How to mark a test, XFAIL

[Nitin Gupta]

Hi,

I am doing something like following line to mark a test file as XFAIL, 
It seems not to work, please let me know, how to do it.

#include <foo.h> /* { dg-error "No such file or directory" "No such file 
or directory" {xfail *-*-* } . } */

Also, is there any document to describe the usage of dg-error, 
dg-excess-errors, etc

Thanks for your help.
Nitin