slimsag / gofumpt

A stricter gofmt

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gofumpt

GO111MODULE=on go get mvdan.cc/gofumpt

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.

A drop-in replacement for goimports is also available:

GO111MODULE=on go get mvdan.cc/gofumpt/gofumports

Most of the Go source files in this repository belong to the Go project. The added formatting rules are in the format package.

Added rules

No empty lines at the beginning or end of a function

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

}
func foo() {
	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,
	},
}

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() {}

Extra rules behind -extra

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 get it as described at the top of this README and use it.

Visual Studio Code

Using the language server is the recommended method of running gofumpt. There is no need of using gofumports in this case, as import ordering is performed in a different step. Some of the settings required to enable it are not yet recognized by VS Code and it will complain about them, but they will still work. This is an expected behaviour until gopls gets a consistent set of settings, as stated in its official documentation.

"go.useLanguageServer": true,

"gopls": {
    "gofumpt": true,
},

"[go]": {
    "editor.formatOnSave": true,
    "editor.codeActionsOnSave": {
        "source.organizeImports": true,
    },
},

"[go.mod]": {
    "editor.formatOnSave": true,
    "editor.codeActionsOnSave": {
        "source.organizeImports": true,
    },
},

Alternatively, if you don't use the language server, you can still configure the IDE to use either gofumpt or goimports. This change must be done through the settings.json file because the formatting tool parameter is shown as a selector and not as a textbox in the interface. For this reason, VS Code will complain about an invalid property value, but this warning can be safely ignored and the correct tool will be used anyways.

"go.formatTool": "gofumports"

You can use gofumpt instead of gofumports if you don't need auto-importing on-save. Remember to disable the language server, as formatting is completely bypassed and delegated to gopls if enabled.

Goland

It's possible to set up Goland IDE to automatically perform gofumpt actions.

After gofumpt installation, follow the following steps to enable it in Goland:

  • 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

A new windows will ask for settings, if you follow instructions below, your project files will be gofumpted automatically by file watcher directives.

  • Name: Just choose the name you want to identify your file watcher
  • 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 unecessary runs, you must disable all checkboxes in the Advanced section.

Vim-go

Release v1.24 adds support for using gopls' gofumpt workspace setting via g:go_gopls_gofumpt.

let g:go_fmt_command="gopls"
let g:go_gopls_gofumpt=1

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.

License

Note that much of the code is copied from Go's gofmt and goimports commands. 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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A stricter gofmt

License:BSD 3-Clause "New" or "Revised" License


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Language:Go 100.0%