This fixes 83287, a case where we failed to mark a lookup occuring 
inside a template definition as being kept for instantiation.  It turns 
out that CAST_EXPR's single argument is a TREE_LIST, so we need to check 
it for OVERLOADS.  CAST_EXPR behaves this way because it's modelling a 
function call. AFAICT it is the only node of this form.

applying to trunk.

nathan
-- 
Nathan Sidwell