I’m attempting to understand how views can be composed and the limitations of the same.
The idea here is to split a string/string_view without creating a temporary variable as shown in the second code block.

Why does the following not compile:

std::string line = "1[2]3";
for (const auto split : line 
                            | std::ranges::views::split('[') 
                            | std::ranges::views::transform([](const auto rng) {return std::string_view(rng); })) 
                            | std::ranges::views::split(']') 
                            | std::ranges::views::transform([](const auto rng) {return std::string_view(rng); })) 
    std::cout << split << 'n';
}

An additional question is why the above code fails to compile but the following work:

for (const auto split_once : line 
                                 | std::ranges::views::split('[')
                                 | std::ranges::views::transform([](const auto rng) {return std::string_view(rng); })) 
{
    for (const auto split_twice : split_once 
                                     | std::ranges::views::split(']') 
                                     | std::ranges::views::transform([](const auto rng) {return std::string_view(rng); })) 
   {
            std::cout << split_twice << 'n';
   }
}

Link to compiler explorer