gofumpt
go install mvdan.cc/gofumpt@latest
Enforce a stricter format than gofmt
, while being backwards compatible. That
is, gofumpt
is happy with a subset of the formats that gofmt
is happy with.
The tool is a modified fork of gofmt
, so it can be used as a drop-in
replacement. Running gofmt
after gofumpt
should be a no-op. For example:
gofumpt -l -w .
Some of the Go source files in this repository belong to the Go project.
The added formatting rules are in the format
package.
Beyond the added rules below, the tool differs from gofmt in the following ways:
- Vendor directories are skipped unless given as explicit arguments
- The added rules are not applied to generated Go files
- The
-r
rewrite feature is removed in favor ofgofmt -r
Added rules
No empty lines following an assignment operator
example
func foo() {
foo :=
"bar"
}
func foo() {
foo := "bar"
}
No empty lines at the beginning or end of a function
example
func foo() {
println("bar")
}
func foo() {
println("bar")
}
Functions using an empty line for readability should use a ) {
line instead
example
func foo(s string,
i int) {
println("bar")
}
func foo(s string,
i int,
) {
println("bar")
}
No empty lines around a lone statement (or comment) in a block
example
if err != nil {
return err
}
if err != nil {
return err
}
No empty lines before a simple error check
example
foo, err := processFoo()
if err != nil {
return err
}
foo, err := processFoo()
if err != nil {
return err
}
Composite literals should use newlines consistently
example
// 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
example
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
example
import (
"foo.com/bar"
"io"
"io/ioutil"
)
import (
"io"
"io/ioutil"
"foo.com/bar"
)
Short case clauses should take a single line
example
switch c {
case 'a', 'b',
'c', 'd':
}
switch c {
case 'a', 'b', 'c', 'd':
}
Multiline top-level declarations must be separated by empty lines
example
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
example
var (
foo = "bar"
)
var foo = "bar"
Contiguous top-level declarations should be grouped together
example
var nicer = "x"
var with = "y"
var alignment = "z"
var (
nicer = "x"
with = "y"
alignment = "z"
)
Simple var-declaration statements should use short assignments
example
var s = "somestring"
s := "somestring"
The -s
code simplification flag is enabled by default
example
var _ = [][]int{[]int{1}}
var _ = [][]int{{1}}
Octal integer literals should use the 0o
prefix on modules using Go 1.13 and later
example
const perm = 0755
const perm = 0o755
Comments which aren't Go directives should start with a whitespace
example
//go:noinline
//Foo is awesome.
func Foo() {}
//go:noinline
// Foo is awesome.
func Foo() {}
Composite literals should not have leading or trailing empty lines
example
var _ = []string{
"foo",
}
var _ = map[string]string{
"foo": "bar",
}
var _ = []string{
"foo",
}
var _ = map[string]string{
"foo": "bar",
}
Remove unnecessary empty lines from interfaces
example
type i interface {
// comment for a
a(x int) int
// comment between a and b
// comment for b
b(x int) int
// comment between b and c
c(x int) int
d(x int) int
// comment for e
e(x int) int
}
type i interface {
// comment for a
a(x int) int
// comment between a and b
// comment for b
b(x int) int
// comment between b and c
c(x int) int
d(x int) int
// comment for e
e(x int) int
}
-extra
Extra rules behind Adjacent parameters with the same type should be grouped together
example
func Foo(bar string, baz string) {}
func Foo(bar, baz string) {}
Installation
gofumpt
is a replacement for gofmt
, so you can simply go install
it as
described at the top of this README and use it.
When using an IDE or editor with Go integration based on gopls
,
it's best to configure the editor to use the gofumpt
support built into gopls
.
The instructions below show how to set up gofumpt
for some of the
major editors out there.
Visual Studio Code
Enable the language server following the official docs,
and then enable gopls's gofumpt
option. Note that VS Code will complain about
the gopls
settings, but they will still work.
"go.useLanguageServer": true,
"gopls": {
"formatting.gofumpt": true,
},
GoLand
GoLand doesn't use gopls
so it should be configured to use gofumpt
directly.
Once gofumpt
is installed, follow the steps below:
- Open Settings (File > Settings)
- Open the Tools section
- Find the File Watchers sub-section
- Click on the
+
on the right side to add a new file watcher - Choose Custom Template
When a window asks for settings, you can enter the following:
- File Types: Select all .go files
- Scope: Project Files
- Program: Select your
gofumpt
executable - Arguments:
-w $FilePath$
- Output path to refresh:
$FilePath$
- Working directory:
$ProjectFileDir$
- Environment variables:
GOROOT=$GOROOT$;GOPATH=$GOPATH$;PATH=$GoBinDirs$
To avoid unnecessary runs, you should disable all checkboxes in the Advanced section.
Vim-go
Ensure you are at least running version
v1.24,
and set up gopls
for formatting code with gofumpt
:
let g:go_fmt_command="gopls"
let g:go_gopls_gofumpt=1
Govim
With a new enough version of govim,
simply configure gopls
to use gofumpt
:
call govim#config#Set("Gofumpt", 1)
Emacs
For lsp-mode users:
(lsp-register-custom-settings
'(("gopls.gofumpt" t)))
For eglot users:
(setq-default eglot-workspace-configuration
'((:gopls . ((gofumpt . t)))))
Sublime Text
With ST4, install the Sublime Text LSP extension according to the documentation,
and enable gopls
's gofumpt
option in the LSP package settings,
including setting lsp_format_on_save
to true
.
"lsp_format_on_save": true,
"clients":
{
"gopls":
{
"enabled": true,
"initializationOptions": {
"gofumpt": true,
}
}
}
Roadmap
This tool is a place to experiment. In the long term, the features that work
well might be proposed for gofmt
itself.
The tool is also compatible with gofmt
and is aimed to be stable, so you can
rely on it for your code as long as you pin a version of it.
Frequently Asked Questions
Why attempt to replace
gofmt
instead of building on top of it?
Our design is to build on top of gofmt
, and we'll never add rules which
disagree with its formatting. So we extend gofmt
rather than compete with it.
The tool is a modified copy of gofmt
, for the purpose of allowing its use as a
drop-in replacement in editors and scripts.
Why are my module imports being grouped with standard library imports?
Any import paths that don't start with a domain name like foo.com
are
effectively reserved by the Go toolchain. Otherwise, adding new standard library
packages like embed
would be a breaking change. See golang/go#32819.
Third party modules should use domain names to avoid conflicts.
If your module is meant for local use only, you can use foo.local
.
For small example or test modules, example/...
and test/...
may be reserved
if a proposal is accepted; see golang/go#37641.
How can I use
gofumpt
if I already usegoimports
to replacegofmt
?
Most editors have replaced the goimports
program with the same functionality
provided by a language server like gopls
. This mechanism is significantly
faster and more powerful, since the language server has more information that is
kept up to date, necessary to add missing imports.
As such, the general recommendation is to let your editor fix your imports -
either via gopls
, such as VSCode or vim-go, or via their own custom
implementation, such as GoLand. Then follow the install instructions above to
enable the use of gofumpt
instead of gofmt
.
If you want to avoid integrating with gopls
, and are OK with the overhead of
calling goimports
from scratch on each save, you should be able to call both
tools; for example, goimports file.go && gofumpt file.go
.
Contributing
Issues and pull requests are welcome! Please open an issue to discuss a feature before sending a pull request.
We also use the #gofumpt
channel over at the
Gophers Slack to chat.
When reporting a formatting bug, insert a //gofumpt:diagnose
comment.
The comment will be rewritten to include useful debugging information.
For instance:
$ cat f.go
package p
//gofumpt:diagnose
$ gofumpt f.go
package p
//gofumpt:diagnose v0.1.1-0.20211103104632-bdfa3b02e50a -lang=v1.16
License
Note that much of the code is copied from Go's gofmt
command. You can tell
which files originate from the Go repository from their copyright headers. Their
license file is LICENSE.google
.
gofumpt
's original source files are also under the 3-clause BSD license, with
the separate file LICENSE
.