Fix http://dartbug.com/1133:

vm/parser.cc

Index: vm/parser.cc
===================================================================
--- vm/parser.cc	(revision 3963)
+++ vm/parser.cc	(working copy)
@@ -5148,77 +5148,83 @@
                               const char* message_header,
                               const char* format,
                               va_list args) {
-  const intptr_t kMessageBufferSize = 512;
-  char message_buffer[kMessageBufferSize];
-  FormatMessage(script, token_index, message_header,
-                message_buffer, kMessageBufferSize,
-                format, args);
-  const String& msg = String::Handle(String::New(message_buffer));
+  const String& msg = String::Handle(
+      FormatMessage(script, token_index, message_header, format, args));
   return LanguageError::New(msg);
 }
 
 
+static RawString* VFormatMessageHelper(const char* format, va_list args) {
+  Zone* zone = Isolate::Current()->current_zone();
+  va_list args2;
+  va_copy(args2, args);
+  int msg_len = OS::VSNPrint(NULL, 0, format, args2) + 1;
+  va_end(args2);
+  char* chars = reinterpret_cast<char*>(zone->Allocate(msg_len));
+  OS::VSNPrint(chars, msg_len, format, args);
+  return String::New(chars);
+}
+
+
+static RawString* FormatMessageHelper(const char* format, ...) {

[hausner, 2012/02/07 01:00:55]

This could be called Stringf(format, ...)   and the above VStringf(format, args)
 ;-)

[Ivan Posva, 2012/02/07 04:09:55]

Actually they might be generally useful factories on the String class. I will
move them to object.cc in a different CL.

+  va_list args;
+  va_start(args, format);
+  const String& result = String::Handle(VFormatMessageHelper(format, args));
+  va_end(args);
+  return result.raw();
+}
+
+
 // Static.
-void Parser::FormatMessage(const Script& script,
+RawString* Parser::FormatMessage(const Script& script,
                            intptr_t token_index,

[Ivan Posva, 2012/02/07 04:09:55]

Bad indentation, will fix...

                            const char* message_header,
-                           char* message_buffer,
-                           intptr_t message_buffer_size,
                            const char* format, va_list args) {
-  intptr_t msg_len = 0;
+  Zone* zone = Isolate::Current()->current_zone();
+  String& message = String::Handle();
+
   if (!script.IsNull()) {
     const String& script_url = String::CheckedHandle(script.url());
+    String& msg_part = String::Handle();
+    // Prepend the script to the message with the format "'%s'".
+    msg_part = String::New("'");
+    message = String::Concat(msg_part, script_url);
+    message = String::Concat(message, msg_part);
+
     if (token_index >= 0) {
       intptr_t line, column;
       script.GetTokenLocation(token_index, &line, &column);
-      msg_len += OS::SNPrint(message_buffer + msg_len,
-                             message_buffer_size - msg_len,
-                             "'%s': %s: line %d pos %d: ",
-                             script_url.ToCString(),
-                             message_header,
-                             line,
-                             column);
-      if (msg_len < message_buffer_size) {
-        // Append the formatted error or warning message.
-        msg_len += OS::VSNPrint(message_buffer + msg_len,
-                                message_buffer_size - msg_len,
-                                format,
-                                args);
-        if (msg_len < message_buffer_size) {
-          // Append the source line.
-          const String& script_line = String::Handle(script.GetLine(line));
-          ASSERT(!script_line.IsNull());
-          msg_len += OS::SNPrint(message_buffer + msg_len,
-                                 message_buffer_size - msg_len,
-                                 "\n%s\n%*s\n",
-                                 script_line.ToCString(),
-                                 column,
-                                 "^");
-        }
-      }
+      msg_part = FormatMessageHelper(": %s: line %d pos %d: ",

[hausner, 2012/02/07 01:00:55]

Why not include the script name in this format string and use
script_url.ToCString() as it was before your change?

[Ivan Posva, 2012/02/07 04:09:55]

Because the script_url could contain Unicode characters that we preserve the way
this is now.

+                                     message_header, line, column);
+      message = String::Concat(message, msg_part);
+
+      // Append the formatted error or warning message.
+      msg_part = VFormatMessageHelper(format, args);
+      message = String::Concat(message, msg_part);

[hausner, 2012/02/07 01:00:55]

These two calls can be factored out.

+
+      // Append the source line.
+      const String& script_line = String::Handle(script.GetLine(line));
+      ASSERT(!script_line.IsNull());
+      msg_part = String::New("\n");
+      message = String::Concat(message, msg_part);
+      message = String::Concat(message, script_line);
+      msg_part = FormatMessageHelper("\n%*s\n", column, "^");
+      message = String::Concat(message, msg_part);
     } else {
       // Token position is unknown.
-      msg_len += OS::SNPrint(message_buffer + msg_len,
-                             message_buffer_size - msg_len,
-                             "'%s': %s: ",
-                             script_url.ToCString(),
-                             message_header);
-      if (msg_len < message_buffer_size) {
-        // Append the formatted error or warning message.
-        msg_len += OS::VSNPrint(message_buffer + msg_len,
-                                message_buffer_size - msg_len,
-                                format,
-                                args);
-      }
+      msg_part = FormatMessageHelper(": %s: ", message_header);
+      message = String::Concat(message, msg_part);
+
+      // Append the formatted error or warning message.
+      msg_part = VFormatMessageHelper(format, args);
+      message = String::Concat(message, msg_part);
     }
   } else {
     // Script is unknown.
     // Append the formatted error or warning message.
-    msg_len += OS::VSNPrint(message_buffer + msg_len,
-                            message_buffer_size - msg_len,
-                            format,
-                            args);
+    message = VFormatMessageHelper(format, args);
   }
+  return message.raw();
 }