CWG Issue 2698 (original) (raw)

This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 118f. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.

2025-11-07

2698. Using extended integer types with z suffix

Section: 5.13.2 [lex.icon]Status: CD7Submitter: Mike MillerDate: 2023-02-17Liaison: WG14, EWG

[Accepted as a DR at the June, 2023 meeting.]

Subclause 5.13.2 [lex.icon] paragraph 4 specifies:

If an integer-literal cannot be represented by any type in its list and an extended integer type (6.9.2 [basic.fundamental]) can represent its value, it may have that extended integer type. If all of the types in the list for the integer-literal are signed, the extended integer type shall be signed. If all of the types in the list for the integer-literal are unsigned, the extended integer type shall be unsigned. If the list contains both signed and unsigned types, the extended integer type may be signed or unsigned. A program is ill-formed if one of its translation units contains an integer-literal that cannot be represented by any of the allowed types.

This implies that an integer-literal with a zsuffix can be of extended integer type, if the literal is larger than what is representable in std::size_t.

According to the author of the paperP0330R8(Literal Suffix for (signed) size_t) introducing the feature, this is unintentional; z should only yield std::size_t and its corresponding signed integer type.

See also the corresponding WG14 paperN2998 Literal Suffixes for size_t.

Proposed resolution (reviewed by CWG 2023-03-03, approved by CWG 2023-05-12):

Change in 5.13.2 [lex.icon] paragraph 4 as follows:

If Except for _integer-literal_s containing a size-suffix, if the value of an integer-literal_cannot be represented by any type in its list and an extended integer type (6.9.2 [basic.fundamental]) can represent its value, it may have that extended integer type. If all of the types in the list for the integer-literal are signed, the extended integer typeshall be is signed. If all of the types in the list for the integer-literal are unsigned, the extended integer type shall be is unsigned. If the list contains both signed and unsigned types, the extended integer type may be signed or unsigned. A program is ill-formed if one of its translation units contains If an_integer-literal that cannot be represented by any of the allowed types, the program is ill-formed.[ Note: An integer-literal with a z or Zsuffix is ill-formed if it cannot be represented bystd::size_t. -- end note ]

Additional notes (February, 2023)

Alerted the chair of SG22 (C/C++ Liaison).

Forwarded to EWG at the request of the EWG chair viacplusplus/papers#1467.

EWG 2023-05-11

The "z" suffixes mean std::size_t (or its corresponding signed type) only. The proposed resolution is accepted by EWG.