Compiler throwing error, losing track of alias names in recursions

[wolfgang371]

That's probably a compiler error that results in a silly error message:

method Base(Cell)#b must return (Base(Cell) | Nil) but it is returning Cell

where Cell actually has exactly this definition.

# double recursion
class Base(T)
    def a : T
        b # calls the method that returns T|Nil
    end
    def b : T|Nil # Error: method Base(Cell)#b must return (Base(Cell) | Nil) but it is returning Cell
        a
    end
end

alias Cell = Base(Cell)|Nil # recursion needed, Nil needed

Base(Cell).new.a # needs to call the method which returns T

I'm running

Crystal 1.9.2 [1908c816f] (2023-07-19)
LLVM: 15.0.7
Default target: x86_64-unknown-linux-gnu

on Ubuntu 18.04

[yxhuvud]

I'd say this is a duplicate of #5155 . At the very least it is extremely related.