tree c13d5a2c83c6fc714018ce454608ebf2bd3c94f4
parent b1a980b714062067864e1f878ae3ef422a1ea89c
author Peng Liu <winner245@hotmail.com> 1741889703 -0400
committer Copybara-Service <copybara-worker@google.com> 1741889945 -0700

[libc++] Fix ambiguous call in {ranges, std}::find (#122641)

This PR fixes an ambiguous call encountered when using the `std::ranges::find` or `std::find`
algorithms with `vector<bool>` with small `allocator_traits::size_type`s, an issue reported
in #122528. The ambiguity arises from integral promotions during the internal bitwise
arithmetic of the `find` algorithms when applied to `vector<bool>` with small integral
`size_type`s. This leads to multiple viable candidates for small integral types:
__libcpp_ctz(unsigned), __libcpp_ctz(unsigned long), and __libcpp_ctz(unsigned long long),
none of which represent a single best viable match, resulting in an ambiguous call error.

To resolve this, we propose invoking an internal function __countr_zero as a dispatcher
that directs the call to the appropriate overload of __libcpp_ctz. Necessary amendments
have also been made to __countr_zero.

GitOrigin-RevId: 3bd71cbec75292f188bee3aaba2dc94c8955ad66