Excluding parametric restrictions allow for defining subtypes which are not truely subtypes

[omus]

When applying a restriction to a abstract type parameter a subtype it is possible to define a subtype that is not actually a subtype:

julia> abstract type AbstractFoo{T<:Integer} end

julia> struct Foo1{T} <: AbstractFoo{T} end

julia> struct Foo2{T <: Integer} <: AbstractFoo{T} end

julia> Foo1 <: AbstractFoo
false

julia> Foo2 <: AbstractFoo
true

I believe this to be a bug as by definition Foo1 is a subtype of AbstractFoo. Similarly definitions where the subtype attempts to expand the scope of the parameter should probably be disallowed:

struct Foo3{T <: Real} <: AbstractFoo{T} end

[vtjnash]

You aren't making a broken subtype, just defining a primary alias that isn't a subtype of the other primary alias:

julia> abstract type AbstractFoo{T<:Integer} end

julia> struct Foo2{T <: Integer} <: AbstractFoo{T} end

julia> (Foo2{T} where T) <: AbstractFoo
false

julia> (Foo2{T} where T) <: (AbstractFoo{T} where T)
true

[JeffBezanson]

Duplicate of #9441