0066a09579
Contrary to the current visibility macro documentation, it appears that gcc does handle visibility attribute on extern templates correctly, e.g. https://godbolt.org/g/EejuV7. We need this so that extern template instantiations of classes not marked _LIBCPP_TEMPLATE_VIS (e.g. __vector_base_common) are correctly exported with gcc when building with hidden visibility. Reviewed By: ldionne Differential Revision: https://reviews.llvm.org/D35388