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 be used directly, while unstable options are opt-in.
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.
934 - **Default value**: `true`
935 - **Possible values**: `true`, `false`
936 - **Stable**: No (tracking issue: [#5080](https://github.com/rust-lang/rustfmt/issues/5080))
938 ## `format_macro_matchers`
940 Format the metavariable matching patterns in macros.
942 - **Default value**: `false`
943 - **Possible values**: `true`, `false`
944 - **Stable**: No (tracking issue: [#3354](https://github.com/rust-lang/rustfmt/issues/3354))
946 #### `false` (default):
950 ($a: ident : $b: ty) => {
953 ($a: ident $b: ident $c: ident) => {
963 ($a:ident : $b:ty) => {
966 ($a:ident $b:ident $c:ident) => {
972 See also [`format_macro_bodies`](#format_macro_bodies).
975 ## `format_macro_bodies`
977 Format the bodies of macros.
979 - **Default value**: `true`
980 - **Possible values**: `true`, `false`
981 - **Stable**: No (tracking issue: [#3355](https://github.com/rust-lang/rustfmt/issues/3355))
983 #### `true` (default):
987 ($a: ident : $b: ty) => {
990 ($a: ident $b: ident $c: ident) => {
1000 ($a: ident : $b: ty) => { $a(42): $b; };
1001 ($a: ident $b: ident $c: ident) => { $a=$b+$c; };
1005 See also [`format_macro_matchers`](#format_macro_matchers).
1010 Format string literals where necessary
1012 - **Default value**: `false`
1013 - **Possible values**: `true`, `false`
1014 - **Stable**: No (tracking issue: [#3353](https://github.com/rust-lang/rustfmt/issues/3353))
1016 #### `false` (default):
1020 let lorem = "ipsum dolor sit amet consectetur adipiscing elit lorem ipsum dolor sit amet consectetur adipiscing";
1028 let lorem = "ipsum dolor sit amet consectetur adipiscing elit lorem ipsum dolor sit amet \
1029 consectetur adipiscing";
1033 See also [`max_width`](#max_width).
1037 Use tab characters for indentation, spaces for alignment
1039 - **Default value**: `false`
1040 - **Possible values**: `true`, `false`
1043 #### `false` (default):
1046 fn lorem() -> usize {
1047 42 // spaces before 42
1054 fn lorem() -> usize {
1055 42 // tabs before 42
1059 See also: [`tab_spaces`](#tab_spaces).
1061 ## `hex_literal_case`
1063 Control the case of the letters in hexadecimal literal values
1065 - **Default value**: `Preserve`
1066 - **Possible values**: `Upper`, `Lower`
1067 - **Stable**: No (tracking issue: [#5081](https://github.com/rust-lang/rustfmt/issues/5081))
1069 ## `hide_parse_errors`
1071 Do not show parse errors if the parser failed to parse files.
1073 - **Default value**: `false`
1074 - **Possible values**: `true`, `false`
1075 - **Stable**: No (tracking issue: [#3390](https://github.com/rust-lang/rustfmt/issues/3390))
1079 Skip formatting files and directories that match the specified pattern.
1080 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.
1082 - **Default value**: format every file
1083 - **Possible values**: See an example below
1084 - **Stable**: No (tracking issue: [#3395](https://github.com/rust-lang/rustfmt/issues/3395))
1088 If you want to ignore specific files, put the following to your config file:
1097 If you want to ignore every file under `examples/`, put the following to your config file:
1105 If you want to ignore every file under the directory where you put your rustfmt.toml:
1113 Indent style of imports
1115 - **Default Value**: `"Block"`
1116 - **Possible values**: `"Block"`, `"Visual"`
1117 - **Stable**: No (tracking issue: [#3360](https://github.com/rust-lang/rustfmt/issues/3360))
1119 #### `"Block"` (default):
1123 xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx, yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy,
1124 zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz,
1131 use foo::{xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx, yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy,
1132 zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz};
1135 See also: [`imports_layout`](#imports_layout).
1139 Item layout inside a imports block
1141 - **Default value**: "Mixed"
1142 - **Possible values**: "Horizontal", "HorizontalVertical", "Mixed", "Vertical"
1143 - **Stable**: No (tracking issue: [#3361](https://github.com/rust-lang/rustfmt/issues/3361))
1145 #### `"Mixed"` (default):
1148 use foo::{xxxxxxxxxxxxxxxxxx, yyyyyyyyyyyyyyyyyy, zzzzzzzzzzzzzzzzzz};
1151 aaaaaaaaaaaaaaaaaa, bbbbbbbbbbbbbbbbbb, cccccccccccccccccc, dddddddddddddddddd,
1152 eeeeeeeeeeeeeeeeee, ffffffffffffffffff,
1156 #### `"Horizontal"`:
1158 **Note**: This option forces all imports onto one line and may exceed `max_width`.
1161 use foo::{xxx, yyy, zzz};
1163 use foo::{aaa, bbb, ccc, ddd, eee, fff};
1166 #### `"HorizontalVertical"`:
1169 use foo::{xxxxxxxxxxxxxxxxxx, yyyyyyyyyyyyyyyyyy, zzzzzzzzzzzzzzzzzz};
1202 Indent on expressions or items.
1204 - **Default value**: `"Block"`
1205 - **Possible values**: `"Block"`, `"Visual"`
1206 - **Stable**: No (tracking issue: [#3346](https://github.com/rust-lang/rustfmt/issues/3346))
1210 #### `"Block"` (default):
1230 let lorem = vec!["ipsum",
1242 #### `"Block"` (default):
1250 && dolor_consectetur
1252 && lorem_consectetur
1267 && dolor_consectetur
1269 && lorem_consectetur
1276 See also: [`control_brace_style`](#control_brace_style).
1278 ### Function arguments
1280 #### `"Block"` (default):
1285 fn lorem(ipsum: usize) {}
1305 fn lorem(ipsum: usize) {}
1307 fn lorem(ipsum: usize,
1320 #### `"Block"` (default):
1354 #### `"Block"` (default):
1362 Adipiscing: Eq = usize,
1363 Consectetur: Eq = usize,
1370 adipiscing: Adipiscing,
1371 consectetur: Consectetur,
1381 fn lorem<Ipsum: Eq = usize,
1385 Adipiscing: Eq = usize,
1386 Consectetur: Eq = usize,
1392 adipiscing: Adipiscing,
1393 consectetur: Consectetur,
1402 #### `"Block"` (default):
1417 let lorem = Lorem { ipsum: dolor,
1422 See also: [`struct_lit_single_line`](#struct_lit_single_line), [`indent_style`](#indent_style).
1424 ### Where predicates
1426 #### `"Block"` (default):
1429 fn lorem<Ipsum, Dolor, Sit, Amet>() -> T
1443 fn lorem<Ipsum, Dolor, Sit, Amet>() -> T
1453 ## `inline_attribute_width`
1455 Write an item and its attribute on the same line if their combined width is below a threshold
1457 - **Default value**: 0
1458 - **Possible values**: any positive integer
1459 - **Stable**: No (tracking issue: [#3343](https://github.com/rust-lang/rustfmt/issues/3343))
1465 #[cfg(feature = "alloc")]
1471 #[cfg(feature = "alloc")] use core::slice;
1474 ## `license_template_path`
1476 Check whether beginnings of files match a license template.
1478 - **Default value**: `""`
1479 - **Possible values**: path to a license template file
1480 - **Stable**: No (tracking issue: [#3352](https://github.com/rust-lang/rustfmt/issues/3352))
1482 A license template is a plain text file which is matched literally against the
1483 beginning of each source file, except for `{}`-delimited blocks, which are
1484 matched as regular expressions. The following license template therefore
1485 matches strings like `// Copyright 2017 The Rust Project Developers.`, `//
1486 Copyright 2018 The Rust Project Developers.`, etc.:
1489 // Copyright {\d+} The Rust Project Developers.
1492 `\{`, `\}` and `\\` match literal braces / backslashes.
1494 ## `match_arm_blocks`
1496 Controls whether arm bodies are wrapped in cases where the first line of the body cannot fit on the same line as the `=>` operator.
1498 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.
1500 - **Default value**: `true`
1501 - **Possible values**: `true`, `false`
1502 - **Stable**: No (tracking issue: [#3373](https://github.com/rust-lang/rustfmt/issues/3373))
1504 #### `true` (default):
1510 foooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo(x)
1512 dolor => println!("{}", sit),
1514 "foooooooooooooooooooooooo",
1515 "baaaaaaaaaaaaaaaaaaaaaaaarr",
1516 "baaaaaaaaaaaaaaaaaaaazzzzzzzzzzzzz",
1517 "qqqqqqqqquuuuuuuuuuuuuuuuuuuuuuuuuuxxx",
1529 foooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo(x),
1530 ipsum => println!("{}", sit),
1532 "foooooooooooooooooooooooo",
1533 "baaaaaaaaaaaaaaaaaaaaaaaarr",
1534 "baaaaaaaaaaaaaaaaaaaazzzzzzzzzzzzz",
1535 "qqqqqqqqquuuuuuuuuuuuuuuuuuuuuuuuuuxxx",
1541 See also: [`match_block_trailing_comma`](#match_block_trailing_comma).
1543 ## `match_arm_leading_pipes`
1545 Controls whether to include a leading pipe on match arms
1547 - **Default value**: `Never`
1548 - **Possible values**: `Always`, `Never`, `Preserve`
1551 #### `Never` (default):
1553 // Leading pipes are removed from this:
1556 // | "foo" | "bar" => {}
1558 // | "something relatively long"
1559 // | "something really really really realllllllllllllly long" => println!("x"),
1560 // | "qux" => println!("y"),
1570 | "something relatively long"
1571 | "something really really really realllllllllllllly long" => println!("x"),
1572 "qux" => println!("y"),
1580 // Leading pipes are emitted on all arms of this:
1583 // "foo" | "bar" => {}
1585 // | "something relatively long"
1586 // | "something really really really realllllllllllllly long" => println!("x"),
1587 // "qux" => println!("y"),
1595 | "foo" | "bar" => {}
1597 | "something relatively long"
1598 | "something really really really realllllllllllllly long" => println!("x"),
1599 | "qux" => println!("y"),
1609 | "foo" | "bar" => {}
1611 | "something relatively long"
1612 | "something really really really realllllllllllllly long" => println!("x"),
1613 | "qux" => println!("y"),
1625 ## `match_block_trailing_comma`
1627 Put a trailing comma after a block based match arm (non-block arms are not affected)
1629 - **Default value**: `false`
1630 - **Possible values**: `true`, `false`
1633 #### `false` (default):
1641 Lorem::Dolor => println!("dolor"),
1654 Lorem::Dolor => println!("dolor"),
1659 See also: [`trailing_comma`](#trailing_comma), [`match_arm_blocks`](#match_arm_blocks).
1663 Maximum width of each line
1665 - **Default value**: `100`
1666 - **Possible values**: any positive integer
1669 See also [`error_on_line_overflow`](#error_on_line_overflow).
1673 Merge multiple derives into a single one.
1675 - **Default value**: `true`
1676 - **Possible values**: `true`, `false`
1679 #### `true` (default):
1682 #[derive(Eq, PartialEq, Debug, Copy, Clone)]
1689 #[derive(Eq, PartialEq, Debug, Copy, Clone)]
1692 #[derive(Eq, PartialEq)]
1694 #[derive(Copy, Clone)]
1698 ## `imports_granularity`
1700 How imports should be grouped into `use` statements. Imports will be merged or split to the configured level of granularity.
1702 - **Default value**: `Preserve`
1703 - **Possible values**: `Preserve`, `Crate`, `Module`, `Item`, `One`
1704 - **Stable**: No (tracking issue: [#4991](https://github.com/rust-lang/rustfmt/issues/4991))
1706 #### `Preserve` (default):
1708 Do not change the granularity of any imports and preserve the original structure written by the developer.
1713 use foo::{a, c, d::e};
1719 Merge imports from the same crate into a single `use` statement. Conversely, imports from different crates are split into separate statements.
1733 Merge imports from the same module into a single `use` statement. Conversely, imports from different modules are split into separate statements.
1744 Flatten imports so that each has its own `use` statement.
1759 Merge all imports into a single `use` statement as long as they have the same visibility.
1762 pub use foo::{x, y};
1776 This option is deprecated. Use `imports_granularity = "Crate"` instead.
1778 - **Default value**: `false`
1779 - **Possible values**: `true`, `false`
1781 #### `false` (default):
1792 use foo::{a, b, c, d, e, f, g};
1798 Unix or Windows line endings
1800 - **Default value**: `"Auto"`
1801 - **Possible values**: `"Auto"`, `"Native"`, `"Unix"`, `"Windows"`
1804 #### `Auto` (default):
1806 The newline style is detected automatically on a per-file basis. Files
1807 with mixed line endings will be converted to the first detected line
1812 Line endings will be converted to `\r\n` on Windows and `\n` on all
1817 Line endings will be converted to `\n`.
1821 Line endings will be converted to `\r\n`.
1823 ## `normalize_comments`
1825 Convert /* */ comments to // comments where possible
1827 - **Default value**: `false`
1828 - **Possible values**: `true`, `false`
1829 - **Stable**: No (tracking issue: [#3350](https://github.com/rust-lang/rustfmt/issues/3350))
1831 #### `false` (default):
1835 fn dolor() -> usize {}
1838 fn adipiscing() -> usize {}
1845 fn dolor() -> usize {}
1848 fn adipiscing() -> usize {}
1851 ## `normalize_doc_attributes`
1853 Convert `#![doc]` and `#[doc]` attributes to `//!` and `///` doc comments.
1855 - **Default value**: `false`
1856 - **Possible values**: `true`, `false`
1857 - **Stable**: No (tracking issue: [#3351](https://github.com/rust-lang/rustfmt/issues/3351))
1859 #### `false` (default):
1862 #![doc = "Example documentation"]
1864 #[doc = "Example item documentation"]
1867 /// Example item documentation
1874 //! Example documentation
1876 /// Example item documentation
1880 ## `overflow_delimited_expr`
1882 When structs, slices, arrays, and block/array-like macros are used as the last
1883 argument in an expression list, allow them to overflow (like blocks/closures)
1884 instead of being indented on a new line.
1886 - **Default value**: `false`
1887 - **Possible values**: `true`, `false`
1888 - **Stable**: No (tracking issue: [#3370](https://github.com/rust-lang/rustfmt/issues/3370))
1890 #### `false` (default):
1963 ## `remove_nested_parens`
1965 Remove nested parens.
1967 - **Default value**: `true`,
1968 - **Possible values**: `true`, `false`
1972 #### `true` (default):
1989 ## `reorder_impl_items`
1991 Reorder impl items. `type` and `const` are put first, then macros and methods.
1993 - **Default value**: `false`
1994 - **Possible values**: `true`, `false`
1995 - **Stable**: No (tracking issue: [#3363](https://github.com/rust-lang/rustfmt/issues/3363))
1997 #### `false` (default)
2002 impl Iterator for Dummy {
2003 fn next(&mut self) -> Option<Self::Item> {
2010 impl Iterator for Dummy {
2013 fn next(&mut self) -> Option<Self::Item> {
2024 impl Iterator for Dummy {
2027 fn next(&mut self) -> Option<Self::Item> {
2033 ## `reorder_imports`
2035 Reorder import and extern crate statements alphabetically in groups (a group is
2036 separated by a newline).
2038 - **Default value**: `true`
2039 - **Possible values**: `true`, `false`
2042 #### `true` (default):
2062 Controls the strategy for how imports are grouped together.
2064 - **Default value**: `Preserve`
2065 - **Possible values**: `Preserve`, `StdExternalCrate`, `One`
2066 - **Stable**: No (tracking issue: [#5083](https://github.com/rust-lang/rustfmt/issues/5083))
2068 #### `Preserve` (default):
2070 Preserve the source file's import groups.
2073 use super::update::convert_publish_payload;
2076 use alloc::alloc::Layout;
2077 use juniper::{FieldError, FieldResult};
2082 use broker::database::PooledConnection;
2084 use super::schema::{Context, Payload};
2085 use crate::models::Event;
2089 #### `StdExternalCrate`:
2091 Discard existing import groups, and create three groups for:
2092 1. `std`, `core` and `alloc`,
2094 3. `self`, `super` and `crate` imports.
2097 use alloc::alloc::Layout;
2101 use broker::database::PooledConnection;
2103 use juniper::{FieldError, FieldResult};
2106 use super::schema::{Context, Payload};
2107 use super::update::convert_publish_payload;
2108 use crate::models::Event;
2113 Discard existing import groups, and create a single group for everything
2116 use super::schema::{Context, Payload};
2117 use super::update::convert_publish_payload;
2118 use crate::models::Event;
2119 use alloc::alloc::Layout;
2120 use broker::database::PooledConnection;
2123 use juniper::{FieldError, FieldResult};
2128 ## `reorder_modules`
2130 Reorder `mod` declarations alphabetically in group.
2132 - **Default value**: `true`
2133 - **Possible values**: `true`, `false`
2136 #### `true` (default)
2160 **Note** `mod` with `#[macro_export]` will not be reordered since that could change the semantics
2161 of the original source code.
2165 Report `FIXME` items in comments.
2167 - **Default value**: `"Never"`
2168 - **Possible values**: `"Always"`, `"Unnumbered"`, `"Never"`
2169 - **Stable**: No (tracking issue: [#3394](https://github.com/rust-lang/rustfmt/issues/3394))
2171 Warns about any comments containing `FIXME` in them when set to `"Always"`. If
2172 it contains a `#X` (with `X` being a number) in parentheses following the
2173 `FIXME`, `"Unnumbered"` will ignore it.
2175 See also [`report_todo`](#report_todo).
2180 Report `TODO` items in comments.
2182 - **Default value**: `"Never"`
2183 - **Possible values**: `"Always"`, `"Unnumbered"`, `"Never"`
2184 - **Stable**: No (tracking issue: [#3393](https://github.com/rust-lang/rustfmt/issues/3393))
2186 Warns about any comments containing `TODO` in them when set to `"Always"`. If
2187 it contains a `#X` (with `X` being a number) in parentheses following the
2188 `TODO`, `"Unnumbered"` will ignore it.
2190 See also [`report_fixme`](#report_fixme).
2192 ## `required_version`
2194 Require a specific version of rustfmt. If you want to make sure that the
2195 specific version of rustfmt is used in your CI, use this option.
2197 - **Default value**: `CARGO_PKG_VERSION`
2198 - **Possible values**: any published version (e.g. `"0.3.8"`)
2199 - **Stable**: No (tracking issue: [#3386](https://github.com/rust-lang/rustfmt/issues/3386))
2203 Don't reformat out of line modules
2205 - **Default value**: `false`
2206 - **Possible values**: `true`, `false`
2207 - **Stable**: No (tracking issue: [#3389](https://github.com/rust-lang/rustfmt/issues/3386))
2209 ## `single_line_if_else_max_width`
2211 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`.
2213 - **Default value**: `50`
2214 - **Possible values**: any positive integer that is less than or equal to the value specified for [`max_width`](#max_width)
2217 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.
2219 See also [`max_width`](#max_width) and [`use_small_heuristics`](#use_small_heuristics)
2221 ## `space_after_colon`
2223 Leave a space after the colon.
2225 - **Default value**: `true`
2226 - **Possible values**: `true`, `false`
2227 - **Stable**: No (tracking issue: [#3366](https://github.com/rust-lang/rustfmt/issues/3366))
2229 #### `true` (default):
2232 fn lorem<T: Eq>(t: T) {
2233 let lorem: Dolor = Lorem {
2243 fn lorem<T:Eq>(t:T) {
2244 let lorem:Dolor = Lorem {
2251 See also: [`space_before_colon`](#space_before_colon).
2253 ## `space_before_colon`
2255 Leave a space before the colon.
2257 - **Default value**: `false`
2258 - **Possible values**: `true`, `false`
2259 - **Stable**: No (tracking issue: [#3365](https://github.com/rust-lang/rustfmt/issues/3365))
2261 #### `false` (default):
2264 fn lorem<T: Eq>(t: T) {
2265 let lorem: Dolor = Lorem {
2275 fn lorem<T : Eq>(t : T) {
2276 let lorem : Dolor = Lorem {
2283 See also: [`space_after_colon`](#space_after_colon).
2285 ## `spaces_around_ranges`
2287 Put spaces around the .., ..=, and ... range operators
2289 - **Default value**: `false`
2290 - **Possible values**: `true`, `false`
2291 - **Stable**: No (tracking issue: [#3367](https://github.com/rust-lang/rustfmt/issues/3367))
2293 #### `false` (default):
2321 let lorem = 0 .. 10;
2322 let ipsum = 0 ..= 10;
2341 ## `struct_field_align_threshold`
2343 The maximum diff of width between struct fields to be aligned with each other.
2345 - **Default value** : 0
2346 - **Possible values**: any non-negative integer
2347 - **Stable**: No (tracking issue: [#3371](https://github.com/rust-lang/rustfmt/issues/3371))
2369 ## `struct_lit_single_line`
2371 Put small struct literals on a single line
2373 - **Default value**: `true`
2374 - **Possible values**: `true`, `false`
2375 - **Stable**: No (tracking issue: [#3357](https://github.com/rust-lang/rustfmt/issues/3357))
2377 #### `true` (default):
2381 let lorem = Lorem { foo: bar, baz: ofo };
2396 See also: [`indent_style`](#indent_style).
2398 ## `struct_lit_width`
2400 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`.
2402 - **Default value**: `18`
2403 - **Possible values**: any positive integer that is less than or equal to the value specified for [`max_width`](#max_width)
2406 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.
2408 See also [`max_width`](#max_width), [`use_small_heuristics`](#use_small_heuristics), and [`struct_lit_single_line`](#struct_lit_single_line)
2410 ## `struct_variant_width`
2412 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`.
2414 - **Default value**: `35`
2415 - **Possible values**: any positive integer that is less than or equal to the value specified for [`max_width`](#max_width)
2418 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.
2420 See also [`max_width`](#max_width) and [`use_small_heuristics`](#use_small_heuristics)
2424 Number of spaces per tab
2426 - **Default value**: `4`
2427 - **Possible values**: any positive integer
2434 let ipsum = dolor();
2436 "amet consectetur adipiscing elit amet",
2437 "consectetur adipiscing elit amet consectetur.",
2446 let ipsum = dolor();
2448 "amet consectetur adipiscing elit amet",
2449 "consectetur adipiscing elit amet consectetur.",
2454 See also: [`hard_tabs`](#hard_tabs).
2459 How to handle trailing commas for lists
2461 - **Default value**: `"Vertical"`
2462 - **Possible values**: `"Always"`, `"Never"`, `"Vertical"`
2463 - **Stable**: No (tracking issue: [#3379](https://github.com/rust-lang/rustfmt/issues/3379))
2465 #### `"Vertical"` (default):
2469 let Lorem { ipsum, dolor, sit } = amet;
2485 let Lorem { ipsum, dolor, sit, } = amet;
2501 let Lorem { ipsum, dolor, sit } = amet;
2513 See also: [`match_block_trailing_comma`](#match_block_trailing_comma).
2515 ## `trailing_semicolon`
2517 Add trailing semicolon after break, continue and return
2519 - **Default value**: `true`
2520 - **Possible values**: `true`, `false`
2521 - **Stable**: No (tracking issue: [#3378](https://github.com/rust-lang/rustfmt/issues/3378))
2523 #### `true` (default):
2537 ## `type_punctuation_density`
2539 Determines if `+` or `=` are wrapped in spaces in the punctuation of types
2541 - **Default value**: `"Wide"`
2542 - **Possible values**: `"Compressed"`, `"Wide"`
2543 - **Stable**: No (tracking issue: [#3364](https://github.com/rust-lang/rustfmt/issues/3364))
2545 #### `"Wide"` (default):
2548 fn lorem<Ipsum: Dolor + Sit = Amet>() {
2553 #### `"Compressed"`:
2556 fn lorem<Ipsum: Dolor+Sit=Amet>() {
2561 ## `unstable_features`
2563 Enable unstable features on the unstable channel.
2565 - **Default value**: `false`
2566 - **Possible values**: `true`, `false`
2567 - **Stable**: No (tracking issue: [#3387](https://github.com/rust-lang/rustfmt/issues/3387))
2569 ## `use_field_init_shorthand`
2571 Use field initialize shorthand if possible.
2573 - **Default value**: `false`
2574 - **Possible values**: `true`, `false`
2577 #### `false` (default):
2590 let a = Foo { x, y, z };
2591 let b = Foo { x: x, y: y, z: z };
2608 let a = Foo { x, y, z };
2612 ## `use_small_heuristics`
2614 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.
2616 Note that explicitly provided values for the width configuration settings take precedence and override the calculated values determined by `use_small_heuristics`.
2618 - **Default value**: `"Default"`
2619 - **Possible values**: `"Default"`, `"Off"`, `"Max"`
2622 #### `Default` (default):
2623 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`.
2626 * [`fn_call_width`](#fn_call_width) - `60%`
2627 * [`attr_fn_like_width`](#attr_fn_like_width) - `70%`
2628 * [`struct_lit_width`](#struct_lit_width) - `18%`
2629 * [`struct_variant_width`](#struct_variant_width) - `35%`
2630 * [`array_width`](#array_width) - `60%`
2631 * [`chain_width`](#chain_width) - `60%`
2632 * [`single_line_if_else_max_width`](#single_line_if_else_max_width) - `50%`
2634 For example when `max_width` is set to `100`, the width settings are:
2635 * `fn_call_width=60`
2636 * `attr_fn_like_width=70`
2637 * `struct_lit_width=18`
2638 * `struct_variant_width=35`
2641 * `single_line_if_else_max_width=50`
2643 and when `max_width` is set to `200`:
2644 * `fn_call_width=120`
2645 * `attr_fn_like_width=140`
2646 * `struct_lit_width=36`
2647 * `struct_variant_width=70`
2650 * `single_line_if_else_max_width=100`
2656 Sit { amet: Consectetur, adipiscing: Elit },
2674 let lorem = Lorem { ipsum: dolor };
2676 let lorem = if ipsum { dolor } else { sit };
2681 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.
2694 lorem("lorem", "ipsum", "dolor", "sit", "amet", "consectetur", "adipiscing");
2701 let lorem = if ipsum {
2710 When `use_small_heuristics` is set to `Max`, then each granular width setting is set to the same value as `max_width`.
2712 So if `max_width` is set to `200`, then all the width settings are also set to `200`.
2713 * `fn_call_width=200`
2714 * `attr_fn_like_width=200`
2715 * `struct_lit_width=200`
2716 * `struct_variant_width=200`
2719 * `single_line_if_else_max_width=200`
2725 Sit { amet: Consectetur, adipiscing: Elit },
2729 lorem("lorem", "ipsum", "dolor", "sit", "amet", "consectetur", "adipiscing");
2731 let lorem = Lorem { ipsum: dolor, sit: amet };
2733 let lorem = if ipsum { dolor } else { sit };
2739 * [`max_width`](#max_width)
2740 * [`fn_call_width`](#fn_call_width)
2741 * [`attr_fn_like_width`](#attr_fn_like_width)
2742 * [`struct_lit_width`](#struct_lit_width)
2743 * [`struct_variant_width`](#struct_variant_width)
2744 * [`array_width`](#array_width)
2745 * [`chain_width`](#chain_width)
2746 * [`single_line_if_else_max_width`](#single_line_if_else_max_width)
2748 ## `use_try_shorthand`
2750 Replace uses of the try! macro by the ? shorthand
2752 - **Default value**: `false`
2753 - **Possible values**: `true`, `false`
2756 #### `false` (default):
2760 let lorem = ipsum.map(|dolor| dolor.sit())?;
2762 let lorem = try!(ipsum.map(|dolor| dolor.sit()));
2770 let lorem = ipsum.map(|dolor| dolor.sit())?;
2776 Which version of the formatting rules to use. `Version::One` is backwards-compatible
2777 with Rustfmt 1.0. Other versions are only backwards compatible within a major
2780 - **Default value**: `One`
2781 - **Possible values**: `One`, `Two`
2782 - **Stable**: No (tracking issue: [#3383](https://github.com/rust-lang/rustfmt/issues/3383))
2790 ## `where_single_line`
2792 Forces the `where` clause to be laid out on a single line.
2794 - **Default value**: `false`
2795 - **Possible values**: `true`, `false`
2796 - **Stable**: No (tracking issue: [#3359](https://github.com/rust-lang/rustfmt/issues/3359))
2798 #### `false` (default):
2813 where Option<T>: Ipsum
2819 See also [`brace_style`](#brace_style), [`control_brace_style`](#control_brace_style).
2824 Break comments to fit on the line
2826 - **Default value**: `false`
2827 - **Possible values**: `true`, `false`
2828 - **Stable**: No (tracking issue: [#3347](https://github.com/rust-lang/rustfmt/issues/3347))
2830 #### `false` (default):
2833 // Lorem ipsum dolor sit amet, consectetur adipiscing elit,
2834 // sed do eiusmod tempor incididunt ut labore et dolore
2835 // magna aliqua. Ut enim ad minim veniam, quis nostrud
2836 // exercitation ullamco laboris nisi ut aliquip ex ea
2837 // commodo consequat.
2839 // 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.
2845 // Lorem ipsum dolor sit amet, consectetur adipiscing elit,
2846 // sed do eiusmod tempor incididunt ut labore et dolore
2847 // magna aliqua. Ut enim ad minim veniam, quis nostrud
2848 // exercitation ullamco laboris nisi ut aliquip ex ea
2849 // commodo consequat.
2860 Internal option, use `--backup`
2862 ## `print_misformatted_file_names`
2864 Internal option, use `-l` or `--files-with-diff`