Segfault in jl_is_globally_rooted

[maleadt]

As spotted on PkgEval in TestSetExtensions.jl: https://s3.amazonaws.com/julialang-reports/nanosoldier/pkgeval/by_date/2025-01/02/TestSetExtensions.primary.log

MWE:

using Test
struct ExtendedTestSet{T<:Test.AbstractTestSet} <: Test.AbstractTestSet
    wrapped::T
    ExtendedTestSet{T}(desc) where {T} = new(T(desc))
end
ExtendedTestSet(desc) = ExtendedTestSet{Test.DefaultTestSet}(desc)

let
    out_reader = @async read(out_rd, String)
    @testset ExtendedTestSet "errors" begin
        throw(ErrorException("This test is supposed to throw an error"))
     end
    ccall(:jl_generating_output, Cint, ())
end

[1879856] signal 11 (128): Segmentation fault
in expression starting at /home/maleadt/julia/wip.jl:8
jl_is_globally_rooted at /source/src/staticdata.c:2753
jl_as_global_root at /source/src/staticdata.c:2768
inst_datatype_inner at /source/src/jltypes.c:2275
jl_inst_arg_tuple_type at /source/src/jltypes.c:2498
arg_type_tuple at /source/src/gf.c:2388 [inlined]
jl_lookup_generic_ at /source/src/gf.c:3432 [inlined]
ijl_apply_generic at /source/src/gf.c:3490
macro expansion at /source/usr/share/julia/stdlib/v1.12/Test/src/Test.jl:1737 [inlined]
top-level scope at /home/maleadt/julia/wip.jl:11

Seems to relate to the Expr(:latestworld-if-toplevel). Bisected to #56509

[vtjnash]

Also looks like it also happens in MatrixEquations tests.

We have an object allocated by a dynamic call to copy at

macro expansion at /home/vtjnash/julia1/usr/share/julia/stdlib/v1.12/Test/src/Test.jl:1756

(rr) p jl_(0x7f3557908340)
Random.Xoshiro(s0=0xeb50203a54383b4d, s1=0x230b8f4e1fdfa4b0, s2=0x52d092b9f301e4c3, s3=0x0aacfda0920739dd, s4=0xe8f89f84afe83155)

which later get garbage-collected during the finally block (during some more inference), after the error, just before getting used in another dynamic call:

Base.copy!(Random.TaskLocalRNG(), <#0x7f3557908340>)

at

macro expansion at /home/vtjnash/julia1/usr/share/julia/stdlib/v1.12/Test/src/Test.jl:1777                     

[vtjnash]

smaller MWE: this always segfaults for me (unless I put it in a function)

let
   ()->() # trigger latestworld expr
   default_rng_orig = []
   try
       throw(ErrorException("This test is supposed to throw an error"))
   catch ex
       GC.gc()
       copy!([], default_rng_orig)
   end
   Base.Experimental.@force_compile
   nothing
end