Encountering mysterious error, hitherto unseen, in project

The complete error is:

  AABBTree.h(3051): [C4499] 'static': an explicit specialization cannot have a storage class (ignored)
  ISpatialAcceleration.h(346): [C4499] see reference to class template instantiation 'Chaos::TAABBTree<Chaos::FAccelerationStructureHandle,Chaos::TAABBTreeLeafArray<Chaos::FAccelerationStructureHandle,true,Chaos::FReal>,true,Chaos::FReal>' being compiled
  SpatialAccelerationBroadPhase.h(114): [C4499] see reference to function template instantiation 'const TConcrete *Chaos::ISpatialAcceleration<Chaos::FAccelerationStructureHandle,Chaos::FReal,3>::As<Chaos::TAABBTree<Chaos::FAccelerationStructureHandle,Chaos::TAABBTreeLeafArray<Chaos::FAccelerationStructureHandle,true,Chaos::FReal>,true,Chaos::FReal>>(void) const' being compiled
  SpatialAccelerationBroadPhase.h(114): [C4499] see reference to function template instantiation 'const TConcrete *Chaos::ISpatialAcceleration<Chaos::FAccelerationStructureHandle,Chaos::FReal,3>::As<Chaos::TAABBTree<Chaos::FAccelerationStructureHandle,Chaos::TAABBTreeLeafArray<Chaos::FAccelerationStructureHandle,true,Chaos::FReal>,true,Chaos::FReal>>(void) const' being compiled
  AABBTree.h(3063): [C4499] 'static': an explicit specialization cannot have a storage class (ignored)
  AABBTree.h(3069): [C4499] 'static': an explicit specialization cannot have a storage class (ignored)

Documenting workaround: MSVC C++20 options at the time of writing are throwing this error. Just using C++17 fixes this issue.

Which I did, and I also had to turn off warnings as errors. In that case, C++20 can be used!

I found the header file which relates to Chaos Physics in my code and push/popped the warning disabling.