3 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](https://docs.rs/dirs/1.0.4/dirs/fn.config_dir.html) (e.g. `.config/rustfmt/`) are checked as well.
5 A possible content of `rustfmt.toml` or `.rustfmt.toml` might look like this:
9 reorder_imports = false
12 Each configuration option is either stable or unstable.
13 Stable options can always be used, while unstable options are only available on a nightly toolchain and must be opted into.
14 To enable unstable options, set `unstable_features = true` in `rustfmt.toml` or pass `--unstable-features` to rustfmt.
16 # Configuration Options
18 Below you find a detailed visual guide on all the supported configuration options of rustfmt:
22 Maximum width of an array literal before falling back to vertical formatting.
24 - **Default value**: `60`
25 - **Possible values**: any positive integer that is less than or equal to the value specified for [`max_width`](#max_width)
28 By default this option is set as a percentage of [`max_width`](#max_width) provided by [`use_small_heuristics`](#use_small_heuristics), but a value set directly for `array_width` will take precedence.
30 See also [`max_width`](#max_width) and [`use_small_heuristics`](#use_small_heuristics)
32 ## `attr_fn_like_width`
34 Maximum width of the args of a function-like attributes before falling back to vertical formatting.
36 - **Default value**: `70`
37 - **Possible values**: any positive integer that is less than or equal to the value specified for [`max_width`](#max_width)
40 By default this option is set as a percentage of [`max_width`](#max_width) provided by [`use_small_heuristics`](#use_small_heuristics), but a value set directly for `attr_fn_like_width` will take precedence.
42 See also [`max_width`](#max_width) and [`use_small_heuristics`](#use_small_heuristics)
46 Where to put a binary operator when a binary expression goes multiline.
48 - **Default value**: `"Front"`
49 - **Possible values**: `"Front"`, `"Back"`
50 - **Stable**: No (tracking issue: [#3368](https://github.com/rust-lang/rustfmt/issues/3368))
52 #### `"Front"` (default):
56 let or = foofoofoofoofoofoofoofoofoofoofoofoofoofoofoofoo
57 || barbarbarbarbarbarbarbarbarbarbarbarbarbarbarbar;
59 let sum = 123456789012345678901234567890
60 + 123456789012345678901234567890
61 + 123456789012345678901234567890;
63 let range = aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
64 ..bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb;
72 let or = foofoofoofoofoofoofoofoofoofoofoofoofoofoofoofoo ||
73 barbarbarbarbarbarbarbarbarbarbarbarbarbarbarbar;
75 let sum = 123456789012345678901234567890 +
76 123456789012345678901234567890 +
77 123456789012345678901234567890;
79 let range = aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa..
80 bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb;
84 ## `blank_lines_lower_bound`
86 Minimum number of blank lines which must be put between items. If two items have fewer blank lines between
87 them, additional blank lines are inserted.
89 - **Default value**: `0`
90 - **Possible values**: *unsigned integer*
91 - **Stable**: No (tracking issue: [#3382](https://github.com/rust-lang/rustfmt/issues/3382))
94 Original Code (rustfmt will not change it with the default value of `0`):
124 ## `blank_lines_upper_bound`
126 Maximum number of blank lines which can be put between items. If more than this number of consecutive empty
127 lines are found, they are trimmed down to match this integer.
129 - **Default value**: `1`
130 - **Possible values**: any non-negative integer
131 - **Stable**: No (tracking issue: [#3381](https://github.com/rust-lang/rustfmt/issues/3381))
181 See also: [`blank_lines_lower_bound`](#blank_lines_lower_bound)
185 Brace style for items
187 - **Default value**: `"SameLineWhere"`
188 - **Possible values**: `"AlwaysNextLine"`, `"PreferSameLine"`, `"SameLineWhere"`
189 - **Stable**: No (tracking issue: [#3376](https://github.com/rust-lang/rustfmt/issues/3376))
193 #### `"SameLineWhere"` (default):
200 fn lorem(ipsum: usize) {
204 fn lorem<T>(ipsum: T)
206 T: Add + Sub + Mul + Div,
212 #### `"AlwaysNextLine"`:
220 fn lorem(ipsum: usize)
225 fn lorem<T>(ipsum: T)
227 T: Add + Sub + Mul + Div,
233 #### `"PreferSameLine"`:
240 fn lorem(ipsum: usize) {
244 fn lorem<T>(ipsum: T)
246 T: Add + Sub + Mul + Div, {
251 ### Structs and enums
253 #### `"SameLineWhere"` (default):
268 #### `"AlwaysNextLine"`:
284 #### `"PreferSameLine"`:
300 Maximum width of a chain to fit on one line.
302 - **Default value**: `60`
303 - **Possible values**: any positive integer that is less than or equal to the value specified for [`max_width`](#max_width)
306 By default this option is set as a percentage of [`max_width`](#max_width) provided by [`use_small_heuristics`](#use_small_heuristics), but a value set directly for `chain_width` will take precedence.
308 See also [`max_width`](#max_width) and [`use_small_heuristics`](#use_small_heuristics)
312 Whether to use colored output or not.
314 - **Default value**: `"Auto"`
315 - **Possible values**: "Auto", "Always", "Never"
316 - **Stable**: No (tracking issue: [#3385](https://github.com/rust-lang/rustfmt/issues/3385))
318 ## `combine_control_expr`
320 Combine control expressions with function calls.
322 - **Default value**: `true`
323 - **Possible values**: `true`, `false`
324 - **Stable**: No (tracking issue: [#3369](https://github.com/rust-lang/rustfmt/issues/3369))
326 #### `true` (default):
338 foo!(if let Some(..) = x {
351 foo!(while let Some(..) = x {
385 if let Some(..) = x {
402 while let Some(..) = x {
428 Maximum length of comments. No effect unless`wrap_comments = true`.
430 - **Default value**: `80`
431 - **Possible values**: any positive integer
432 - **Stable**: No (tracking issue: [#3349](https://github.com/rust-lang/rustfmt/issues/3349))
434 **Note:** A value of `0` results in [`wrap_comments`](#wrap_comments) being applied regardless of a line's width.
436 #### `80` (default; comments shorter than `comment_width`):
438 // Lorem ipsum dolor sit amet, consectetur adipiscing elit.
441 #### `60` (comments longer than `comment_width`):
443 // Lorem ipsum dolor sit amet,
444 // consectetur adipiscing elit.
447 See also [`wrap_comments`](#wrap_comments).
449 ## `condense_wildcard_suffixes`
451 Replace strings of _ wildcards by a single .. in tuple patterns
453 - **Default value**: `false`
454 - **Possible values**: `true`, `false`
455 - **Stable**: No (tracking issue: [#3384](https://github.com/rust-lang/rustfmt/issues/3384))
457 #### `false` (default):
461 let (lorem, ipsum, _, _) = (1, 2, 3, 4);
462 let (lorem, ipsum, ..) = (1, 2, 3, 4);
470 let (lorem, ipsum, ..) = (1, 2, 3, 4);
474 ## `control_brace_style`
476 Brace style for control flow constructs
478 - **Default value**: `"AlwaysSameLine"`
479 - **Possible values**: `"AlwaysNextLine"`, `"AlwaysSameLine"`, `"ClosingNextLine"`
480 - **Stable**: No (tracking issue: [#3377](https://github.com/rust-lang/rustfmt/issues/3377))
482 #### `"AlwaysSameLine"` (default):
494 #### `"AlwaysNextLine"`:
509 #### `"ClosingNextLine"`:
522 ## `disable_all_formatting`
524 Don't reformat anything.
526 Note that this option may be soft-deprecated in the future once the [ignore](#ignore) option is stabilized. Nightly toolchain users are encouraged to use [ignore](#ignore) instead when possible.
528 - **Default value**: `false`
529 - **Possible values**: `true`, `false`
534 Specifies which edition is used by the parser.
536 - **Default value**: `"2015"`
537 - **Possible values**: `"2015"`, `"2018"`, `"2021"`
540 Rustfmt is able to pick up the edition used by reading the `Cargo.toml` file if executed
541 through the Cargo's formatting tool `cargo fmt`. Otherwise, the edition needs to be specified
548 ## `empty_item_single_line`
550 Put empty-body functions and impls on a single line
552 - **Default value**: `true`
553 - **Possible values**: `true`, `false`
554 - **Stable**: No (tracking issue: [#3356](https://github.com/rust-lang/rustfmt/issues/3356))
556 #### `true` (default):
574 See also [`brace_style`](#brace_style), [`control_brace_style`](#control_brace_style).
577 ## `enum_discrim_align_threshold`
579 The maximum length of enum variant having discriminant, that gets vertically aligned with others.
580 Variants without discriminants would be ignored for the purpose of alignment.
582 Note that this is not how much whitespace is inserted, but instead the longest variant name that
583 doesn't get ignored when aligning.
585 - **Default value** : 0
586 - **Possible values**: any positive integer
587 - **Stable**: No (tracking issue: [#3372](https://github.com/rust-lang/rustfmt/issues/3372))
595 RandomLongVariantGoesHere = 10,
600 VeryLongVariantNameHereA = 0,
601 VeryLongVariantNameHereBb = 1,
602 VeryLongVariantNameHereCcc = 2,
612 RandomLongVariantGoesHere = 10,
617 VeryLongVariantNameHereA = 0,
618 VeryLongVariantNameHereBb = 1,
619 VeryLongVariantNameHereCcc = 2,
624 ## `error_on_line_overflow`
626 Error if Rustfmt is unable to get all lines within `max_width`, except for comments and string
627 literals. If this happens, then it is a bug in Rustfmt. You might be able to work around the bug by
628 refactoring your code to avoid long/complex expressions, usually by extracting a local variable or
629 using a shorter name.
631 - **Default value**: `false`
632 - **Possible values**: `true`, `false`
633 - **Stable**: No (tracking issue: [#3391](https://github.com/rust-lang/rustfmt/issues/3391))
635 See also [`max_width`](#max_width).
637 ## `error_on_unformatted`
639 Error if unable to get comments or string literals within `max_width`, or they are left with
640 trailing whitespaces.
642 - **Default value**: `false`
643 - **Possible values**: `true`, `false`
644 - **Stable**: No (tracking issue: [#3392](https://github.com/rust-lang/rustfmt/issues/3392))
648 Control the layout of arguments in a function
650 - **Default value**: `"Tall"`
651 - **Possible values**: `"Compressed"`, `"Tall"`, `"Vertical"`
654 #### `"Tall"` (default):
658 fn lorem(ipsum: Ipsum, dolor: Dolor, sit: Sit, amet: Amet);
660 fn lorem(ipsum: Ipsum, dolor: Dolor, sit: Sit, amet: Amet) {
669 consectetur: Consectetur,
670 adipiscing: Adipiscing,
679 consectetur: Consectetur,
680 adipiscing: Adipiscing,
692 fn lorem(ipsum: Ipsum, dolor: Dolor, sit: Sit, amet: Amet);
694 fn lorem(ipsum: Ipsum, dolor: Dolor, sit: Sit, amet: Amet) {
699 ipsum: Ipsum, dolor: Dolor, sit: Sit, amet: Amet, consectetur: Consectetur,
700 adipiscing: Adipiscing, elit: Elit,
704 ipsum: Ipsum, dolor: Dolor, sit: Sit, amet: Amet, consectetur: Consectetur,
705 adipiscing: Adipiscing, elit: Elit,
737 consectetur: Consectetur,
738 adipiscing: Adipiscing,
747 consectetur: Consectetur,
748 adipiscing: Adipiscing,
758 Maximum width of the args of a function call before falling back to vertical formatting.
760 - **Default value**: `60`
761 - **Possible values**: any positive integer that is less than or equal to the value specified for [`max_width`](#max_width)
764 By default this option is set as a percentage of [`max_width`](#max_width) provided by [`use_small_heuristics`](#use_small_heuristics), but a value set directly for `fn_call_width` will take precedence.
766 See also [`max_width`](#max_width) and [`use_small_heuristics`](#use_small_heuristics)
770 Put single-expression functions on a single line
772 - **Default value**: `false`
773 - **Possible values**: `true`, `false`
774 - **Stable**: No (tracking issue: [#3358](https://github.com/rust-lang/rustfmt/issues/3358))
776 #### `false` (default):
779 fn lorem() -> usize {
783 fn lorem() -> usize {
792 fn lorem() -> usize { 42 }
794 fn lorem() -> usize {
800 See also [`control_brace_style`](#control_brace_style).
803 ## `force_explicit_abi`
805 Always print the abi for extern items
807 - **Default value**: `true`
808 - **Possible values**: `true`, `false`
811 **Note:** Non-"C" ABIs are always printed. If `false` then "C" is removed.
813 #### `true` (default):
817 pub static lorem: c_int;
825 pub static lorem: c_int;
829 ## `force_multiline_blocks`
831 Force multiline closure and match arm bodies to be wrapped in a block
833 - **Default value**: `false`
834 - **Possible values**: `false`, `true`
835 - **Stable**: No (tracking issue: [#3374](https://github.com/rust-lang/rustfmt/issues/3374))
837 #### `false` (default):
841 result.and_then(|maybe_value| match maybe_value {
843 Some(value) => bar(),
848 println!("Hello World");
850 Some(dolor) => foo(),
859 result.and_then(|maybe_value| {
862 Some(value) => bar(),
869 println!("Hello World");
872 Some(dolor) => foo(),
878 ## `format_code_in_doc_comments`
880 Format code snippet included in doc comments.
882 - **Default value**: `false`
883 - **Possible values**: `true`, `false`
884 - **Stable**: No (tracking issue: [#3348](https://github.com/rust-lang/rustfmt/issues/3348))
886 #### `false` (default):
889 /// Adds one to the number given.
900 /// # fn add_one(x: i32) -> i32 {
904 fn add_one(x: i32) -> i32 {
912 /// Adds one to the number given.
919 /// assert_eq!(6, add_one(5));
920 /// # fn add_one(x: i32) -> i32 {
924 fn add_one(x: i32) -> i32 {
929 ## `format_generated_files`
931 Format generated files. A file is considered generated
932 if any of the first five lines contain a `@generated` comment marker.
933 By default, generated files are reformatted, i. e. `@generated` marker is ignored.
934 This option is currently ignored for stdin (`@generated` in stdin is ignored.)
936 - **Default value**: `true`
937 - **Possible values**: `true`, `false`
938 - **Stable**: No (tracking issue: [#5080](https://github.com/rust-lang/rustfmt/issues/5080))
940 ## `format_macro_matchers`
942 Format the metavariable matching patterns in macros.
944 - **Default value**: `false`
945 - **Possible values**: `true`, `false`
946 - **Stable**: No (tracking issue: [#3354](https://github.com/rust-lang/rustfmt/issues/3354))
948 #### `false` (default):
952 ($a: ident : $b: ty) => {
955 ($a: ident $b: ident $c: ident) => {
965 ($a:ident : $b:ty) => {
968 ($a:ident $b:ident $c:ident) => {
974 See also [`format_macro_bodies`](#format_macro_bodies).
977 ## `format_macro_bodies`
979 Format the bodies of macros.
981 - **Default value**: `true`
982 - **Possible values**: `true`, `false`
983 - **Stable**: No (tracking issue: [#3355](https://github.com/rust-lang/rustfmt/issues/3355))
985 #### `true` (default):
989 ($a: ident : $b: ty) => {
992 ($a: ident $b: ident $c: ident) => {
1002 ($a: ident : $b: ty) => { $a(42): $b; };
1003 ($a: ident $b: ident $c: ident) => { $a=$b+$c; };
1007 See also [`format_macro_matchers`](#format_macro_matchers).
1012 Format string literals where necessary
1014 - **Default value**: `false`
1015 - **Possible values**: `true`, `false`
1016 - **Stable**: No (tracking issue: [#3353](https://github.com/rust-lang/rustfmt/issues/3353))
1018 #### `false` (default):
1022 let lorem = "ipsum dolor sit amet consectetur adipiscing elit lorem ipsum dolor sit amet consectetur adipiscing";
1030 let lorem = "ipsum dolor sit amet consectetur adipiscing elit lorem ipsum dolor sit amet \
1031 consectetur adipiscing";
1035 See also [`max_width`](#max_width).
1039 Use tab characters for indentation, spaces for alignment
1041 - **Default value**: `false`
1042 - **Possible values**: `true`, `false`
1045 #### `false` (default):
1048 fn lorem() -> usize {
1049 42 // spaces before 42
1056 fn lorem() -> usize {
1057 42 // tabs before 42
1061 See also: [`tab_spaces`](#tab_spaces).
1063 ## `hex_literal_case`
1065 Control the case of the letters in hexadecimal literal values
1067 - **Default value**: `Preserve`
1068 - **Possible values**: `Preserve`, `Upper`, `Lower`
1069 - **Stable**: No (tracking issue: [#5081](https://github.com/rust-lang/rustfmt/issues/5081))
1071 ## `hide_parse_errors`
1073 Do not show parse errors if the parser failed to parse files.
1075 - **Default value**: `false`
1076 - **Possible values**: `true`, `false`
1077 - **Stable**: No (tracking issue: [#3390](https://github.com/rust-lang/rustfmt/issues/3390))
1081 Skip formatting files and directories that match the specified pattern.
1082 The pattern format is the same as [.gitignore](https://git-scm.com/docs/gitignore#_pattern_format). Be sure to use Unix/forwardslash `/` style paths. This path style will work on all platforms. Windows style paths with backslashes `\` are not supported.
1084 - **Default value**: format every file
1085 - **Possible values**: See an example below
1086 - **Stable**: No (tracking issue: [#3395](https://github.com/rust-lang/rustfmt/issues/3395))
1090 If you want to ignore specific files, put the following to your config file:
1099 If you want to ignore every file under `examples/`, put the following to your config file:
1107 If you want to ignore every file under the directory where you put your rustfmt.toml:
1115 Indent style of imports
1117 - **Default Value**: `"Block"`
1118 - **Possible values**: `"Block"`, `"Visual"`
1119 - **Stable**: No (tracking issue: [#3360](https://github.com/rust-lang/rustfmt/issues/3360))
1121 #### `"Block"` (default):
1125 xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx, yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy,
1126 zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz,
1133 use foo::{xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx, yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy,
1134 zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz};
1137 See also: [`imports_layout`](#imports_layout).
1141 Item layout inside a imports block
1143 - **Default value**: "Mixed"
1144 - **Possible values**: "Horizontal", "HorizontalVertical", "Mixed", "Vertical"
1145 - **Stable**: No (tracking issue: [#3361](https://github.com/rust-lang/rustfmt/issues/3361))
1147 #### `"Mixed"` (default):
1150 use foo::{xxxxxxxxxxxxxxxxxx, yyyyyyyyyyyyyyyyyy, zzzzzzzzzzzzzzzzzz};
1153 aaaaaaaaaaaaaaaaaa, bbbbbbbbbbbbbbbbbb, cccccccccccccccccc, dddddddddddddddddd,
1154 eeeeeeeeeeeeeeeeee, ffffffffffffffffff,
1158 #### `"Horizontal"`:
1160 **Note**: This option forces all imports onto one line and may exceed `max_width`.
1163 use foo::{xxx, yyy, zzz};
1165 use foo::{aaa, bbb, ccc, ddd, eee, fff};
1168 #### `"HorizontalVertical"`:
1171 use foo::{xxxxxxxxxxxxxxxxxx, yyyyyyyyyyyyyyyyyy, zzzzzzzzzzzzzzzzzz};
1204 Indent on expressions or items.
1206 - **Default value**: `"Block"`
1207 - **Possible values**: `"Block"`, `"Visual"`
1208 - **Stable**: No (tracking issue: [#3346](https://github.com/rust-lang/rustfmt/issues/3346))
1212 #### `"Block"` (default):
1232 let lorem = vec!["ipsum",
1244 #### `"Block"` (default):
1252 && dolor_consectetur
1254 && lorem_consectetur
1269 && dolor_consectetur
1271 && lorem_consectetur
1278 See also: [`control_brace_style`](#control_brace_style).
1280 ### Function arguments
1282 #### `"Block"` (default):
1287 fn lorem(ipsum: usize) {}
1307 fn lorem(ipsum: usize) {}
1309 fn lorem(ipsum: usize,
1322 #### `"Block"` (default):
1356 #### `"Block"` (default):
1364 Adipiscing: Eq = usize,
1365 Consectetur: Eq = usize,
1372 adipiscing: Adipiscing,
1373 consectetur: Consectetur,
1383 fn lorem<Ipsum: Eq = usize,
1387 Adipiscing: Eq = usize,
1388 Consectetur: Eq = usize,
1394 adipiscing: Adipiscing,
1395 consectetur: Consectetur,
1404 #### `"Block"` (default):
1419 let lorem = Lorem { ipsum: dolor,
1424 See also: [`struct_lit_single_line`](#struct_lit_single_line), [`indent_style`](#indent_style).
1426 ### Where predicates
1428 #### `"Block"` (default):
1431 fn lorem<Ipsum, Dolor, Sit, Amet>() -> T
1445 fn lorem<Ipsum, Dolor, Sit, Amet>() -> T
1455 ## `inline_attribute_width`
1457 Write an item and its attribute on the same line if their combined width is below a threshold
1459 - **Default value**: 0
1460 - **Possible values**: any positive integer
1461 - **Stable**: No (tracking issue: [#3343](https://github.com/rust-lang/rustfmt/issues/3343))
1467 #[cfg(feature = "alloc")]
1473 #[cfg(feature = "alloc")] use core::slice;
1476 ## `match_arm_blocks`
1478 Controls whether arm bodies are wrapped in cases where the first line of the body cannot fit on the same line as the `=>` operator.
1480 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.
1482 - **Default value**: `true`
1483 - **Possible values**: `true`, `false`
1484 - **Stable**: No (tracking issue: [#3373](https://github.com/rust-lang/rustfmt/issues/3373))
1486 #### `true` (default):
1492 foooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo(x)
1494 dolor => println!("{}", sit),
1496 "foooooooooooooooooooooooo",
1497 "baaaaaaaaaaaaaaaaaaaaaaaarr",
1498 "baaaaaaaaaaaaaaaaaaaazzzzzzzzzzzzz",
1499 "qqqqqqqqquuuuuuuuuuuuuuuuuuuuuuuuuuxxx",
1511 foooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo(x),
1512 ipsum => println!("{}", sit),
1514 "foooooooooooooooooooooooo",
1515 "baaaaaaaaaaaaaaaaaaaaaaaarr",
1516 "baaaaaaaaaaaaaaaaaaaazzzzzzzzzzzzz",
1517 "qqqqqqqqquuuuuuuuuuuuuuuuuuuuuuuuuuxxx",
1523 See also: [`match_block_trailing_comma`](#match_block_trailing_comma).
1525 ## `match_arm_leading_pipes`
1527 Controls whether to include a leading pipe on match arms
1529 - **Default value**: `Never`
1530 - **Possible values**: `Always`, `Never`, `Preserve`
1533 #### `Never` (default):
1535 // Leading pipes are removed from this:
1538 // | "foo" | "bar" => {}
1540 // | "something relatively long"
1541 // | "something really really really realllllllllllllly long" => println!("x"),
1542 // | "qux" => println!("y"),
1552 | "something relatively long"
1553 | "something really really really realllllllllllllly long" => println!("x"),
1554 "qux" => println!("y"),
1562 // Leading pipes are emitted on all arms of this:
1565 // "foo" | "bar" => {}
1567 // | "something relatively long"
1568 // | "something really really really realllllllllllllly long" => println!("x"),
1569 // "qux" => println!("y"),
1577 | "foo" | "bar" => {}
1579 | "something relatively long"
1580 | "something really really really realllllllllllllly long" => println!("x"),
1581 | "qux" => println!("y"),
1591 | "foo" | "bar" => {}
1593 | "something relatively long"
1594 | "something really really really realllllllllllllly long" => println!("x"),
1595 | "qux" => println!("y"),
1607 ## `match_block_trailing_comma`
1609 Put a trailing comma after a block based match arm (non-block arms are not affected)
1611 - **Default value**: `false`
1612 - **Possible values**: `true`, `false`
1615 #### `false` (default):
1623 Lorem::Dolor => println!("dolor"),
1636 Lorem::Dolor => println!("dolor"),
1641 See also: [`trailing_comma`](#trailing_comma), [`match_arm_blocks`](#match_arm_blocks).
1645 Maximum width of each line
1647 - **Default value**: `100`
1648 - **Possible values**: any positive integer
1651 See also [`error_on_line_overflow`](#error_on_line_overflow).
1655 Merge multiple derives into a single one.
1657 - **Default value**: `true`
1658 - **Possible values**: `true`, `false`
1661 #### `true` (default):
1664 #[derive(Eq, PartialEq, Debug, Copy, Clone)]
1671 #[derive(Eq, PartialEq, Debug, Copy, Clone)]
1674 #[derive(Eq, PartialEq)]
1676 #[derive(Copy, Clone)]
1680 ## `imports_granularity`
1682 How imports should be grouped into `use` statements. Imports will be merged or split to the configured level of granularity.
1684 - **Default value**: `Preserve`
1685 - **Possible values**: `Preserve`, `Crate`, `Module`, `Item`, `One`
1686 - **Stable**: No (tracking issue: [#4991](https://github.com/rust-lang/rustfmt/issues/4991))
1688 Note that rustfmt will not modify the granularity of imports containing comments if doing so could potentially lose or misplace said comments.
1690 #### `Preserve` (default):
1692 Do not change the granularity of any imports and preserve the original structure written by the developer.
1697 use foo::{a, c, d::e};
1703 Merge imports from the same crate into a single `use` statement. Conversely, imports from different crates are split into separate statements.
1717 Merge imports from the same module into a single `use` statement. Conversely, imports from different modules are split into separate statements.
1728 Flatten imports so that each has its own `use` statement.
1743 Merge all imports into a single `use` statement as long as they have the same visibility.
1746 pub use foo::{x, y};
1760 This option is deprecated. Use `imports_granularity = "Crate"` instead.
1762 - **Default value**: `false`
1763 - **Possible values**: `true`, `false`
1765 #### `false` (default):
1776 use foo::{a, b, c, d, e, f, g};
1782 Unix or Windows line endings
1784 - **Default value**: `"Auto"`
1785 - **Possible values**: `"Auto"`, `"Native"`, `"Unix"`, `"Windows"`
1788 #### `Auto` (default):
1790 The newline style is detected automatically on a per-file basis. Files
1791 with mixed line endings will be converted to the first detected line
1796 Line endings will be converted to `\r\n` on Windows and `\n` on all
1801 Line endings will be converted to `\n`.
1805 Line endings will be converted to `\r\n`.
1807 ## `normalize_comments`
1809 Convert /* */ comments to // comments where possible
1811 - **Default value**: `false`
1812 - **Possible values**: `true`, `false`
1813 - **Stable**: No (tracking issue: [#3350](https://github.com/rust-lang/rustfmt/issues/3350))
1815 #### `false` (default):
1819 fn dolor() -> usize {}
1822 fn adipiscing() -> usize {}
1829 fn dolor() -> usize {}
1832 fn adipiscing() -> usize {}
1835 ## `normalize_doc_attributes`
1837 Convert `#![doc]` and `#[doc]` attributes to `//!` and `///` doc comments.
1839 - **Default value**: `false`
1840 - **Possible values**: `true`, `false`
1841 - **Stable**: No (tracking issue: [#3351](https://github.com/rust-lang/rustfmt/issues/3351))
1843 #### `false` (default):
1846 #![doc = "Example documentation"]
1848 #[doc = "Example item documentation"]
1851 /// Example item documentation
1858 //! Example documentation
1860 /// Example item documentation
1864 ## `overflow_delimited_expr`
1866 When structs, slices, arrays, and block/array-like macros are used as the last
1867 argument in an expression list, allow them to overflow (like blocks/closures)
1868 instead of being indented on a new line.
1870 - **Default value**: `false`
1871 - **Possible values**: `true`, `false`
1872 - **Stable**: No (tracking issue: [#3370](https://github.com/rust-lang/rustfmt/issues/3370))
1874 #### `false` (default):
1947 ## `remove_nested_parens`
1949 Remove nested parens.
1951 - **Default value**: `true`,
1952 - **Possible values**: `true`, `false`
1956 #### `true` (default):
1973 ## `reorder_impl_items`
1975 Reorder impl items. `type` and `const` are put first, then macros and methods.
1977 - **Default value**: `false`
1978 - **Possible values**: `true`, `false`
1979 - **Stable**: No (tracking issue: [#3363](https://github.com/rust-lang/rustfmt/issues/3363))
1981 #### `false` (default)
1986 impl Iterator for Dummy {
1987 fn next(&mut self) -> Option<Self::Item> {
1994 impl Iterator for Dummy {
1997 fn next(&mut self) -> Option<Self::Item> {
2008 impl Iterator for Dummy {
2011 fn next(&mut self) -> Option<Self::Item> {
2017 ## `reorder_imports`
2019 Reorder import and extern crate statements alphabetically in groups (a group is
2020 separated by a newline).
2022 - **Default value**: `true`
2023 - **Possible values**: `true`, `false`
2026 #### `true` (default):
2046 Controls the strategy for how consecutive imports are grouped together.
2048 Controls the strategy for grouping sets of consecutive imports. Imports may contain newlines between imports and still be grouped together as a single set, but other statements between imports will result in different grouping sets.
2050 - **Default value**: `Preserve`
2051 - **Possible values**: `Preserve`, `StdExternalCrate`, `One`
2052 - **Stable**: No (tracking issue: [#5083](https://github.com/rust-lang/rustfmt/issues/5083))
2054 Each set of imports (one or more `use` statements, optionally separated by newlines) will be formatted independently. Other statements such as `mod ...` or `extern crate ...` will cause imports to not be grouped together.
2056 #### `Preserve` (default):
2058 Preserve the source file's import groups.
2061 use super::update::convert_publish_payload;
2064 use alloc::alloc::Layout;
2065 use juniper::{FieldError, FieldResult};
2070 use broker::database::PooledConnection;
2072 use super::schema::{Context, Payload};
2073 use crate::models::Event;
2077 #### `StdExternalCrate`:
2079 Discard existing import groups, and create three groups for:
2080 1. `std`, `core` and `alloc`,
2082 3. `self`, `super` and `crate` imports.
2085 use alloc::alloc::Layout;
2089 use broker::database::PooledConnection;
2091 use juniper::{FieldError, FieldResult};
2094 use super::schema::{Context, Payload};
2095 use super::update::convert_publish_payload;
2096 use crate::models::Event;
2101 Discard existing import groups, and create a single group for everything
2104 use super::schema::{Context, Payload};
2105 use super::update::convert_publish_payload;
2106 use crate::models::Event;
2107 use alloc::alloc::Layout;
2108 use broker::database::PooledConnection;
2111 use juniper::{FieldError, FieldResult};
2116 ## `reorder_modules`
2118 Reorder `mod` declarations alphabetically in group.
2120 - **Default value**: `true`
2121 - **Possible values**: `true`, `false`
2124 #### `true` (default)
2148 **Note** `mod` with `#[macro_export]` will not be reordered since that could change the semantics
2149 of the original source code.
2151 ## `required_version`
2153 Require a specific version of rustfmt. If you want to make sure that the
2154 specific version of rustfmt is used in your CI, use this option.
2156 - **Default value**: `CARGO_PKG_VERSION`
2157 - **Possible values**: any published version (e.g. `"0.3.8"`)
2158 - **Stable**: No (tracking issue: [#3386](https://github.com/rust-lang/rustfmt/issues/3386))
2160 ## `short_array_element_width_threshold`
2162 The width threshold for an array element to be considered "short".
2164 The layout of an array is dependent on the length of each of its elements.
2165 If the length of every element in an array is below this threshold (all elements are "short") then the array can be formatted in the mixed/compressed style, but if any one element has a length that exceeds this threshold then the array elements will have to be formatted vertically.
2167 - **Default value**: `10`
2168 - **Possible values**: any positive integer that is less than or equal to the value specified for [`max_width`](#max_width)
2171 #### `10` (default):
2174 pub const FORMAT_TEST: [u64; 5] = [
2186 pub const FORMAT_TEST: [u64; 5] = [
2187 0x0000000000000000, 0xaaaaaaaaaaaaaaaa, 0xbbbbbbbbbbbbbbbb, 0xcccccccccccccccc,
2192 See also [`max_width`](#max_width).
2196 Don't reformat out of line modules
2198 - **Default value**: `false`
2199 - **Possible values**: `true`, `false`
2200 - **Stable**: No (tracking issue: [#3389](https://github.com/rust-lang/rustfmt/issues/3389))
2202 ## `single_line_if_else_max_width`
2204 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`.
2206 - **Default value**: `50`
2207 - **Possible values**: any positive integer that is less than or equal to the value specified for [`max_width`](#max_width)
2210 By default this option is set as a percentage of [`max_width`](#max_width) provided by [`use_small_heuristics`](#use_small_heuristics), but a value set directly for `single_line_if_else_max_width` will take precedence.
2212 See also [`max_width`](#max_width) and [`use_small_heuristics`](#use_small_heuristics)
2214 ## `space_after_colon`
2216 Leave a space after the colon.
2218 - **Default value**: `true`
2219 - **Possible values**: `true`, `false`
2220 - **Stable**: No (tracking issue: [#3366](https://github.com/rust-lang/rustfmt/issues/3366))
2222 #### `true` (default):
2225 fn lorem<T: Eq>(t: T) {
2226 let lorem: Dolor = Lorem {
2236 fn lorem<T:Eq>(t:T) {
2237 let lorem:Dolor = Lorem {
2244 See also: [`space_before_colon`](#space_before_colon).
2246 ## `space_before_colon`
2248 Leave a space before the colon.
2250 - **Default value**: `false`
2251 - **Possible values**: `true`, `false`
2252 - **Stable**: No (tracking issue: [#3365](https://github.com/rust-lang/rustfmt/issues/3365))
2254 #### `false` (default):
2257 fn lorem<T: Eq>(t: T) {
2258 let lorem: Dolor = Lorem {
2268 fn lorem<T : Eq>(t : T) {
2269 let lorem : Dolor = Lorem {
2276 See also: [`space_after_colon`](#space_after_colon).
2278 ## `spaces_around_ranges`
2280 Put spaces around the .., ..=, and ... range operators
2282 - **Default value**: `false`
2283 - **Possible values**: `true`, `false`
2284 - **Stable**: No (tracking issue: [#3367](https://github.com/rust-lang/rustfmt/issues/3367))
2286 #### `false` (default):
2314 let lorem = 0 .. 10;
2315 let ipsum = 0 ..= 10;
2334 ## `struct_field_align_threshold`
2336 The maximum diff of width between struct fields to be aligned with each other.
2338 - **Default value** : 0
2339 - **Possible values**: any non-negative integer
2340 - **Stable**: No (tracking issue: [#3371](https://github.com/rust-lang/rustfmt/issues/3371))
2362 ## `struct_lit_single_line`
2364 Put small struct literals on a single line
2366 - **Default value**: `true`
2367 - **Possible values**: `true`, `false`
2368 - **Stable**: No (tracking issue: [#3357](https://github.com/rust-lang/rustfmt/issues/3357))
2370 #### `true` (default):
2374 let lorem = Lorem { foo: bar, baz: ofo };
2389 See also: [`indent_style`](#indent_style).
2391 ## `struct_lit_width`
2393 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`.
2395 - **Default value**: `18`
2396 - **Possible values**: any positive integer that is less than or equal to the value specified for [`max_width`](#max_width)
2399 By default this option is set as a percentage of [`max_width`](#max_width) provided by [`use_small_heuristics`](#use_small_heuristics), but a value set directly for `struct_lit_width` will take precedence.
2401 See also [`max_width`](#max_width), [`use_small_heuristics`](#use_small_heuristics), and [`struct_lit_single_line`](#struct_lit_single_line)
2403 ## `struct_variant_width`
2405 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`.
2407 - **Default value**: `35`
2408 - **Possible values**: any positive integer that is less than or equal to the value specified for [`max_width`](#max_width)
2411 By default this option is set as a percentage of [`max_width`](#max_width) provided by [`use_small_heuristics`](#use_small_heuristics), but a value set directly for `struct_variant_width` will take precedence.
2413 See also [`max_width`](#max_width) and [`use_small_heuristics`](#use_small_heuristics)
2417 Number of spaces per tab
2419 - **Default value**: `4`
2420 - **Possible values**: any positive integer
2427 let ipsum = dolor();
2429 "amet consectetur adipiscing elit amet",
2430 "consectetur adipiscing elit amet consectetur.",
2439 let ipsum = dolor();
2441 "amet consectetur adipiscing elit amet",
2442 "consectetur adipiscing elit amet consectetur.",
2447 See also: [`hard_tabs`](#hard_tabs).
2452 How to handle trailing commas for lists
2454 - **Default value**: `"Vertical"`
2455 - **Possible values**: `"Always"`, `"Never"`, `"Vertical"`
2456 - **Stable**: No (tracking issue: [#3379](https://github.com/rust-lang/rustfmt/issues/3379))
2458 #### `"Vertical"` (default):
2462 let Lorem { ipsum, dolor, sit } = amet;
2478 let Lorem { ipsum, dolor, sit, } = amet;
2494 let Lorem { ipsum, dolor, sit } = amet;
2506 See also: [`match_block_trailing_comma`](#match_block_trailing_comma).
2508 ## `trailing_semicolon`
2510 Add trailing semicolon after break, continue and return
2512 - **Default value**: `true`
2513 - **Possible values**: `true`, `false`
2514 - **Stable**: No (tracking issue: [#3378](https://github.com/rust-lang/rustfmt/issues/3378))
2516 #### `true` (default):
2530 ## `type_punctuation_density`
2532 Determines if `+` or `=` are wrapped in spaces in the punctuation of types
2534 - **Default value**: `"Wide"`
2535 - **Possible values**: `"Compressed"`, `"Wide"`
2536 - **Stable**: No (tracking issue: [#3364](https://github.com/rust-lang/rustfmt/issues/3364))
2538 #### `"Wide"` (default):
2541 fn lorem<Ipsum: Dolor + Sit = Amet>() {
2546 #### `"Compressed"`:
2549 fn lorem<Ipsum: Dolor+Sit=Amet>() {
2554 ## `unstable_features`
2556 Enable unstable features on the unstable channel.
2558 - **Default value**: `false`
2559 - **Possible values**: `true`, `false`
2560 - **Stable**: No (tracking issue: [#3387](https://github.com/rust-lang/rustfmt/issues/3387))
2562 ## `use_field_init_shorthand`
2564 Use field initialize shorthand if possible.
2566 - **Default value**: `false`
2567 - **Possible values**: `true`, `false`
2570 #### `false` (default):
2583 let a = Foo { x, y, z };
2584 let b = Foo { x: x, y: y, z: z };
2601 let a = Foo { x, y, z };
2605 ## `use_small_heuristics`
2607 This option can be used to simplify the management and bulk updates of the granular width configuration settings ([`fn_call_width`](#fn_call_width), [`attr_fn_like_width`](#attr_fn_like_width), [`struct_lit_width`](#struct_lit_width), [`struct_variant_width`](#struct_variant_width), [`array_width`](#array_width), [`chain_width`](#chain_width), [`single_line_if_else_max_width`](#single_line_if_else_max_width)), that respectively control when formatted constructs are multi-lined/vertical based on width.
2609 Note that explicitly provided values for the width configuration settings take precedence and override the calculated values determined by `use_small_heuristics`.
2611 - **Default value**: `"Default"`
2612 - **Possible values**: `"Default"`, `"Off"`, `"Max"`
2615 #### `Default` (default):
2616 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`.
2619 * [`fn_call_width`](#fn_call_width) - `60%`
2620 * [`attr_fn_like_width`](#attr_fn_like_width) - `70%`
2621 * [`struct_lit_width`](#struct_lit_width) - `18%`
2622 * [`struct_variant_width`](#struct_variant_width) - `35%`
2623 * [`array_width`](#array_width) - `60%`
2624 * [`chain_width`](#chain_width) - `60%`
2625 * [`single_line_if_else_max_width`](#single_line_if_else_max_width) - `50%`
2627 For example when `max_width` is set to `100`, the width settings are:
2628 * `fn_call_width=60`
2629 * `attr_fn_like_width=70`
2630 * `struct_lit_width=18`
2631 * `struct_variant_width=35`
2634 * `single_line_if_else_max_width=50`
2636 and when `max_width` is set to `200`:
2637 * `fn_call_width=120`
2638 * `attr_fn_like_width=140`
2639 * `struct_lit_width=36`
2640 * `struct_variant_width=70`
2643 * `single_line_if_else_max_width=100`
2649 Sit { amet: Consectetur, adipiscing: Elit },
2667 let lorem = Lorem { ipsum: dolor };
2669 let lorem = if ipsum { dolor } else { sit };
2674 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.
2687 lorem("lorem", "ipsum", "dolor", "sit", "amet", "consectetur", "adipiscing");
2694 let lorem = if ipsum {
2703 When `use_small_heuristics` is set to `Max`, then each granular width setting is set to the same value as `max_width`.
2705 So if `max_width` is set to `200`, then all the width settings are also set to `200`.
2706 * `fn_call_width=200`
2707 * `attr_fn_like_width=200`
2708 * `struct_lit_width=200`
2709 * `struct_variant_width=200`
2712 * `single_line_if_else_max_width=200`
2718 Sit { amet: Consectetur, adipiscing: Elit },
2722 lorem("lorem", "ipsum", "dolor", "sit", "amet", "consectetur", "adipiscing");
2724 let lorem = Lorem { ipsum: dolor, sit: amet };
2726 let lorem = if ipsum { dolor } else { sit };
2732 * [`max_width`](#max_width)
2733 * [`fn_call_width`](#fn_call_width)
2734 * [`attr_fn_like_width`](#attr_fn_like_width)
2735 * [`struct_lit_width`](#struct_lit_width)
2736 * [`struct_variant_width`](#struct_variant_width)
2737 * [`array_width`](#array_width)
2738 * [`chain_width`](#chain_width)
2739 * [`single_line_if_else_max_width`](#single_line_if_else_max_width)
2741 ## `use_try_shorthand`
2743 Replace uses of the try! macro by the ? shorthand
2745 - **Default value**: `false`
2746 - **Possible values**: `true`, `false`
2749 #### `false` (default):
2753 let lorem = ipsum.map(|dolor| dolor.sit())?;
2755 let lorem = try!(ipsum.map(|dolor| dolor.sit()));
2763 let lorem = ipsum.map(|dolor| dolor.sit())?;
2769 Which version of the formatting rules to use. `Version::One` is backwards-compatible
2770 with Rustfmt 1.0. Other versions are only backwards compatible within a major
2773 - **Default value**: `One`
2774 - **Possible values**: `One`, `Two`
2775 - **Stable**: No (tracking issue: [#3383](https://github.com/rust-lang/rustfmt/issues/3383))
2783 ## `where_single_line`
2785 Forces the `where` clause to be laid out on a single line.
2787 - **Default value**: `false`
2788 - **Possible values**: `true`, `false`
2789 - **Stable**: No (tracking issue: [#3359](https://github.com/rust-lang/rustfmt/issues/3359))
2791 #### `false` (default):
2806 where Option<T>: Ipsum
2812 See also [`brace_style`](#brace_style), [`control_brace_style`](#control_brace_style).
2817 Break comments to fit on the line
2819 - **Default value**: `false`
2820 - **Possible values**: `true`, `false`
2821 - **Stable**: No (tracking issue: [#3347](https://github.com/rust-lang/rustfmt/issues/3347))
2823 #### `false` (default):
2826 // Lorem ipsum dolor sit amet, consectetur adipiscing elit,
2827 // sed do eiusmod tempor incididunt ut labore et dolore
2828 // magna aliqua. Ut enim ad minim veniam, quis nostrud
2829 // exercitation ullamco laboris nisi ut aliquip ex ea
2830 // commodo consequat.
2832 // 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.
2838 // Lorem ipsum dolor sit amet, consectetur adipiscing elit,
2839 // sed do eiusmod tempor incididunt ut labore et dolore
2840 // magna aliqua. Ut enim ad minim veniam, quis nostrud
2841 // exercitation ullamco laboris nisi ut aliquip ex ea
2842 // commodo consequat.
2853 Internal option, use `--backup`
2855 ## `print_misformatted_file_names`
2857 Internal option, use `-l` or `--files-with-diff`