dnl @ ../doc/m4.texi:6270: Origin of test
dnl @ expected status: 1
dnl @ extra options: 
dnl @ Copyright (C) 2006, 2007, 2008, 2009 Free Software
dnl @ Foundation, Inc.
dnl @ This file is free software; the Free Software Foundation
dnl @ gives unlimited permission to copy and/or distribute it
dnl @ with or without modifications, as long as this notice
dnl @ is preserved.
eval(`2 = 2')
dnl @error{}m4:stdin:1: Warning: recommend ==, not =, for equality operator
dnl @result{}1
eval(`++0')
dnl @error{}m4:stdin:2: invalid operator in eval: ++0
dnl @result{}
eval(`0 |= 1')
dnl @error{}m4:stdin:3: invalid operator in eval: 0 |= 1
dnl @result{}