StackOverflowError in type intersection / inference

[goerch]

Reported on discourse:

using Graphs

abstract type MyAbstract end

struct Composite{T <: MyAbstract,R <: MyAbstract} <: MyAbstract
    a::T
    av::Vector{Union{T,R}}
end

struct Leaf <: MyAbstract
    b
end
Leaf() = Leaf(1)

Composite{T,R}() where {T<:MyAbstract,R<:MyAbstract} = Composite{T,R}(T(),Vector{Union{T,R}}([T()]))

randcomp1(firsttype::Type) = Composite{firsttype, Composite}()

randcomp1(Leaf)

crashes 1.7.2 with

Internal error: encountered unexpected error in runtime:
StackOverflowError()
intersect at /cygdrive/c/buildbot/worker/package_win64/build/src\subtype.c:2960

and seems to work on nightly.

[vtjnash]

semi-MWE fails on all (recent) Julia versions, so something merely avoided reaching this case in inference for 1.8+:

julia> using StaticArrays
julia> abstract type MyAbstract end
julia> typeintersect(
  Tuple{typeof(Base.convert), Type{Array{Union{T, R}, 1}}, StaticArrays.SizedArray{S, Union{T, R}, 1, 1, Array{Union{T, R}, 1}}} where R<:Main.MyAbstract where T<:Main.MyAbstract where S,
  Tuple{typeof(Base.convert), Type{T}, T} where T<:(Array{Union{T, R}, 1} where R<:Main.MyAbstract where T<:Main.MyAbstract)
)