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Don't require std::locale in chrono.h when FMT_USE_LOCALE is 0 #4921

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Don't require std::locale in chrono.h when FMT_USE_LOCALE is 0 #4921

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44 changes: 39 additions & 5 deletions include/fmt/chrono.h
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Original file line number Diff line number Diff line change
Expand Up @@ -378,6 +378,14 @@ auto write_tm_str(OutputIt out, string_view sv, const std::locale& loc)
return write_encoded_tm_str(out, sv, loc);
}

#if !FMT_USE_LOCALE
// Zone names are ASCII, so there is nothing to transcode without a locale.
template <typename Char, typename OutputIt>
auto write_tm_str(OutputIt out, string_view sv) -> OutputIt {
return copy<Char>(sv.data(), sv.data() + sv.size(), out);
}
#endif

template <typename Char>
inline void do_write(buffer<Char>& buf, const std::tm& time,
const std::locale& loc, char format, char modifier) {
Expand Down Expand Up @@ -1039,14 +1047,20 @@ void write_floating_seconds(memory_buffer& buf, Duration duration,
num_fractional_digits);
}

class get_locale;

template <typename OutputIt, typename Char,
typename Duration = std::chrono::seconds>
class tm_writer {
private:
static constexpr int days_per_week = 7;

#if FMT_USE_LOCALE
const std::locale& loc_;
bool is_classic_;
#else
static constexpr bool is_classic_ = true;
#endif
OutputIt out_;
const Duration* subsecs_;
const std::tm& tm_;
Expand Down Expand Up @@ -1192,25 +1206,40 @@ class tm_writer {
template <typename T, FMT_ENABLE_IF(has_tm_zone<T>::value)>
void format_tz_name(const T& tm) {
if (!tm.tm_zone) FMT_THROW(format_error("no timezone"));
#if FMT_USE_LOCALE
out_ = write_tm_str<Char>(out_, tm.tm_zone, loc_);
#else
out_ = write_tm_str<Char>(out_, tm.tm_zone);
#endif
}
template <typename T, FMT_ENABLE_IF(!has_tm_zone<T>::value)>
void format_tz_name(const T&) {
out_ = std::copy_n(utc(), 3, out_);
}

void format_localized(char format, char modifier = 0) {
#if FMT_USE_LOCALE
out_ = write<Char>(out_, tm_, loc_, format, modifier);
#else
// Unreachable: is_classic_ is always true without locale support.
ignore_unused(format, modifier);
#endif
}

public:
#if FMT_USE_LOCALE
tm_writer(const std::locale& loc, OutputIt out, const std::tm& tm,
const Duration* subsecs = nullptr)
: loc_(loc),
is_classic_(loc_ == get_classic_locale()),
out_(out),
subsecs_(subsecs),
tm_(tm) {}
#else
tm_writer(const get_locale&, OutputIt out, const std::tm& tm,
const Duration* subsecs = nullptr)
: out_(out), subsecs_(subsecs), tm_(tm) {}
#endif

auto out() const -> OutputIt { return out_; }

Expand Down Expand Up @@ -1583,6 +1612,7 @@ auto format_duration_unit(OutputIt out) -> OutputIt {
return out;
}

#if FMT_USE_LOCALE
class get_locale {
private:
union {
Expand All @@ -1594,11 +1624,7 @@ class get_locale {
inline get_locale(bool localized, locale_ref loc) : has_locale_(localized) {
if (!localized) return;
ignore_unused(loc);
::new (&locale_) std::locale(
#if FMT_USE_LOCALE
loc.template get<std::locale>()
#endif
);
::new (&locale_) std::locale(loc.template get<std::locale>());
}
inline ~get_locale() {
if (has_locale_) locale_.~locale();
Expand All @@ -1607,6 +1633,14 @@ class get_locale {
return has_locale_ ? locale_ : get_classic_locale();
}
};
#else
class get_locale {
public:
inline get_locale(bool localized, locale_ref loc) {
ignore_unused(localized, loc);
}
};
#endif

template <typename Char, typename Rep, typename Period>
struct duration_formatter {
Expand Down
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