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 fork of gofmt as of Go 1.22, and requires Go 1.21 or later.
It can be used as a drop-in replacement to format your Go code,
and running gofmt after gofumpt should produce no changes.
For example:
gofumpt -l -w .
Some of the Go source files in this repository belong to the Go project.
The project includes copies of go/printer and go/doc/comment as of Go 1.22
to ensure consistent formatting independent of what Go version is being used.
The added formatting rules are implemented in the format package.
vendor and testdata directories are skipped unless given as explicit arguments.
Similarly, the added rules do not apply to generated Go files unless they are
given as explicit arguments.
Finally, note that the -r rewrite flag is removed in favor of gofmt -r,
and the -s flag is hidden as it is always enabled.
No empty lines following an assignment operator
Example
func foo() {
foo :=
"bar"
}func foo() {
foo := "bar"
}No empty lines around function bodies
Example
func foo() {
println("bar")
}func foo() {
println("bar")
}Functions should separate ) { where the indentation helps readability
Example
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
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 = 0755const perm = 0o755Comments 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",
}Field lists should not have leading or trailing empty lines
Example
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.
}Adjacent parameters with the same type should be grouped together
Example
func Foo(bar string, baz string) {}func Foo(bar, baz string) {}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.
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 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
gofumptexecutable - 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.
The configuration depends on the plugin you are using: vim-go or govim.
To configure gopls to use gofumpt:
let g:go_fmt_command="gopls"
let g:go_gopls_gofumpt=1To configure gopls to use gofumpt:
call govim#config#Set("Gofumpt", 1)When using lspconfig, pass the gofumpt setting to gopls:
require('lspconfig').gopls.setup({
settings = {
gopls = {
gofumpt = true
}
}
})For lsp-mode users on version 8.0.0 or higher:
(setq lsp-go-use-gofumpt t)For users of lsp-mode before 8.0.0:
(lsp-register-custom-settings
'(("gopls.gofumpt" t)))For eglot users:
(setq-default eglot-workspace-configuration
'((:gopls . ((gofumpt . t)))))When using the gopls language server, modify the Go settings in ~/.config/helix/languages.toml:
[language-server.gopls.config]
"formatting.gofumpt" = trueWith 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,
}
}
}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.
Why attempt to replace
gofmtinstead 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.
Third party modules should either start with a domain name,
even a local one like foo.local, or use a reserved path prefix.
For backwards compatibility with modules set up before these rules were clear,
gofumpt will treat any import path sharing a prefix with the current module
path as third party. For example, if the current module is mycorp/mod1, then
all import paths in mycorp/... will be considered third party.
How can I use
gofumptif I already usegoimportsto 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.
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
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.
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