This page is a snapshot from the LWG issues list, see the Library Active Issues List for more information and the meaning of New status.
3641. Addoperator== to format_to_n_result
Section: 28.5.1 [format.syn] Status: New Submitter: Mark de Wever Opened: 2021-11-14 Last modified: 2022-01-30
Priority: 3
View other active issues in [format.syn].
View all other issues in [format.syn].
View all issues with New status.
Discussion:
During the 2019 Cologne meeting the papers P1614R2 "The Mothership has Landed" and P0645R10 "Text Formatting" have been accepted. P1614R2 adds operator== to to_chars_result and from_chars_result. P0645R10 adds a similar type format_to_n_result without an operator==. LWG 3373(i) reaffirms these three types are similar by ensuring they can be used in structured bindings.
operator== wasn't applied to format_to_n_result. I propose to add operator== to format_to_n_result to keep these types similar. The Out template argument of format_to_n_result is unconstrained. Since it's returned from format_to_n it's indirectly constrained to an output_iterator. An output_iterator doesn't require equality_comparable, thus the defaulted operator== can be defined deleted.
[2022-01-30; Reflector poll]
Set priority to 3 after reflector poll. Several votes for NAD. Unclear why to_chars_result is equality comparable, but whatever the reason, this is unrelated to them and doesn't need to be.
Proposed resolution:
This wording is relative to N4901.
Modify 28.5.1 [format.syn], header <format> synopsis, as indicated:
[…]
template<class Out> struct format_to_n_result {
Out out;
iter_difference_t<Out> size;
friend bool operator==(const format_to_n_result&, const format_to_n_result&) = default;
};
[…]
RetroSearch is an open source project built by @garambo | Open a GitHub Issue
Search and Browse the WWW like it's 1997 | Search results from DuckDuckGo
HTML:
3.2
| Encoding:
UTF-8
| Version:
0.7.4