57 KiB
Configuring Rustfmt
Rustfmt is designed to be very configurable. You can create a TOML file called rustfmt.toml
or .rustfmt.toml
, place it in the project or any other parent directory and it will apply the options in that file. If none of these directories contain such a file, both your home directory and a directory called rustfmt
in your global config directory (e.g. .config/rustfmt/
) are checked as well.
A possible content of rustfmt.toml
or .rustfmt.toml
might look like this:
indent_style = "Block"
reorder_imports = false
Each configuration option is either stable or unstable.
Stable options can be used directly, while unstable options are opt-in.
To enable unstable options, set unstable_features = true
in rustfmt.toml
or pass --unstable-features
to rustfmt.
Configuration Options
Below you find a detailed visual guide on all the supported configuration options of rustfmt:
array_width
Maximum width of an array literal before falling back to vertical formatting.
- Default value:
60
- Possible values: any positive integer that is less than or equal to the value specified for
max_width
- Stable: Yes
By default this option is set as a percentage of max_width
provided by use_small_heuristics
, but a value set directly for array_width
will take precedence.
See also max_width
and use_small_heuristics
attr_fn_like_width
Maximum width of the args of a function-like attributes before falling back to vertical formatting.
- Default value:
70
- Possible values: any positive integer that is less than or equal to the value specified for
max_width
- Stable: Yes
By default this option is set as a percentage of max_width
provided by use_small_heuristics
, but a value set directly for attr_fn_like_width
will take precedence.
See also max_width
and use_small_heuristics
binop_separator
Where to put a binary operator when a binary expression goes multiline.
- Default value:
"Front"
- Possible values:
"Front"
,"Back"
- Stable: No (tracking issue: #3368)
"Front"
(default):
fn main() {
let or = foofoofoofoofoofoofoofoofoofoofoofoofoofoofoofoo
|| barbarbarbarbarbarbarbarbarbarbarbarbarbarbarbar;
let sum = 123456789012345678901234567890
+ 123456789012345678901234567890
+ 123456789012345678901234567890;
let range = aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
..bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb;
}
"Back"
:
fn main() {
let or = foofoofoofoofoofoofoofoofoofoofoofoofoofoofoofoo ||
barbarbarbarbarbarbarbarbarbarbarbarbarbarbarbar;
let sum = 123456789012345678901234567890 +
123456789012345678901234567890 +
123456789012345678901234567890;
let range = aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa..
bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb;
}
blank_lines_lower_bound
Minimum number of blank lines which must be put between items. If two items have fewer blank lines between them, additional blank lines are inserted.
- Default value:
0
- Possible values: unsigned integer
- Stable: No (tracking issue: #3382)
Example
Original Code (rustfmt will not change it with the default value of 0
):
#![rustfmt::skip]
fn foo() {
println!("a");
}
fn bar() {
println!("b");
println!("c");
}
1
fn foo() {
println!("a");
}
fn bar() {
println!("b");
println!("c");
}
blank_lines_upper_bound
Maximum number of blank lines which can be put between items. If more than this number of consecutive empty lines are found, they are trimmed down to match this integer.
- Default value:
1
- Possible values: any non-negative integer
- Stable: No (tracking issue: #3381)
Example
Original Code:
#![rustfmt::skip]
fn foo() {
println!("a");
}
fn bar() {
println!("b");
println!("c");
}
1
(default):
fn foo() {
println!("a");
}
fn bar() {
println!("b");
println!("c");
}
2
:
fn foo() {
println!("a");
}
fn bar() {
println!("b");
println!("c");
}
See also: blank_lines_lower_bound
brace_style
Brace style for items
- Default value:
"SameLineWhere"
- Possible values:
"AlwaysNextLine"
,"PreferSameLine"
,"SameLineWhere"
- Stable: No (tracking issue: #3376)
Functions
"SameLineWhere"
(default):
fn lorem() {
// body
}
fn lorem(ipsum: usize) {
// body
}
fn lorem<T>(ipsum: T)
where
T: Add + Sub + Mul + Div,
{
// body
}
"AlwaysNextLine"
:
fn lorem()
{
// body
}
fn lorem(ipsum: usize)
{
// body
}
fn lorem<T>(ipsum: T)
where
T: Add + Sub + Mul + Div,
{
// body
}
"PreferSameLine"
:
fn lorem() {
// body
}
fn lorem(ipsum: usize) {
// body
}
fn lorem<T>(ipsum: T)
where
T: Add + Sub + Mul + Div, {
// body
}
Structs and enums
"SameLineWhere"
(default):
struct Lorem {
ipsum: bool,
}
struct Dolor<T>
where
T: Eq,
{
sit: T,
}
"AlwaysNextLine"
:
struct Lorem
{
ipsum: bool,
}
struct Dolor<T>
where
T: Eq,
{
sit: T,
}
"PreferSameLine"
:
struct Lorem {
ipsum: bool,
}
struct Dolor<T>
where
T: Eq, {
sit: T,
}
chain_width
Maximum width of a chain to fit on one line.
- Default value:
60
- Possible values: any positive integer that is less than or equal to the value specified for
max_width
- Stable: Yes
By default this option is set as a percentage of max_width
provided by use_small_heuristics
, but a value set directly for chain_width
will take precedence.
See also max_width
and use_small_heuristics
color
Whether to use colored output or not.
- Default value:
"Auto"
- Possible values: "Auto", "Always", "Never"
- Stable: No (tracking issue: #3385)
combine_control_expr
Combine control expressions with function calls.
- Default value:
true
- Possible values:
true
,false
- Stable: No (tracking issue: #3369)
true
(default):
fn example() {
// If
foo!(if x {
foo();
} else {
bar();
});
// IfLet
foo!(if let Some(..) = x {
foo();
} else {
bar();
});
// While
foo!(while x {
foo();
bar();
});
// WhileLet
foo!(while let Some(..) = x {
foo();
bar();
});
// ForLoop
foo!(for x in y {
foo();
bar();
});
// Loop
foo!(loop {
foo();
bar();
});
}
false
:
fn example() {
// If
foo!(
if x {
foo();
} else {
bar();
}
);
// IfLet
foo!(
if let Some(..) = x {
foo();
} else {
bar();
}
);
// While
foo!(
while x {
foo();
bar();
}
);
// WhileLet
foo!(
while let Some(..) = x {
foo();
bar();
}
);
// ForLoop
foo!(
for x in y {
foo();
bar();
}
);
// Loop
foo!(
loop {
foo();
bar();
}
);
}
comment_width
Maximum length of comments. No effect unlesswrap_comments = true
.
- Default value:
80
- Possible values: any positive integer
- Stable: No (tracking issue: #3349)
Note: A value of 0
results in wrap_comments
being applied regardless of a line's width.
80
(default; comments shorter than comment_width
):
// Lorem ipsum dolor sit amet, consectetur adipiscing elit.
60
(comments longer than comment_width
):
// Lorem ipsum dolor sit amet,
// consectetur adipiscing elit.
See also wrap_comments
.
condense_wildcard_suffixes
Replace strings of _ wildcards by a single .. in tuple patterns
- Default value:
false
- Possible values:
true
,false
- Stable: No (tracking issue: #3384)
false
(default):
fn main() {
let (lorem, ipsum, _, _) = (1, 2, 3, 4);
let (lorem, ipsum, ..) = (1, 2, 3, 4);
}
true
:
fn main() {
let (lorem, ipsum, ..) = (1, 2, 3, 4);
}
control_brace_style
Brace style for control flow constructs
- Default value:
"AlwaysSameLine"
- Possible values:
"AlwaysNextLine"
,"AlwaysSameLine"
,"ClosingNextLine"
- Stable: No (tracking issue: #3377)
"AlwaysSameLine"
(default):
fn main() {
if lorem {
println!("ipsum!");
} else {
println!("dolor!");
}
}
"AlwaysNextLine"
:
fn main() {
if lorem
{
println!("ipsum!");
}
else
{
println!("dolor!");
}
}
"ClosingNextLine"
:
fn main() {
if lorem {
println!("ipsum!");
}
else {
println!("dolor!");
}
}
disable_all_formatting
Don't reformat anything.
Note that this option may be soft-deprecated in the future once the ignore option is stabilized. Nightly toolchain users are encouraged to use ignore instead when possible.
- Default value:
false
- Possible values:
true
,false
- Stable: Yes
edition
Specifies which edition is used by the parser.
- Default value:
"2015"
- Possible values:
"2015"
,"2018"
,"2021"
- Stable: Yes
Rustfmt is able to pick up the edition used by reading the Cargo.toml
file if executed
through the Cargo's formatting tool cargo fmt
. Otherwise, the edition needs to be specified
in your config file:
edition = "2018"
empty_item_single_line
Put empty-body functions and impls on a single line
- Default value:
true
- Possible values:
true
,false
- Stable: No (tracking issue: #3356)
true
(default):
fn lorem() {}
impl Lorem {}
false
:
fn lorem() {
}
impl Lorem {
}
See also brace_style
, control_brace_style
.
enum_discrim_align_threshold
The maximum length of enum variant having discriminant, that gets vertically aligned with others. Variants without discriminants would be ignored for the purpose of alignment.
Note that this is not how much whitespace is inserted, but instead the longest variant name that doesn't get ignored when aligning.
- Default value : 0
- Possible values: any positive integer
- Stable: No (tracking issue: #3372)
0
(default):
enum Bar {
A = 0,
Bb = 1,
RandomLongVariantGoesHere = 10,
Ccc = 71,
}
enum Bar {
VeryLongVariantNameHereA = 0,
VeryLongVariantNameHereBb = 1,
VeryLongVariantNameHereCcc = 2,
}
20
:
enum Foo {
A = 0,
Bb = 1,
RandomLongVariantGoesHere = 10,
Ccc = 2,
}
enum Bar {
VeryLongVariantNameHereA = 0,
VeryLongVariantNameHereBb = 1,
VeryLongVariantNameHereCcc = 2,
}
error_on_line_overflow
Error if Rustfmt is unable to get all lines within max_width
, except for comments and string
literals. If this happens, then it is a bug in Rustfmt. You might be able to work around the bug by
refactoring your code to avoid long/complex expressions, usually by extracting a local variable or
using a shorter name.
- Default value:
false
- Possible values:
true
,false
- Stable: No (tracking issue: #3391)
See also max_width
.
error_on_unformatted
Error if unable to get comments or string literals within max_width
, or they are left with
trailing whitespaces.
- Default value:
false
- Possible values:
true
,false
- Stable: No (tracking issue: #3392)
fn_args_layout
Control the layout of arguments in a function
- Default value:
"Tall"
- Possible values:
"Compressed"
,"Tall"
,"Vertical"
- Stable: Yes
"Tall"
(default):
trait Lorem {
fn lorem(ipsum: Ipsum, dolor: Dolor, sit: Sit, amet: Amet);
fn lorem(ipsum: Ipsum, dolor: Dolor, sit: Sit, amet: Amet) {
// body
}
fn lorem(
ipsum: Ipsum,
dolor: Dolor,
sit: Sit,
amet: Amet,
consectetur: Consectetur,
adipiscing: Adipiscing,
elit: Elit,
);
fn lorem(
ipsum: Ipsum,
dolor: Dolor,
sit: Sit,
amet: Amet,
consectetur: Consectetur,
adipiscing: Adipiscing,
elit: Elit,
) {
// body
}
}
"Compressed"
:
trait Lorem {
fn lorem(ipsum: Ipsum, dolor: Dolor, sit: Sit, amet: Amet);
fn lorem(ipsum: Ipsum, dolor: Dolor, sit: Sit, amet: Amet) {
// body
}
fn lorem(
ipsum: Ipsum, dolor: Dolor, sit: Sit, amet: Amet, consectetur: Consectetur,
adipiscing: Adipiscing, elit: Elit,
);
fn lorem(
ipsum: Ipsum, dolor: Dolor, sit: Sit, amet: Amet, consectetur: Consectetur,
adipiscing: Adipiscing, elit: Elit,
) {
// body
}
}
"Vertical"
:
trait Lorem {
fn lorem(
ipsum: Ipsum,
dolor: Dolor,
sit: Sit,
amet: Amet,
);
fn lorem(
ipsum: Ipsum,
dolor: Dolor,
sit: Sit,
amet: Amet,
) {
// body
}
fn lorem(
ipsum: Ipsum,
dolor: Dolor,
sit: Sit,
amet: Amet,
consectetur: Consectetur,
adipiscing: Adipiscing,
elit: Elit,
);
fn lorem(
ipsum: Ipsum,
dolor: Dolor,
sit: Sit,
amet: Amet,
consectetur: Consectetur,
adipiscing: Adipiscing,
elit: Elit,
) {
// body
}
}
fn_call_width
Maximum width of the args of a function call before falling back to vertical formatting.
- Default value:
60
- Possible values: any positive integer that is less than or equal to the value specified for
max_width
- Stable: Yes
By default this option is set as a percentage of max_width
provided by use_small_heuristics
, but a value set directly for fn_call_width
will take precedence.
See also max_width
and use_small_heuristics
fn_single_line
Put single-expression functions on a single line
- Default value:
false
- Possible values:
true
,false
- Stable: No (tracking issue: #3358)
false
(default):
fn lorem() -> usize {
42
}
fn lorem() -> usize {
let ipsum = 42;
ipsum
}
true
:
fn lorem() -> usize { 42 }
fn lorem() -> usize {
let ipsum = 42;
ipsum
}
See also control_brace_style
.
force_explicit_abi
Always print the abi for extern items
- Default value:
true
- Possible values:
true
,false
- Stable: Yes
Note: Non-"C" ABIs are always printed. If false
then "C" is removed.
true
(default):
extern "C" {
pub static lorem: c_int;
}
false
:
extern {
pub static lorem: c_int;
}
force_multiline_blocks
Force multiline closure and match arm bodies to be wrapped in a block
- Default value:
false
- Possible values:
false
,true
- Stable: No (tracking issue: #3374)
false
(default):
fn main() {
result.and_then(|maybe_value| match maybe_value {
None => foo(),
Some(value) => bar(),
});
match lorem {
None => |ipsum| {
println!("Hello World");
},
Some(dolor) => foo(),
}
}
true
:
fn main() {
result.and_then(|maybe_value| {
match maybe_value {
None => foo(),
Some(value) => bar(),
}
});
match lorem {
None => {
|ipsum| {
println!("Hello World");
}
}
Some(dolor) => foo(),
}
}
format_code_in_doc_comments
Format code snippet included in doc comments.
- Default value:
false
- Possible values:
true
,false
- Stable: No (tracking issue: #3348)
false
(default):
/// Adds one to the number given.
///
/// # Examples
///
/// ```rust
/// let five=5;
///
/// assert_eq!(
/// 6,
/// add_one(5)
/// );
/// # fn add_one(x: i32) -> i32 {
/// # x + 1
/// # }
/// ```
fn add_one(x: i32) -> i32 {
x + 1
}
true
/// Adds one to the number given.
///
/// # Examples
///
/// ```rust
/// let five = 5;
///
/// assert_eq!(6, add_one(5));
/// # fn add_one(x: i32) -> i32 {
/// # x + 1
/// # }
/// ```
fn add_one(x: i32) -> i32 {
x + 1
}
format_generated_files
Format generated files. A file is considered generated
if any of the first five lines contain a @generated
comment marker.
By default, generated files are reformatted, i. e. @generated
marker is ignored.
This option is currently ignored for stdin (@generated
in stdin is ignored.)
- Default value:
true
- Possible values:
true
,false
- Stable: No (tracking issue: #5080)
format_macro_matchers
Format the metavariable matching patterns in macros.
- Default value:
false
- Possible values:
true
,false
- Stable: No (tracking issue: #3354)
false
(default):
macro_rules! foo {
($a: ident : $b: ty) => {
$a(42): $b;
};
($a: ident $b: ident $c: ident) => {
$a = $b + $c;
};
}
true
:
macro_rules! foo {
($a:ident : $b:ty) => {
$a(42): $b;
};
($a:ident $b:ident $c:ident) => {
$a = $b + $c;
};
}
See also format_macro_bodies
.
format_macro_bodies
Format the bodies of macros.
- Default value:
true
- Possible values:
true
,false
- Stable: No (tracking issue: #3355)
true
(default):
macro_rules! foo {
($a: ident : $b: ty) => {
$a(42): $b;
};
($a: ident $b: ident $c: ident) => {
$a = $b + $c;
};
}
false
:
macro_rules! foo {
($a: ident : $b: ty) => { $a(42): $b; };
($a: ident $b: ident $c: ident) => { $a=$b+$c; };
}
See also format_macro_matchers
.
format_strings
Format string literals where necessary
- Default value:
false
- Possible values:
true
,false
- Stable: No (tracking issue: #3353)
false
(default):
fn main() {
let lorem = "ipsum dolor sit amet consectetur adipiscing elit lorem ipsum dolor sit amet consectetur adipiscing";
}
true
:
fn main() {
let lorem = "ipsum dolor sit amet consectetur adipiscing elit lorem ipsum dolor sit amet \
consectetur adipiscing";
}
See also max_width
.
hard_tabs
Use tab characters for indentation, spaces for alignment
- Default value:
false
- Possible values:
true
,false
- Stable: Yes
false
(default):
fn lorem() -> usize {
42 // spaces before 42
}
true
:
fn lorem() -> usize {
42 // tabs before 42
}
See also: tab_spaces
.
hex_literal_case
Control the case of the letters in hexadecimal literal values
- Default value:
Preserve
- Possible values:
Upper
,Lower
- Stable: No (tracking issue: #5081)
hide_parse_errors
Do not show parse errors if the parser failed to parse files.
- Default value:
false
- Possible values:
true
,false
- Stable: No (tracking issue: #3390)
ignore
Skip formatting files and directories that match the specified pattern.
The pattern format is the same as .gitignore. Be sure to use Unix/forwardslash /
style paths. This path style will work on all platforms. Windows style paths with backslashes \
are not supported.
- Default value: format every file
- Possible values: See an example below
- Stable: No (tracking issue: #3395)
Example
If you want to ignore specific files, put the following to your config file:
ignore = [
"src/types.rs",
"src/foo/bar.rs",
]
If you want to ignore every file under examples/
, put the following to your config file:
ignore = [
"examples",
]
If you want to ignore every file under the directory where you put your rustfmt.toml:
ignore = ["/"]
imports_indent
Indent style of imports
- Default Value:
"Block"
- Possible values:
"Block"
,"Visual"
- Stable: No (tracking issue: #3360)
"Block"
(default):
use foo::{
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx, yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy,
zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz,
};
"Visual"
:
use foo::{xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx, yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy,
zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz};
See also: imports_layout
.
imports_layout
Item layout inside a imports block
- Default value: "Mixed"
- Possible values: "Horizontal", "HorizontalVertical", "Mixed", "Vertical"
- Stable: No (tracking issue: #3361)
"Mixed"
(default):
use foo::{xxxxxxxxxxxxxxxxxx, yyyyyyyyyyyyyyyyyy, zzzzzzzzzzzzzzzzzz};
use foo::{
aaaaaaaaaaaaaaaaaa, bbbbbbbbbbbbbbbbbb, cccccccccccccccccc, dddddddddddddddddd,
eeeeeeeeeeeeeeeeee, ffffffffffffffffff,
};
"Horizontal"
:
Note: This option forces all imports onto one line and may exceed max_width
.
use foo::{xxx, yyy, zzz};
use foo::{aaa, bbb, ccc, ddd, eee, fff};
"HorizontalVertical"
:
use foo::{xxxxxxxxxxxxxxxxxx, yyyyyyyyyyyyyyyyyy, zzzzzzzzzzzzzzzzzz};
use foo::{
aaaaaaaaaaaaaaaaaa,
bbbbbbbbbbbbbbbbbb,
cccccccccccccccccc,
dddddddddddddddddd,
eeeeeeeeeeeeeeeeee,
ffffffffffffffffff,
};
"Vertical"
:
use foo::{
xxx,
yyy,
zzz,
};
use foo::{
aaa,
bbb,
ccc,
ddd,
eee,
fff,
};
indent_style
Indent on expressions or items.
- Default value:
"Block"
- Possible values:
"Block"
,"Visual"
- Stable: No (tracking issue: #3346)
Array
"Block"
(default):
fn main() {
let lorem = vec![
"ipsum",
"dolor",
"sit",
"amet",
"consectetur",
"adipiscing",
"elit",
];
}
"Visual"
:
fn main() {
let lorem = vec!["ipsum",
"dolor",
"sit",
"amet",
"consectetur",
"adipiscing",
"elit"];
}
Control flow
"Block"
(default):
fn main() {
if lorem_ipsum
&& dolor_sit
&& amet_consectetur
&& lorem_sit
&& dolor_consectetur
&& amet_ipsum
&& lorem_consectetur
{
// ...
}
}
"Visual"
:
fn main() {
if lorem_ipsum
&& dolor_sit
&& amet_consectetur
&& lorem_sit
&& dolor_consectetur
&& amet_ipsum
&& lorem_consectetur
{
// ...
}
}
See also: control_brace_style
.
Function arguments
"Block"
(default):
fn lorem() {}
fn lorem(ipsum: usize) {}
fn lorem(
ipsum: usize,
dolor: usize,
sit: usize,
amet: usize,
consectetur: usize,
adipiscing: usize,
elit: usize,
) {
// body
}
"Visual"
:
fn lorem() {}
fn lorem(ipsum: usize) {}
fn lorem(ipsum: usize,
dolor: usize,
sit: usize,
amet: usize,
consectetur: usize,
adipiscing: usize,
elit: usize) {
// body
}
Function calls
"Block"
(default):
fn main() {
lorem(
"lorem",
"ipsum",
"dolor",
"sit",
"amet",
"consectetur",
"adipiscing",
"elit",
);
}
"Visual"
:
fn main() {
lorem("lorem",
"ipsum",
"dolor",
"sit",
"amet",
"consectetur",
"adipiscing",
"elit");
}
Generics
"Block"
(default):
fn lorem<
Ipsum: Eq = usize,
Dolor: Eq = usize,
Sit: Eq = usize,
Amet: Eq = usize,
Adipiscing: Eq = usize,
Consectetur: Eq = usize,
Elit: Eq = usize,
>(
ipsum: Ipsum,
dolor: Dolor,
sit: Sit,
amet: Amet,
adipiscing: Adipiscing,
consectetur: Consectetur,
elit: Elit,
) -> T {
// body
}
"Visual"
:
fn lorem<Ipsum: Eq = usize,
Dolor: Eq = usize,
Sit: Eq = usize,
Amet: Eq = usize,
Adipiscing: Eq = usize,
Consectetur: Eq = usize,
Elit: Eq = usize>(
ipsum: Ipsum,
dolor: Dolor,
sit: Sit,
amet: Amet,
adipiscing: Adipiscing,
consectetur: Consectetur,
elit: Elit)
-> T {
// body
}
Struct
"Block"
(default):
fn main() {
let lorem = Lorem {
ipsum: dolor,
sit: amet,
};
}
"Visual"
:
fn main() {
let lorem = Lorem { ipsum: dolor,
sit: amet };
}
See also: struct_lit_single_line
, indent_style
.
Where predicates
"Block"
(default):
fn lorem<Ipsum, Dolor, Sit, Amet>() -> T
where
Ipsum: Eq,
Dolor: Eq,
Sit: Eq,
Amet: Eq,
{
// body
}
"Visual"
:
fn lorem<Ipsum, Dolor, Sit, Amet>() -> T
where Ipsum: Eq,
Dolor: Eq,
Sit: Eq,
Amet: Eq
{
// body
}
inline_attribute_width
Write an item and its attribute on the same line if their combined width is below a threshold
- Default value: 0
- Possible values: any positive integer
- Stable: No (tracking issue: #3343)
Example
0
(default):
#[cfg(feature = "alloc")]
use core::slice;
50
:
#[cfg(feature = "alloc")] use core::slice;
license_template_path
Check whether beginnings of files match a license template.
- Default value:
""
- Possible values: path to a license template file
- Stable: No (tracking issue: #3352)
A license template is a plain text file which is matched literally against the
beginning of each source file, except for {}
-delimited blocks, which are
matched as regular expressions. The following license template therefore
matches strings like // Copyright 2017 The Rust Project Developers.
, // Copyright 2018 The Rust Project Developers.
, etc.:
// Copyright {\d+} The Rust Project Developers.
\{
, \}
and \\
match literal braces / backslashes.
match_arm_blocks
Controls whether arm bodies are wrapped in cases where the first line of the body cannot fit on the same line as the =>
operator.
The Style Guide requires that bodies are block wrapped by default if a line break is required after the =>
, but this option can be used to disable that behavior to prevent wrapping arm bodies in that event, so long as the body does not contain multiple statements nor line comments.
- Default value:
true
- Possible values:
true
,false
- Stable: No (tracking issue: #3373)
true
(default):
fn main() {
match lorem {
ipsum => {
foooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo(x)
}
dolor => println!("{}", sit),
sit => foo(
"foooooooooooooooooooooooo",
"baaaaaaaaaaaaaaaaaaaaaaaarr",
"baaaaaaaaaaaaaaaaaaaazzzzzzzzzzzzz",
"qqqqqqqqquuuuuuuuuuuuuuuuuuuuuuuuuuxxx",
),
}
}
false
:
fn main() {
match lorem {
lorem =>
foooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo(x),
ipsum => println!("{}", sit),
sit => foo(
"foooooooooooooooooooooooo",
"baaaaaaaaaaaaaaaaaaaaaaaarr",
"baaaaaaaaaaaaaaaaaaaazzzzzzzzzzzzz",
"qqqqqqqqquuuuuuuuuuuuuuuuuuuuuuuuuuxxx",
),
}
}
See also: match_block_trailing_comma
.
match_arm_leading_pipes
Controls whether to include a leading pipe on match arms
- Default value:
Never
- Possible values:
Always
,Never
,Preserve
- Stable: Yes
Never
(default):
// Leading pipes are removed from this:
// fn foo() {
// match foo {
// | "foo" | "bar" => {}
// | "baz"
// | "something relatively long"
// | "something really really really realllllllllllllly long" => println!("x"),
// | "qux" => println!("y"),
// _ => {}
// }
// }
// Becomes
fn foo() {
match foo {
"foo" | "bar" => {}
"baz"
| "something relatively long"
| "something really really really realllllllllllllly long" => println!("x"),
"qux" => println!("y"),
_ => {}
}
}
Always
:
// Leading pipes are emitted on all arms of this:
// fn foo() {
// match foo {
// "foo" | "bar" => {}
// "baz"
// | "something relatively long"
// | "something really really really realllllllllllllly long" => println!("x"),
// "qux" => println!("y"),
// _ => {}
// }
// }
// Becomes:
fn foo() {
match foo {
| "foo" | "bar" => {}
| "baz"
| "something relatively long"
| "something really really really realllllllllllllly long" => println!("x"),
| "qux" => println!("y"),
| _ => {}
}
}
Preserve
:
fn foo() {
match foo {
| "foo" | "bar" => {}
| "baz"
| "something relatively long"
| "something really really really realllllllllllllly long" => println!("x"),
| "qux" => println!("y"),
_ => {}
}
match baz {
"qux" => {}
"foo" | "bar" => {}
_ => {}
}
}
match_block_trailing_comma
Put a trailing comma after a block based match arm (non-block arms are not affected)
- Default value:
false
- Possible values:
true
,false
- Stable: Yes
false
(default):
fn main() {
match lorem {
Lorem::Ipsum => {
println!("ipsum");
}
Lorem::Dolor => println!("dolor"),
}
}
true
:
fn main() {
match lorem {
Lorem::Ipsum => {
println!("ipsum");
},
Lorem::Dolor => println!("dolor"),
}
}
See also: trailing_comma
, match_arm_blocks
.
max_width
Maximum width of each line
- Default value:
100
- Possible values: any positive integer
- Stable: Yes
See also error_on_line_overflow
.
merge_derives
Merge multiple derives into a single one.
- Default value:
true
- Possible values:
true
,false
- Stable: Yes
true
(default):
#[derive(Eq, PartialEq, Debug, Copy, Clone)]
pub enum Foo {}
false
:
#[derive(Eq, PartialEq, Debug, Copy, Clone)]
pub enum Bar {}
#[derive(Eq, PartialEq)]
#[derive(Debug)]
#[derive(Copy, Clone)]
pub enum Foo {}
imports_granularity
How imports should be grouped into use
statements. Imports will be merged or split to the configured level of granularity.
- Default value:
Preserve
- Possible values:
Preserve
,Crate
,Module
,Item
,One
- Stable: No (tracking issue: #4991)
Preserve
(default):
Do not change the granularity of any imports and preserve the original structure written by the developer.
use foo::b;
use foo::b::{f, g};
use foo::{a, c, d::e};
use qux::{h, i};
Crate
:
Merge imports from the same crate into a single use
statement. Conversely, imports from different crates are split into separate statements.
use foo::{
a, b,
b::{f, g},
c,
d::e,
};
use qux::{h, i};
Module
:
Merge imports from the same module into a single use
statement. Conversely, imports from different modules are split into separate statements.
use foo::b::{f, g};
use foo::d::e;
use foo::{a, b, c};
use qux::{h, i};
Item
:
Flatten imports so that each has its own use
statement.
use foo::a;
use foo::b;
use foo::b::f;
use foo::b::g;
use foo::c;
use foo::d::e;
use qux::h;
use qux::i;
One
:
Merge all imports into a single use
statement as long as they have the same visibility.
pub use foo::{x, y};
use {
bar::{
a,
b::{self, f, g},
c,
d::e,
},
qux::{h, i},
};
merge_imports
This option is deprecated. Use imports_granularity = "Crate"
instead.
- Default value:
false
- Possible values:
true
,false
false
(default):
use foo::{a, c, d};
use foo::{b, g};
use foo::{e, f};
true
:
use foo::{a, b, c, d, e, f, g};
newline_style
Unix or Windows line endings
- Default value:
"Auto"
- Possible values:
"Auto"
,"Native"
,"Unix"
,"Windows"
- Stable: Yes
Auto
(default):
The newline style is detected automatically on a per-file basis. Files with mixed line endings will be converted to the first detected line ending style.
Native
Line endings will be converted to \r\n
on Windows and \n
on all
other platforms.
Unix
Line endings will be converted to \n
.
Windows
Line endings will be converted to \r\n
.
normalize_comments
Convert /* */ comments to // comments where possible
- Default value:
false
- Possible values:
true
,false
- Stable: No (tracking issue: #3350)
false
(default):
// Lorem ipsum:
fn dolor() -> usize {}
/* sit amet: */
fn adipiscing() -> usize {}
true
:
// Lorem ipsum:
fn dolor() -> usize {}
// sit amet:
fn adipiscing() -> usize {}
normalize_doc_attributes
Convert #![doc]
and #[doc]
attributes to //!
and ///
doc comments.
- Default value:
false
- Possible values:
true
,false
- Stable: No (tracking issue: #3351)
false
(default):
#![doc = "Example documentation"]
#[doc = "Example item documentation"]
pub enum Bar {}
/// Example item documentation
pub enum Foo {}
true
:
//! Example documentation
/// Example item documentation
pub enum Foo {}
overflow_delimited_expr
When structs, slices, arrays, and block/array-like macros are used as the last argument in an expression list, allow them to overflow (like blocks/closures) instead of being indented on a new line.
- Default value:
false
- Possible values:
true
,false
- Stable: No (tracking issue: #3370)
false
(default):
fn example() {
foo(ctx, |param| {
action();
foo(param)
});
foo(
ctx,
Bar {
x: value,
y: value2,
},
);
foo(
ctx,
&[
MAROON_TOMATOES,
PURPLE_POTATOES,
ORGANE_ORANGES,
GREEN_PEARS,
RED_APPLES,
],
);
foo(
ctx,
vec![
MAROON_TOMATOES,
PURPLE_POTATOES,
ORGANE_ORANGES,
GREEN_PEARS,
RED_APPLES,
],
);
}
true
:
fn example() {
foo(ctx, |param| {
action();
foo(param)
});
foo(ctx, Bar {
x: value,
y: value2,
});
foo(ctx, &[
MAROON_TOMATOES,
PURPLE_POTATOES,
ORGANE_ORANGES,
GREEN_PEARS,
RED_APPLES,
]);
foo(ctx, vec![
MAROON_TOMATOES,
PURPLE_POTATOES,
ORGANE_ORANGES,
GREEN_PEARS,
RED_APPLES,
]);
}
remove_nested_parens
Remove nested parens.
- Default value:
true
, - Possible values:
true
,false
- Stable: Yes
true
(default):
fn main() {
(foo());
}
false
:
fn main() {
(foo());
((((foo()))));
}
reorder_impl_items
Reorder impl items. type
and const
are put first, then macros and methods.
- Default value:
false
- Possible values:
true
,false
- Stable: No (tracking issue: #3363)
false
(default)
struct Dummy;
impl Iterator for Dummy {
fn next(&mut self) -> Option<Self::Item> {
None
}
type Item = i32;
}
impl Iterator for Dummy {
type Item = i32;
fn next(&mut self) -> Option<Self::Item> {
None
}
}
true
struct Dummy;
impl Iterator for Dummy {
type Item = i32;
fn next(&mut self) -> Option<Self::Item> {
None
}
}
reorder_imports
Reorder import and extern crate statements alphabetically in groups (a group is separated by a newline).
- Default value:
true
- Possible values:
true
,false
- Stable: Yes
true
(default):
use dolor;
use ipsum;
use lorem;
use sit;
false
:
use lorem;
use ipsum;
use dolor;
use sit;
group_imports
Controls the strategy for how imports are grouped together.
- Default value:
Preserve
- Possible values:
Preserve
,StdExternalCrate
,One
- Stable: No (tracking issue: #5083)
Preserve
(default):
Preserve the source file's import groups.
use super::update::convert_publish_payload;
use chrono::Utc;
use alloc::alloc::Layout;
use juniper::{FieldError, FieldResult};
use uuid::Uuid;
use std::sync::Arc;
use broker::database::PooledConnection;
use super::schema::{Context, Payload};
use crate::models::Event;
use core::f32;
StdExternalCrate
:
Discard existing import groups, and create three groups for:
std
,core
andalloc
,- external crates,
self
,super
andcrate
imports.
use alloc::alloc::Layout;
use core::f32;
use std::sync::Arc;
use broker::database::PooledConnection;
use chrono::Utc;
use juniper::{FieldError, FieldResult};
use uuid::Uuid;
use super::schema::{Context, Payload};
use super::update::convert_publish_payload;
use crate::models::Event;
One
:
Discard existing import groups, and create a single group for everything
use super::schema::{Context, Payload};
use super::update::convert_publish_payload;
use crate::models::Event;
use alloc::alloc::Layout;
use broker::database::PooledConnection;
use chrono::Utc;
use core::f32;
use juniper::{FieldError, FieldResult};
use std::sync::Arc;
use uuid::Uuid;
reorder_modules
Reorder mod
declarations alphabetically in group.
- Default value:
true
- Possible values:
true
,false
- Stable: Yes
true
(default)
mod a;
mod b;
mod dolor;
mod ipsum;
mod lorem;
mod sit;
false
mod b;
mod a;
mod lorem;
mod ipsum;
mod dolor;
mod sit;
Note mod
with #[macro_export]
will not be reordered since that could change the semantics
of the original source code.
report_fixme
Report FIXME
items in comments.
- Default value:
"Never"
- Possible values:
"Always"
,"Unnumbered"
,"Never"
- Stable: No (tracking issue: #3394)
Warns about any comments containing FIXME
in them when set to "Always"
. If
it contains a #X
(with X
being a number) in parentheses following the
FIXME
, "Unnumbered"
will ignore it.
See also report_todo
.
report_todo
Report TODO
items in comments.
- Default value:
"Never"
- Possible values:
"Always"
,"Unnumbered"
,"Never"
- Stable: No (tracking issue: #3393)
Warns about any comments containing TODO
in them when set to "Always"
. If
it contains a #X
(with X
being a number) in parentheses following the
TODO
, "Unnumbered"
will ignore it.
See also report_fixme
.
required_version
Require a specific version of rustfmt. If you want to make sure that the specific version of rustfmt is used in your CI, use this option.
- Default value:
CARGO_PKG_VERSION
- Possible values: any published version (e.g.
"0.3.8"
) - Stable: No (tracking issue: #3386)
skip_children
Don't reformat out of line modules
- Default value:
false
- Possible values:
true
,false
- Stable: No (tracking issue: #3389)
single_line_if_else_max_width
Maximum line length for single line if-else expressions. A value of 0
(zero) results in if-else expressions always being broken into multiple lines. Note this occurs when use_small_heuristics
is set to Off
.
- Default value:
50
- Possible values: any positive integer that is less than or equal to the value specified for
max_width
- Stable: Yes
By default this option is set as a percentage of max_width
provided by use_small_heuristics
, but a value set directly for single_line_if_else_max_width
will take precedence.
See also max_width
and use_small_heuristics
space_after_colon
Leave a space after the colon.
- Default value:
true
- Possible values:
true
,false
- Stable: No (tracking issue: #3366)
true
(default):
fn lorem<T: Eq>(t: T) {
let lorem: Dolor = Lorem {
ipsum: dolor,
sit: amet,
};
}
false
:
fn lorem<T:Eq>(t:T) {
let lorem:Dolor = Lorem {
ipsum:dolor,
sit:amet,
};
}
See also: space_before_colon
.
space_before_colon
Leave a space before the colon.
- Default value:
false
- Possible values:
true
,false
- Stable: No (tracking issue: #3365)
false
(default):
fn lorem<T: Eq>(t: T) {
let lorem: Dolor = Lorem {
ipsum: dolor,
sit: amet,
};
}
true
:
fn lorem<T : Eq>(t : T) {
let lorem : Dolor = Lorem {
ipsum : dolor,
sit : amet,
};
}
See also: space_after_colon
.
spaces_around_ranges
Put spaces around the .., ..=, and ... range operators
- Default value:
false
- Possible values:
true
,false
- Stable: No (tracking issue: #3367)
false
(default):
fn main() {
let lorem = 0..10;
let ipsum = 0..=10;
match lorem {
1..5 => foo(),
_ => bar,
}
match lorem {
1..=5 => foo(),
_ => bar,
}
match lorem {
1...5 => foo(),
_ => bar,
}
}
true
:
fn main() {
let lorem = 0 .. 10;
let ipsum = 0 ..= 10;
match lorem {
1 .. 5 => foo(),
_ => bar,
}
match lorem {
1 ..= 5 => foo(),
_ => bar,
}
match lorem {
1 ... 5 => foo(),
_ => bar,
}
}
struct_field_align_threshold
The maximum diff of width between struct fields to be aligned with each other.
- Default value : 0
- Possible values: any non-negative integer
- Stable: No (tracking issue: #3371)
0
(default):
struct Foo {
x: u32,
yy: u32,
zzz: u32,
}
20
:
struct Foo {
x: u32,
yy: u32,
zzz: u32,
}
struct_lit_single_line
Put small struct literals on a single line
- Default value:
true
- Possible values:
true
,false
- Stable: No (tracking issue: #3357)
true
(default):
fn main() {
let lorem = Lorem { foo: bar, baz: ofo };
}
false
:
fn main() {
let lorem = Lorem {
foo: bar,
baz: ofo,
};
}
See also: indent_style
.
struct_lit_width
Maximum width in the body of a struct literal before falling back to vertical formatting. A value of 0
(zero) results in struct literals always being broken into multiple lines. Note this occurs when use_small_heuristics
is set to Off
.
- Default value:
18
- Possible values: any positive integer that is less than or equal to the value specified for
max_width
- Stable: Yes
By default this option is set as a percentage of max_width
provided by use_small_heuristics
, but a value set directly for struct_lit_width
will take precedence.
See also max_width
, use_small_heuristics
, and struct_lit_single_line
struct_variant_width
Maximum width in the body of a struct variant before falling back to vertical formatting. A value of 0
(zero) results in struct literals always being broken into multiple lines. Note this occurs when use_small_heuristics
is set to Off
.
- Default value:
35
- Possible values: any positive integer that is less than or equal to the value specified for
max_width
- Stable: Yes
By default this option is set as a percentage of max_width
provided by use_small_heuristics
, but a value set directly for struct_variant_width
will take precedence.
See also max_width
and use_small_heuristics
tab_spaces
Number of spaces per tab
- Default value:
4
- Possible values: any positive integer
- Stable: Yes
4
(default):
fn lorem() {
let ipsum = dolor();
let sit = vec![
"amet consectetur adipiscing elit amet",
"consectetur adipiscing elit amet consectetur.",
];
}
2
:
fn lorem() {
let ipsum = dolor();
let sit = vec![
"amet consectetur adipiscing elit amet",
"consectetur adipiscing elit amet consectetur.",
];
}
See also: hard_tabs
.
trailing_comma
How to handle trailing commas for lists
- Default value:
"Vertical"
- Possible values:
"Always"
,"Never"
,"Vertical"
- Stable: No (tracking issue: #3379)
"Vertical"
(default):
fn main() {
let Lorem { ipsum, dolor, sit } = amet;
let Lorem {
ipsum,
dolor,
sit,
amet,
consectetur,
adipiscing,
} = elit;
}
"Always"
:
fn main() {
let Lorem { ipsum, dolor, sit, } = amet;
let Lorem {
ipsum,
dolor,
sit,
amet,
consectetur,
adipiscing,
} = elit;
}
"Never"
:
fn main() {
let Lorem { ipsum, dolor, sit } = amet;
let Lorem {
ipsum,
dolor,
sit,
amet,
consectetur,
adipiscing
} = elit;
}
See also: match_block_trailing_comma
.
trailing_semicolon
Add trailing semicolon after break, continue and return
- Default value:
true
- Possible values:
true
,false
- Stable: No (tracking issue: #3378)
true
(default):
fn foo() -> usize {
return 0;
}
false
:
fn foo() -> usize {
return 0
}
type_punctuation_density
Determines if +
or =
are wrapped in spaces in the punctuation of types
- Default value:
"Wide"
- Possible values:
"Compressed"
,"Wide"
- Stable: No (tracking issue: #3364)
"Wide"
(default):
fn lorem<Ipsum: Dolor + Sit = Amet>() {
// body
}
"Compressed"
:
fn lorem<Ipsum: Dolor+Sit=Amet>() {
// body
}
unstable_features
Enable unstable features on the unstable channel.
- Default value:
false
- Possible values:
true
,false
- Stable: No (tracking issue: #3387)
use_field_init_shorthand
Use field initialize shorthand if possible.
- Default value:
false
- Possible values:
true
,false
- Stable: Yes
false
(default):
struct Foo {
x: u32,
y: u32,
z: u32,
}
fn main() {
let x = 1;
let y = 2;
let z = 3;
let a = Foo { x, y, z };
let b = Foo { x: x, y: y, z: z };
}
true
:
struct Foo {
x: u32,
y: u32,
z: u32,
}
fn main() {
let x = 1;
let y = 2;
let z = 3;
let a = Foo { x, y, z };
}
use_small_heuristics
This option can be used to simplify the management and bulk updates of the granular width configuration settings (fn_call_width
, attr_fn_like_width
, struct_lit_width
, struct_variant_width
, array_width
, chain_width
, single_line_if_else_max_width
), that respectively control when formatted constructs are multi-lined/vertical based on width.
Note that explicitly provided values for the width configuration settings take precedence and override the calculated values determined by use_small_heuristics
.
- Default value:
"Default"
- Possible values:
"Default"
,"Off"
,"Max"
- Stable: Yes
Default
(default):
When use_small_heuristics
is set to Default
, the values for the granular width settings are calculated as a ratio of the value for max_width
.
The ratios are:
fn_call_width
-60%
attr_fn_like_width
-70%
struct_lit_width
-18%
struct_variant_width
-35%
array_width
-60%
chain_width
-60%
single_line_if_else_max_width
-50%
For example when max_width
is set to 100
, the width settings are:
fn_call_width=60
attr_fn_like_width=70
struct_lit_width=18
struct_variant_width=35
array_width=60
chain_width=60
single_line_if_else_max_width=50
and when max_width
is set to 200
:
fn_call_width=120
attr_fn_like_width=140
struct_lit_width=36
struct_variant_width=70
array_width=120
chain_width=120
single_line_if_else_max_width=100
enum Lorem {
Ipsum,
Dolor(bool),
Sit { amet: Consectetur, adipiscing: Elit },
}
fn main() {
lorem(
"lorem",
"ipsum",
"dolor",
"sit",
"amet",
"consectetur",
"adipiscing",
);
let lorem = Lorem {
ipsum: dolor,
sit: amet,
};
let lorem = Lorem { ipsum: dolor };
let lorem = if ipsum { dolor } else { sit };
}
Off
:
When use_small_heuristics
is set to Off
, the granular width settings are functionally disabled and ignored. See the documentation for the respective width config options for specifics.
enum Lorem {
Ipsum,
Dolor(bool),
Sit {
amet: Consectetur,
adipiscing: Elit,
},
}
fn main() {
lorem("lorem", "ipsum", "dolor", "sit", "amet", "consectetur", "adipiscing");
let lorem = Lorem {
ipsum: dolor,
sit: amet,
};
let lorem = if ipsum {
dolor
} else {
sit
};
}
Max
:
When use_small_heuristics
is set to Max
, then each granular width setting is set to the same value as max_width
.
So if max_width
is set to 200
, then all the width settings are also set to 200
.
fn_call_width=200
attr_fn_like_width=200
struct_lit_width=200
struct_variant_width=200
array_width=200
chain_width=200
single_line_if_else_max_width=200
enum Lorem {
Ipsum,
Dolor(bool),
Sit { amet: Consectetur, adipiscing: Elit },
}
fn main() {
lorem("lorem", "ipsum", "dolor", "sit", "amet", "consectetur", "adipiscing");
let lorem = Lorem { ipsum: dolor, sit: amet };
let lorem = if ipsum { dolor } else { sit };
}
See also:
max_width
fn_call_width
attr_fn_like_width
struct_lit_width
struct_variant_width
array_width
chain_width
single_line_if_else_max_width
use_try_shorthand
Replace uses of the try! macro by the ? shorthand
- Default value:
false
- Possible values:
true
,false
- Stable: Yes
false
(default):
fn main() {
let lorem = ipsum.map(|dolor| dolor.sit())?;
let lorem = try!(ipsum.map(|dolor| dolor.sit()));
}
true
:
fn main() {
let lorem = ipsum.map(|dolor| dolor.sit())?;
}
version
Which version of the formatting rules to use. Version::One
is backwards-compatible
with Rustfmt 1.0. Other versions are only backwards compatible within a major
version number.
- Default value:
One
- Possible values:
One
,Two
- Stable: No (tracking issue: #3383)
Example
version = "Two"
where_single_line
Forces the where
clause to be laid out on a single line.
- Default value:
false
- Possible values:
true
,false
- Stable: No (tracking issue: #3359)
false
(default):
impl<T> Lorem for T
where
Option<T>: Ipsum,
{
// body
}
true
:
impl<T> Lorem for T
where Option<T>: Ipsum
{
// body
}
See also brace_style
, control_brace_style
.
wrap_comments
Break comments to fit on the line
- Default value:
false
- Possible values:
true
,false
- Stable: No (tracking issue: #3347)
false
(default):
// Lorem ipsum dolor sit amet, consectetur adipiscing elit,
// sed do eiusmod tempor incididunt ut labore et dolore
// magna aliqua. Ut enim ad minim veniam, quis nostrud
// exercitation ullamco laboris nisi ut aliquip ex ea
// commodo consequat.
// Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.
true
:
// Lorem ipsum dolor sit amet, consectetur adipiscing elit,
// sed do eiusmod tempor incididunt ut labore et dolore
// magna aliqua. Ut enim ad minim veniam, quis nostrud
// exercitation ullamco laboris nisi ut aliquip ex ea
// commodo consequat.
Internal Options
emit_mode
Internal option
make_backup
Internal option, use --backup
print_misformatted_file_names
Internal option, use -l
or --files-with-diff