser_line_counter_t debugger_column = context_p->token.column;
@@ -2636,6 +2665,7 @@ parser_parse_statements (parser_context_t *context_p) /**< context */
 #if ENABLED (JERRY_ES2015)
       case LEXER_KEYW_CLASS:
       {
+        parser_validate_lexical_context (context_p);
         parser_parse_class (context_p, true);
         goto consume_last_statement;
       }

jerry-core/parser/js/js-parser-util.c

@@ -1089,6 +1089,10 @@ parser_error_to_string (parser_error_t error) /**< error code */
     {
       return "Local variable is redeclared.";
     }
+    case PARSER_ERR_LEXICAL_SINGLE_STATEMENT:
+    {
+      return "Lexical declaration cannot appear in a single-statement context.";
+    }
     case PARSER_ERR_MISSING_ASSIGN_AFTER_CONST:
     {
       return "Value assignment is expected after a const declaration.";

jerry-core/parser/js/js-parser.h

@@ -115,6 +115,7 @@ typedef enum
   PARSER_ERR_OBJECT_PROPERTY_REDEFINED,               /**< property of object literal redefined */
 #if ENABLED (JERRY_ES2015)
   PARSER_ERR_VARIABLE_REDECLARED,                     /**< a variable redeclared */
+  PARSER_ERR_LEXICAL_SINGLE_STATEMENT,                /**< lexical variable in single statement context */
   PARSER_ERR_MISSING_ASSIGN_AFTER_CONST,              /**< an assignment is required after a const declaration */
 
   PARSER_ERR_MULTIPLE_CLASS_CONSTRUCTORS,             /**< multiple class constructor */

tests/jerry/es2015/let12.js

@@ -0,0 +1,41 @@
+// Copyright JS Foundation and other contributors, http://js.foundation
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+function checkSyntax (str) {
+  try {
+    eval (str);
+    assert (false);
+  } catch (e) {
+    assert (e instanceof SyntaxError);
+  }
+}
+
+checkSyntax ("if (5) let a;");
+checkSyntax ("if (5) const a;");
+checkSyntax ("if (0) {} else let a;");
+checkSyntax ("if (0) {} else const a;");
+checkSyntax ("while (5) let a;");
+checkSyntax ("while (5) const a;");
+checkSyntax ("do let a; while (5)");
+checkSyntax ("do const a; while (5)");
+checkSyntax ("for (a in b) let c;");
+checkSyntax ("for (a in b) const c;");
+checkSyntax ("for (a of b) let c;");
+checkSyntax ("for (a of b) const c;");
+checkSyntax ("for (;;) let c;");
+checkSyntax ("for (;;) const c;");
+checkSyntax ("with ({}) let c;");
+checkSyntax ("with ({}) const c;");
+checkSyntax ("a: let c;");
+checkSyntax ("a: const c;");

tests/jerry/fail/regression-test-issue-3276.js

@@ -12,4 +12,4 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-do class $ { } while (0);
+with ({ }) class ${ $( ) { $ } }

tests/jerry/fail/regresssion-test-issue-3275.js

@@ -0,0 +1,15 @@
+// Copyright JS Foundation and other contributors, http://js.foundation
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+for ( i in this ) class ${ } eval ( )