13 Overloading [over]

13.3 Overload resolution [over.match]

13.3.3 Best viable function [over.match.best] Implicit conversion sequences [over.best.ics] Standard conversion sequences [over.ics.scs]

Table [tab:over.conversions] summarizes the conversions defined in Clause [conv] and partitions them into four disjoint categories: Lvalue Transformation, Qualification Adjustment, Promotion, and Conversion. [ Note: These categories are orthogonal with respect to value category, cv-qualification, and data representation: the Lvalue Transformations do not change the cv-qualification or data representation of the type; the Qualification Adjustments do not change the value category or data representation of the type; and the Promotions and Conversions do not change the value category or cv-qualification of the type.  — end note ]

Note: As described in Clause [conv], a standard conversion sequence is either the Identity conversion by itself (that is, no conversion) or consists of one to three conversions from the other four categories. At most one conversion from each category is allowed in a single standard conversion sequence. If there are two or more conversions in the sequence, the conversions are applied in the canonical order: Lvalue Transformation, Promotion or Conversion, Qualification Adjustment.  — end note ]

Each conversion in Table [tab:over.conversions] also has an associated rank (Exact Match, Promotion, or Conversion). These are used to rank standard conversion sequences ([over.ics.rank]). The rank of a conversion sequence is determined by considering the rank of each conversion in the sequence and the rank of any reference binding ([over.ics.ref]). If any of those has Conversion rank, the sequence has Conversion rank; otherwise, if any of those has Promotion rank, the sequence has Promotion rank; otherwise, the sequence has Exact Match rank.

Table 12 — Conversions
Conversion Category Rank Subclause
No conversions required Identity
Lvalue-to-rvalue conversion [conv.lval]
Array-to-pointer conversion Lvalue Transformation Exact Match [conv.array]
Function-to-pointer conversion [conv.func]
Qualification conversions Qualification Adjustment [conv.qual]
Integral promotions [conv.prom]
Floating point promotion Promotion Promotion [conv.fpprom]
Integral conversions [conv.integral]
Floating point conversions [conv.double]
Floating-integral conversions [conv.fpint]
Pointer conversions Conversion Conversion [conv.ptr]
Pointer to member conversions [conv.mem]
Boolean conversions [conv.bool]