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From: "redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/114244] Need to use round when parsing fractional
 seconds
Date: Thu, 07 Mar 2024 00:37:24 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D114244

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Jonathan Wakely from comment #1)
> Yup, the seconds part "00.002" is parsed using std::numpunct (in order to

Oops, std::num_get obviously.

> handle the locale's decimal point) and then converted to milliseconds usi=
ng
> duration_cast:
>=20
> 			  auto& __ng =3D use_facet<num_get<_CharT>>(__loc);
> 			  long double __val;
> 			  ios_base::iostate __err2{};
> 			  __ng.get(__buf, {}, __buf, __err2, __val);
> 			  if (__is_failed(__err2)) [[unlikely]]
> 			    __err |=3D __err2;
> 			  else
> 			    {
> 			      duration<long double> __fs(__val);
> 			      __s =3D duration_cast<_Duration>(__fs);
> 			    }

As an unrelated optimization, when the locale is "C" we could use
std::from_chars or std::stod instead of std::num_get.=