main.go

package main

import (
	"fmt"
	"reflect"
)

func Foo(int) {}
func Bar(int) {}

type S struct{}

func (s *S) M(int) {}

func main() {
	{
		rt := reflect.TypeOf(Foo)
		fmt.Println(rt, rt.Kind())

		rt2 := reflect.TypeOf(Bar)
		fmt.Println(rt2, rt2.Kind())

		rt3 := reflect.TypeOf(func(int) {})
		fmt.Println(rt3, rt3.Kind())

		rt4 := reflect.TypeOf(func(int) {})
		fmt.Println(rt4, rt4.Kind())

		rt5 := reflect.TypeOf(new(S).M)
		fmt.Println(rt5, rt5.Kind())

		fmt.Println("rt1 == rt2", rt == rt2)  // true
		fmt.Println("rt1 == rt3", rt == rt3)  // true
		fmt.Println("rt1 == rt4", rt == rt4)  // true
		fmt.Println("rt1 == rt5", rt == rt5)  // true
		fmt.Println("rt3 == rt4", rt3 == rt4) // true
	}

	{
		x := id(Foo)
		fmt.Println(x)

		x2 := id(Bar)
		fmt.Println(x2)

		x3 := id(func(int) {})
		fmt.Println(x3)

		x4 := id(func(int) {})
		fmt.Println(x4)

		x5 := id(new(S).M)
		fmt.Println(x5)

		x6 := id(Foo)
		fmt.Println(x6)

		x7 := id(new(S).M)
		fmt.Println(x7)

		fmt.Println("x1 == x2", x == x2)  // false
		fmt.Println("x1 == x3", x == x3)  // false
		fmt.Println("x1 == x4", x == x4)  // false
		fmt.Println("x1 == x5", x == x5)  // false
		fmt.Println("x1 == x6", x == x6)  // true
		fmt.Println("x1 == x7", x == x7)  // false
		fmt.Println("x3 == x4", x3 == x4) // false
		fmt.Println("x5 == x7", x5 == x7) // true
	}

	{
		type Foo struct{ Name string }
		type Bar struct{ Name string }

		x := id(Foo{})
		fmt.Println(x)

		x2 := id(Bar{})
		fmt.Println(x2)

		x3 := id(struct{ Name string }{})
		fmt.Println(x3)

		x4 := id(struct{ Name string }{})
		fmt.Println(x3)

		x5 := id(Foo{})
		fmt.Println(x5)

		fmt.Println("x1 == x2", x == x2)  // false
		fmt.Println("x1 == x3", x == x3)  // false
		fmt.Println("x1 == x4", x == x4)  // false
		fmt.Println("x1 == x5", x == x5)  // true
		fmt.Println("x3 == x4", x3 == x4) // true
	}
}

func id(ob any) ID {
	// see: reflect.TypeOf()
	x := ID{Type: reflect.TypeOf(ob)}
	if x.Type.Kind() == reflect.Func {
		x.pc = reflect.ValueOf(ob).Pointer()
	}
	return x
}

type ID struct {
	Type reflect.Type
	pc   uintptr
}

func (id *ID) Kind() reflect.Kind {
	return id.Type.Kind()
}