[libcxx-commits] [PATCH] D122092: [libc++] `bitset::operator[] const` should return bool

[Richard Smith - zygoloid via Phabricator via libcxx-commits]

rsmith added a comment.

In D122092#3452383 <https://reviews.llvm.org/D122092#3452383>, @rsmith wrote:

> Is it intentional that this leaves `std::vector<bool>::const_iterator::reference` as the class type? We're seeing some breakage in `absl` due to that.

FWIW, the broken code looks roughly like this:

  struct NumberLike {
    // ...
    template<typename T> NumberLike(T) requires std::is_arithmetic_v<T>;
    NumberLike(std::vector<bool>::reference);
    NumberLike(std::vector<bool>::const_reference);
  }
  void Consume(NumberLike);
  template<typename Container>
  void ConsumeAll(const Container &c) {
    for (const auto &v : c) Consume(v);
  }

This works if `vector<bool>::const_reference` and `vector<bool>::const_iterator::reference` are the same type, but if the iterator produces the class type but `vector<bool>::const_reference` is simply `bool` then the `Consume` call fails.


Repository:
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  https://reviews.llvm.org/D122092/new/

https://reviews.llvm.org/D122092