copy_symbol
struct symbol *label_symbol = copy_symbol(expr->pos, expr->label_symbol);
struct symbol *newsym = copy_symbol(stmt->pos, sym);
struct symbol *sym = copy_symbol(stmt->pos, stmt->ret_target);
stmt->case_label = copy_symbol(stmt->pos, stmt->case_label);
struct symbol *switch_break = copy_symbol(stmt->pos, stmt->switch_break);
struct symbol *switch_case = copy_symbol(stmt->pos, stmt->switch_case);
stmt->iterator_break = copy_symbol(stmt->pos, stmt->iterator_break);
stmt->iterator_continue = copy_symbol(stmt->pos, stmt->iterator_continue);
stmt->label_identifier = copy_symbol(stmt->pos, stmt->label_identifier);
stmt->goto_label = copy_symbol(stmt->pos, stmt->goto_label);
dst->ret = copy_symbol(src->pos, src->ret);
struct symbol *newsym = copy_symbol(sym->pos, sym);
struct symbol *sym = copy_symbol(expr->pos, expr->symbol);