obvious-subtype bug observed on ill-formed types

[vtjnash]

pkg> test Tulip
Assertion failed: (subtype_ab == 3 || subtype_ab == subtype || jl_has_free_typevars(a) || jl_has_free_typevars(b)), function jl_types_equal, file /Users/jameson/julia/src/subtype.c, line 1919.
(lldb) p jl_(a)
Tuple{typeof(MathOptInterface.Utilities.operate), typeof(Base.:(+)), Type{T}, MathOptInterface.ScalarAffineFunction{T}, T where T<:Union{MathOptInterface.ScalarAffineFunction{T}, T}} where T<:(T where T<:MathOptInterface.ScalarAffineFunction{T} where T)
(lldb) p jl_(b)
Tuple{typeof(MathOptInterface.Utilities.operate), typeof(Base.:(+)), Type{T}, MathOptInterface.ScalarAffineFunction{T}, T where T<:Union{MathOptInterface.ScalarAffineFunction{T}, T}} where T<:(T where T<:MathOptInterface.ScalarAffineFunction{T} where T)
(lldb) bt
* thread #1, queue = 'com.apple.main-thread', stop reason = signal SIGABRT
    frame #0: 0x00007fff5f9722c2 libsystem_kernel.dylib`__pthread_kill + 10
    frame #1: 0x00007fff5fa2dbf1 libsystem_pthread.dylib`pthread_kill + 284
    frame #2: 0x00007fff5f8dc6a6 libsystem_c.dylib`abort + 127
    frame #3: 0x00007fff5f8a520d libsystem_c.dylib`__assert_rtn + 324
  * frame #4: 0x00000001002cbea9 libjulia-debug.dylib`jl_types_equal(a=0x0000000111d82350, b=0x0000000112e07330) at subtype.c:1919:9
    frame #5: 0x00000001061c8fcc sys-debug.dylib`julia_==_1810 at operators.jl:163
    frame #6: 0x00000001061c9026 sys-debug.dylib`jfptr_==_1811 + 22
    frame #7: 0x000000010023a03c libjulia-debug.dylib`_jl_invoke(F=0x000000010997cbd0, args=0x0000000122fec7b8, nargs=2, mfunc=0x0000000107773da0, world=3870) at gf.c:2144:31
    frame #8: 0x000000010023a793 libjulia-debug.dylib`jl_apply_generic(F=0x000000010997cbd0, args=0x0000000122fec7b8, nargs=2) at gf.c:2322:12
    frame #9: 0x0000000106120d34 sys-debug.dylib`julia_abstract_call_method_735 at abstractinterpretation.jl:281
    frame #10: 0x00000001061225ca sys-debug.dylib`julia_abstract_call_gf_by_type_653 at abstractinterpretation.jl:101
    frame #11: 0x000000010612f088 sys-debug.dylib`julia_abstract_call_known_566 at abstractinterpretation.jl:873
    frame #12: 0x000000010613276f sys-debug.dylib`julia_abstract_call_564 at abstractinterpretation.jl:895
    frame #13: 0x0000000106132876 sys-debug.dylib`japi1_abstract_call_563 at abstractinterpretation.jl:880
    frame #14: 0x000000010613429f sys-debug.dylib`japi1_abstract_eval_558 at abstractinterpretation.jl:974
    frame #15: 0x00000001061373db sys-debug.dylib`japi1_typeinf_local_468 at abstractinterpretation.jl:1227
    frame #16: 0x000000010613b29a sys-debug.dylib`julia_typeinf_nocycle_466 at abstractinterpretation.jl:1283
    frame #17: 0x00000001061c43af sys-debug.dylib`julia_typeinf_464 at typeinfer.jl:12
    frame #18: 0x000000010612066c sys-debug.dylib`japi1_typeinf_edge_746 at typeinfer.jl:488

[maleadt]

This issue (or this assertion, at least) is happening a lot on 1.6/master: 95 packages abort compared to master, many of which with this exact failure. See #37214 (comment) and the report at https://github.com/JuliaCI/NanosoldierReports/blob/master/pkgeval/by_hash/c3bb6df_vs_599ecd8/report.md.

I'd put this on the 1.6 milestone, but we only have a features milestone right now.

[KristofferC]

Regarding the milestone, I think it's the same thing.

[maleadt]

Another bump here, out of the 125 aborts on the latest PkgEval run with assertions, #37214 (comment), 95 packages did so with this assertion. Specifically, the following packages: SimpleSDMLayers, DataEnvelopmentAnalysis, SemidefiniteOptInterface, LinearFractional, PolyJuMP, Polyhedra, ECOS, PolyhedralRelaxations, LazySets, PetroleumModels, PowerModelsACDC, PiecewiseLinearOpt, QuantumInformation, ImplicitPlots, BundleMethod, ClimateMARGO, ProjectManagement, sparseQFCA, SecretSanta, HomotopyContinuation, LightGraphsMatching, PowerModelsWildfire, BilevelJuMP, GasModels, vOptGeneric, ComplexOptInterface, InfrastructureModels, PowerModelsSecurityConstrained, Pavito, BirkhoffDecomposition, ParameterJuMP, Seleroute, PowerModelsRestoration, SDPA, MosekTools, PowerModelsAnnex, ConstraintSolver, PowerSimulations, Tulip, BranchAndBound, SimplePosetAlgorithms, TravelingSalesmanExact, Ipopt, RiskAdjustedLinearizations, MaximinOPF, OpSel, SwitchOnSafety, RELOG, CDDLib, DiscreteFunctions, BilevelOptimization, Alpine, MathOptInterface, JuliaGrid, SDPAFamily, LightGraphsFlows, GLPK, NaiveNASlib, UnitCommitment, AnyMOD, PowerModels, CSDP, MINLPTests, Cbc, StochDynamicProgramming, LatinSquares, QHull, Sudoku, SDDP, SpectralDistances, Convex, EAGO, PowerModelsDistribution, Clp, Impute, RandomizedProgressiveHedging, QuadraticToBinary, NaiveGAflux, WaterModels, CutPruners, Empirikos, DualDecomposition, GasPowerModels, LinearCovarianceModels, Juniper, SetProg, UnbalancedOptimalTransport, NaiveNASflux, GuessworkQuantumSideInfo, OPFSampler, PowerWaterModels, SCS, Fri, DensityRatioEstimation, LayeredLayouts.