Generics: How to use Type approximation for generic structs

[globalflea]

Was trying to play with generics and tried using type approximation in the following sample code below with compile errors.

My questions are:

1. How to use type approximation to a generic struct, see EmbedApprox
2. Hiow to create a struct that contains a type approximation to another struct, see Contain & Contain2

package main

import "fmt"

type Embed[T any] struct {
	AttrEmbed T
}

type EmbedApprox[T any] interface {
	~Embed[T] // A: compile error: invalid use of ~ (underlying type of Embed[T] is struct{AttrEmbed T})
}

type Contain[T EmbedApprox[T]] struct {
	Embed[T]
	AttrContain T
}

type EmbedApprox2[T any] interface {
	~struct{ AttrEmbed T } // compiles ok
}

type Contain2[T EmbedApprox2[T]] struct { // compiles ok
	Embed[T]
	AttrContain T
}

func main() {
	e := Embed[int]{AttrEmbed: 10}

	c := Contain[Embed[int]]{Embed[int]{AttrEmbed: 10}, AttrContain: 10} // compiles errors

	c2 := Contain2[Embed[int]]{Embed[int]{AttrEmbed: 10}, AttrContain: 10} // compiles errors

	fmt.Println(e, c)
}

Compilation errors:

# github.com/globalflea/trygenerics
./main.go:10:2: invalid use of ~ (underlying type of Embed[T] is struct{AttrEmbed T})
./main.go:30:15: cannot implement EmbedApprox[Embed[int]] (empty type set)
./main.go:30:27: cannot use Embed[int]{…} (value of type Embed[int]) as type Embed[Embed[int]] in struct literal
./main.go:30:65: mixture of field:value and value elements in struct literal
./main.go:32:2: c2 declared but not used
./main.go:32:17: Embed[int] does not implement EmbedApprox2[Embed[int]]
./main.go:32:29: cannot use Embed[int]{…} (value of type Embed[int]) as type Embed[Embed[int]] in struct literal
./main.go:32:67: mixture of field:value and value elements in struct literal