Can crash julia on 1.13?

[KristofferC]

https://s3.amazonaws.com/julialang-reports/nanosoldier/pkgeval/by_hash/5abf758_vs_01a2ead/SymbolicTracingUtils.primary.log

Unreachable reached at 0x79a7f4ba057f

[55] signal 4 (2): Illegal instruction
in expression starting at /home/pkgeval/.julia/packages/SymbolicTracingUtils/A3yKh/test/runtests.jl:14
getindex at ./tuple.jl:33 [inlined]
macro expansion at /home/pkgeval/.julia/packages/RuntimeGeneratedFunctions/BenR2/src/RuntimeGeneratedFunctions.jl:164 [inlined]
macro expansion at ./none:0 [inlined]
generated_callfunc at ./none:0 [inlined]
RuntimeGeneratedFunction at /home/pkgeval/.julia/packages/RuntimeGeneratedFunctions/BenR2/src/RuntimeGeneratedFunctions.jl:152
#11 at /home/pkgeval/.julia/packages/SymbolicTracingUtils/A3yKh/src/tracing.jl:77
#18 at /home/pkgeval/.julia/packages/SymbolicTracingUtils/A3yKh/src/tracing.jl:99
* at /home/pkgeval/.julia/packages/SciMLOperators/2UPBq/src/func.jl:705
unknown function (ip: 0x79a7f4ba00e6) at (unknown file)
_jl_invoke at /source/src/gf.c:4116 [inlined]
ijl_apply_generic at /source/src/gf.c:4313
macro expansion at /home/pkgeval/.julia/packages/SymbolicTracingUtils/A3yKh/test/runtests.jl:97 [inlined]
macro expansion at /source/usr/share/julia/stdlib/v1.13/Test/src/Test.jl:1961 [inlined]
macro expansion at /home/pkgeval/.julia/packages/SymbolicTracingUtils/A3yKh/test/runtests.jl:91 [inlined]
macro expansion at /source/usr/share/julia/stdlib/v1.13/Test/src/Test.jl:1961 [inlined]
macro expansion at /home/pkgeval/.julia/packages/SymbolicTracingUtils/A3yKh/test/runtests.jl:62 [inlined]
macro expansion at /source/usr/share/julia/stdlib/v1.13/Test/src/Test.jl:1961 [inlined]
macro expansion at /home/pkgeval/.julia/packages/SymbolicTracingUtils/A3yKh/test/runtests.jl:17 [inlined]
macro expansion at /source/usr/share/julia/stdlib/v1.13/Test/src/Test.jl:1961 [inlined]
top-level scope at /home/pkgeval/.julia/packages/SymbolicTracingUtils/A3yKh/test/runtests.jl:15
_jl_invoke at /source/src/gf.c:4116 [inlined]

the stacktrace suggests something is going wrong here I think

[ChrisRackauckas-Claude]

Investigation Summary

What's Happening

The issue reports a crash on Julia 1.13 (specifically 1.13.0-alpha2.30) with the error:

Unreachable reached at 0x79a7f4ba057f
signal 4 (2): Illegal instruction

The crash was discovered via PkgEval nanosoldier when testing SymbolicTracingUtils.jl. The crash occurs in the @generated function generated_callfunc at RuntimeGeneratedFunctions.jl:164 when accessing argnames[i] via tuple indexing.

Stack Trace Analysis

The crash path is:

1. FunctionOperator * v_value (SciMLOperators.jl)
2. → Anonymous function in build_linear_operator (SymbolicTracingUtils.jl:99)
3. → RuntimeGeneratedFunction call (RuntimeGeneratedFunctions.jl:152)
4. → generated_callfunc (@generated function)
5. → CRASH: getindex on tuple (tuple.jl:33) with "Unreachable reached"

Root Cause Analysis

The crash is triggered by Julia PR #60312, a large backport PR for Julia 1.13.0-beta1 that includes many compiler and codegen changes. The comparison shows:

• Primary: 5abf758bb17ae8d469e70a4ed18390fa86073c18
• Against: 01a2eadb0474c395845e66ed3382b52e0c1f1b8f

Key relevant changes include:

1. Proactive lambda/closure precompilation - New compiler behavior that precompiles closures when their types are known
2. Build and linking changes - Static linking changes affecting codegen
3. GC heuristics changes - Heap-size-based GC improvements

Historical Context

RuntimeGeneratedFunctions.jl has had previous Julia version compatibility issues:

1. Issue #95 (Julia 1.12): Fixed in PR #96 by changing from internal :opaque_closure expression to proper @opaque macro usage

2. Issue #57701 in Julia: New restrictions on generated functions accessing global bindings with stricter world-age semantics

3. Issue #100: Known segfault when calling RGF with wrong number of arguments (unrelated but shows sensitivity)

Impact

From the PkgEval report, 50 packages started crashing on this Julia version, including many SciML ecosystem packages. SymbolicTracingUtils specifically shows the "unreachable instruction" crash, suggesting it's the canonical reproducer.

Recommendations

1. File an issue on JuliaLang/julia - This appears to be a compiler bug introduced in Julia 1.13 that causes incorrect codegen for @generated functions. The "Unreachable reached" error typically indicates the compiler generated invalid code paths.

2. Create a minimal reproducer - Strip down to just RuntimeGeneratedFunctions + a simple RGF call on Julia 1.13

3. Contact Julia compiler team - Since @JeffBezanson helped fix the 1.12 issue, the compiler team should be aware of this regression

4. Consider workaround: If the issue is related to the @generated function accessing cached bodies, consider whether invokelatest or other patterns could help

Related Issues/PRs

• Julia #57701 - New generated function restrictions in 1.12
• Julia #60312 - Backport PR that introduced the regression
• RGF #95 / #96 - Previous Julia 1.12 fix