// do not have a position.
	if !pos.IsKnown() {
		return src.NoXPos
	}

	posBase := m.makeSrcPosBase(pos.Base())
	return base.Ctxt.PosTable.XPos(src.MakePos(posBase, pos.Line(), pos.Col()))
}

// makeSrcPosBase translates from a *syntax.PosBase to a *src.PosBase.
func (m *posMap) makeSrcPosBase(b0 *syntax.PosBase) *src.PosBase {
	// fast path: most likely PosBase hasn't changed
	if m.cache.last == b0 {