`descend(Base.show_unquoted, ...)` fails

[nsajko]

Versions

Julia Version 1.13.0-DEV.1030
Commit c6e7650d1e4 (2025-08-22 16:10 UTC)
Build Info:
  Official https://julialang.org release
Platform Info:
  OS: Linux (x86_64-linux-gnu)
  CPU: 8 × AMD Ryzen 3 5300U with Radeon Graphics
  WORD_SIZE: 64
  LLVM: libLLVM-20.1.8 (ORCJIT, znver2)
  GC: Built with stock GC
Threads: 1 default, 1 interactive, 1 GC (on 8 virtual cores)

(@v1.13) pkg> st Cthulhu
Status `~/.julia/environments/v1.13/Project.toml`
  [f68482b8] Cthulhu v2.17.4

Reproducers

Reproducer 1

using Cthulhu: descend
descend(Base.show_unquoted, Tuple{IOBuffer, Expr, Int, Int})

The output is missing any items to descend to:

show_unquoted(io::IO, ex::Expr, indent::Int64, prec::Int64) @ Base show.jl:1898
[ Info: This method only fills in default arguments; descend into the body method to see the full source.
1898 function show_unquoted(io::IOBuffer::IO, ex::Expr::Expr, indent::Int64::Int, prec::Int64::Int, quote_level::Int = 0)::Core.Const(nothing)
Select a call to descend into or ↩ to ascend. [q]uit. [b]ookmark.
Toggles: [w]arn, [h]ide type-stable statements, [t]ype annotations, [s]yntax highlight for Source/LLVM/Native, [j]ump to source always.
Show: [S]ource code, [A]ST, [T]yped code, [L]LVM IR, [N]ative code
Actions: [E]dit source code, [R]evise and redisplay
 • ↩

Reproducer 2

using Cthulhu: descend
descend(Base.show_unquoted, Tuple{IOBuffer, Expr, Int, Int, Int})

An assertion error gets thrown right away:

ERROR: AssertionError: length(infos) == length(info.results)
Stacktrace:
  [1] process_info(interp::Cthulhu.CthulhuInterpreter, info::Compiler.CallInfo, argtypes::Vector{Any}, rt::Any, optimize::Bool, exct::Any, effects::Nothing)
    @ Cthulhu ~/.julia/packages/Cthulhu/dkzKO/src/reflection.jl:189
  [2] find_callsites(interp::Cthulhu.CthulhuInterpreter, CI::Core.CodeInfo, stmt_infos::Vector{Compiler.CallInfo}, ci::Core.CodeInstance, slottypes::Vector{Any}, optimize::Bool, annotate_source::Bool, pc2excts::Nothing)
    @ Cthulhu ~/.julia/packages/Cthulhu/dkzKO/src/reflection.jl:64
  [3] 
    @ Cthulhu ~/.julia/packages/Cthulhu/dkzKO/src/CthulhuBase.jl:381
  [4] _descend
    @ ~/.julia/packages/Cthulhu/dkzKO/src/CthulhuBase.jl:289 [inlined]
  [5] _descend
    @ ~/.julia/packages/Cthulhu/dkzKO/src/CthulhuBase.jl:672 [inlined]
  [6] #_descend#114
    @ ~/.julia/packages/Cthulhu/dkzKO/src/CthulhuBase.jl:683 [inlined]
  [7] __descend_with_error_handling(args::Any; terminal::Any, kwargs...)
    @ Cthulhu ~/.julia/packages/Cthulhu/dkzKO/src/CthulhuBase.jl:133
  [8] top-level scope
    @ ~/.julia/packages/Cthulhu/dkzKO/src/CthulhuBase.jl:122
  [9] top-level scope
    @ ~/.julia/packages/Cthulhu/dkzKO/src/CthulhuBase.jl:114
 [10] top-level scope
    @ ~/.julia/packages/Cthulhu/dkzKO/src/CthulhuBase.jl:151
 [11] top-level scope
    @ ~/.julia/packages/Cthulhu/dkzKO/src/CthulhuBase.jl:151
 [12] descend(::Any, ::Vararg{Any}; kwargs...)
    @ Cthulhu ~/.julia/packages/Cthulhu/dkzKO/src/Cthulhu.jl:111
 [13] top-level scope
    @ ~/.julia/packages/Cthulhu/dkzKO/src/Cthulhu.jl:110
 [14] top-level scope
    @ REPL[3]:1
Some type information was truncated. Use `show(err)` to see complete types.