tree 23b65a17e779e2ebd4a700f5752d3b16b490eae1
parent 1f7f5ed99daaef3ddfd2a16fd17eaca917041985
author Peng Liu <winner245@hotmail.com> 1736415760 -0500
committer Copybara-Service <copybara-worker@google.com> 1736415928 -0800

[libc++] Uglify non-standard member typedef const_reference in bitset (#121620)

According to
[[template.bitset.general]](https://eel.is/c++draft/template.bitset.general),
`std::bitset` is supposed to have only
one (public) member typedef, `reference`. However, libc++'s
implementation of `std::bitset` offers more that that. Specifically, it
offers a public typedef `const_reference` and two private typedefs
`size_type` and `difference_type`. These non-standard member typedefs,
despite being private, can cause potential ambiguities in name lookup in
user-defined classes, as demonstrated in issue #121618.

Fixing the public member typedef `const_reference` is straightforward:
we can simply replace it with an `__ugly_name` such as
`__const_reference`. However, fixing the private member typedefs
`size_type` and `difference_type` is not so straightforward as they are
required by the `__bit_iterator` class and the corresponding algorithms
optimized for `__bit_iterator`s (e.g., `ranges::fill`).

This PR fixes the member typedef `const_reference` by using uglified
name for it. Further work will be undertaken to address `size_type` and
`difference_type`.

Follows up #80706, #111127, and #112843,

GitOrigin-RevId: 06673a9e9b186a65f5eb60a59a4ee9afba6637d4