The "reached type-length limit" error is not very helpful

[lovasoa]

This issue is close to #58952, but I think it's different. Feel free to close it if I'm mistaken.

The issue

Here is the code I am trying to compile: lovasoa/seamcarving @ f6be585.
The compilation fails with :

error: reached the type-length limit while instantiating `<std::iter::Once<u32> as std::it...ving::seamfinder::SeamElem), !>>`

The issue probably comes from my code, and not from the compiler, but the compiler makes it quite difficult to debug !

The compiler error does not point to a precise place in the code, and does not even print the full name of the type it is trying to instantiate. I only know that is starts with <std::iter::Once<u32> as std::it and ends with ving::seamfinder::SeamElem), !>>.
Moreover, it notes :

note: consider adding a `#![type_length_limit="1814752"]` attribute to your crate

... even if the attribute is already there.

[lovasoa]

The type that reaches the limit seems to be the one of this iterator, which is generated by that function.