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to_chars(bool)
should be deletedSection: 22.13.1 [charconv.syn] Status: C++20 Submitter: Jens Maurer Opened: 2019-08-23 Last modified: 2021-02-25
Priority: 0
View all other issues in [charconv.syn].
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Discussion:
22.13.2 [charconv.to.chars] does not present an overload for bool
(because it is neither a signed nor unsigned integer type), so an attempt to call
to_chars
with a bool argument would promote it to int
and
unambiguously call the int
overload of to_chars
.
bool
is 0/1
(as opposed to, say, "true"/"false"
).
The user should cast explicitly if he wants the 0/1
behavior. (Correspondingly,
there is no bool
overload for from_chars
in the status quo, and
conversions do not apply there because of the reference parameter.)
[2019-09-14 Issue Prioritization]
Status to Tentatively Ready and priority to 0 after eight positive votes on the reflector.
Proposed resolution:
This wording is relative to N4830.
Modify 22.13.1 [charconv.syn], header <charconv>
synopsis,
as indicated:
[…] // 22.13.2 [charconv.to.chars], primitive numerical output conversion struct to_chars_result { char* ptr; errc ec; friend bool operator==(const to_chars_result&, const to_chars_result&) = default; }; to_chars_result to_chars(char* first, char* last, see below value, int base = 10); to_chars_result to_chars(char* first, char* last, bool value, int base = 10) = delete; to_chars_result to_chars(char* first, char* last, float value); […]