Fix redeclaration of existing var variables in functions with argument context. (#3891)

Fixes #3888

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

jerry-core/vm/vm.c

@@ -1421,17 +1421,31 @@ vm_loop (vm_frame_ctx_t *frame_ctx_p) /**< frame context */
           JERRY_ASSERT (ecma_get_lex_env_type (lex_env_p) == ECMA_LEXICAL_ENVIRONMENT_DECLARATIVE);
           JERRY_ASSERT (prev_lex_env_p != NULL
                         && ecma_get_lex_env_type (prev_lex_env_p) == ECMA_LEXICAL_ENVIRONMENT_DECLARATIVE);
-          JERRY_ASSERT (ecma_find_named_property (prev_lex_env_p, name_p) == NULL);
 
+          ecma_property_t *property_p = ecma_find_named_property (prev_lex_env_p, name_p);
           ecma_property_value_t *property_value_p;
-          property_value_p = ecma_create_named_data_property (prev_lex_env_p,
-                                                              name_p,
-                                                              ECMA_PROPERTY_CONFIGURABLE_WRITABLE,
-                                                              NULL);
 
-          if (lit_value == ECMA_VALUE_UNDEFINED)
+          if (property_p == NULL)
           {
-            continue;
+            property_value_p = ecma_create_named_data_property (prev_lex_env_p,
+                                                                name_p,
+                                                                ECMA_PROPERTY_CONFIGURABLE_WRITABLE,
+                                                                NULL);
+
+            if (lit_value == ECMA_VALUE_UNDEFINED)
+            {
+              continue;
+            }
+          }
+          else
+          {
+            if (lit_value == ECMA_VALUE_UNDEFINED)
+            {
+              continue;
+            }
+
+            property_value_p = ECMA_PROPERTY_VALUE_PTR (property_p);
+            ecma_free_value_if_not_object (property_value_p->value);
           }
 
           property_value_p->value = lit_value;

tests/jerry/es2015/function-scope2.js

@@ -95,3 +95,17 @@ function i([a], get = () => a, set = (v) => a = v) {
   assert(get() === 3);
 }
 i([1]);
+
+function j(a = eval()) {
+  var a = 3.14;
+
+  try {
+    eval("throw 1; function a() { return 8; }")
+    assert(false)
+  } catch (e) {
+    assert(e === 1)
+  }
+
+  assert(a() === 8)
+}
+j()

tests/jerry/es2015/regresssion-test-issue-3888.js

@@ -0,0 +1,19 @@
+// 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 i(id_0, b = (eval("var x"))) {
+    function x() {}
+    eval(!eval("var x = {}; x instanceof assert;"))
+}
+i()