In emacs 25.2.1.

Relevant code:

    draw_add(&battle.draw, (Drawn){
            .kind = DRAW_RECT,
                .size = {40,24},
                .pos.border = {
                .align = {ALIGN_LEFT, ALIGN_TOP},
                .dist = 3
            }
        }
        );

My guess is that it's reading (Drawn){...} as a statement, and the , as
the (,) C operator.