[libcxx-commits] [libcxx] [libc++] P3168R2 Give std::optional Range Support (PR #146491)

[via libcxx-commits]

dywoq wrote:

```c++
 _LIBCPP_HIDE_FROM_ABI constexpr reference operator*() const {
    if (__ptr_ == nullptr)
      std::__throw_runtime_error("deferencering end iterator");
    return *__ptr_;
  }

  _LIBCPP_HIDE_FROM_ABI constexpr pointer operator->() const {
    if (__ptr_ == nullptr)
      std::__throw_runtime_error("deferencering end iterator");
    return *__ptr_;
  }
```

Should these functions return `__ptr_` instead of throwing exceptions if `__ptr_` is nullptr? Throwing exceptions is not allowed in constexpr functions.

https://github.com/llvm/llvm-project/pull/146491