int _u_n_d_e_r_s_c_o_r_e_s_; int a_r_e_; int _c_o_o_l; int __two_underscores_at_the_front; int two_underscores__in_the_middle; int two_underscores_at_the_end__; int __; // two underscores in isolation int three___underscores; int contains_mangle_marker_X_; struct two_underscores__in_a_structname { int two_underscores__in_a_struct_field; } two_underscores__in_struct_var; two_underscores__in_an_interface_block { int two_underscores__in_a_interface_block_field; } two_underscores__in_a_interface_block_var; // Code is not meaningful, but uses mangled identifiers and prevents elimination via optimizer. noinline two_underscores__in_a_structname two_underscores__in_a_funcname( two_underscores__in_a_structname two_underscores__in_a_parameter) { if (__two_underscores_at_the_front == two_underscores_at_the_end__) { if (two_underscores__in_the_middle == contains_mangle_marker_X_) { ++contains_mangle_marker_X_; } } two_underscores__in_a_parameter.two_underscores__in_a_struct_field = __; return two_underscores__in_a_structname(three___underscores); } void main() { _u_n_d_e_r_s_c_o_r_e_s_ = a_r_e_ = _c_o_o_l; two_underscores__in_a_funcname(two_underscores__in_struct_var); }