Creating Pattern from declared String variable with pattern = ~stringvariable fails

An attempt to create a java.util.regex.Pattern from a variable that is declared as a String fails with a java.lang.ClassCastException: java.util.regex.Pattern cannot be cast to java.lang.String

The code below worked with Groovy 1.7.8 but fails with Groovy 1.8.0
String value="test"
String s = "^\\S+$value\$"
def p = ~s <==Fails here

A workaround is to change the last statement to:
def p = ~/$s/
but that adds clutter