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Workaround a CUDA issue in handing UTF-32 literals (#4719)

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Cazadorro 2026-04-10 18:28:52 -05:00 committed by GitHub
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1 changed files with 19 additions and 2 deletions
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21
include/fmt/format.h
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@ -3161,8 +3161,25 @@ constexpr auto fractional_part_rounding_thresholds(int index) -> uint32_t {
// It is equal to ceil(2^31 + 2^32/10^(k + 1)).
// These are stored in a string literal because we cannot have static arrays
// in constexpr functions and non-static ones are poorly optimized.
return U"\x9999999a\x828f5c29\x80418938\x80068db9\x8000a7c6\x800010c7"
U"\x800001ae\x8000002b"[index];
// while in C++23 we can use static constexpr, and in c++17 we can use out of
// function definition of inline constexpr, in C++11 we have to rely on string
// literals in order to avoid duplicating constant definitions across
// translation units. We take the following uint32 array definition:
// {0x9999999au, 0x828f5c29u, 0x80418938u, 0x80068db9,
// 0x8000a7c6u, 0x800010c7u, 0x800001aeu, 0x8000002b};
// and convert that into a series of char hexidecimal literals in a char16_t
// array:
// "\x9999\x999a \x828f\x5c29 \x8041\x8938 \x8006\x8db9
// \x8000\xa7c6 \x8000\x10c7 \x8000\x01ae \x8000\x002b";
// Then we split this up into two separate arrays of char16_ts, so they can
// be properly recombined into uint32_t.
return static_cast<uint32_t>(
u"\x9999\x828f\x8041\x8006\x8000\x8000\x8000\x8000"[index])
<< 16u |
static_cast<uint32_t>(
u"\x999a\x5c29\x8938\x8db9\xa7c6\x10c7\x01ae\x002b"[index]);
}
template <typename Float>