Allocation at nonexisting line

[ForceBru]

I've just wasted like 2 hours trying to debug some code, only to find that the allocation happens at a line that doesn't exist. Also seems to always be line 139, irrespective of the number of line in my code.

This code has 83 lines:

import Pkg
Pkg.activate(temp=true)
Pkg.add(name="AllocCheck", version="0.2.0")

import Random
using AllocCheck

const AV{T} = AbstractVector{T}

struct Prealloc{T<:Real}
	As::Vector{T}
	Bs::Vector{T}
	Cs::Vector{T}
	qs::Vector{T}
	function Prealloc(As::AV{T}, Bs::AV{T}, Cs::AV{T}, qs::AV{T}) where T<:Real
		@warn "Preallocating" length(As)
		@assert length(As) == length(Bs) == length(Cs) == length(qs)
		new{T}(As, Bs, Cs, qs)
	end
end

Prealloc{T}(K::Integer) where T<:Real =
	Prealloc(zeros(T, K), zeros(T, K), zeros(T, K), zeros(T, K))

Prealloc(K::Integer) = Prealloc{Float64}(K)

@check_allocs function step_mle!(
	ps::AV{T}, ms::AV{T}, ts::AV{T}, data::AV{<:Real},
	l2norm::Bool, lmb::Real, aux::Prealloc{T}
) where T<:Real
	As, Bs, Cs, qs = aux.As, aux.Bs, aux.Cs, aux.qs
	As .= zero(T); Bs .= zero(T); Cs .= zero(T)
	nothing
end

struct Mixture{T<:Real}
	ps::Vector{T}
	ms::Vector{T}
	ts::Vector{T}
	function Mixture(ps::AV{T}, ms::AV{T}, ts::AV{T}) where T<:Real
		@assert length(ps) == length(ms) == length(ts)	
		new{T}(ps, ms, ts)
	end
end

rand_categorical(rng::Random.AbstractRNG, weights::AV)::Integer =
	findfirst(cumsum(weights) .> rand(rng))

Random.rand(
	rng::Random.AbstractRNG, d::Mixture{T}
) where T<:Real = begin
	k = rand_categorical(rng, d.ps);
	randn(rng, T) / d.ts[k] + d.ms[k]
end

function Random.rand(d::Mixture, n::Integer)
	rng = Random.default_rng()
	[rand(rng, d) for _ in 1:n]
end

@check_allocs function fit_basic!(
	mix::Mixture{T}, data::AV{<:Real};
	niter::Integer=300,
	aux::Prealloc{T}
) where T<:Real
	ps, ms, ts = mix.ps, mix.ms, mix.ts
	for ep in 1:niter
		step_mle!(ps, ms, ts, data, true, 0.0, aux) # LINE 68
	end
end

let
	K = 50
	mix0 = Mixture(ones(K) ./ K, randn(K), rand(K))
	data = rand(mix0, 200);
	aux = Prealloc(K)

	try
		fit_basic!(mix0, data; aux, niter=2000)
	catch err
		@show err.errors[1]
	end
end

Running this:

> julia --version
julia version 1.11.1
> julia test.jl
  Activating new project at `/var/folders/61/p7f15sln0gxd7lwbr58cy6f00000gn/T/jl_oQS2Dn`
   Resolving package versions...
    Updating `/private/var/folders/61/p7f15sln0gxd7lwbr58cy6f00000gn/T/jl_oQS2Dn/Project.toml`
  [9b6a8646] + AllocCheck v0.2.0
    Updating `/private/var/folders/61/p7f15sln0gxd7lwbr58cy6f00000gn/T/jl_oQS2Dn/Manifest.toml`
  [9b6a8646] + AllocCheck v0.2.0
...
  [3f19e933] + p7zip_jll v17.4.0+2
        Info Packages marked with ⌅ have new versions available but compatibility constraints restrict them from upgrading. To see why use `status --outdated -m`
┌ Warning: Preallocating
│   length(As) = 50
└ @ Main ~/Desktop/dev/test.jl:16
err.errors[1] = Allocating runtime call to "jl_f_getfield" in ./Base.jl:49
  | getproperty(x, f::Symbol) = (@inline; getfield(x, f))

Stacktrace:
 [1] getproperty
   @ ./Base.jl:49 [inlined]
 [2] step_mle!(ps::Vector{Float64}, ms::Vector{Float64}, ts::Vector{Float64}, data::Vector{Float64}, l2norm::Bool, lmb::Float64, aux::Prealloc{Float64})
   @ Main ~/Desktop/dev/test.jl:139
 [3] var"##fit_basic!#239"(mix::Mixture{Float64}, data::Vector{Float64}, niter::Int64, aux::Prealloc{Float64})
   @ Main ~/Desktop/dev/test.jl:68

> 

It says @ Main ~/Desktop/dev/test.jl:139, but there's no line 139! Same error happens in a longer file that I can't post here, also at line 139, no matter how I reorganize the code, no matter what code happens to be at line 139.