Is there a reason why GL_LINE_STRIP_ADJACENCY, GL_LINES_ADJACENCY, GL_TRIANGLE_STRIP_ADJACENCY, and GL_TRIANGLES_ADJACENCY are not supported as sf::PrimitiveTypes?
I needed to use GL_LINE_STRIP_ADJACENCY so I downloaded the source, added a sf::PrimitiveTypes, modified sf::RenderTarget::draw, and it worked fine. I couldn't think of a reason why they are not included other than not being used often.