Limit completion to Field when completing inside a struct

[njkevlani]

Is it possible to limit completion to Field when completing inside a struct?

Example

Only a and b should be shown in the completion options.

Reproduce

Example Code

package main

import "fmt"

type testStruct struct {
	a int
	b int
}

func main() {
	s := testStruct{a: 10}
	fmt.Println(s)
}

Configs

• gopls config
• nvim-cmp config

[Shougo]

It seems LSP's problem instead of nvim-cmp.
nvim-cmp cannot detect the syntax.