C++23 modules/header-unit compatibility when consuming Folly

Hi maintainers,

I’m seeing build failures when consuming Folly from a project that enables C++23 modules / header units.

I couldn’t find an existing open issue specifically tracking Folly compatibility with modules/header units, so I’m opening this for clarification.

Environment:

• Folly commit:
• Compiler:
• Stdlib: <libc++/libstdc++/MSVC STL>
• OS:
• CMake:

Observed behavior:

• <when it fails: header unit generation / import / mixed build>

Expected behavior:

• Either Folly should build cleanly in this setup, or the current limitation should be documented.

I can provide a minimal repro if helpful.