Mysterious Subtyping

General Usage
1

I have an abstract parent type PrimitiveBlock from package Yao.jl

In another package QuAlgorithmZoo.jl that depend on Yao.jl I defined a new type

struct QFTBlock{N} <: PrimitiveBlock{N,ComplexF64} end

Now I am using QuAlgorithmZoo like

using Yao
using Yao.Blocks
using QuAlgorithmZoo: QFTBlock

println(supertype(QFTBlock))

It will print Yao.Blocks.PrimitiveBlock{N,Complex{Float64}} where N just as expected.

But!

QFTBlock <: Yao.Blocks.PrimitiveBlock

will return false! why?

Note:

  • appear in both julia0.7 and julia1.0
  • I can not repeat this bug on another laptop.
2

It is related to keeping multiple version of same package Yao.jl, especially when developing multiple packages at the same time. Julia’s package loading is working in a wield way.