I don’t quite understand the type instability in the following MWE.

```
julia> function foo(A::AbstractArray{T, 2}) where T
w = Int(sqrt(size(A, 1)))
n = size(A, 3)
A = reshape(A, w, w, n)
end
foo (generic function with 1 method)
julia> x = rand(100, 4);
julia> @code_warntype foo(x)
Variables:
#self# <optimized out>
A@_2::Array{Float64,2}
w::Int64
n::Int64
A@_5::Any
Body:
begin
A@_5::Any = A@_2::Array{Float64,2}
SSAValue(1) = (Base.arraysize)(A@_5::Array{Float64,2}, 1)::Int64
SSAValue(2) = (Base.Math.sqrt_llvm)((Base.sitofp)(Float64, SSAValue(1))::Float64)::Float64
w::Int64 = $(Expr(:invoke, MethodInstance for convert(::Type{Int64}, ::Float64), :(Base.convert), Int64, SSAValue(2))) # line 3:
n::Int64 = (Base.arraysize)(A@_5::Array{Float64,2}, 3)::Int64 # line 4:
SSAValue(0) = $(Expr(:invoke, MethodInstance for reshape(::Array{Float64,2}, ::Tuple{Int64,Int64,Int64}), :(Base.reshape), :(A@_5::Array{Float64,2}), :((Core.tuple)(w, w, n)::Tuple{Int64,Int64,Int64})))
A@_5::Any = SSAValue(0)
return SSAValue(0)
end::Array{Float64,3}
```

Why the type of `A`

is `Any`

? Thanks!