Fix Error.prototype.toString to be ES5 conform.

R=lrn@chromium.org
TEST=test262/15.11.4.4-8-1,mjsunit/error-tostring

Review URL: http://codereview.chromium.org/8341021

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@9790 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/messages.js

@@ -83,7 +83,7 @@ function IsNativeErrorObject(obj) {
 // objects between script tags in a browser setting.
 function ToStringCheckErrorObject(obj) {
   if (IsNativeErrorObject(obj)) {
-    return %_CallFunction(obj, errorToString);
+    return %_CallFunction(obj, ErrorToString);
   } else {
     return ToString(obj);
   }
@@ -1146,42 +1146,43 @@ $Error.captureStackTrace = captureStackTrace;
 
 %SetProperty($Error.prototype, 'message', '', DONT_ENUM);
 
-// Global list of error objects visited during errorToString. This is
+// Global list of error objects visited during ErrorToString. This is
 // used to detect cycles in error toString formatting.
 const visited_errors = new InternalArray();
 const cyclic_error_marker = new $Object();
 
-function errorToStringDetectCycle(error) {
+function ErrorToStringDetectCycle(error) {
   if (!%PushIfAbsent(visited_errors, error)) throw cyclic_error_marker;
   try {
     var type = error.type;
+    var name = error.name
+    name = IS_UNDEFINED(name) ? "Error" : TO_STRING_INLINE(name);
+    var message = error.message;
     var hasMessage = %_CallFunction(error, "message", ObjectHasOwnProperty);
     if (type && !hasMessage) {
-      var formatted = FormatMessage(%NewMessageObject(type, error.arguments));
-      return error.name + ": " + formatted;
+      message = FormatMessage(%NewMessageObject(type, error.arguments));
     }
-    var message = hasMessage ? (": " + error.message) : "";
-    return error.name + message;
+    message = IS_UNDEFINED(message) ? "" : TO_STRING_INLINE(message);
+    if (name === "") return message;
+    if (message === "") return name;
+    return name + ": " + message;
   } finally {
     visited_errors.length = visited_errors.length - 1;
   }
 }
 
-function errorToString() {
+function ErrorToString() {
   if (IS_NULL_OR_UNDEFINED(this) && !IS_UNDETECTABLE(this)) {
     throw MakeTypeError("called_on_null_or_undefined",
                         ["Error.prototype.toString"]);
   }
-  // This helper function is needed because access to properties on
-  // the builtins object do not work inside of a catch clause.
-  function isCyclicErrorMarker(o) { return o === cyclic_error_marker; }
 
   try {
-    return errorToStringDetectCycle(this);
+    return ErrorToStringDetectCycle(this);
   } catch(e) {
     // If this error message was encountered already return the empty
     // string for it instead of recursively formatting it.
-    if (isCyclicErrorMarker(e)) {
+    if (e === cyclic_error_marker) {
       return '';
     }
     throw e;
@@ -1189,7 +1190,7 @@ function errorToString() {
 }
 
 
-InstallFunctions($Error.prototype, DONT_ENUM, ['toString', errorToString]);
+InstallFunctions($Error.prototype, DONT_ENUM, ['toString', ErrorToString]);
 
 // Boilerplate for exceptions for stack overflows. Used from
 // Isolate::StackOverflow().

src/mirror-debugger.js

@@ -1087,7 +1087,7 @@ ErrorMirror.prototype.toText = function() {
   // Use the same text representation as in messages.js.
   var text;
   try {
-    str = %_CallFunction(this.value_, builtins.errorToString);
+    str = %_CallFunction(this.value_, builtins.ErrorToString);
   } catch (e) {
     str = '#<Error>';
   }

test/mjsunit/cyclic-error-to-string.js → test/mjsunit/error-tostring.js

@@ -25,22 +25,61 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-// Test printing of cyclic errors which return the empty string for
-// compatibility with Safari and Firefox.
+
+// Test default string representation of an Error object.
 
 var e = new Error();
-assertEquals('Error', e + '');
+assertEquals('Error', e.toString());
+
+
+// Test printing of cyclic errors which return the empty string for
+// compatibility with Safari and Firefox.
 
 e = new Error();
 e.name = e;
 e.message = e;
-e.stack = e;
-e.arguments = e;
-assertEquals(': ', e + '');
+e.stack = "Does not occur in output";
+e.arguments = "Does not occur in output";
+e.type = "Does not occur in output";
+assertEquals('', e.toString());
 
 e = new Error();
 e.name = [ e ];
 e.message = [ e ];
-e.stack = [ e ];
-e.arguments = [ e ];
-assertEquals(': ', e + '');
+e.stack = "Does not occur in output";
+e.arguments = "Does not occur in output";
+e.type = "Does not occur in output";
+assertEquals('', e.toString());
+
+
+// Test the sequence in which getters and toString operations are called
+// on a given Error object.  Verify the produced string representation.
+
+function testErrorToString(nameValue, messageValue) {
+  var seq = [];
+  var e = {
+    get name() {
+      seq.push(1);
+      return (nameValue === undefined) ? nameValue : {
+        toString: function() { seq.push(2); return nameValue; }
+      };
+    },
+    get message() {
+      seq.push(3);
+      return (messageValue === undefined) ? messageValue : {
+        toString: function() { seq.push(4); return messageValue; }
+      };
+    }
+  };
+  var string = Error.prototype.toString.call(e);
+  return [string,seq];
+}
+
+assertEquals(["Error",[1,3]], testErrorToString(undefined, undefined));
+assertEquals(["e1",[1,2,3]], testErrorToString("e1", undefined));
+assertEquals(["e1: null",[1,2,3,4]], testErrorToString("e1", null));
+assertEquals(["e1",[1,2,3,4]], testErrorToString("e1", ""));
+assertEquals(["Error: e2",[1,3,4]], testErrorToString(undefined, "e2"));
+assertEquals(["null: e2",[1,2,3,4]], testErrorToString(null, "e2"));
+assertEquals(["e2",[1,2,3,4]], testErrorToString("", "e2"));
+assertEquals(["e1: e2",[1,2,3,4]], testErrorToString("e1", "e2"));

test/test262/test262.status

@@ -502,9 +502,6 @@ S15.4.4.3_A2_T1: FAIL_OK
 # Bug? Date.prototype.toISOString - value of year is Infinity
 #      Date.prototype.toISOString throw the RangeError
 15.9.5.43-0-15: FAIL
-# Bug? Error.prototype.toString return the value of 'msg' when 'name' is empty
-#      string and 'msg' isn't undefined
-15.11.4.4-8-1: FAIL
 
 ############################ SKIPPED TESTS #############################