[libcxx-commits] [PATCH] D138826: [libc++][chrono] Fixes formatter duration.
Eric Fiselier via Phabricator via libcxx-commits
libcxx-commits at lists.llvm.org
Mon Jul 10 16:46:54 PDT 2023
EricWF added inline comments.
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Comment at: libcxx/include/__chrono/convert_to_tm.h:123
+ // conversion errors. In that case the conversion to seconds works.
+ if constexpr (is_convertible_v<_ChronoT, chrono::hours>) {
+ auto __hour = chrono::floor<chrono::hours>(__value);
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If it can't be converted to hours because it potentially overflows, why is it that converting to seconds works?
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Comment at: libcxx/test/std/time/time.syn/formatter.duration.pass.cpp:1089
+ check(SV("06:20:44.415"), SV("{:%T}"), std::chrono::milliseconds{0x0000'fff'ffff'ffffll}); // 45 bit signed value max
+ check(SV("01:53:03"), SV("{:%T}"), std::chrono::seconds{0x0000'0003'ffff'ffffll}); // 35 bit signed value max
+ check(SV("12:15:00"), SV("{:%T}"), std::chrono::minutes{0x0fff'ffff}); // 29 bit signed value max
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EricWF wrote:
> Mordante wrote:
> > EricWF wrote:
> > > Can't we just use `std::chrono::years::max`?
> > >
> > > Do these test cases fail before your fixes? It looks to me that they're actively avoiding constructing test values that will overflow.
> > These tests test the Standard mandated limits as stated by the comment on line 1081. Using larger values will make the tests non-portable.
> Right, but it's important we don't introduce UB if a user violates the limits (which they will).
I don't understand where in the standard you're finding this requirement. Could you please provide the stable name?
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D138826/new/
https://reviews.llvm.org/D138826
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