demangle.go
func (st *state) unnamedTypeName() AST {
	st.checkChar('U')
	st.checkChar('t')
	num := st.compactNumber()
	ret := &UnnamedType{Num: num}
	st.subs.add(ret)
	return ret
}
func (st *state) unnamedTypeName() AST {
	st.checkChar('U')
	st.checkChar('t')
	num := st.compactNumber()
	ret := &UnnamedType{Num: num}
	st.subs.add(ret)
	return ret
}
func ( st * state ) unnamedTypeName ( ) AST { st . checkChar ( 'U' ) st . checkChar ( 't' ) num := st . compactNumber ( ) ret := & UnnamedType { Num : num } st . subs . add ( ret ) return ret }
// <unnamed-type-name> ::= Ut [ <nonnegative number> ] _
<unnamed - type - name > :: = Ut [ <nonnegative number > ] _