1> struct Foo { 2. var bar: Int 3. var foo: Foo? 4. } error: repl.swift:1:8: error: value type 'Foo' cannot have a stored property that references itself struct Foo { ^ 1> struct Foo { 2. var bar: Int 3. var foo: Foo? 4. } error: repl.swift:1:8: error: value type 'Foo' cannot have a stored property that references itself struct Foo { ^