Unreachable reached by deleting an extended method (v1.11.5) #58986
Description
I am able to trigger an "Unreachable reached at 0x7c4859693328" error with the following:
"Using Revise" approach
This is my original MWE.
- Create this file (test.jl):
import Base: *, ^
struct D<: Number
val::Float64
deriv::Float64
end
*(x::D,y::D) = D(x.val*y.val,
x.val*y.deriv+x.deriv*y.val)
^(x::D,y::D) = D(x.val^y.val,
x.val^(y.val-1)*
(y.val*x.deriv + x.val*y.deriv*log(x.val))
)
^(x::D,n::Real) = D(x.val^n,n*x.val^(n-1)*x.deriv)
function test()
D(1.0,1.0)^2
end- Start a new Julia session, use Revise to includet this file, and run the test function (the startup-file=no is not necessary to trigger the bug)
$ julia --startup-file=no
julia> using Revise
julia> includet("test.jl")
julia> test()
ERROR: MethodError: ^(::D, ::Int64) is ambiguous.
Candidates:
^(x::D, n::Real)
@ Main ~/test/bug/test.jl:15
^(x::Number, p::Integer)
@ Base intfuncs.jl:349
Possible fix, define
^(::D, ::Integer)
Stacktrace:
[1] literal_pow
@ ./intfuncs.jl:389 [inlined]
[2] test()
@ Main ~/test/bug/test.jl:18
[3] top-level scope
@ REPL[2]:1-
Switch back to the test.jl file and comment out the second of the two exponentiation methods (the
^(x::D,n::Real) = D(x.val^n,n*x.val^(n-1)*x.deriv)one, that is), and save the file. -
Back in the REPL:
julia> test()
Unreachable reached at 0x7c4859693328
[3277] signal 4 (2): Illegal instruction
in expression starting at REPL[2]:1
literal_pow at ./intfuncs.jl:389 [inlined]
test at /home/daniel/test/bug/test.jl:18
unknown function (ip: 0x7c485969334f)
jl_apply at /cache/build/tester-amdci5-12/julialang/julia-release-1-dot-11/src/julia.h:2157 [inlined]
do_call at /cache/build/tester-amdci5-12/julialang/julia-release-1-dot-11/src/interpreter.c:126
eval_value at /cache/build/tester-amdci5-12/julialang/julia-release-1-dot-11/src/interpreter.c:223
eval_stmt_value at /cache/build/tester-amdci5-12/julialang/julia-release-1-dot-11/src/interpreter.c:174 [inlined]
eval_body at /cache/build/tester-amdci5-12/julialang/julia-release-1-dot-11/src/interpreter.c:666
jl_interpret_toplevel_thunk at /cache/build/tester-amdci5-12/julialang/julia-release-1-dot-11/src/interpreter.c:824
jl_toplevel_eval_flex at /cache/build/tester-amdci5-12/julialang/julia-release-1-dot-11/src/toplevel.c:943
jl_toplevel_eval_flex at /cache/build/tester-amdci5-12/julialang/julia-release-1-dot-11/src/toplevel.c:886
jl_toplevel_eval_flex at /cache/build/tester-amdci5-12/julialang/julia-release-1-dot-11/src/toplevel.c:886
jl_toplevel_eval_flex at /cache/build/tester-amdci5-12/julialang/julia-release-1-dot-11/src/toplevel.c:886
ijl_toplevel_eval_in at /cache/build/tester-amdci5-12/julialang/julia-release-1-dot-11/src/toplevel.c:994
eval at ./boot.jl:430 [inlined]
eval_user_input at /cache/build/tester-amdci5-12/julialang/julia-release-1-dot-11/usr/share/julia/stdlib/v1.11/REPL/src/REPL.jl:261
repl_backend_loop at /cache/build/tester-amdci5-12/julialang/julia-release-1-dot-11/usr/share/julia/stdlib/v1.11/REPL/src/REPL.jl:368
#start_repl_backend#59 at /cache/build/tester-amdci5-12/julialang/julia-release-1-dot-11/usr/share/julia/stdlib/v1.11/REPL/src/REPL.jl:343
start_repl_backend at /cache/build/tester-amdci5-12/julialang/julia-release-1-dot-11/usr/share/julia/stdlib/v1.11/REPL/src/REPL.jl:340
#run_repl#76 at /cache/build/tester-amdci5-12/julialang/julia-release-1-dot-11/usr/share/julia/stdlib/v1.11/REPL/src/REPL.jl:500
run_repl at /cache/build/tester-amdci5-12/julialang/julia-release-1-dot-11/usr/share/julia/stdlib/v1.11/REPL/src/REPL.jl:486
jfptr_run_repl_10123.1 at /home/daniel/.julia/juliaup/julia-1.11.5+0.x64.linux.gnu/share/julia/compiled/v1.11/REPL/u0gqU_4x0TT.so (unknown line)
#1150 at ./client.jl:446
jfptr_YY.1150_14797.1 at /home/daniel/.julia/juliaup/julia-1.11.5+0.x64.linux.gnu/share/julia/compiled/v1.11/REPL/u0gqU_4x0TT.so (unknown line)
jl_apply at /cache/build/tester-amdci5-12/julialang/julia-release-1-dot-11/src/julia.h:2157 [inlined]
jl_f__call_latest at /cache/build/tester-amdci5-12/julialang/julia-release-1-dot-11/src/builtins.c:875
#invokelatest#2 at ./essentials.jl:1055 [inlined]
invokelatest at ./essentials.jl:1052 [inlined]
run_main_repl at ./client.jl:430
repl_main at ./client.jl:567 [inlined]
_start at ./client.jl:541
jfptr__start_73430.1 at /home/daniel/.julia/juliaup/julia-1.11.5+0.x64.linux.gnu/lib/julia/sys.so (unknown line)
jl_apply at /cache/build/tester-amdci5-12/julialang/julia-release-1-dot-11/src/julia.h:2157 [inlined]
true_main at /cache/build/tester-amdci5-12/julialang/julia-release-1-dot-11/src/jlapi.c:900
jl_repl_entrypoint at /cache/build/tester-amdci5-12/julialang/julia-release-1-dot-11/src/jlapi.c:1059
main at /cache/build/tester-amdci5-12/julialang/julia-release-1-dot-11/cli/loader_exe.c:58
unknown function (ip: 0x7c4865e2a1c9)
__libc_start_main at /lib/x86_64-linux-gnu/libc.so.6 (unknown line)
unknown function (ip: 0x4010b8)
Allocations: 1309182 (Pool: 1309102; Big: 80); GC: 2
Illegal instruction (core dumped)version info
julia> versioninfo()
Julia Version 1.11.5
Commit 760b2e5b739 (2025-04-14 06:53 UTC)
Build Info:
Official https://julialang.org/ release
Platform Info:
OS: Linux (x86_64-linux-gnu)
CPU: 22 × Intel(R) Core(TM) Ultra 7 155H
WORD_SIZE: 64
LLVM: libLLVM-16.0.6 (ORCJIT, alderlake)
Threads: 1 default, 0 interactive, 1 GC (on 22 virtual cores)I have also reproduced this on a different Windows 11 machine (also v1.11.5)
Other similar (simpler) failure modes
When I first had this come up I posted a discourse thread here. I don't want to take credit for other people's (much better) sleuthing: user /u/benny pointed out that Revise.jl is not needed at all, and that the same bug reproduces in v1.11.6, v1.10.10, v1.9.4, Windows 11.
/u/benny also proposed an even simpler MWE here, which I copy to this issue since it seems to get to the heart of things directly:
julia> begin
abstract type AbstractBlah end
struct Blah<:AbstractBlah end
foo(::Blah, ::AbstractBlah) = 1
foo(::AbstractBlah, ::Blah) = -1
test() = foo(Blah(), Blah())
end
test (generic function with 1 method)
julia> foo(Blah(), Blah())
ERROR: MethodError: foo(::Blah, ::Blah) is ambiguous.
Candidates:
foo(::AbstractBlah, ::Blah)
@ Main REPL[1]:5
foo(::Blah, ::AbstractBlah)
@ Main REPL[1]:4
Possible fix, define
foo(::Blah, ::Blah)
Stacktrace:
[1] top-level scope
@ REPL[2]:1
julia> test() # same outcome as expected from forwarding to same call
ERROR: MethodError: foo(::Blah, ::Blah) is ambiguous.
Candidates:
foo(::AbstractBlah, ::Blah)
@ Main REPL[1]:5
foo(::Blah, ::AbstractBlah)
@ Main REPL[1]:4
Possible fix, define
foo(::Blah, ::Blah)
Stacktrace:
[1] test()
@ Main .\REPL[1]:6
[2] top-level scope
@ REPL[3]:1
julia> Base.delete_method(methods(foo)[2]) # no Base methods to avoid deleting
julia> foo(Blah(), Blah()) # properly invalidated previous MethodError call
-1
julia> test()
Unreachable reached at 00000204af55136f
Please submit a bug report with steps to reproduce this fault, and any error messages that follow (in their entirety). Thanks.
Exception: EXCEPTION_ILLEGAL_INSTRUCTION at 0x204af55136f -- test at .\REPL[1]:6
in expression starting at REPL[6]:1
test at .\REPL[1]:6
unknown function (ip: 00000204af5513a4)
jl_apply at C:/workdir/src\julia.h:2157 [inlined]
...