From 9e0709e4013c7071e2a7b6d5894f8ba02eeb9263 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Csaba=20Osztrogon=C3=A1c?= <oszi@inf.u-szeged.hu>
Date: Mon, 6 Jan 2020 15:17:54 +0100
Subject: [PATCH] Fix Array.prototype.reduce and reduceRight (#3487)
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Don't throw TypeError when object length is 0 and initialValue is undefined.
Additionally the error message should be more precise and match other engines.

Fixes #3463

JerryScript-DCO-1.0-Signed-off-by: Csaba Osztrogonác oszi@inf.u-szeged.hu
---
 .../builtin-objects/ecma-builtin-array-prototype.c     |  4 ++--
 .../builtin-objects/ecma-builtin-array-prototype.inc.h |  4 ++--
 tests/jerry/array-prototype-reduce-right.js            | 10 ++--------
 tests/jerry/array-prototype-reduce.js                  |  2 ++
 4 files changed, 8 insertions(+), 12 deletions(-)

diff --git a/jerry-core/ecma/builtin-objects/ecma-builtin-array-prototype.c b/jerry-core/ecma/builtin-objects/ecma-builtin-array-prototype.c
index acb05f525..c63298850 100644
--- a/jerry-core/ecma/builtin-objects/ecma-builtin-array-prototype.c
+++ b/jerry-core/ecma/builtin-objects/ecma-builtin-array-prototype.c
@@ -2069,9 +2069,9 @@ ecma_builtin_array_reduce_from (ecma_value_t callbackfn, /**< routine's 1st argu
   }
 
   /* 5. */
-  if (len == 0 && ecma_is_value_undefined (initial_value))
+  if (len == 0 && args_number == 1)
   {
-    return ecma_raise_type_error (ECMA_ERR_MSG ("Initial value cannot be undefined."));
+    return ecma_raise_type_error (ECMA_ERR_MSG ("Reduce of empty array with no initial value."));
   }
 
   JERRY_ASSERT (ecma_is_value_object (callbackfn));
diff --git a/jerry-core/ecma/builtin-objects/ecma-builtin-array-prototype.inc.h b/jerry-core/ecma/builtin-objects/ecma-builtin-array-prototype.inc.h
index 59ba8d323..5f12393d8 100644
--- a/jerry-core/ecma/builtin-objects/ecma-builtin-array-prototype.inc.h
+++ b/jerry-core/ecma/builtin-objects/ecma-builtin-array-prototype.inc.h
@@ -67,8 +67,8 @@ ROUTINE (LIT_MAGIC_STRING_FOR_EACH_UL, ECMA_ARRAY_PROTOTYPE_FOR_EACH, 2, 1)
 ROUTINE (LIT_MAGIC_STRING_MAP, ECMA_ARRAY_PROTOTYPE_MAP, 2, 1)
 ROUTINE (LIT_MAGIC_STRING_FILTER, ECMA_ARRAY_PROTOTYPE_FILTER, 2, 1)
 /* Note these 2 routines must be in this order */
-ROUTINE (LIT_MAGIC_STRING_REDUCE, ECMA_ARRAY_PROTOTYPE_REDUCE, NON_FIXED, 1)
-ROUTINE (LIT_MAGIC_STRING_REDUCE_RIGHT_UL, ECMA_ARRAY_PROTOTYPE_REDUCE_RIGHT, NON_FIXED, 1)
+ROUTINE (LIT_MAGIC_STRING_REDUCE, ECMA_ARRAY_PROTOTYPE_REDUCE, 2, 1)
+ROUTINE (LIT_MAGIC_STRING_REDUCE_RIGHT_UL, ECMA_ARRAY_PROTOTYPE_REDUCE_RIGHT, 2, 1)
 #if ENABLED (JERRY_ES2015)
 ROUTINE (LIT_MAGIC_STRING_FIND, ECMA_ARRAY_PROTOTYPE_FIND, 2, 1)
 ROUTINE (LIT_MAGIC_STRING_FIND_INDEX, ECMA_ARRAY_PROTOTYPE_FIND_INDEX, 2, 1)
diff --git a/tests/jerry/array-prototype-reduce-right.js b/tests/jerry/array-prototype-reduce-right.js
index a9a71cb27..9b3ca5fa8 100644
--- a/tests/jerry/array-prototype-reduce-right.js
+++ b/tests/jerry/array-prototype-reduce-right.js
@@ -34,14 +34,6 @@ try {
   assert(e instanceof TypeError);
 }
 
-try {
-  var arg2;
-  [].reduceRight(func, arg2);
-  assert(false);
-} catch(e) {
-  assert(e instanceof TypeError);
-}
-
 try {
   var a = new Array();
   a.length = 10;
@@ -54,6 +46,8 @@ try {
 // various checks
 assert([].reduceRight(func, 1) === 1);
 
+assert([].reduceRight(func, undefined) === undefined);
+
 assert([0].reduceRight(func) === 0);
 
 assert([0, 1].reduceRight(func) === 1);
diff --git a/tests/jerry/array-prototype-reduce.js b/tests/jerry/array-prototype-reduce.js
index 6193ec7f0..908818a60 100644
--- a/tests/jerry/array-prototype-reduce.js
+++ b/tests/jerry/array-prototype-reduce.js
@@ -39,6 +39,8 @@ catch(e) {
 // various checks
 assert ([].reduce(func, 1) === 1);
 
+assert ([].reduce(func, undefined) === undefined);
+
 assert ([0].reduce(func) === 0);
 
 assert ([0, 1].reduce(func) === 1);