This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 120c. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.
2026-08-20
———
1473. Syntax of literal-operator-id
Section: 12.6 [
] Status: CD3 Submitter: Richard Smith Date: 2012-03-05 [Moved to DR at the April, 2013 meeting.]
The current grammar requires that there be no whitespace between the literal and the ud-suffix, e.g., ""_abc, but that there be whitespace between the "" and the identifier in a literal-operator-id, e.g., operator "" _abc. This seems unfortunate. Would it be possible to provide an alternate production,
operatoruser-defined-string-literalwith the requirement that the string-literal be empty?
The current wording is also unclear regarding interactions with phases of translation. We have the following production:
literal-operator-id:operator ""identifierAs this is after translation phase 6, would something like
operator "" "" _foo be accepted?
Proposed resolution (October, 2012):
Change 12.6 [
] as follows:
literal-operator-id:Change 12.6 [
] paragraph 1 as follows:
The string-literal or user-defined-string-literal in a literal-operator-id shall have no encoding-prefix and shall contain no characters other than the implicit terminating '\0'. The ud-suffix of the user-defined-string-literal or theidentifier in a literal-operator-id is called a literal suffix identifier. [Note: some literal suffix identifiers are reserved for future standardization; see 16.4.5.3.6 [
]. —end note]
Change the example in 12.6 [
] paragraph 8 as follows:
void operator "" _km(long double); // OK string operator "" _i18n(const char*, std::size_t); // OK template <char...> int operator "" \u03C0(); // OK: UCN for lowercase pi float operator ""E(const char*); // error: ""E (with no intervening space) // is a single token OK float operator " " B(const char*); // error: non-adjacent quotesempty string-literal string operator "" 5X(const char*, std::size_t); // error: invalid literal suffix identifier double operator "" _miles(double); // error: invalid parameter-declaration-clause template <char...> int operator "" _j(const char*); // error: invalid parameter-declaration-clause