This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 115f. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.
2024-12-06
[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 (6.8.2 [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 z suffix 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 paper P0330R8 (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 paper N2998 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:
IfExcept for integer-literals 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 (6.8.2 [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 beis signed. If all of the types in the list for the integer-literal are unsigned, the extended integer typeshall beis 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 containsIf an integer-literalthatcannot be represented by any of the allowed types, the program is ill-formed. [ Note: An integer-literal with a z or Z suffix is ill-formed if it cannot be represented by std::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 via cplusplus/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.