[Bug c++/121142] New: warning "potential null pointer dereference" raised when using generator with -O1 -Wnull-dereference

[hewillk at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121142

            Bug ID: 121142
           Summary: warning "potential null pointer dereference" raised
                    when using generator with -O1 -Wnull-dereference
           Product: gcc
           Version: 15.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hewillk at gmail dot com
  Target Milestone: ---

#include <generator>
#include <iostream>

template<typename T>
struct Tree
{
    T value;
    Tree *left{}, *right{};

    std::generator<const T&> traverse_inorder() const
    {
        if (left)
            co_yield std::ranges::elements_of(left->traverse_inorder());

        co_yield value;

        if (right)
            co_yield std::ranges::elements_of(right->traverse_inorder());
    }
};

int main()
{
    Tree<char> tree[]
    {
                                    {'D', tree + 1, tree + 2},
        //                            │
        //            ┌───────────────┴────────────────┐
        //            │                                │
                    {'B', tree + 3, tree + 4},       {'F', tree + 5, tree + 6},
        //            │                                │
        //  ┌─────────┴─────────────┐      ┌───────────┴─────────────┐
        //  │                       │      │                         │
          {'A'},                  {'C'}, {'E'},                    {'G'}
    };

    for (char x : tree->traverse_inorder())
        std::cout << x << ' ';
    std::cout << '\n';
}

https://godbolt.org/z/Ej48dneff