From a7cff6fec3c4e8051c2249ca8948025a4990d6f8 Mon Sep 17 00:00:00 2001
From: Dmitry Volyntsev <xeioex@nginx.com>
Date: Mon, 27 Aug 2018 16:06:33 +0300
Subject: [PATCH] Fixed toString() for -0.

---
 njs/njs_vm.c             | 12 +++++++++++-
 njs/njs_vm.h             |  1 +
 njs/test/njs_unit_test.c |  6 ++++++
 nxt/nxt_dtoa.c           | 12 ++++++------
 4 files changed, 24 insertions(+), 7 deletions(-)

diff --git a/njs/njs_vm.c b/njs/njs_vm.c
index e60a5bb7..a63378a6 100644
--- a/njs/njs_vm.c
+++ b/njs/njs_vm.c
@@ -88,6 +88,7 @@ const njs_value_t  njs_string_boolean =     njs_string("boolean");
 const njs_value_t  njs_string_false =       njs_string("false");
 const njs_value_t  njs_string_true =        njs_string("true");
 const njs_value_t  njs_string_number =      njs_string("number");
+const njs_value_t  njs_string_minus_zero =  njs_string("-0");
 const njs_value_t  njs_string_minus_infinity =
                                             njs_string("-Infinity");
 const njs_value_t  njs_string_plus_infinity =
@@ -3310,7 +3311,16 @@ again:
             }
         }
 
-        ret = njs_primitive_value_to_string(vm, &value, &value);
+        if (nxt_slow_path((value.type == NJS_NUMBER
+                            && value.data.u.number == 0
+                            && signbit(value.data.u.number))))
+        {
+            value = njs_string_minus_zero;
+            ret = NXT_OK;
+
+        } else {
+            ret = njs_primitive_value_to_string(vm, &value, &value);
+        }
 
         if (nxt_fast_path(ret == NXT_OK)) {
             size = value.short_string.size;
diff --git a/njs/njs_vm.h b/njs/njs_vm.h
index ea961988..ee256598 100644
--- a/njs/njs_vm.h
+++ b/njs/njs_vm.h
@@ -1269,6 +1269,7 @@ extern const njs_value_t  njs_string_null;
 extern const njs_value_t  njs_string_false;
 extern const njs_value_t  njs_string_true;
 extern const njs_value_t  njs_string_native;
+extern const njs_value_t  njs_string_minus_zero;
 extern const njs_value_t  njs_string_minus_infinity;
 extern const njs_value_t  njs_string_plus_infinity;
 extern const njs_value_t  njs_string_nan;
diff --git a/njs/test/njs_unit_test.c b/njs/test/njs_unit_test.c
index 38c4fd6a..a42f0d75 100644
--- a/njs/test/njs_unit_test.c
+++ b/njs/test/njs_unit_test.c
@@ -420,6 +420,9 @@ static njs_unit_test_t  njs_test[] =
     { nxt_string("1 + 1 + '2' + 1 + 1"),
       nxt_string("2211") },
 
+    { nxt_string("'gg' + -0"),
+      nxt_string("gg0") },
+
     { nxt_string("1.2 - '5.7'"),
       nxt_string("-4.5") },
 
@@ -8976,6 +8979,9 @@ static njs_unit_test_t  njs_test[] =
     { nxt_string("JSON.stringify(123)"),
       nxt_string("123") },
 
+    { nxt_string("JSON.stringify(-0)"),
+      nxt_string("0") },
+
     { nxt_string("JSON.stringify(0.00000123)"),
       nxt_string("0.00000123") },
 
diff --git a/nxt/nxt_dtoa.c b/nxt/nxt_dtoa.c
index 6453f87f..20ea2ebe 100644
--- a/nxt/nxt_dtoa.c
+++ b/nxt/nxt_dtoa.c
@@ -346,18 +346,18 @@ nxt_dtoa(double value, char *start)
     minus = 0;
     p = start;
 
-    if (signbit(value)) {
-        *p++ = '-';
-        value = -value;
-        minus = 1;
-    }
-
     if (value == 0) {
         *p++ = '0';
 
         return (p - start);
     }
 
+    if (signbit(value)) {
+        *p++ = '-';
+        value = -value;
+        minus = 1;
+    }
+
     length = nxt_grisu2(value, p, &dec_exp);
 
     length = nxt_prettify(p, length, dec_exp);
-- 
2.47.3