rerun_cpp_sdk does not compile on windows

[alokpr]

Multiple compiler errors like:

C:\re_cwd\third-party\rerun_cpp_sdk\src\rerun\loggable.hpp(18): error C2338: static_assert failed: 'Loggable is not implemented for this type. It is implemented for all built-in datatypes and components. To check ahead of template instantiation whether a type is loggable, use `is_loggable<T>`'
C:\re_cwd\third-party\rerun_cpp_sdk\src\rerun\loggable.hpp(18): note: the template instantiation context (the oldest one first) is
C:\re_cwd\third-party\rerun_cpp_sdk\src\rerun\archetypes\../component_batch.hpp(68): note: see reference to class template instantiation 'rerun::Loggable<T>' being compiled
        with
        [
            T=rerun::Collection<rerun::components::Blob>
        ]

It seems like function overloading for collection and component is not working as expected on windows:

template <typename T>
static Result<ComponentBatch> from_loggable(
            const rerun::Collection<T>& components,
            const ComponentDescriptor& descriptor = rerun::Loggable<T>::Descriptor
) 

template <typename T>
static Result<ComponentBatch> from_loggable(
            const T& component,
            const ComponentDescriptor& descriptor = rerun::Loggable<T>::Descriptor
) 

[alokpr]

@Wumpf Do you see it on your end or is this something specific to the compiler we are using?

[Wumpf]

@alokpr what compiler are you using? We test on CI with VS2022 (14.43.34808 to be accurate https://github.com/rerun-io/rerun/actions/runs/14876516385/job/41774776838)

[alokpr]

We are using VS2022 14.39.33519 with c++20.

It looks like the compiler does not treat from_loggable(const rerun::Collection<T>&) a more specialized overload of from_loggable(const T&) and is matching the call for collection-types to from_loggable(const T&). Might need to make the substitution less ambiguous.

[Wumpf]

Strange, seems unlikely that the minor version difference would cause this. More likely none of our examples & tests are triggering this error.
It's not pretty but I figure we could make the resolution less ambiguous by using SFINAE to disable overloads that aren't valid (i.e. disable from_loggable(const T&) iff T is a rerun::Collection) 🤔

Do you get this error on the most minimal rerun examples or is there specific calls you have to do to run into this?

[alokpr]

It might have to do with C++20. Would you mind enabling C++20 if possible?

[Wumpf]

Was able to repro the issue with C++20 enabled on Windows 👍 . We'll have to add this to our test matrix