case (); in [a, a]; end
                ^ duplicated variable name
case (); in [a, *a]; end
                 ^ duplicated variable name
case (); in {a: a, b: a}; end
                      ^ duplicated variable name
case (); in {a: a, **a}; end
                     ^ duplicated variable name
case (); in [a, {a:}]; end
                 ^ duplicated variable name
case (); in [a, {a: {a: {a: [a]}}}]; end
                             ^ duplicated variable name
case (); in a => a; end
                 ^ duplicated variable name
case (); in [A => a, {a: b => a}]; end
                              ^ duplicated variable name