Use gofumpt instead of gofmt

[MrAlias]

gofumpt is a stricter version of gofmt.

Notably:

No empty lines following an assignment operator

func foo() {
    foo :=
        "bar"
}

func foo() {
	foo := "bar"
}

No empty lines around function bodies

func foo() {

	println("bar")

}

func foo() {
	println("bar")
}

Functions should separate ) { where the indentation helps readability

func foo(s string,
	i int) {
	println("bar")
}

// With an empty line it's slightly better, but still not great.
func bar(s string,
	i int) {

	println("bar")
}

func foo(s string,
	i int,
) {
	println("bar")
}

// With an empty line it's slightly better, but still not great.
func bar(s string,
	i int,
) {
	println("bar")
}

No empty lines around a lone statement (or comment) in a block

if err != nil {

	return err
}

if err != nil {
	return err
}

No empty lines before a simple error check

foo, err := processFoo()

if err != nil {
	return err
}

foo, err := processFoo()
if err != nil {
	return err
}

Composite literals should use newlines consistently

// A newline before or after an element requires newlines for the opening and
// closing braces.
var ints = []int{1, 2,
	3, 4}

// A newline between consecutive elements requires a newline between all
// elements.
var matrix = [][]int{
	{1},
	{2}, {
		3,
	},
}

var ints = []int{
	1, 2,
	3, 4,
}

var matrix = [][]int{
	{1},
	{2},
	{
		3,
	},
}

Empty field lists should use a single line

var V interface {
} = 3

type T struct {
}

func F(
)

var V interface{} = 3

type T struct{}

func F()

std imports must be in a separate group at the top

import (
	"foo.com/bar"

	"io"

	"io/ioutil"
)

import (
	"io"
	"io/ioutil"

	"foo.com/bar"
)

Short case clauses should take a single line

switch c {
case 'a', 'b',
	'c', 'd':
}

switch c {
case 'a', 'b', 'c', 'd':
}

Multiline top-level declarations must be separated by empty lines

func foo() {
	println("multiline foo")
}
func bar() {
	println("multiline bar")
}

func foo() {
	println("multiline foo")
}

func bar() {
	println("multiline bar")
}

Single var declarations should not be grouped with parentheses

var (
	foo = "bar"
)

var foo = "bar"

Contiguous top-level declarations should be grouped together

var nicer = "x"
var with = "y"
var alignment = "z"

var (
	nicer     = "x"
	with      = "y"
	alignment = "z"
)

Simple var-declaration statements should use short assignments

var s = "somestring"

s := "somestring"

The -s code simplification flag is enabled by default

var _ = [][]int{[]int{1}}

var _ = [][]int{{1}}

Octal integer literals should use the 0o prefix on modules using Go 1.13 and later

const perm = 0755

const perm = 0o755

Comments which aren't Go directives should start with a whitespace

//go:noinline

//Foo is awesome.
func Foo() {}

//go:noinline

// Foo is awesome.
func Foo() {}

Composite literals should not have leading or trailing empty lines

var _ = []string{

	"foo",

}

var _ = map[string]string{

	"foo": "bar",

}

var _ = []string{
	"foo",
}

var _ = map[string]string{
	"foo": "bar",
}

Field lists should not have leading or trailing empty lines

type Person interface {

	Name() string

	Age() int

}

type ZeroFields struct {

	// No fields are needed here.

}

type Person interface {
	Name() string

	Age() int
}

type ZeroFields struct {
	// No fields are needed here.
}

[pellared]

I love gofumpt and there is no need to convince me (I use it since v0.1.0) 😉

PS. I see that there is still some formatting missing, but the CI anyway will make sure that you will fix it.

[codecov]

Codecov Report

Merging #4623 (f73d7c6) into main (c047088) will increase coverage by 0.0%.
Report is 1 commits behind head on main.
The diff coverage is 50.0%.

@@          Coverage Diff          @@
##            main   #4623   +/-   ##
=====================================
  Coverage   81.3%   81.3%           
=====================================
  Files        222     222           
  Lines      17683   17682    -1     
=====================================
+ Hits       14390   14391    +1     
+ Misses      2993    2991    -2     
  Partials     300     300           

Files	Coverage Δ
bridge/opentracing/bridge.go	63.7% <ø> (ø)
bridge/opentracing/internal/mock.go	67.0% <ø> (ø)
bridge/opentracing/wrapper.go	100.0% <ø> (ø)
...otlpmetric/otlpmetricgrpc/internal/otest/client.go	97.1% <ø> (ø)
...otlpmetric/otlpmetrichttp/internal/otest/client.go	97.1% <ø> (ø)
exporters/otlp/otlptrace/exporter.go	66.6% <100.0%> (ø)
exporters/stdout/stdoutmetric/exporter.go	90.1% <ø> (ø)
exporters/zipkin/internal/matchers/expectation.go	0.0% <ø> (ø)
internal/global/instruments.go	60.8% <ø> (ø)
internal/matchers/expectation.go	0.0% <ø> (ø)
... and 18 more