[Diagnostics] NFC: Add a comment about special handling of opaque result types
[Diagnostics] NFC: Add a comment about special handling of opaque result types

CodaFi/swift,stephentyrone/swift,atrick/swift,stephentyrone/swift,rudkx/swift,ahoppen/swift,aschwaighofer/swift,gregomni/swift,gregomni/swift,aschwaighofer/swift,harlanhaskins/swift,hooman/swift,roambotics/swift,aschwaighofer/swift,nathawes/swift,atrick/swift,jmgc/swift,roambotics/swift,rudkx/swift,nathawes/swift,roambotics/swift,harlanhaskins/swift,xwu/swift,benlangmuir/swift,ahoppen/swift,allevato/swift,parkera/swift,CodaFi/swift,glessard/swift,hooman/swift,xwu/swift,JGiola/swift,nathawes/swift,allevato/swift,glessard/swift,allevato/swift,parkera/swift,benlangmuir/swift,hooman/swift,parkera/swift,harlanhaskins/swift,atrick/swift,JGiola/swift,jckarter/swift,nathawes/swift,gregomni/swift,roambotics/swift,stephentyrone/swift,airspeedswift/swift,allevato/swift,jckarter/swift,rudkx/swift,nathawes/swift,nathawes/swift,parkera/swift,jmgc/swift,stephentyrone/swift,jmgc/swift,glessard/swift,allevato/swift,jmgc/swift,tkremenek/swift,atrick/swift,ahoppen/swift,aschwaighofer/swift,parkera/swift,airspeedswift/swift,tkremenek/swift,tkremenek/swift,JGiola/swift,xwu/swift,nathawes/swift,hooman/swift,xwu/swift,tkremenek/swift,jmgc/swift,harlanhaskins/swift,stephentyrone/swift,harlanhaskins/swift,airspeedswift/swift,apple/swift,gregomni/swift,apple/swift,tkremenek/swift,jmgc/swift,jckarter/swift,glessard/swift,aschwaighofer/swift,CodaFi/swift,CodaFi/swift,xwu/swift,ahoppen/swift,apple/swift,JGiola/swift,aschwaighofer/swift,airspeedswift/swift,CodaFi/swift,benlangmuir/swift,aschwaighofer/swift,gregomni/swift,jckarter/swift,rudkx/swift,airspeedswift/swift,stephentyrone/swift,tkremenek/swift,stephentyrone/swift,hooman/swift,CodaFi/swift,tkremenek/swift,parkera/swift,xwu/swift,glessard/swift,xwu/swift,apple/swift,harlanhaskins/swift,hooman/swift,benlangmuir/swift,apple/swift,CodaFi/swift,JGiola/swift,glessard/swift,rudkx/swift,parkera/swift,rudkx/swift,gregomni/swift,ahoppen/swift,JGiola/swift,jckarter/swift,airspeedswift/swift,atrick/swift,atrick/swift,apple/swift,ahoppen/swift,hooman/swift,airspeedswift/swift,benlangmuir/swift,parkera/swift,roambotics/swift,jckarter/swift,jckarter/swift,roambotics/swift,allevato/swift,allevato/swift,jmgc/swift,harlanhaskins/swift,benlangmuir/swift