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Cleanup bit_cast

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This commit is contained in:
Victor Zverovich
2021-12-29 12:12:25 -08:00
parent 3617c2795a
commit 4fac7daaef
1 changed files with 12 additions and 16 deletions
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28
include/fmt/format.h
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@ -297,28 +297,23 @@ template <typename Streambuf> class formatbuf : public Streambuf {
} }
}; };
// An equivalent of `*reinterpret_cast<Dest*>(&source)` that doesn't have // Implementation of std::bit_cast for pre-C++20.
// undefined behavior (e.g. due to type aliasing). template <typename To, typename From>
// Example: uint64_t d = bit_cast<uint64_t>(2.718); FMT_CONSTEXPR20 auto bit_cast(const From& from) -> To {
template <typename Dest, typename Source> static_assert(sizeof(To) == sizeof(From), "size mismatch");
FMT_CONSTEXPR20 auto bit_cast(const Source& source) -> Dest {
static_assert(sizeof(Dest) == sizeof(Source), "size mismatch");
#ifdef __cpp_lib_bit_cast #ifdef __cpp_lib_bit_cast
if (is_constant_evaluated()) { if (is_constant_evaluated()) return std::bit_cast<To>(from);
return std::bit_cast<Dest>(source);
}
#endif #endif
Dest dest; auto to = To();
std::memcpy(&dest, &source, sizeof(dest)); std::memcpy(&to, &from, sizeof(to));
return dest; return to;
} }
inline auto is_big_endian() -> bool { inline auto is_big_endian() -> bool {
const auto u = 1u;
struct bytes { struct bytes {
char data[sizeof(u)]; char data[sizeof(int)];
}; };
return bit_cast<bytes>(u).data[0] == 0; return bit_cast<bytes>(1).data[0] == 0;
} }
// A fallback implementation of uintptr_t for systems that lack it. // A fallback implementation of uintptr_t for systems that lack it.
@ -785,7 +780,8 @@ class basic_memory_buffer final : public detail::buffer<T> {
}; };
template <typename T, size_t SIZE, typename Allocator> template <typename T, size_t SIZE, typename Allocator>
FMT_CONSTEXPR20 void basic_memory_buffer<T, SIZE, Allocator>::grow(size_t size) { FMT_CONSTEXPR20 void basic_memory_buffer<T, SIZE, Allocator>::grow(
size_t size) {
#ifdef FMT_FUZZ #ifdef FMT_FUZZ
if (size > 5000) throw std::runtime_error("fuzz mode - won't grow that much"); if (size > 5000) throw std::runtime_error("fuzz mode - won't grow that much");
#endif #endif