https://github.com/bitcoin/bitcoin/blob/68f3c7eb080e461cfeac37f8db7034fe507241d0/src/prevector.h#L152-L158

I'm opening an issue as its fix is too tiny to become a pull request.

Can be solved by renaming the struct to
```c
     struct indirect_contents { 
         size_type capacity; 
         char* indirect; 
     }; 
```
std::swap(_union, other._union);
        std::swap(_size, other._size);
    }
    ~prevector() {
        if (!std::is_trivially_destructible<T>::value) {
            clear();
        }
        if (!is_direct()) {
            free(_union.indirect);
            _union.indirect = nullptr;
        }
    }
    bool operator==(const prevector<N, T, Size, Diff>& other) const {
        if (other.size() != size()) {
            return false;
        }
        const_iterator b1 = begin();
        const_iterator b2 = other.begin();
        const_iterator e1 = end();
        while (b1 != e1) {
            if ((*b1) != (*b2)) {
                return false;
            }
            ++b1;
            ++b2;
        }
        return true;
    }
    bool operator!=(const prevector<N, T, Size, Diff>& other) const {