Testing Arrow asserts in subtyping on 1.9

[KristofferC]

(jl_sshwyM) pkg> add Arrow; test Arrow
...
testing: dictencode keyword
testing: nesteddictencode keyword
Assertion failed: (obvious_subtype == 3 || obvious_subtype == subtype || jl_has_free_typevars(x) || jl_has_free_typevars(y)), function ijl_subtype_env, file subtype.c, line 1946.

[21676] signal (6): Abort trap: 6
in expression starting at /Users/kristoffercarlsson/.julia/packages/Arrow/P0wVk/test/runtests.jl:46
__pthread_kill at /usr/lib/system/libsystem_kernel.dylib (unknown line)

Seems to work fine on master. Regression introduced in one of the backports it seems.

Ref: https://s3.amazonaws.com/julialang-reports/nanosoldier/pkgeval/by_hash/9aa7669_vs_7b39515/Arrow.primary.log

[maleadt]

julia> function fromarrow end

julia> x = Tuple{typeof(fromarrow), Type{Union{Missing, NamedTuple{(:c,), Tuple{String}}}}, Missing}

julia> y = Tuple{typeof(fromarrow), Type{Union{Missing, T}}, T} where T<:NamedTuple

julia> x <: y
julia: /home/tim/Julia/src/julia/src/subtype.c:1961: ijl_subtype_env: Assertion `obvious_subtype == 3 || obvious_subtype == subtype || jl_has_free_typevars(x) || jl_has_free_typevars(y)' failed.

[maleadt]

2a2068d2677eae3fe2101c89f9ed6c98e51f3a62 is the first bad commit
commit 2a2068d2677eae3fe2101c89f9ed6c98e51f3a62
Author: N5N3 <2642243996@qq.com>
Date:   Thu Feb 2 11:41:26 2023 +0800

    Subtype: avoid false alarm caused by eager `forall_exists_subtype`. (#48441)

ref #48441, cc @N5N3

[N5N3]

This looks quite similar to #48935 (comment), simple_meet fails to give Union{Missing, @NamedTuple{c::String}} ∩ NamedTuple = @NamedTuple{c::String}}.
Before #48441, we check Missing <: T before the over-estimation, thus there's no problem.

This case is not hard to fix, but I'm afraid there're more remaining issues.

[KristofferC]

This case is not hard to fix, but I'm afraid there're more remaining issues.

This is the one that comes up on PkgEval so we could at least start with fixing this one.