Aqualification-decomposition of a typeTis a sequence ofcvi andPisuch thatT is“cv0P0cv1P1⋯cvn−1Pn−1cvnU” forn  ≥ 0,whereeachcvi is a set of cv-qualifiers ([basic.type.qualifier]), andeachPi is“pointer to” ([dcl.ptr]),“pointer to member of classCi of type” ([dcl.mptr]),“array ofNi”, or“array of unknown bound of” ([dcl.array]).

IfPi designates an array,the cv-qualifierscvi+1 on the element type are also taken asthe cv-qualifierscvi of the array.

Two typesT1 andT2 aresimilar ifthey have qualification-decompositions with the samensuch that correspondingPi components are either the sameor one is “array ofNi” and the other is “array of unknown bound of”,and the types denoted byU are the same.

Thequalification-combined type of two typesT1 andT2is the typeT3similar toT1 whose qualification-decomposition is such that:

• (3.1)
  for everyi>0,cv3i is the union ofcv1i andcv2i,
• (3.2)
  if eitherP1i orP2i is “array of unknown bound of”,P3i is “array of unknown bound of”, otherwise it isP1i, and
• (3.3)
  if the resultingcv3i is different fromcv1i orcv2i,or the resultingP3i is different fromP1i orP2i,thenconst is added to everycv3k for0<k<i,

wherecvji andPji are the components ofthe qualification-decomposition ofTj.

A prvalue of typeT1can be converted to typeT2if the qualification-combined type ofT1 andT2 isT2.