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 ## `doc_comment_code_block_width`
931 Max width for code snippets included in doc comments. Only used if [`format_code_in_doc_comments`](#format_code_in_doc_comments) is true.
933 - **Default value**: `100`
934 - **Possible values**: any positive integer that is less than or equal to the value specified for [`max_width`](#max_width)
935 - **Stable**: No (tracking issue: [#5359](https://github.com/rust-lang/rustfmt/issues/5359))
937 ## `format_generated_files`
939 Format generated files. A file is considered generated
940 if any of the first five lines contain a `@generated` comment marker.
941 By default, generated files are reformatted, i. e. `@generated` marker is ignored.
942 This option is currently ignored for stdin (`@generated` in stdin is ignored.)
944 - **Default value**: `true`
945 - **Possible values**: `true`, `false`
946 - **Stable**: No (tracking issue: [#5080](https://github.com/rust-lang/rustfmt/issues/5080))
948 ## `format_macro_matchers`
950 Format the metavariable matching patterns in macros.
952 - **Default value**: `false`
953 - **Possible values**: `true`, `false`
954 - **Stable**: No (tracking issue: [#3354](https://github.com/rust-lang/rustfmt/issues/3354))
956 #### `false` (default):
960 ($a: ident : $b: ty) => {
963 ($a: ident $b: ident $c: ident) => {
973 ($a:ident : $b:ty) => {
976 ($a:ident $b:ident $c:ident) => {
982 See also [`format_macro_bodies`](#format_macro_bodies).
985 ## `format_macro_bodies`
987 Format the bodies of macros.
989 - **Default value**: `true`
990 - **Possible values**: `true`, `false`
991 - **Stable**: No (tracking issue: [#3355](https://github.com/rust-lang/rustfmt/issues/3355))
993 #### `true` (default):
997 ($a: ident : $b: ty) => {
1000 ($a: ident $b: ident $c: ident) => {
1010 ($a: ident : $b: ty) => { $a(42): $b; };
1011 ($a: ident $b: ident $c: ident) => { $a=$b+$c; };
1015 See also [`format_macro_matchers`](#format_macro_matchers).
1020 Format string literals where necessary
1022 - **Default value**: `false`
1023 - **Possible values**: `true`, `false`
1024 - **Stable**: No (tracking issue: [#3353](https://github.com/rust-lang/rustfmt/issues/3353))
1026 #### `false` (default):
1030 let lorem = "ipsum dolor sit amet consectetur adipiscing elit lorem ipsum dolor sit amet consectetur adipiscing";
1038 let lorem = "ipsum dolor sit amet consectetur adipiscing elit lorem ipsum dolor sit amet \
1039 consectetur adipiscing";
1043 See also [`max_width`](#max_width).
1047 Use tab characters for indentation, spaces for alignment
1049 - **Default value**: `false`
1050 - **Possible values**: `true`, `false`
1053 #### `false` (default):
1056 fn lorem() -> usize {
1057 42 // spaces before 42
1064 fn lorem() -> usize {
1065 42 // tabs before 42
1069 See also: [`tab_spaces`](#tab_spaces).
1071 ## `hex_literal_case`
1073 Control the case of the letters in hexadecimal literal values
1075 - **Default value**: `Preserve`
1076 - **Possible values**: `Preserve`, `Upper`, `Lower`
1077 - **Stable**: No (tracking issue: [#5081](https://github.com/rust-lang/rustfmt/issues/5081))
1079 ## `hide_parse_errors`
1081 Do not show parse errors if the parser failed to parse files.
1083 - **Default value**: `false`
1084 - **Possible values**: `true`, `false`
1085 - **Stable**: No (tracking issue: [#3390](https://github.com/rust-lang/rustfmt/issues/3390))
1089 Skip formatting files and directories that match the specified pattern.
1090 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.
1092 - **Default value**: format every file
1093 - **Possible values**: See an example below
1094 - **Stable**: No (tracking issue: [#3395](https://github.com/rust-lang/rustfmt/issues/3395))
1098 If you want to ignore specific files, put the following to your config file:
1107 If you want to ignore every file under `examples/`, put the following to your config file:
1115 If you want to ignore every file under the directory where you put your rustfmt.toml:
1123 Indent style of imports
1125 - **Default Value**: `"Block"`
1126 - **Possible values**: `"Block"`, `"Visual"`
1127 - **Stable**: No (tracking issue: [#3360](https://github.com/rust-lang/rustfmt/issues/3360))
1129 #### `"Block"` (default):
1133 xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx, yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy,
1134 zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz,
1141 use foo::{xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx, yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy,
1142 zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz};
1145 See also: [`imports_layout`](#imports_layout).
1149 Item layout inside a imports block
1151 - **Default value**: "Mixed"
1152 - **Possible values**: "Horizontal", "HorizontalVertical", "Mixed", "Vertical"
1153 - **Stable**: No (tracking issue: [#3361](https://github.com/rust-lang/rustfmt/issues/3361))
1155 #### `"Mixed"` (default):
1158 use foo::{xxxxxxxxxxxxxxxxxx, yyyyyyyyyyyyyyyyyy, zzzzzzzzzzzzzzzzzz};
1161 aaaaaaaaaaaaaaaaaa, bbbbbbbbbbbbbbbbbb, cccccccccccccccccc, dddddddddddddddddd,
1162 eeeeeeeeeeeeeeeeee, ffffffffffffffffff,
1166 #### `"Horizontal"`:
1168 **Note**: This option forces all imports onto one line and may exceed `max_width`.
1171 use foo::{xxx, yyy, zzz};
1173 use foo::{aaa, bbb, ccc, ddd, eee, fff};
1176 #### `"HorizontalVertical"`:
1179 use foo::{xxxxxxxxxxxxxxxxxx, yyyyyyyyyyyyyyyyyy, zzzzzzzzzzzzzzzzzz};
1212 Indent on expressions or items.
1214 - **Default value**: `"Block"`
1215 - **Possible values**: `"Block"`, `"Visual"`
1216 - **Stable**: No (tracking issue: [#3346](https://github.com/rust-lang/rustfmt/issues/3346))
1220 #### `"Block"` (default):
1240 let lorem = vec!["ipsum",
1252 #### `"Block"` (default):
1260 && dolor_consectetur
1262 && lorem_consectetur
1277 && dolor_consectetur
1279 && lorem_consectetur
1286 See also: [`control_brace_style`](#control_brace_style).
1288 ### Function arguments
1290 #### `"Block"` (default):
1295 fn lorem(ipsum: usize) {}
1315 fn lorem(ipsum: usize) {}
1317 fn lorem(ipsum: usize,
1330 #### `"Block"` (default):
1364 #### `"Block"` (default):
1372 Adipiscing: Eq = usize,
1373 Consectetur: Eq = usize,
1380 adipiscing: Adipiscing,
1381 consectetur: Consectetur,
1391 fn lorem<Ipsum: Eq = usize,
1395 Adipiscing: Eq = usize,
1396 Consectetur: Eq = usize,
1402 adipiscing: Adipiscing,
1403 consectetur: Consectetur,
1412 #### `"Block"` (default):
1427 let lorem = Lorem { ipsum: dolor,
1432 See also: [`struct_lit_single_line`](#struct_lit_single_line), [`indent_style`](#indent_style).
1434 ### Where predicates
1436 #### `"Block"` (default):
1439 fn lorem<Ipsum, Dolor, Sit, Amet>() -> T
1453 fn lorem<Ipsum, Dolor, Sit, Amet>() -> T
1463 ## `inline_attribute_width`
1465 Write an item and its attribute on the same line if their combined width is below a threshold
1467 - **Default value**: 0
1468 - **Possible values**: any positive integer
1469 - **Stable**: No (tracking issue: [#3343](https://github.com/rust-lang/rustfmt/issues/3343))
1475 #[cfg(feature = "alloc")]
1481 #[cfg(feature = "alloc")] use core::slice;
1484 ## `match_arm_blocks`
1486 Controls whether arm bodies are wrapped in cases where the first line of the body cannot fit on the same line as the `=>` operator.
1488 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.
1490 - **Default value**: `true`
1491 - **Possible values**: `true`, `false`
1492 - **Stable**: No (tracking issue: [#3373](https://github.com/rust-lang/rustfmt/issues/3373))
1494 #### `true` (default):
1500 foooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo(x)
1502 dolor => println!("{}", sit),
1504 "foooooooooooooooooooooooo",
1505 "baaaaaaaaaaaaaaaaaaaaaaaarr",
1506 "baaaaaaaaaaaaaaaaaaaazzzzzzzzzzzzz",
1507 "qqqqqqqqquuuuuuuuuuuuuuuuuuuuuuuuuuxxx",
1519 foooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo(x),
1520 ipsum => println!("{}", sit),
1522 "foooooooooooooooooooooooo",
1523 "baaaaaaaaaaaaaaaaaaaaaaaarr",
1524 "baaaaaaaaaaaaaaaaaaaazzzzzzzzzzzzz",
1525 "qqqqqqqqquuuuuuuuuuuuuuuuuuuuuuuuuuxxx",
1531 See also: [`match_block_trailing_comma`](#match_block_trailing_comma).
1533 ## `match_arm_leading_pipes`
1535 Controls whether to include a leading pipe on match arms
1537 - **Default value**: `Never`
1538 - **Possible values**: `Always`, `Never`, `Preserve`
1541 #### `Never` (default):
1543 // Leading pipes are removed from this:
1546 // | "foo" | "bar" => {}
1548 // | "something relatively long"
1549 // | "something really really really realllllllllllllly long" => println!("x"),
1550 // | "qux" => println!("y"),
1560 | "something relatively long"
1561 | "something really really really realllllllllllllly long" => println!("x"),
1562 "qux" => println!("y"),
1570 // Leading pipes are emitted on all arms of this:
1573 // "foo" | "bar" => {}
1575 // | "something relatively long"
1576 // | "something really really really realllllllllllllly long" => println!("x"),
1577 // "qux" => println!("y"),
1585 | "foo" | "bar" => {}
1587 | "something relatively long"
1588 | "something really really really realllllllllllllly long" => println!("x"),
1589 | "qux" => println!("y"),
1599 | "foo" | "bar" => {}
1601 | "something relatively long"
1602 | "something really really really realllllllllllllly long" => println!("x"),
1603 | "qux" => println!("y"),
1615 ## `match_block_trailing_comma`
1617 Put a trailing comma after a block based match arm (non-block arms are not affected)
1619 - **Default value**: `false`
1620 - **Possible values**: `true`, `false`
1623 #### `false` (default):
1631 Lorem::Dolor => println!("dolor"),
1644 Lorem::Dolor => println!("dolor"),
1649 See also: [`trailing_comma`](#trailing_comma), [`match_arm_blocks`](#match_arm_blocks).
1653 Maximum width of each line
1655 - **Default value**: `100`
1656 - **Possible values**: any positive integer
1659 See also [`error_on_line_overflow`](#error_on_line_overflow).
1663 Merge multiple derives into a single one.
1665 - **Default value**: `true`
1666 - **Possible values**: `true`, `false`
1669 #### `true` (default):
1672 #[derive(Eq, PartialEq, Debug, Copy, Clone)]
1679 #[derive(Eq, PartialEq, Debug, Copy, Clone)]
1682 #[derive(Eq, PartialEq)]
1684 #[derive(Copy, Clone)]
1688 ## `imports_granularity`
1690 How imports should be grouped into `use` statements. Imports will be merged or split to the configured level of granularity.
1692 - **Default value**: `Preserve`
1693 - **Possible values**: `Preserve`, `Crate`, `Module`, `Item`, `One`
1694 - **Stable**: No (tracking issue: [#4991](https://github.com/rust-lang/rustfmt/issues/4991))
1696 Note that rustfmt will not modify the granularity of imports containing comments if doing so could potentially lose or misplace said comments.
1698 #### `Preserve` (default):
1700 Do not change the granularity of any imports and preserve the original structure written by the developer.
1705 use foo::{a, c, d::e};
1711 Merge imports from the same crate into a single `use` statement. Conversely, imports from different crates are split into separate statements.
1725 Merge imports from the same module into a single `use` statement. Conversely, imports from different modules are split into separate statements.
1736 Flatten imports so that each has its own `use` statement.
1751 Merge all imports into a single `use` statement as long as they have the same visibility.
1754 pub use foo::{x, y};
1768 This option is deprecated. Use `imports_granularity = "Crate"` instead.
1770 - **Default value**: `false`
1771 - **Possible values**: `true`, `false`
1773 #### `false` (default):
1784 use foo::{a, b, c, d, e, f, g};
1790 Unix or Windows line endings
1792 - **Default value**: `"Auto"`
1793 - **Possible values**: `"Auto"`, `"Native"`, `"Unix"`, `"Windows"`
1796 #### `Auto` (default):
1798 The newline style is detected automatically on a per-file basis. Files
1799 with mixed line endings will be converted to the first detected line
1804 Line endings will be converted to `\r\n` on Windows and `\n` on all
1809 Line endings will be converted to `\n`.
1813 Line endings will be converted to `\r\n`.
1815 ## `normalize_comments`
1817 Convert /* */ comments to // comments where possible
1819 - **Default value**: `false`
1820 - **Possible values**: `true`, `false`
1821 - **Stable**: No (tracking issue: [#3350](https://github.com/rust-lang/rustfmt/issues/3350))
1823 #### `false` (default):
1827 fn dolor() -> usize {}
1830 fn adipiscing() -> usize {}
1837 fn dolor() -> usize {}
1840 fn adipiscing() -> usize {}
1843 ## `normalize_doc_attributes`
1845 Convert `#![doc]` and `#[doc]` attributes to `//!` and `///` doc comments.
1847 - **Default value**: `false`
1848 - **Possible values**: `true`, `false`
1849 - **Stable**: No (tracking issue: [#3351](https://github.com/rust-lang/rustfmt/issues/3351))
1851 #### `false` (default):
1854 #![doc = "Example documentation"]
1856 #[doc = "Example item documentation"]
1859 /// Example item documentation
1866 //! Example documentation
1868 /// Example item documentation
1872 ## `overflow_delimited_expr`
1874 When structs, slices, arrays, and block/array-like macros are used as the last
1875 argument in an expression list, allow them to overflow (like blocks/closures)
1876 instead of being indented on a new line.
1878 - **Default value**: `false`
1879 - **Possible values**: `true`, `false`
1880 - **Stable**: No (tracking issue: [#3370](https://github.com/rust-lang/rustfmt/issues/3370))
1882 #### `false` (default):
1955 ## `remove_nested_parens`
1957 Remove nested parens.
1959 - **Default value**: `true`,
1960 - **Possible values**: `true`, `false`
1964 #### `true` (default):
1981 ## `reorder_impl_items`
1983 Reorder impl items. `type` and `const` are put first, then macros and methods.
1985 - **Default value**: `false`
1986 - **Possible values**: `true`, `false`
1987 - **Stable**: No (tracking issue: [#3363](https://github.com/rust-lang/rustfmt/issues/3363))
1989 #### `false` (default)
1994 impl Iterator for Dummy {
1995 fn next(&mut self) -> Option<Self::Item> {
2002 impl Iterator for Dummy {
2005 fn next(&mut self) -> Option<Self::Item> {
2016 impl Iterator for Dummy {
2019 fn next(&mut self) -> Option<Self::Item> {
2025 ## `reorder_imports`
2027 Reorder import and extern crate statements alphabetically in groups (a group is
2028 separated by a newline).
2030 - **Default value**: `true`
2031 - **Possible values**: `true`, `false`
2034 #### `true` (default):
2054 Controls the strategy for how consecutive imports are grouped together.
2056 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.
2058 - **Default value**: `Preserve`
2059 - **Possible values**: `Preserve`, `StdExternalCrate`, `One`
2060 - **Stable**: No (tracking issue: [#5083](https://github.com/rust-lang/rustfmt/issues/5083))
2062 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.
2064 #### `Preserve` (default):
2066 Preserve the source file's import groups.
2069 use super::update::convert_publish_payload;
2072 use alloc::alloc::Layout;
2073 use juniper::{FieldError, FieldResult};
2078 use broker::database::PooledConnection;
2080 use super::schema::{Context, Payload};
2081 use crate::models::Event;
2085 #### `StdExternalCrate`:
2087 Discard existing import groups, and create three groups for:
2088 1. `std`, `core` and `alloc`,
2090 3. `self`, `super` and `crate` imports.
2093 use alloc::alloc::Layout;
2097 use broker::database::PooledConnection;
2099 use juniper::{FieldError, FieldResult};
2102 use super::schema::{Context, Payload};
2103 use super::update::convert_publish_payload;
2104 use crate::models::Event;
2109 Discard existing import groups, and create a single group for everything
2112 use super::schema::{Context, Payload};
2113 use super::update::convert_publish_payload;
2114 use crate::models::Event;
2115 use alloc::alloc::Layout;
2116 use broker::database::PooledConnection;
2119 use juniper::{FieldError, FieldResult};
2124 ## `reorder_modules`
2126 Reorder `mod` declarations alphabetically in group.
2128 - **Default value**: `true`
2129 - **Possible values**: `true`, `false`
2132 #### `true` (default)
2156 **Note** `mod` with `#[macro_export]` will not be reordered since that could change the semantics
2157 of the original source code.
2159 ## `required_version`
2161 Require a specific version of rustfmt. If you want to make sure that the
2162 specific version of rustfmt is used in your CI, use this option.
2164 - **Default value**: `CARGO_PKG_VERSION`
2165 - **Possible values**: any published version (e.g. `"0.3.8"`)
2166 - **Stable**: No (tracking issue: [#3386](https://github.com/rust-lang/rustfmt/issues/3386))
2168 ## `short_array_element_width_threshold`
2170 The width threshold for an array element to be considered "short".
2172 The layout of an array is dependent on the length of each of its elements.
2173 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.
2175 - **Default value**: `10`
2176 - **Possible values**: any positive integer that is less than or equal to the value specified for [`max_width`](#max_width)
2179 #### `10` (default):
2182 pub const FORMAT_TEST: [u64; 5] = [
2194 pub const FORMAT_TEST: [u64; 5] = [
2195 0x0000000000000000, 0xaaaaaaaaaaaaaaaa, 0xbbbbbbbbbbbbbbbb, 0xcccccccccccccccc,
2200 See also [`max_width`](#max_width).
2204 Don't reformat out of line modules
2206 - **Default value**: `false`
2207 - **Possible values**: `true`, `false`
2208 - **Stable**: No (tracking issue: [#3389](https://github.com/rust-lang/rustfmt/issues/3389))
2210 ## `single_line_if_else_max_width`
2212 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`.
2214 - **Default value**: `50`
2215 - **Possible values**: any positive integer that is less than or equal to the value specified for [`max_width`](#max_width)
2218 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.
2220 See also [`max_width`](#max_width) and [`use_small_heuristics`](#use_small_heuristics)
2222 ## `space_after_colon`
2224 Leave a space after the colon.
2226 - **Default value**: `true`
2227 - **Possible values**: `true`, `false`
2228 - **Stable**: No (tracking issue: [#3366](https://github.com/rust-lang/rustfmt/issues/3366))
2230 #### `true` (default):
2233 fn lorem<T: Eq>(t: T) {
2234 let lorem: Dolor = Lorem {
2244 fn lorem<T:Eq>(t:T) {
2245 let lorem:Dolor = Lorem {
2252 See also: [`space_before_colon`](#space_before_colon).
2254 ## `space_before_colon`
2256 Leave a space before the colon.
2258 - **Default value**: `false`
2259 - **Possible values**: `true`, `false`
2260 - **Stable**: No (tracking issue: [#3365](https://github.com/rust-lang/rustfmt/issues/3365))
2262 #### `false` (default):
2265 fn lorem<T: Eq>(t: T) {
2266 let lorem: Dolor = Lorem {
2276 fn lorem<T : Eq>(t : T) {
2277 let lorem : Dolor = Lorem {
2284 See also: [`space_after_colon`](#space_after_colon).
2286 ## `spaces_around_ranges`
2288 Put spaces around the .., ..=, and ... range operators
2290 - **Default value**: `false`
2291 - **Possible values**: `true`, `false`
2292 - **Stable**: No (tracking issue: [#3367](https://github.com/rust-lang/rustfmt/issues/3367))
2294 #### `false` (default):
2322 let lorem = 0 .. 10;
2323 let ipsum = 0 ..= 10;
2342 ## `struct_field_align_threshold`
2344 The maximum diff of width between struct fields to be aligned with each other.
2346 - **Default value** : 0
2347 - **Possible values**: any non-negative integer
2348 - **Stable**: No (tracking issue: [#3371](https://github.com/rust-lang/rustfmt/issues/3371))
2370 ## `struct_lit_single_line`
2372 Put small struct literals on a single line
2374 - **Default value**: `true`
2375 - **Possible values**: `true`, `false`
2376 - **Stable**: No (tracking issue: [#3357](https://github.com/rust-lang/rustfmt/issues/3357))
2378 #### `true` (default):
2382 let lorem = Lorem { foo: bar, baz: ofo };
2397 See also: [`indent_style`](#indent_style).
2399 ## `struct_lit_width`
2401 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`.
2403 - **Default value**: `18`
2404 - **Possible values**: any positive integer that is less than or equal to the value specified for [`max_width`](#max_width)
2407 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.
2409 See also [`max_width`](#max_width), [`use_small_heuristics`](#use_small_heuristics), and [`struct_lit_single_line`](#struct_lit_single_line)
2411 ## `struct_variant_width`
2413 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`.
2415 - **Default value**: `35`
2416 - **Possible values**: any positive integer that is less than or equal to the value specified for [`max_width`](#max_width)
2419 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.
2421 See also [`max_width`](#max_width) and [`use_small_heuristics`](#use_small_heuristics)
2425 Number of spaces per tab
2427 - **Default value**: `4`
2428 - **Possible values**: any positive integer
2435 let ipsum = dolor();
2437 "amet consectetur adipiscing elit amet",
2438 "consectetur adipiscing elit amet consectetur.",
2447 let ipsum = dolor();
2449 "amet consectetur adipiscing elit amet",
2450 "consectetur adipiscing elit amet consectetur.",
2455 See also: [`hard_tabs`](#hard_tabs).
2460 How to handle trailing commas for lists
2462 - **Default value**: `"Vertical"`
2463 - **Possible values**: `"Always"`, `"Never"`, `"Vertical"`
2464 - **Stable**: No (tracking issue: [#3379](https://github.com/rust-lang/rustfmt/issues/3379))
2466 #### `"Vertical"` (default):
2470 let Lorem { ipsum, dolor, sit } = amet;
2486 let Lorem { ipsum, dolor, sit, } = amet;
2502 let Lorem { ipsum, dolor, sit } = amet;
2514 See also: [`match_block_trailing_comma`](#match_block_trailing_comma).
2516 ## `trailing_semicolon`
2518 Add trailing semicolon after break, continue and return
2520 - **Default value**: `true`
2521 - **Possible values**: `true`, `false`
2522 - **Stable**: No (tracking issue: [#3378](https://github.com/rust-lang/rustfmt/issues/3378))
2524 #### `true` (default):
2538 ## `type_punctuation_density`
2540 Determines if `+` or `=` are wrapped in spaces in the punctuation of types
2542 - **Default value**: `"Wide"`
2543 - **Possible values**: `"Compressed"`, `"Wide"`
2544 - **Stable**: No (tracking issue: [#3364](https://github.com/rust-lang/rustfmt/issues/3364))
2546 #### `"Wide"` (default):
2549 fn lorem<Ipsum: Dolor + Sit = Amet>() {
2554 #### `"Compressed"`:
2557 fn lorem<Ipsum: Dolor+Sit=Amet>() {
2562 ## `unstable_features`
2564 Enable unstable features on the unstable channel.
2566 - **Default value**: `false`
2567 - **Possible values**: `true`, `false`
2568 - **Stable**: No (tracking issue: [#3387](https://github.com/rust-lang/rustfmt/issues/3387))
2570 ## `use_field_init_shorthand`
2572 Use field initialize shorthand if possible.
2574 - **Default value**: `false`
2575 - **Possible values**: `true`, `false`
2578 #### `false` (default):
2591 let a = Foo { x, y, z };
2592 let b = Foo { x: x, y: y, z: z };
2609 let a = Foo { x, y, z };
2613 ## `use_small_heuristics`
2615 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.
2617 Note that explicitly provided values for the width configuration settings take precedence and override the calculated values determined by `use_small_heuristics`.
2619 - **Default value**: `"Default"`
2620 - **Possible values**: `"Default"`, `"Off"`, `"Max"`
2623 #### `Default` (default):
2624 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`.
2627 * [`fn_call_width`](#fn_call_width) - `60%`
2628 * [`attr_fn_like_width`](#attr_fn_like_width) - `70%`
2629 * [`struct_lit_width`](#struct_lit_width) - `18%`
2630 * [`struct_variant_width`](#struct_variant_width) - `35%`
2631 * [`array_width`](#array_width) - `60%`
2632 * [`chain_width`](#chain_width) - `60%`
2633 * [`single_line_if_else_max_width`](#single_line_if_else_max_width) - `50%`
2635 For example when `max_width` is set to `100`, the width settings are:
2636 * `fn_call_width=60`
2637 * `attr_fn_like_width=70`
2638 * `struct_lit_width=18`
2639 * `struct_variant_width=35`
2642 * `single_line_if_else_max_width=50`
2644 and when `max_width` is set to `200`:
2645 * `fn_call_width=120`
2646 * `attr_fn_like_width=140`
2647 * `struct_lit_width=36`
2648 * `struct_variant_width=70`
2651 * `single_line_if_else_max_width=100`
2657 Sit { amet: Consectetur, adipiscing: Elit },
2675 let lorem = Lorem { ipsum: dolor };
2677 let lorem = if ipsum { dolor } else { sit };
2682 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.
2695 lorem("lorem", "ipsum", "dolor", "sit", "amet", "consectetur", "adipiscing");
2702 let lorem = if ipsum {
2711 When `use_small_heuristics` is set to `Max`, then each granular width setting is set to the same value as `max_width`.
2713 So if `max_width` is set to `200`, then all the width settings are also set to `200`.
2714 * `fn_call_width=200`
2715 * `attr_fn_like_width=200`
2716 * `struct_lit_width=200`
2717 * `struct_variant_width=200`
2720 * `single_line_if_else_max_width=200`
2726 Sit { amet: Consectetur, adipiscing: Elit },
2730 lorem("lorem", "ipsum", "dolor", "sit", "amet", "consectetur", "adipiscing");
2732 let lorem = Lorem { ipsum: dolor, sit: amet };
2734 let lorem = if ipsum { dolor } else { sit };
2740 * [`max_width`](#max_width)
2741 * [`fn_call_width`](#fn_call_width)
2742 * [`attr_fn_like_width`](#attr_fn_like_width)
2743 * [`struct_lit_width`](#struct_lit_width)
2744 * [`struct_variant_width`](#struct_variant_width)
2745 * [`array_width`](#array_width)
2746 * [`chain_width`](#chain_width)
2747 * [`single_line_if_else_max_width`](#single_line_if_else_max_width)
2749 ## `use_try_shorthand`
2751 Replace uses of the try! macro by the ? shorthand
2753 - **Default value**: `false`
2754 - **Possible values**: `true`, `false`
2757 #### `false` (default):
2761 let lorem = ipsum.map(|dolor| dolor.sit())?;
2763 let lorem = try!(ipsum.map(|dolor| dolor.sit()));
2771 let lorem = ipsum.map(|dolor| dolor.sit())?;
2777 Which version of the formatting rules to use. `Version::One` is backwards-compatible
2778 with Rustfmt 1.0. Other versions are only backwards compatible within a major
2781 - **Default value**: `One`
2782 - **Possible values**: `One`, `Two`
2783 - **Stable**: No (tracking issue: [#3383](https://github.com/rust-lang/rustfmt/issues/3383))
2791 ## `where_single_line`
2793 Forces the `where` clause to be laid out on a single line.
2795 - **Default value**: `false`
2796 - **Possible values**: `true`, `false`
2797 - **Stable**: No (tracking issue: [#3359](https://github.com/rust-lang/rustfmt/issues/3359))
2799 #### `false` (default):
2814 where Option<T>: Ipsum
2820 See also [`brace_style`](#brace_style), [`control_brace_style`](#control_brace_style).
2825 Break comments to fit on the line
2827 - **Default value**: `false`
2828 - **Possible values**: `true`, `false`
2829 - **Stable**: No (tracking issue: [#3347](https://github.com/rust-lang/rustfmt/issues/3347))
2831 #### `false` (default):
2834 // Lorem ipsum dolor sit amet, consectetur adipiscing elit,
2835 // sed do eiusmod tempor incididunt ut labore et dolore
2836 // magna aliqua. Ut enim ad minim veniam, quis nostrud
2837 // exercitation ullamco laboris nisi ut aliquip ex ea
2838 // commodo consequat.
2840 // 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.
2846 // Lorem ipsum dolor sit amet, consectetur adipiscing elit,
2847 // sed do eiusmod tempor incididunt ut labore et dolore
2848 // magna aliqua. Ut enim ad minim veniam, quis nostrud
2849 // exercitation ullamco laboris nisi ut aliquip ex ea
2850 // commodo consequat.
2861 Internal option, use `--backup`
2863 ## `print_misformatted_file_names`
2865 Internal option, use `-l` or `--files-with-diff`