[libc-commits] [libc] [libc] Make `stdc_first_trailing_one` spec compliant (PR #116493)

[Nick Desaulniers via libc-commits]

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@@ -146,8 +146,7 @@ first_trailing_zero(T value) {
 template <typename T>
 [[nodiscard]] LIBC_INLINE constexpr cpp::enable_if_t<cpp::is_unsigned_v<T>, int>
 first_trailing_one(T value) {
-  return value == cpp::numeric_limits<T>::max() ? 0
-                                                : cpp::countr_zero(value) + 1;
+  return value == T(0) ? 0 : cpp::countr_zero(value) + 1;
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nickdesaulniers wrote:

I'm not concerned with platforms where `sizeof(short) == sizeof(int)`; if we need to support those, ever, there will need to be other changes throughout llvm-libc. At that point, I'd prefer to know what platforms those are, and who cares about them, such that we can then stand up proper CI upstream for ensuring we don't break them.

https://github.com/llvm/llvm-project/pull/116493