anchor.diff:  #endif
       // Struct members have a byref 'this' type (unless they are extrinsic extension members)
       let thisTy = 
  -        if tcref.IsStructOrEnumTycon && not isExtrinsic then 
  +        if not isExtrinsic && tcref.IsStructOrEnumTycon then 
               mkByrefTy cenv.g objTy 
           else 
               objTy
  
positive.code:         if isVolatile then 
              error(Error(FSComp.SR.tcVolatileOnlyOnClassLetBindings(),m))
  
          if isIncrClass  && (not zeroInit || not isMutable) then errorR(Error(FSComp.SR.tcUninitializedValFieldsMustBeMutable(),m))
          if isStatic && (not zeroInit || not isMutable || vis <> Some SynAccess.Private ) then errorR(Error(FSComp.SR.tcStaticValFieldsMustBeMutableAndPrivate(),m))
          let konst = if zeroInit then Some Const.Zero else None
          let rfspec = MakeRecdFieldSpec cenv env parent  (isStatic,konst,ty',attrsForProperty,attrsForField,id,isMutable,isVolatile,xmldoc,vis,m)
  
negative.code:         CheckMemberFlags cenv.g None newslotsOK overridesOK memberFlags id.idRange
          CheckForNonAbstractInterface declKind tcref memberFlags id.idRange
  
          if memberFlags.MemberKind = MemberKind.Constructor && tcref.Deref.IsExceptionDecl then
              error(Error(FSComp.SR.tcConstructorsDisallowedInExceptionAugmentation(),id.idRange))                  
  
          let isExtrinsic = (declKind = ExtrinsicExtensionBinding)
  