I've forked duckdb and I'm in the process of making appropriate changes to get it to compile to c++23 and c++26, would you like that as a contribution?

It is mainly reorganising things for cases where a class is forward declared for use as member variable held a smart pointer. If that owning class has a default constructor or destructor it will now fail in c++23, i.e.:

class A;

struct B {
  unique_ptr<A> a;
};

I've now got it building locally to C++23 and C++26, passing all the unit tests.

I'm also tweaking it so you can pass any C++ standard into make or cmake and it will pass it onto to the compiler being used.

I'm doing that as I have a c++26 project and I'd like to experiment with duckdb directly connecting to the internals (yes I know it's not stable).

My repo is... https://github.com/bruno-j-nicoletti/duckdb, it's on the branch dev/bruno/c++26.