Some recursive definitions of structs/enums cause compiler to hang

[harveyadcock]

The following code causes the compiler to loop indefinitely (until the system runs out of memory):

enum Node {
    Branch(Branch),
    Leaf(Leaf)
}

struct Branch {
    value: i32,
    left: Node,
    right: Node
}

struct Leaf {
    value: i32
}

This seems to be a failure of the compiler to recognise when a struct/enum would be infinite in size, interestingly commenting out one of the Nodes (either left or right in Branch) allows the compiler to identify an infinite recursion and give the appropriate error message.

[jonas-schievink]

Duplicate of #32619, #32326, #33180

[harveyadcock]

Ah, clearly my previous bug searching is pretty poor, apologies!

[nagisa]

Closing.