Bug 1454207 - Part 3: Introduces a new function |ValueToPrintableUtf8| so that we report ReferenceError with readable Unicode characters instead of unreadable Unicode escape sequences r=arai

MozReview-Commit-ID: HtAVxVg54IL

--HG--
extra : rebase_source : 2079f41bbd3723aa633bac58c1661444f5862985

js/src/vm/JSContext.cpp

@@ -884,9 +884,9 @@ void
 js::ReportIsNotDefined(JSContext* cx, HandleId id)
 {
     JSAutoByteString printable;
-    if (!ValueToPrintableLatin1(cx, IdToValue(id), &printable))
+    if (!ValueToPrintableUTF8(cx, IdToValue(id), &printable))
         return;
-    JS_ReportErrorNumberLatin1(cx, GetErrorMessage, nullptr, JSMSG_NOT_DEFINED, printable.ptr());
+    JS_ReportErrorNumberUTF8(cx, GetErrorMessage, nullptr, JSMSG_NOT_DEFINED, printable.ptr());
 }
 
 void

js/src/vm/StringType.cpp

@@ -1926,6 +1926,20 @@ js::ValueToPrintableLatin1(JSContext* cx, const Value& vArg, JSAutoByteString* b
     return bytes->encodeLatin1(cx, str);
 }
 
+const char*
+js::ValueToPrintableUTF8(JSContext* cx, const Value& vArg, JSAutoByteString* bytes, bool asSource)
+{
+    RootedValue v(cx, vArg);
+    JSString* str;
+    if (asSource)
+        str = ValueToSource(cx, v);
+    else
+        str = ToString<CanGC>(cx, v);
+    if (!str)
+        return nullptr;
+    return bytes->encodeUtf8(cx, RootedString(cx, str));
+}
+
 template <AllowGC allowGC>
 JSString*
 js::ToStringSlow(JSContext* cx, typename MaybeRooted<Value, allowGC>::HandleType arg)

js/src/vm/StringType.h

@@ -1598,6 +1598,12 @@ extern const char*
 ValueToPrintableLatin1(JSContext* cx, const Value&, JSAutoByteString* bytes,
                        bool asSource = false);
 
+/*
+ * Convert a value to a printable C string encoded in UTF-8.
+ */
+extern const char*
+ValueToPrintableUTF8(JSContext* cx, const Value&, JSAutoByteString* bytes, bool asSource = false);
+
 /*
  * Convert a non-string value to a string, returning null after reporting an
  * error, otherwise returning a new string reference.