panic("Assigning a bogus line to XPos with no file will cause mysterious downstream failures.")
	}
	p.lico = makeBogusLico()
	return p
}

// WithXlogue returns the same location but marked with DWARF function prologue/epilogue
func (p XPos) WithXlogue(x PosXlogue) XPos {
	p.lico = p.lico.withXlogue(x)
	return p
}

// LineNumber returns a string for the line number, "?" if it is not known.
func (p XPos) LineNumber() string {