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[libc] fix -Wshift-count-overflow in UInt.h #74649

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Merged
merged 1 commit into from
Dec 7, 2023
Merged

[libc] fix -Wshift-count-overflow in UInt.h #74649

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20 changes: 13 additions & 7 deletions libc/src/__support/UInt.h
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Original file line number Diff line number Diff line change
Expand Up @@ -103,13 +103,20 @@ template <size_t Bits, bool Signed> struct BigInt {
val[i] = words[i];
}

template <typename T, typename = cpp::enable_if_t<cpp::is_integral_v<T> &&
sizeof(T) <= 16 &&
!cpp::is_same_v<T, bool>>>
LIBC_INLINE constexpr explicit operator T() const {
if constexpr (sizeof(T) <= 8)
return static_cast<T>(val[0]);
template <typename T> LIBC_INLINE constexpr explicit operator T() const {
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does this template need any sort of limit (e.g. enable_if_t<is_integral_v<T>>)?

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We don't need extra guard here, since it is already guarded with to<T>() templates.

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yeah, if it doesn't fail here it will fail there. I don't feel strongly either way, so merging for now. If you feel strongly otherwise I'll send another patch to add that.

return to<T>();
}

template <typename T>
LIBC_INLINE constexpr cpp::enable_if_t<
cpp::is_integral_v<T> && sizeof(T) <= 8 && !cpp::is_same_v<T, bool>, T>
to() const {
return static_cast<T>(val[0]);
}
template <typename T>
LIBC_INLINE constexpr cpp::enable_if_t<
cpp::is_integral_v<T> && sizeof(T) == 16, T>
to() const {
// T is 128-bit.
T lo = static_cast<T>(val[0]);

Expand All @@ -121,7 +128,6 @@ template <size_t Bits, bool Signed> struct BigInt {
return lo;
}
} else {
// TODO: silence shift warning
return static_cast<T>((static_cast<T>(val[1]) << 64) + lo);
}
}
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