Should I believe this Core.Box()?

[joa-quim]

In a debug session.
Note that D3_ becomes instantly a Core.Box() but the precedent line, which is virtually equal, gets assigned as expected.

[Mason]

Nowhere even close to enough information here to say for sure, but I assume this is because you’re rebinding D3_ in a closure somewhere else.

Observe:

julia> function foo_maker()
           x = 3 # <---- This will be boxed
           y = 4 # <---- This won't
           function ()
               x = x + y
           end
       end
foo_maker (generic function with 1 method)

julia> @code_typed foo_maker()
CodeInfo(
1 ─ %1 = Core.Box::Type{Core.Box}
│   %2 = %new(%1)::Core.Box
│        Core.setfield!(%2, :contents, 3)::Int64
│   %4 = π (4, Int64)
│   %5 = %new(var"#13#14"{Int64}, %4, %2)::var"#13#14"{Int64}
└──      return %5
) => var"#13#14"{Int64}

[joa-quim]

Thanks for looking. I thought in something like that might be happening and renamed that variable such that it’s only used in that function. And @code_typed has no references to Core.Box

@code_typed boxplot(vvv, separator=true, show=1)
CodeInfo(
1 ─       goto #3 if not false
2 ─       nothing::Nothing
3 ┄ %3  = $(Expr(:foreigncall, :(:jl_alloc_array_1d), Vector{Real}, svec(Any, Int64), 0, :(:ccall), Vector{Real}, 0, 0))::Vector{Real}
└──       goto #5 if not false
4 ─       nothing::Nothing
5 ┄ %6  = π (true, Bool)
└──       goto #7 if not false
6 ─       nothing::Nothing
7 ┄ %9  = π (0.75, Float64)
└──       goto #9 if not false
8 ─       nothing::Nothing
9 ┄ %12 = π (false, Bool)
│   %13 = Base.getfield(@_2, 1)::Bool
│   %14 = Base.getfield(@_2, 2)::Int64
│   %15 = %new(NamedTuple{(:separator, :show), Tuple{Bool, Int64}}, %13, %14)::NamedTuple{(:separator, :show), Tuple{Bool, Int64}}
│   %16 = %new(Base.Pairs{Symbol, Integer, Tuple{Symbol, Symbol}, NamedTuple{(:separator, :show), Tuple{Bool, Int64}}}, %15, (:separator, :show))::Base.Pairs{Symbol, Integer, Tuple{Symbol, Symbol}, NamedTuple{(:separator, :show), Tuple{Bool, Int64}}}
│   %17 = invoke GMT.:(var"#boxplot#817")(%3::Vector{Real}, %6::Bool, %9::Float64, %12::Bool, %16::Base.Pairs{Symbol, Integer, Tuple{Symbol, Symbol}, NamedTuple{(:separator, :show), Tuple{Bool, Int64}}}, @_3::typeof(boxplot), data::Vector{Vector{Vector{Float64}}})::Any
└──       return %17
) => Any