Unlike other algorithms, the return types of ranges::fold_meow are specified in terms of auto and see below, and its implementation details depend on the return types of other overloads through decltype(fold_meow(...)).

This makes determining the return type of a certain overload (such as fold_right_last) extremely difficult even for experts, requiring several trips back and forth to different overloads to finally understand what the actual return type is. The situation is even worse for newbies because such a form of specifying the return type makes it impossible for the IDE to deduce the real return type, which is extremely user-unfriendly.

I think that explicitly specifying the return type for these overloads not only greatly improves readability but also offloads the compiler from deducing the return type, which can definitely be considered an improvement.

The proposed resolution does not touch the Effects clause and only changes the function signature to seek minimal changes.