[Bug 3686] fn-matches2args-1 fails static typechecking.

http://www.w3.org/Bugs/Public/show_bug.cgi?id=3686

           Summary: fn-matches2args-1 fails static typechecking.
           Product: XML Query Test Suite
           Version: 1.0
          Platform: PC
        OS/Version: Windows XP
            Status: NEW
          Severity: normal
          Priority: P2
         Component: XML Query Test Suite
        AssignedTo: andrew.eisenberg@us.ibm.com
        ReportedBy: tim@cbcl.co.uk
         QAContact: public-qt-comments@w3.org


Queries such as:

fn:matches(xs:string("This is a characte"),xs:string("This is a characte"))

from:

fn-matches2args-1 

fail under static type checking, because

fn:matches($input as xs:string?, $pattern as xs:string) as xs:boolean
xs:string($arg as xs:anyAtomicType?) as xs:string?

i.e. the second argument is not guaranteed to return a string.  It may return
an empty sequence.