gofumpt -w foo.go
cmp foo.go foo.go.golden

gofumpt -d foo.go.golden
! stdout .

-- foo.go --
package p

var single = "foo"
var another = "bar"

const one = 'q'
const two = 'w'
const three = 'e'
const four = 'r'

var not = 'a'

var v1 = 's'
// comment, e.g. directive
var v2 = 'd'

var v1 = "mixed"
const c1 = "mixed"

// comment, e.g. directive
var v1 = 's'
var v2 = 'd'
var v3 = 'd'

const inline1 = "s1" // c1
const inline2 = "s2" // c2
const inline3 = "s3" // c3
-- foo.go.golden --
package p

var (
	single  = "foo"
	another = "bar"
)

const (
	one   = 'q'
	two   = 'w'
	three = 'e'
	four  = 'r'
)

var not = 'a'

var v1 = 's'

// comment, e.g. directive
var v2 = 'd'

var v1 = "mixed"

const c1 = "mixed"

// comment, e.g. directive
var v1 = 's'

var (
	v2 = 'd'
	v3 = 'd'
)

const (
	inline1 = "s1" // c1
	inline2 = "s2" // c2
	inline3 = "s3" // c3
)