Inference problem with findall

General Usage
1

Hi, the following code is not correctly inferred in julia 1.7.0.

function test()
    k = 1
    if k == 1
        k = 2
    end
    return findall(x -> x >= k, [1])
end

julia> @code_warntype(test())
MethodInstance for test()
  from test() in Main at none:1
Arguments
  #self#::Core.Const(test)
Locals
  #17::var"#17#18"
  k@_3::Core.Box
  k@_4::Union{}
Body::Any
1 ─       Core.NewvarNode(:(#17))
│         (k@_3 = Core.Box())
│         Core.setfield!(k@_3, :contents, 1)
│   %4  = Core.isdefined(k@_3, :contents)::Bool
└──       goto #3 if not %4
2 ─       goto #4
3 ─       Core.NewvarNode(:(k@_4))
└──       k@_4
4 ┄ %9  = Core.getfield(k@_3, :contents)::Any
│   %10 = (%9 == 1)::Any
└──       goto #6 if not %10
5 ─       Core.setfield!(k@_3, :contents, 2)
6 ┄       (#17 = %new(Main.:(var"#17#18"), k@_3))
│   %14 = #17::var"#17#18"
│   %15 = Base.vect(1)::Vector{Int64}
│   %16 = Main.findall(%14, %15)::Any
└──       return %16

It is correctly inferred in julia 1.6.1 to an Int64[].
Is it expected or should I file an issue ?

2

Hi @etienne_dg , I am getting correct type inferencing with this function on my Mac (macOS Catalina 10.15.7).
Here is the output and details of my Julia installation:

➜ julia
               _
   _       _ _(_)_     |  Documentation: https://docs.julialang.org
  (_)     | (_) (_)    |
   _ _   _| |_  __ _   |  Type "?" for help, "]?" for Pkg help.
  | | | | | | |/ _` |  |
  | | |_| | | | (_| |  |  Version 1.7.0 (2021-11-30)
 _/ |\__'_|_|_|\__'_|  |  Official https://julialang.org/ release
|__/                   |

julia> function test()
           k = 1
           if k == 1
               k = 2
           end
           return findall(x -> x >= k, [1])
       end
test (generic function with 1 method)

julia> test() |> typeof
Vector{Int64} (alias for Array{Int64, 1})

Also, I get this as the output of the function

julia> test()
Int64[]
1 Like
3

Strange, I built this as a MWE of failing tests in Graphs.jl, and it fails for every OS.

I tested my example on Ubuntu 20.04

4

What do you get if you try @code_warntype(test()) or @inferred test()?
I get the same as you with :

julia> test() |> typeof
Vector{Int64} (alias for Array{Int64, 1})
5

This is not about findall but captured values in closures.

1 Like
6

I thought about it but it was working on julia 1.6, what is going on 1.7 ?