Arrow functions should be parsed as assignment expressions. (#3336)

JerryScript-DCO-1.0-Signed-off-by: Zoltan Herczeg zherczeg.u-szeged@partner.samsung.com

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

@@ -1177,12 +1177,39 @@ parser_parse_template_literal (parser_context_t *context_p) /**< context */
   return;
 } /* parser_parse_template_literal */
 
+/**
+ * Throws an error if the current expression is not an assignment expression.
+ */
+static inline void JERRY_ATTR_ALWAYS_INLINE
+parser_check_assignment_expr (parser_context_t *context_p)
+{
+  if (context_p->stack_top_uint8 != LEXER_EXPRESSION_START
+      && context_p->stack_top_uint8 != LEXER_LEFT_PAREN
+      && context_p->stack_top_uint8 != LEXER_COMMA_SEP_LIST
+      && !LEXER_IS_BINARY_LVALUE_TOKEN (context_p->stack_top_uint8))
+  {
+    parser_raise_error (context_p, PARSER_ERR_ASSIGNMENT_EXPECTED);
+  }
+} /* parser_check_assignment_expr */
+
+/**
+ * Checks whether the next token is a valid continuation token after an arrow function.
+ */
+static inline bool JERRY_ATTR_ALWAYS_INLINE
+parser_abort_parsing_after_arrow (parser_context_t *context_p)
+{
+  return (context_p->token.type != LEXER_RIGHT_PAREN
+          && context_p->token.type != LEXER_COMMA);
+} /* parser_abort_parsing_after_arrow */
+
 #endif /* ENABLED (JERRY_ES2015) */
 
 /**
  * Parse and record unary operators, and parse the primary literal.
+ *
+ * @return true if parsing should be aborted, true otherwise
  */
-static void
+static bool
 parser_parse_unary_expression (parser_context_t *context_p, /**< context */
                                size_t *grouping_level_p) /**< grouping level */
 {
@@ -1255,9 +1282,10 @@ parser_parse_unary_expression (parser_context_t *context_p, /**< context */
       {
         JERRY_ASSERT (context_p->next_scanner_info_p->type == SCANNER_TYPE_FUNCTION);
 
+        parser_check_assignment_expr (context_p);
         parser_parse_function_expression (context_p,
                                           PARSER_IS_FUNCTION | PARSER_IS_ARROW_FUNCTION);
-        return;
+        return parser_abort_parsing_after_arrow (context_p);
       }
 #endif /* ENABLED (JERRY_ES2015) */
 
@@ -1346,7 +1374,7 @@ parser_parse_unary_expression (parser_context_t *context_p, /**< context */
       {
         JERRY_ASSERT (context_p->next_scanner_info_p->type == SCANNER_TYPE_INITIALIZER);
         parser_parse_object_initializer (context_p, PARSER_PATTERN_NO_OPTS);
-        return;
+        return false;
       }
 #endif /* ENABLED (JERRY_ES2015) */
 
@@ -1360,7 +1388,7 @@ parser_parse_unary_expression (parser_context_t *context_p, /**< context */
       {
         JERRY_ASSERT (context_p->next_scanner_info_p->type == SCANNER_TYPE_INITIALIZER);
         parser_parse_array_initializer (context_p, PARSER_PATTERN_NO_OPTS);
-        return;
+        return false;
       }
 #endif /* ENABLED (JERRY_ES2015) */
 
@@ -1435,7 +1463,7 @@ parser_parse_unary_expression (parser_context_t *context_p, /**< context */
     case LEXER_KEYW_CLASS:
     {
       parser_parse_class (context_p, false);
-      return;
+      return false;
     }
     case LEXER_KEYW_SUPER:
     {
@@ -1479,10 +1507,11 @@ parser_parse_unary_expression (parser_context_t *context_p, /**< context */
       JERRY_ASSERT (context_p->next_scanner_info_p->source_p == context_p->source_p
                     && context_p->next_scanner_info_p->type == SCANNER_TYPE_FUNCTION);
 
+      parser_check_assignment_expr (context_p);
       lexer_next_token (context_p);
       parser_parse_function_expression (context_p,
                                         PARSER_IS_FUNCTION | PARSER_IS_ARROW_FUNCTION | PARSER_ARROW_PARSE_ARGS);
-      return;
+      return parser_abort_parsing_after_arrow (context_p);
     }
 #endif /* ENABLED (JERRY_ES2015) */
     default:
@@ -1494,6 +1523,7 @@ parser_parse_unary_expression (parser_context_t *context_p, /**< context */
     }
   }
   lexer_next_token (context_p);
+  return false;
 } /* parser_parse_unary_expression */
 
 /**
@@ -2730,7 +2760,11 @@ parser_parse_expression (parser_context_t *context_p, /**< context */
 
   while (true)
   {
-    parser_parse_unary_expression (context_p, &grouping_level);
+    if (parser_parse_unary_expression (context_p, &grouping_level))
+    {
+      parser_process_binary_opcodes (context_p, 0);
+      break;
+    }
 
     while (true)
     {

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

@@ -1121,6 +1121,10 @@ parser_error_to_string (parser_error_t error) /**< error code */
     {
       return "Expected 'of' token.";
     }
+    case PARSER_ERR_ASSIGNMENT_EXPECTED:
+    {
+      return "Unexpected arrow function or yield expression (parentheses around the expression may help).";
+    }
     case PARSER_ERR_DUPLICATED_ARGUMENT_NAMES:
     {
       return "Duplicated function argument names are not allowed here.";

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

@@ -126,6 +126,7 @@ typedef enum
   PARSER_ERR_RIGHT_BRACE_EXPECTED,                    /**< right brace expected */
   PARSER_ERR_OF_EXPECTED,                             /**< of keyword expected */
 
+  PARSER_ERR_ASSIGNMENT_EXPECTED,                     /**< assignment expression expected */
   PARSER_ERR_FORMAL_PARAM_AFTER_REST_PARAMETER,       /**< formal parameter after rest parameter */
   PARSER_ERR_SETTER_REST_PARAMETER,                   /**< setter rest parameter */
   PARSER_ERR_REST_PARAMETER_DEFAULT_INITIALIZER,      /**< rest parameter default initializer */

tests/jerry/es2015/arrow-function.js

@@ -100,13 +100,13 @@ default:
 
   var global_var = 7;
 
-  assert (
+  assert ((
     (
     static
     ,
     package
     ) => { global_var = 5; return static + package }
-  (4, 5) == 9);
+  )(4, 5) == 9);
 
   assert (global_var == 5);
 
@@ -146,6 +146,13 @@ must_throw ("x\n => 0");
 must_throw ("this => 0");
 must_throw ("(true) => 0");
 must_throw ("()\n=>5");
+must_throw ("3 + x => 3");
+must_throw ("3 || x => 3");
+must_throw ("a = 3 || (x,y) => 3");
+must_throw ("x => {} (4)");
+must_throw ("!x => 4");
+must_throw ("x => {} = 1");
+must_throw ("x => {} a = 1");
 must_throw_strict ("(package) => 0");
 must_throw_strict ("(package) => { return 5 }");
 must_throw_strict ("(x,x,x) => 0");
@@ -174,3 +181,21 @@ assert(f()()() === 7);
 
 var f = (((a=1,b=2) => ((x => (((a) => 8))))));
 assert(f()()() === 8);
+
+var s;
+// This is not a function call
+assert(eval("s = x => { return 1 }\n(3)") === 3);
+assert(typeof s === "function")
+
+// This is a function call
+assert(eval("s = function () { return 1 }\n(3)") === 1);
+assert(s === 1)
+
+var f = 5 ? x => 1 : x => 2
+assert(f() === 1)
+
+var f = [x => 2][0]
+assert(f() === 2)
+
+var f = 123; f += x => y;
+assert(typeof f === "string");

tests/jerry/es2015/regression-test-issue-2825.js

@@ -25,9 +25,9 @@ var B = class extends f {
 }
 C = class extends B {
     g() {
-        () => {
+        (() => {
           called = true;
-        }()
+        })()
     }
 }
 D = class extends C {