constraint struct fields

main.go

package main

import (
	"fmt"
	"time"
)

type common struct {
	ID      string
	Created time.Time
}

type entity[T any] struct {
	common
	data T
}

type userEntity struct {
	common
	FirstName string
	LastName  string
}

type otherEntity struct {
	common
	FirstName string
	LastName  string
}

type Vector[T constraint] []T

type constraint interface {
	common | userEntity
}

func (v *Vector[T]) PrintID() {
	e := (*v)[0]
	fmt.Printf("hello %v", e.ID)
}

func main() {
	//	var v = Vector[otherEntity]{}
	var v = Vector[userEntity]{}

	v.PrintID()
}

maybe here

golang/go#48522

The Go compiler does not support accessing a struct field x.f where x is of type parameter type even if all types in the type parameter's type set have a field f. We may remove this restriction in a future release.
https://tip.golang.org/doc/go1.18#:~:text=The%20Go%20compiler%20does%20not%20support%20accessing%20a%20struct%20field%20x.f%20where%20x%20is%20of%20type%20parameter%20type%20even%20if%20all%20types%20in%20the%20type%20parameter%27s%20type%20set%20have%20a%20field%20f.%20We%20may%20remove%20this%20restriction%20in%20a%20future%20release.