Hmm..., with boost (develop branch) + GCC 7.3 or Clang trunk,
the following code runs fine:

    std::vector<int> v1{1, 1, 1};
    std::vector<int> v2{2, 2, 2};

    for (auto&& tpl : boost::range::combine(v1, v2)) {
        auto [x, y] = tpl; // `auto&`, `auto const&` and `auto&&` also work fine
        x = 10;
        y = 20;
    }

    for (auto&& [x, y] : boost::range::combine(v1, v2)) {
        x = 200;
        y = 200;
    }