# Is this type-piracy, and is the resulting crash expected?

**URL:** <https://discourse.julialang.org/t/is-this-type-piracy-and-is-the-resulting-crash-expected/117914>\
**Category:** General Usage\
**Tags:** crash, type-piracy\
**Created:** [August 7, 2024, 10:06am UTC](https://discourse.julialang.org/t/is-this-type-piracy-and-is-the-resulting-crash-expected/117914 "2024-08-07T10:06:03Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![cmarcotte](https://avatars.discourse-cdn.com/v4/letter/c/a3d4f5/32.png) [@cmarcotte](https://discourse.julialang.org/u/cmarcotte)\
**Post date:** [August 7, 2024, 10:06am UTC](https://discourse.julialang.org/t/is-this-type-piracy-and-is-the-resulting-crash-expected/117914/1 "2024-08-07T10:06:03Z")

</div>

Hello,

In a temp session, if I `import Base.∈` and extend it with

```julia
∈(A,Interval) = (minimum(Interval) <= A <= maximum(Interval))

```

attempting to tab-complete the line `-1.0 \in` causes the session to crash (`versioninfo()` and error message below the fold).

If I instead write a function with a generic but matching type (e.g. `∈(A::T, Interval::Tuple{T,T}) where {T}`) the tab-complete works fine.

Certainly the error message could be more clear and ideally the session should not crash; my question is whether this is a form of type-piracy and so the crash should be anticipated, or if this is something more subtle?

> ****
>
> `versioninfo()`:
> 
> ```julia
> Julia Version 1.10.4
> Commit 48d4fd48430 (2024-06-04 10:41 UTC)
> Build Info:
> Official https://julialang.org/ release
> Platform Info:
> OS: Linux (x86_64-linux-gnu)
> CPU: 32 × AMD Ryzen 9 7950X 16-Core Processor
> WORD_SIZE: 64
> LIBM: libopenlibm
> LLVM: libLLVM-15.0.7 (ORCJIT, znver3)
> Threads: 1 default, 0 interactive, 1 GC (on 32 virtual cores)
> 
> ```
> 
> ```julia
> Unhandled Task ERROR: MethodError: reducing over an empty collection is not allowed; consider supplying `init` to the reducer
> Stacktrace:
> [1] reduce_empty(op::Base.BottomRF{typeof(min)}, ::Type{Union{}})
> @ Base ./reduce.jl:360
> [2] reduce_empty_iter(op::Base.BottomRF{typeof(min)}, itr::Tuple{}, ::Base.HasEltype)
> @ Base ./reduce.jl:384
> [3] reduce_empty_iter(op::Base.BottomRF{typeof(min)}, itr::Tuple{})
> @ Base ./reduce.jl:383
> [4] foldl_impl(op::Base.BottomRF{typeof(min)}, nt::Base._InitialValue, itr::Tuple{})
> @ Base ./reduce.jl:49
> [5] mapfoldl_impl(f::typeof(identity), op::typeof(min), nt::Base._InitialValue, itr::Tuple{})
> @ Base ./reduce.jl:44
> [6] mapfoldl(f::Function, op::Function, itr::Tuple{}; init::Base._InitialValue)
> @ Base ./reduce.jl:175
> [7] mapfoldl
> @ ./reduce.jl:175 [inlined]
> [8] mapreduce(f::Function, op::Function, itr::Tuple{})
> @ Base ./reduce.jl:307
> [9] minimum(a::Tuple{}; kw::@Kwargs{})
> @ Base ./reduce.jl:796
> [10] in(A::Char, Interval::Tuple{})
> @ Main ./REPL[7]:1
> [11] escape_string(io::IOBuffer, s::String, esc::Tuple{Char, Char}; keep::Tuple{})
> @ Base ./strings/io.jl:411
> [12] escape_string
> @ ./strings/io.jl:406 [inlined]
> [13] print_quoted
> @ ./strings/io.jl:440 [inlined]
> [14] show(io::IOBuffer, s::String)
> @ Base ./strings/io.jl:197
> [15] sprint(f::Function, args::String; context::Nothing, sizehint::Int64)
> @ Base ./strings/io.jl:114
> [16] repr(x::String; context::Nothing)
> @ Base ./strings/io.jl:286
> [17] show_sym(io::IOContext{IOBuffer}, sym::Symbol; allow_macroname::Bool)
> @ Base ./show.jl:1747
> [18] show_sym
> @ ./show.jl:1740 [inlined]
> [19] show_type_name(io::IOContext{IOBuffer}, tn::Core.TypeName)
> @ Base ./show.jl:1054
> [20] _show_type(io::IOContext{IOBuffer}, x::Type)
> @ Base ./show.jl:956
> [21] show(io::IOContext{IOBuffer}, x::Type)
> @ Base ./show.jl:953
> [22] print(io::IOContext{IOBuffer}, x::Type)
> @ Base ./strings/io.jl:35
> [23] print(::IOContext{IOBuffer}, ::String, ::Type, ::Vararg{Any})
> @ Base ./strings/io.jl:46
> [24] with_output_color(::Function, ::Symbol, ::IOContext{IOBuffer}, ::String, ::Vararg{Any}; bold::Bool, italic::Bool, underline::Bool, blink::Bool, reverse::Bool, hidden::Bool)
> @ Base ./util.jl:78
> [25] printstyled(::IOContext{IOBuffer}, ::String, ::Vararg{Any}; bold::Bool, italic::Bool, underline::Bool, blink::Bool, reverse::Bool, hidden::Bool, color::Symbol)
> @ Base ./util.jl:141
> [26] print_within_stacktrace(::IOContext{IOBuffer}, ::String, ::Vararg{Any}; color::Symbol, bold::Bool)
> @ Base ./show.jl:2501
> [27] print_within_stacktrace
> @ ./show.jl:2499 [inlined]
> [28] show_signature_function(io::IOContext{IOBuffer}, ft::Any, demangle::Bool, fargname::String, html::Bool, qualified::Bool)
> @ Base ./show.jl:2493
> [29] show_tuple_as_call(out::IOContext{IOBuffer}, name::Symbol, sig::Type; demangle::Bool, kwargs::Nothing, argnames::Vector{Symbol}, qualified::Bool, hasfirst::Bool)
> @ Base ./show.jl:2526
> [30] show_tuple_as_call
> @ ./show.jl:2507 [inlined]
> [31] show_spec_sig(io::IOContext{IOBuffer}, m::Method, sig::Type)
> @ Base.StackTraces ./stacktraces.jl:265
> [32] show_spec_linfo(io::IOContext{IOBuffer}, frame::Base.StackTraces.StackFrame)
> @ Base.StackTraces ./stacktraces.jl:232
> [33] print_stackframe(io::IOContext{IOBuffer}, i::Int64, frame::Base.StackTraces.StackFrame, n::Int64, ndigits_max::Int64, modulecolor::Symbol)
> @ Base ./errorshow.jl:742
> [34] print_stackframe(io::IOContext{IOBuffer}, i::Int64, frame::Base.StackTraces.StackFrame, n::Int64, ndigits_max::Int64, modulecolordict::IdDict{Module, Symbol}, modulecolorcycler::Base.Iterators.Stateful{Base.Iterators.Cycle{Vector{Symbol}}, Union{Nothing, Tuple{Symbol, Int64}}, Int64})
> @ Base ./errorshow.jl:706
> [35] show_full_backtrace(io::IOContext{IOBuffer}, trace::Vector{Any}; print_linebreaks::Bool)
> @ Base ./errorshow.jl:605
> [36] show_full_backtrace
> @ ./errorshow.jl:598 [inlined]
> [37] show_backtrace(io::IOContext{IOBuffer}, t::Vector{Union{Ptr{Nothing}, Base.InterpreterIP}})
> @ Base ./errorshow.jl:802
> [38] showerror(io::IOContext{IOBuffer}, ex::MethodError, bt::Vector{Union{Ptr{Nothing}, Base.InterpreterIP}}; backtrace::Bool)
> @ Base ./errorshow.jl:97
> [39] showerror
> @ ./errorshow.jl:93 [inlined]
> [40] showvalue(io::IOContext{IOBuffer}, e::Tuple{MethodError, Vector{Union{Ptr{Nothing}, Base.InterpreterIP}}})
> @ Logging ~/.julia/juliaup/julia-1.10.4+0.x64.linux.gnu/share/julia/stdlib/v1.10/Logging/src/ConsoleLogger.jl:56
> [41] handle_message(logger::Logging.ConsoleLogger, level::Base.CoreLogging.LogLevel, message::Any, _module::Any, group::Any, id::Any, filepath::Any, line::Any; kwargs...)
> @ Logging ~/.julia/juliaup/julia-1.10.4+0.x64.linux.gnu/share/julia/stdlib/v1.10/Logging/src/ConsoleLogger.jl:134
> [42] invokelatest(::Any, ::Any, ::Vararg{Any}; kwargs::@Kwargs{exception::Tuple{MethodError, Vector{Union{Ptr{Nothing}, Base.InterpreterIP}}}})
> @ Base ./essentials.jl:894
> [43] macro expansion
> @ ./logging.jl:377 [inlined]
> [44] prompt!(term::REPL.Terminals.TextTerminal, prompt::REPL.LineEdit.ModalInterface, s::REPL.LineEdit.MIState)
> @ REPL.LineEdit ~/.julia/juliaup/julia-1.10.4+0.x64.linux.gnu/share/julia/stdlib/v1.10/REPL/src/LineEdit.jl:2751
> [45] run_interface(terminal::REPL.Terminals.TextTerminal, m::REPL.LineEdit.ModalInterface, s::REPL.LineEdit.MIState)
> @ REPL.LineEdit ~/.julia/juliaup/julia-1.10.4+0.x64.linux.gnu/share/julia/stdlib/v1.10/REPL/src/LineEdit.jl:2651
> [46] run_frontend(repl::REPL.LineEditREPL, backend::REPL.REPLBackendRef)
> @ REPL ~/.julia/juliaup/julia-1.10.4+0.x64.linux.gnu/share/julia/stdlib/v1.10/REPL/src/REPL.jl:1312
> [47] (::REPL.var"#62#68"{REPL.LineEditREPL, REPL.REPLBackendRef})()
> @ REPL ~/.julia/juliaup/julia-1.10.4+0.x64.linux.gnu/share/julia/stdlib/v1.10/REPL/src/REPL.jl:386
> 
> caused by: MethodError: reducing over an empty collection is not allowed; consider supplying `init` to the reducer
> Stacktrace:
> [1] reduce_empty(op::Base.BottomRF{typeof(min)}, ::Type{Union{}})
> @ Base ./reduce.jl:360
> [2] reduce_empty_iter(op::Base.BottomRF{typeof(min)}, itr::Tuple{}, ::Base.HasEltype)
> @ Base ./reduce.jl:384
> [3] reduce_empty_iter(op::Base.BottomRF{typeof(min)}, itr::Tuple{})
> @ Base ./reduce.jl:383
> [4] foldl_impl(op::Base.BottomRF{typeof(min)}, nt::Base._InitialValue, itr::Tuple{})
> @ Base ./reduce.jl:49
> [5] mapfoldl_impl(f::typeof(identity), op::typeof(min), nt::Base._InitialValue, itr::Tuple{})
> @ Base ./reduce.jl:44
> [6] mapfoldl(f::Function, op::Function, itr::Tuple{}; init::Base._InitialValue)
> @ Base ./reduce.jl:175
> [7] mapfoldl
> @ ./reduce.jl:175 [inlined]
> [8] mapreduce(f::Function, op::Function, itr::Tuple{})
> @ Base ./reduce.jl:307
> [9] minimum(a::Tuple{}; kw::@Kwargs{})
> @ Base ./reduce.jl:796
> [10] in(A::Char, Interval::Tuple{})
> @ Main ./REPL[7]:1
> [11] escape_string(io::IOBuffer, s::String, esc::Tuple{Char, Char}; keep::Tuple{})
> @ Base ./strings/io.jl:411
> [12] escape_string
> @ ./strings/io.jl:406 [inlined]
> [13] print_quoted
> @ ./strings/io.jl:440 [inlined]
> [14] show(io::IOBuffer, s::String)
> @ Base ./strings/io.jl:197
> [15] sprint(f::Function, args::String; context::Nothing, sizehint::Int64)
> @ Base ./strings/io.jl:114
> [16] repr(x::String; context::Nothing)
> @ Base ./strings/io.jl:286
> [17] repr
> @ ./strings/io.jl:286 [inlined]
> [18] show_sym(io::IOBuffer, sym::Symbol; allow_macroname::Bool)
> @ Base ./show.jl:1747
> [19] show_sym
> @ ./show.jl:1740 [inlined]
> [20] (::REPL.REPLCompletions.var"#3#8")(io::IOBuffer, s::Symbol)
> @ REPL.REPLCompletions ~/.julia/juliaup/julia-1.10.4+0.x64.linux.gnu/share/julia/stdlib/v1.10/REPL/src/REPLCompletions.jl:141
> [21] sprint(f::Function, args::Symbol; context::Nothing, sizehint::Int64)
> @ Base ./strings/io.jl:114
> [22] sprint
> @ ./strings/io.jl:107 [inlined]
> [23] #2
> @ ./none:0 [inlined]
> [24] iterate
> @ ./generator.jl:47 [inlined]
> [25] _collect(::Type{String}, itr::Base.Generator{Base.Iterators.Filter{REPL.REPLCompletions.var"#4#9"{String}, Vector{Symbol}}, REPL.REPLCompletions.var"#2#7"}, isz::Base.SizeUnknown)
> @ Base ./array.jl:702
> [26] collect
> @ ./array.jl:694 [inlined]
> [27] filtered_mod_names(ffunc::Function, mod::Module, name::String, all::Bool, imported::Bool)
> @ REPL.REPLCompletions ~/.julia/juliaup/julia-1.10.4+0.x64.linux.gnu/share/julia/stdlib/v1.10/REPL/src/REPLCompletions.jl:141
> [28] filtered_mod_names
> @ ~/.julia/juliaup/julia-1.10.4+0.x64.linux.gnu/share/julia/stdlib/v1.10/REPL/src/REPLCompletions.jl:138 [inlined]
> [29] complete_symbol(ex::Any, name::String, ffunc::Any, context_module::Module)
> @ REPL.REPLCompletions ~/.julia/juliaup/julia-1.10.4+0.x64.linux.gnu/share/julia/stdlib/v1.10/REPL/src/REPLCompletions.jl:185
> [30] complete_identifiers!(suggestions::Vector{REPL.REPLCompletions.Completion}, ffunc::Any, context_module::Module, string::String, name::String, pos::Int64, dotpos::Int64, startpos::Int64; comp_keywords::Bool)
> @ REPL.REPLCompletions ~/.julia/juliaup/julia-1.10.4+0.x64.linux.gnu/share/julia/stdlib/v1.10/REPL/src/REPLCompletions.jl:1081
> [31] complete_identifiers!
> @ ~/.julia/juliaup/julia-1.10.4+0.x64.linux.gnu/share/julia/stdlib/v1.10/REPL/src/REPLCompletions.jl:983 [inlined]
> [32] completions(string::String, pos::Int64, context_module::Module, shift::Bool)
> @ REPL.REPLCompletions ~/.julia/juliaup/julia-1.10.4+0.x64.linux.gnu/share/julia/stdlib/v1.10/REPL/src/REPLCompletions.jl:1299
> [33] complete_line(c::REPL.REPLCompletionProvider, s::REPL.LineEdit.PromptState, mod::Module)
> @ REPL ~/.julia/juliaup/julia-1.10.4+0.x64.linux.gnu/share/julia/stdlib/v1.10/REPL/src/REPL.jl:545
> [34] complete_line(s::REPL.LineEdit.PromptState, repeats::Int64, mod::Module)
> @ REPL.LineEdit ~/.julia/juliaup/julia-1.10.4+0.x64.linux.gnu/share/julia/stdlib/v1.10/REPL/src/LineEdit.jl:376
> [35] complete_line(s::REPL.LineEdit.MIState)
> @ REPL.LineEdit ~/.julia/juliaup/julia-1.10.4+0.x64.linux.gnu/share/julia/stdlib/v1.10/REPL/src/LineEdit.jl:367
> [36] edit_tab(s::REPL.LineEdit.MIState, jump_spaces::Bool, delete_trailing::Bool)
> @ REPL.LineEdit ~/.julia/juliaup/julia-1.10.4+0.x64.linux.gnu/share/julia/stdlib/v1.10/REPL/src/LineEdit.jl:2320
> [37] edit_tab
> @ ~/.julia/juliaup/julia-1.10.4+0.x64.linux.gnu/share/julia/stdlib/v1.10/REPL/src/LineEdit.jl:2320 [inlined]
> [38] (::REPL.LineEdit.var"#114#170")(::REPL.LineEdit.MIState, ::Any, ::Vararg{Any})
> @ REPL.LineEdit ~/.julia/juliaup/julia-1.10.4+0.x64.linux.gnu/share/julia/stdlib/v1.10/REPL/src/LineEdit.jl:2366
> [39] #invokelatest#2
> @ ./essentials.jl:892 [inlined]
> [40] invokelatest
> @ ./essentials.jl:889 [inlined]
> [41] (::REPL.LineEdit.var"#27#28"{REPL.LineEdit.var"#114#170", String})(s::Any, p::Any)
> @ REPL.LineEdit ~/.julia/juliaup/julia-1.10.4+0.x64.linux.gnu/share/julia/stdlib/v1.10/REPL/src/LineEdit.jl:1612
> [42] prompt!(term::REPL.Terminals.TextTerminal, prompt::REPL.LineEdit.ModalInterface, s::REPL.LineEdit.MIState)
> @ REPL.LineEdit ~/.julia/juliaup/julia-1.10.4+0.x64.linux.gnu/share/julia/stdlib/v1.10/REPL/src/LineEdit.jl:2749
> [43] run_interface(terminal::REPL.Terminals.TextTerminal, m::REPL.LineEdit.ModalInterface, s::REPL.LineEdit.MIState)
> @ REPL.LineEdit ~/.julia/juliaup/julia-1.10.4+0.x64.linux.gnu/share/julia/stdlib/v1.10/REPL/src/LineEdit.jl:2651
> [44] run_frontend(repl::REPL.LineEditREPL, backend::REPL.REPLBackendRef)
> @ REPL ~/.julia/juliaup/julia-1.10.4+0.x64.linux.gnu/share/julia/stdlib/v1.10/REPL/src/REPL.jl:1312
> [45] (::REPL.var"#62#68"{REPL.LineEditREPL, REPL.REPLBackendRef})()
> @ REPL ~/.julia/juliaup/julia-1.10.4+0.x64.linux.gnu/share/julia/stdlib/v1.10/REPL/src/REPL.jl:386
> ERROR: TaskFailedException
> Stacktrace:
> [1] try_yieldto(undo::typeof(Base.ensure_rescheduled))
> @ Base ./task.jl:931
> [2] wait()
> @ Base ./task.jl:995
> [3] wait(c::Base.GenericCondition{ReentrantLock}; first::Bool)
> @ Base ./condition.jl:130
> [4] wait
> @ ./condition.jl:125 [inlined]
> [5] take_buffered(c::Channel{Any})
> @ Base ./channels.jl:477
> [6] take!
> @ ./channels.jl:471 [inlined]
> [7] repl_backend_loop(backend::REPL.REPLBackend, get_module::Function)
> @ REPL ~/.julia/juliaup/julia-1.10.4+0.x64.linux.gnu/share/julia/stdlib/v1.10/REPL/src/REPL.jl:241
> [8] start_repl_backend(backend::REPL.REPLBackend, consumer::Any; get_module::Function)
> @ REPL ~/.julia/juliaup/julia-1.10.4+0.x64.linux.gnu/share/julia/stdlib/v1.10/REPL/src/REPL.jl:231
> [9] run_repl(repl::REPL.AbstractREPL, consumer::Any; backend_on_current_task::Bool, backend::Any)
> @ REPL ~/.julia/juliaup/julia-1.10.4+0.x64.linux.gnu/share/julia/stdlib/v1.10/REPL/src/REPL.jl:389
> [10] run_repl(repl::REPL.AbstractREPL, consumer::Any)
> @ REPL ~/.julia/juliaup/julia-1.10.4+0.x64.linux.gnu/share/julia/stdlib/v1.10/REPL/src/REPL.jl:375
> [11] fatal: error thrown and no exception handler available.
> MethodError(f=Base.reduce_empty, args=(typeof(Base.min)(), Core.TypeofBottom()), world=0x0000000000007ae2)
> jl_method_error_bare at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-10/src/gf.c:2208
> jl_method_error at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-10/src/gf.c:2226
> jl_lookup_generic_ at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-10/src/gf.c:3058 [inlined]
> ijl_apply_generic at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-10/src/gf.c:3073
> reduce_empty at ./reduce.jl:360
> reduce_empty_iter at ./reduce.jl:384
> reduce_empty_iter at ./reduce.jl:383
> foldl_impl at ./reduce.jl:49
> mapfoldl_impl at ./reduce.jl:44
> unknown function (ip: 0x7b0bb0306af2)
> _jl_invoke at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-10/src/gf.c:2895 [inlined]
> ijl_apply_generic at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-10/src/gf.c:3077
> #mapfoldl#298 at ./reduce.jl:175
> mapfoldl at ./reduce.jl:175 [inlined]
> #mapreduce#302 at ./reduce.jl:307 [inlined]
> mapreduce at ./reduce.jl:307
> #minimum#313 at ./reduce.jl:796
> minimum at ./reduce.jl:796
> in at ./REPL[7]:1
> #escape_string#505 at ./strings/io.jl:411
> escape_string at ./strings/io.jl:406 [inlined]
> print_quoted at ./strings/io.jl:440 [inlined]
> show at ./strings/io.jl:197
> unknown function (ip: 0x7b0bb0347109)
> _jl_invoke at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-10/src/gf.c:2895 [inlined]
> ijl_apply_generic at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-10/src/gf.c:3077
> #sprint#501 at ./strings/io.jl:114
> sprint at ./strings/io.jl:107
> #repr#504 at ./strings/io.jl:286
> repr at ./strings/io.jl:286
> #show_sym#549 at ./show.jl:1747
> show_sym at ./show.jl:1740 [inlined]
> show_type_name at ./show.jl:1054
> show_datatype at ./show.jl:1129
> show_datatype at ./show.jl:1077 [inlined]
> _show_type at ./show.jl:961
> show at ./show.jl:953
> print at ./strings/io.jl:35
> unknown function (ip: 0x7b0bb03613f9)
> _jl_invoke at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-10/src/gf.c:2895 [inlined]
> ijl_apply_generic at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-10/src/gf.c:3077
> print at ./strings/io.jl:46
> _jl_invoke at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-10/src/gf.c:2895 [inlined]
> ijl_apply_generic at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-10/src/gf.c:3077
> jl_apply at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-10/src/julia.h:1982 [inlined]
> do_apply at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-10/src/builtins.c:768
> #with_output_color#994 at ./util.jl:78
> _jl_invoke at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-10/src/gf.c:2895 [inlined]
> ijl_apply_generic at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-10/src/gf.c:3077
> jl_apply at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-10/src/julia.h:1982 [inlined]
> do_apply at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-10/src/builtins.c:768
> with_output_color at ./util.jl:73
> _jl_invoke at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-10/src/gf.c:2895 [inlined]
> ijl_apply_generic at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-10/src/gf.c:3077
> jl_apply at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-10/src/julia.h:1982 [inlined]
> do_apply at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-10/src/builtins.c:768
> #printstyled#995 at ./util.jl:141
> _jl_invoke at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-10/src/gf.c:2895 [inlined]
> ijl_apply_generic at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-10/src/gf.c:3077
> jl_apply at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-10/src/julia.h:1982 [inlined]
> do_apply at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-10/src/builtins.c:768
> printstyled at ./util.jl:141
> _jl_invoke at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-10/src/gf.c:2895 [inlined]
> ijl_apply_generic at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-10/src/gf.c:3077
> jl_apply at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-10/src/julia.h:1982 [inlined]
> do_apply at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-10/src/builtins.c:768
> #print_within_stacktrace#557 at ./show.jl:2501
> print_within_stacktrace at ./show.jl:2499 [inlined]
> show_signature_function at ./show.jl:2493
> #show_tuple_as_call#558 at ./show.jl:2526
> show_tuple_as_call at ./show.jl:2507 [inlined]
> show_spec_sig at ./stacktraces.jl:265
> show_spec_linfo at ./stacktraces.jl:232
> print_stackframe at ./errorshow.jl:742
> print_stackframe at ./errorshow.jl:706
> #show_full_backtrace#942 at ./errorshow.jl:605
> show_full_backtrace at ./errorshow.jl:598 [inlined]
> show_backtrace at ./errorshow.jl:802
> #showerror#666 at ./task.jl:83
> showerror at ./task.jl:80
> unknown function (ip: 0x7b0bb03a00a5)
> _jl_invoke at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-10/src/gf.c:2895 [inlined]
> ijl_apply_generic at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-10/src/gf.c:3077
> show_exception_stack at ./errorshow.jl:975
> display_error at ./client.jl:111
> unknown function (ip: 0x7b0bb038c009)
> _jl_invoke at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-10/src/gf.c:2895 [inlined]
> ijl_apply_generic at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-10/src/gf.c:3077
> display_error at ./client.jl:114
> unknown function (ip: 0x7b0bb038b845)
> _jl_invoke at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-10/src/gf.c:2895 [inlined]
> ijl_apply_generic at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-10/src/gf.c:3077
> jl_apply at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-10/src/julia.h:1982 [inlined]
> jl_f__call_latest at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-10/src/builtins.c:812
> #invokelatest#2 at ./essentials.jl:892 [inlined]
> invokelatest at ./essentials.jl:889 [inlined]
> _start at ./client.jl:554
> jfptr__start_82729.1 at /home/chris/.julia/juliaup/julia-1.10.4+0.x64.linux.gnu/lib/julia/sys.so (unknown line)
> _jl_invoke at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-10/src/gf.c:2895 [inlined]
> ijl_apply_generic at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-10/src/gf.c:3077
> jl_apply at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-10/src/julia.h:1982 [inlined]
> true_main at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-10/src/jlapi.c:582
> jl_repl_entrypoint at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-10/src/jlapi.c:731
> main at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-10/cli/loader_exe.c:58
> unknown function (ip: 0x7b0bb0a2a1c9)
> __libc_start_main at /lib/x86_64-linux-gnu/libc.so.6 (unknown line)
> unknown function (ip: 0x4010b8)
> 
> ```

---

<div class="post-metadata">

**Author:** ![fredrikekre](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/fredrikekre/32/1688_2.png) [@fredrikekre](https://discourse.julialang.org/u/fredrikekre)\
**Post date:** [August 7, 2024, 10:13am UTC](https://discourse.julialang.org/t/is-this-type-piracy-and-is-the-resulting-crash-expected/117914/2 "2024-08-07T10:13:07Z")

</div>

Type piracy happens if you don’t own the function or any of the argument types.

> [@cmarcotte](#):
>
> `∈(A,Interval)`

In this case you don’t own the function (you import Base’s `∈` ) and you don’t own any of the types of the arguments (`Any` and `Any`) so yes this is type piracy.

> [@cmarcotte](#):
>
> `∈(A::T, Interval::Tuple{T,T}) where {T}`)

This is also type piracy with the same argumentation (you don’t own `∈` or any of `Any` and `Tuple{Any, Any}`).

The “punishment” for piracy is pretty unpredictable and depends on if any other code happen to hit your pirated method etc.

---

<div class="post-metadata">

**Author:** ![mikmoore](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/mikmoore/32/31109_2.png) [@mikmoore](https://discourse.julialang.org/u/mikmoore)\
**Post date:** [August 7, 2024, 3:03pm UTC](https://discourse.julialang.org/t/is-this-type-piracy-and-is-the-resulting-crash-expected/117914/3 "2024-08-07T15:03:05Z")

</div>

A typical remedy here is to simply not overload `Base.∈`. You can still create your own `MyModule.∈` and it will not conflict.

Another remedy would be to define your own `Interval` type and define `Base.∈(::Any, ::Interval)`. Since you would own `Interval`, this would not be piracy and would not cause conflicts. More simply, packages like Intervals.jl appear to already provide interval types you could use.