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.
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:
23 Indent on expressions or items.
25 - **Default value**: `"Block"`
26 - **Possible values**: `"Block"`, `"Visual"`
31 #### `"Block"` (default):
51 let lorem = vec!["ipsum",
63 #### `"Block"` (default):
67 if lorem_ipsum && dolor_sit && amet_consectetur && lorem_sit && dolor_consectetur && amet_ipsum
79 if lorem_ipsum && dolor_sit && amet_consectetur && lorem_sit && dolor_consectetur && amet_ipsum
87 See also: [`control_brace_style`](#control_brace_style).
89 ### Function arguments
91 #### `"Block"` (default):
96 fn lorem(ipsum: usize) {}
116 fn lorem(ipsum: usize) {}
118 fn lorem(ipsum: usize,
131 #### `"Block"` (default):
165 #### `"Block"` (default):
173 Adipiscing: Eq = usize,
174 Consectetur: Eq = usize,
181 adipiscing: Adipiscing,
182 consectetur: Consectetur,
192 fn lorem<Ipsum: Eq = usize,
196 Adipiscing: Eq = usize,
197 Consectetur: Eq = usize,
203 adipiscing: Adipiscing,
204 consectetur: Consectetur,
213 #### `"Block"` (default):
228 let lorem = Lorem { ipsum: dolor,
233 See also: [`struct_lit_single_line`](#struct_lit_single_line), [`indent_style`](#indent_style).
237 #### `"Block"` (default):
240 fn lorem<Ipsum, Dolor, Sit, Amet>() -> T
254 fn lorem<Ipsum, Dolor, Sit, Amet>() -> T
264 ## `use_small_heuristics`
266 Whether to use different formatting for items and expressions if they satisfy a heuristic notion of 'small'.
268 - **Default value**: `true`
269 - **Possible values**: `true`, `false`
272 #### `true` (default):
278 Sit { amet: Consectetur, adipiscing: Elit },
296 let lorem = Lorem { ipsum: dolor };
298 let lorem = if ipsum { dolor } else { sit };
315 lorem("lorem", "ipsum", "dolor", "sit", "amet", "consectetur", "adipiscing");
322 let lorem = if ipsum {
332 Where to put a binary operator when a binary expression goes multiline.
334 - **Default value**: `"Front"`
335 - **Possible values**: `"Front"`, `"Back"`
338 #### `"Front"` (default):
342 let or = foofoofoofoofoofoofoofoofoofoofoofoofoofoofoofoo
343 || barbarbarbarbarbarbarbarbarbarbarbarbarbarbarbar;
345 let sum = 123456789012345678901234567890 + 123456789012345678901234567890
346 + 123456789012345678901234567890;
348 let range = aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
349 ..bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb;
357 let or = foofoofoofoofoofoofoofoofoofoofoofoofoofoofoofoo ||
358 barbarbarbarbarbarbarbarbarbarbarbarbarbarbarbar;
360 let sum = 123456789012345678901234567890 + 123456789012345678901234567890 +
361 123456789012345678901234567890;
363 let range = aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa..
364 bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb;
368 ## `combine_control_expr`
370 Combine control expressions with function calls.
372 - **Default value**: `true`
373 - **Possible values**: `true`, `false`
376 #### `true` (default):
388 foo!(if let Some(..) = x {
401 foo!(while let Some(..) = x {
435 if let Some(..) = x {
452 while let Some(..) = x {
478 Maximum length of comments. No effect unless`wrap_comments = true`.
480 - **Default value**: `80`
481 - **Possible values**: any positive integer
484 **Note:** A value of `0` results in [`wrap_comments`](#wrap_comments) being applied regardless of a line's width.
486 #### `80` (default; comments shorter than `comment_width`):
488 // Lorem ipsum dolor sit amet, consectetur adipiscing elit.
491 #### `60` (comments longer than `comment_width`):
493 // Lorem ipsum dolor sit amet,
494 // consectetur adipiscing elit.
497 See also [`wrap_comments`](#wrap_comments).
499 ## `condense_wildcard_suffixes`
501 Replace strings of _ wildcards by a single .. in tuple patterns
503 - **Default value**: `false`
504 - **Possible values**: `true`, `false`
507 #### `false` (default):
511 let (lorem, ipsum, _, _) = (1, 2, 3, 4);
512 let (lorem, ipsum, ..) = (1, 2, 3, 4);
520 let (lorem, ipsum, ..) = (1, 2, 3, 4);
524 ## `control_brace_style`
526 Brace style for control flow constructs
528 - **Default value**: `"AlwaysSameLine"`
529 - **Possible values**: `"AlwaysNextLine"`, `"AlwaysSameLine"`, `"ClosingNextLine"`
532 #### `"AlwaysSameLine"` (default):
544 #### `"AlwaysNextLine"`:
559 #### `"ClosingNextLine"`:
572 ## `disable_all_formatting`
574 Don't reformat anything
576 - **Default value**: `false`
577 - **Possible values**: `true`, `false`
580 ## `error_on_line_overflow`
582 Error if Rustfmt is unable to get all lines within `max_width`, except for comments and string
583 literals. If this happens, then it is a bug in Rustfmt. You might be able to work around the bug by
584 refactoring your code to avoid long/complex expressions, usually by extracting a local variable or
585 using a shorter name.
587 - **Default value**: `false`
588 - **Possible values**: `true`, `false`
591 See also [`max_width`](#max_width).
593 ## `error_on_unformatted`
595 Error if unable to get comments or string literals within `max_width`, or they are left with
596 trailing whitespaces.
598 - **Default value**: `false`
599 - **Possible values**: `true`, `false`
604 Argument density in functions
606 - **Default value**: `"Tall"`
607 - **Possible values**: `"Compressed"`, `"Tall"`, `"Vertical"`
610 #### `"Tall"` (default):
614 fn lorem(ipsum: Ipsum, dolor: Dolor, sit: Sit, amet: Amet);
616 fn lorem(ipsum: Ipsum, dolor: Dolor, sit: Sit, amet: Amet) {
625 consectetur: Consectetur,
626 adipiscing: Adipiscing,
635 consectetur: Consectetur,
636 adipiscing: Adipiscing,
648 fn lorem(ipsum: Ipsum, dolor: Dolor, sit: Sit, amet: Amet);
650 fn lorem(ipsum: Ipsum, dolor: Dolor, sit: Sit, amet: Amet) {
655 ipsum: Ipsum, dolor: Dolor, sit: Sit, amet: Amet, consectetur: Consectetur,
656 adipiscing: Adipiscing, elit: Elit,
660 ipsum: Ipsum, dolor: Dolor, sit: Sit, amet: Amet, consectetur: Consectetur,
661 adipiscing: Adipiscing, elit: Elit,
693 consectetur: Consectetur,
694 adipiscing: Adipiscing,
703 consectetur: Consectetur,
704 adipiscing: Adipiscing,
715 Brace style for items
717 - **Default value**: `"SameLineWhere"`
718 - **Possible values**: `"AlwaysNextLine"`, `"PreferSameLine"`, `"SameLineWhere"`
723 #### `"SameLineWhere"` (default):
730 fn lorem(ipsum: usize) {
734 fn lorem<T>(ipsum: T)
736 T: Add + Sub + Mul + Div,
742 #### `"AlwaysNextLine"`:
750 fn lorem(ipsum: usize)
755 fn lorem<T>(ipsum: T)
757 T: Add + Sub + Mul + Div,
763 #### `"PreferSameLine"`:
770 fn lorem(ipsum: usize) {
774 fn lorem<T>(ipsum: T)
776 T: Add + Sub + Mul + Div, {
781 ### Structs and enums
783 #### `"SameLineWhere"` (default):
798 #### `"AlwaysNextLine"`:
814 #### `"PreferSameLine"`:
829 ## `empty_item_single_line`
831 Put empty-body functions and impls on a single line
833 - **Default value**: `true`
834 - **Possible values**: `true`, `false`
837 #### `true` (default):
855 See also [`brace_style`](#brace_style), [`control_brace_style`](#control_brace_style).
860 Put single-expression functions on a single line
862 - **Default value**: `false`
863 - **Possible values**: `true`, `false`
866 #### `false` (default):
869 fn lorem() -> usize {
873 fn lorem() -> usize {
882 fn lorem() -> usize { 42 }
884 fn lorem() -> usize {
890 See also [`control_brace_style`](#control_brace_style).
893 ## `where_single_line`
895 Forces the `where` clause to be laid out on a single line.
897 - **Default value**: `false`
898 - **Possible values**: `true`, `false`
901 #### `false` (default):
916 where Option<T>: Ipsum
922 See also [`brace_style`](#brace_style), [`control_brace_style`](#control_brace_style).
925 ## `force_explicit_abi`
927 Always print the abi for extern items
929 - **Default value**: `true`
930 - **Possible values**: `true`, `false`
933 **Note:** Non-"C" ABIs are always printed. If `false` then "C" is removed.
935 #### `true` (default):
939 pub static lorem: c_int;
947 pub static lorem: c_int;
953 Format string literals where necessary
955 - **Default value**: `false`
956 - **Possible values**: `true`, `false`
959 #### `false` (default):
964 "ipsum dolor sit amet consectetur adipiscing elit lorem ipsum dolor sit amet consectetur adipiscing";
972 let lorem = "ipsum dolor sit amet consectetur adipiscing elit lorem ipsum dolor sit amet \
973 consectetur adipiscing";
977 See also [`max_width`](#max_width).
981 Use tab characters for indentation, spaces for alignment
983 - **Default value**: `false`
984 - **Possible values**: `true`, `false`
987 #### `false` (default):
990 fn lorem() -> usize {
991 42 // spaces before 42
998 fn lorem() -> usize {
1003 See also: [`tab_spaces`](#tab_spaces).
1008 Indent style of imports
1010 - **Default Value**: `"Visual"`
1011 - **Possible values**: `"Block"`, `"Visual"`
1014 #### `"Visual"` (default):
1017 use foo::{xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx, yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy,
1018 zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz};
1025 xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx, yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy,
1026 zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz,
1030 See also: [`imports_layout`](#imports_layout).
1034 Item layout inside a imports block
1036 - **Default value**: "Mixed"
1037 - **Possible values**: "Horizontal", "HorizontalVertical", "Mixed", "Vertical"
1040 #### `"Mixed"` (default):
1043 use foo::{xxxxxxxxxxxxxxxxxx, yyyyyyyyyyyyyyyyyy, zzzzzzzzzzzzzzzzzz};
1046 aaaaaaaaaaaaaaaaaa, bbbbbbbbbbbbbbbbbb, cccccccccccccccccc, dddddddddddddddddd,
1047 eeeeeeeeeeeeeeeeee, ffffffffffffffffff,
1051 #### `"Horizontal"`:
1053 **Note**: This option forces all imports onto one line and may exceed `max_width`.
1056 use foo::{xxx, yyy, zzz};
1058 use foo::{aaa, bbb, ccc, ddd, eee, fff};
1061 #### `"HorizontalVertical"`:
1064 use foo::{xxxxxxxxxxxxxxxxxx, yyyyyyyyyyyyyyyyyy, zzzzzzzzzzzzzzzzzz};
1097 Merge multiple imports into a single nested import.
1099 - **Default value**: `false`
1100 - **Possible values**: `true`, `false`
1103 #### `false` (default):
1114 use foo::{a, b, c, d, e, f, g};
1118 ## `match_block_trailing_comma`
1120 Put a trailing comma after a block based match arm (non-block arms are not affected)
1122 - **Default value**: `false`
1123 - **Possible values**: `true`, `false`
1126 #### `false` (default):
1134 Lorem::Dolor => println!("dolor"),
1147 Lorem::Dolor => println!("dolor"),
1152 See also: [`trailing_comma`](#trailing_comma), [`match_arm_blocks`](#match_arm_blocks).
1156 Maximum width of each line
1158 - **Default value**: `100`
1159 - **Possible values**: any positive integer
1162 See also [`error_on_line_overflow`](#error_on_line_overflow).
1166 Merge multiple derives into a single one.
1168 - **Default value**: `true`
1169 - **Possible values**: `true`, `false`
1172 #### `true` (default):
1175 #[derive(Eq, PartialEq, Debug, Copy, Clone)]
1182 #[derive(Eq, PartialEq)]
1184 #[derive(Copy, Clone)]
1188 ## `force_multiline_blocks`
1190 Force multiline closure and match arm bodies to be wrapped in a block
1192 - **Default value**: `false`
1193 - **Possible values**: `false`, `true`
1196 #### `false` (default):
1200 result.and_then(|maybe_value| match maybe_value {
1202 Some(value) => bar(),
1207 println!("Hello World");
1209 Some(dolor) => foo(),
1218 result.and_then(|maybe_value| {
1221 Some(value) => bar(),
1228 println!("Hello World");
1231 Some(dolor) => foo(),
1239 Unix or Windows line endings
1241 - **Default value**: `"Unix"`
1242 - **Possible values**: `"Native"`, `"Unix"`, `"Windows"`
1245 ## `normalize_comments`
1247 Convert /* */ comments to // comments where possible
1249 - **Default value**: `false`
1250 - **Possible values**: `true`, `false`
1253 #### `false` (default):
1257 fn dolor() -> usize {}
1260 fn adipiscing() -> usize {}
1267 fn dolor() -> usize {}
1270 fn adipiscing() -> usize {}
1274 ## `reorder_imports`
1276 Reorder import and extern crate statements alphabetically in groups (a group is
1277 separated by a newline).
1279 - **Default value**: `true`
1280 - **Possible values**: `true`, `false`
1283 #### `true` (default):
1302 ## `reorder_modules`
1304 Reorder `mod` declarations alphabetically in group.
1306 - **Default value**: `true`
1307 - **Possible values**: `true`, `false`
1310 #### `true` (default)
1334 **Note** `mod` with `#[macro_export]` will not be reordered since that could change the semantic
1335 of the original source code.
1337 ## `reorder_impl_items`
1339 Reorder impl items. `type` and `const` are put first, then macros and methods.
1341 - **Default value**: `false`
1342 - **Possible values**: `true`, `false`
1345 #### `false` (default)
1350 impl Iterator for Dummy {
1351 fn next(&mut self) -> Option<Self::Item> {
1364 impl Iterator for Dummy {
1367 fn next(&mut self) -> Option<Self::Item> {
1375 Report `TODO` items in comments.
1377 - **Default value**: `"Never"`
1378 - **Possible values**: `"Always"`, `"Unnumbered"`, `"Never"`
1381 Warns about any comments containing `TODO` in them when set to `"Always"`. If
1382 it contains a `#X` (with `X` being a number) in parentheses following the
1383 `TODO`, `"Unnumbered"` will ignore it.
1385 See also [`report_fixme`](#report_fixme).
1389 Report `FIXME` items in comments.
1391 - **Default value**: `"Never"`
1392 - **Possible values**: `"Always"`, `"Unnumbered"`, `"Never"`
1395 Warns about any comments containing `FIXME` in them when set to `"Always"`. If
1396 it contains a `#X` (with `X` being a number) in parentheses following the
1397 `FIXME`, `"Unnumbered"` will ignore it.
1399 See also [`report_todo`](#report_todo).
1404 Don't reformat out of line modules
1406 - **Default value**: `false`
1407 - **Possible values**: `true`, `false`
1410 ## `space_after_colon`
1412 Leave a space after the colon.
1414 - **Default value**: `true`
1415 - **Possible values**: `true`, `false`
1418 #### `true` (default):
1421 fn lorem<T: Eq>(t: T) {
1422 let lorem: Dolor = Lorem {
1432 fn lorem<T:Eq>(t:T) {
1433 let lorem:Dolor = Lorem {
1440 See also: [`space_before_colon`](#space_before_colon).
1442 ## `space_before_colon`
1444 Leave a space before the colon.
1446 - **Default value**: `false`
1447 - **Possible values**: `true`, `false`
1450 #### `false` (default):
1453 fn lorem<T: Eq>(t: T) {
1454 let lorem: Dolor = Lorem {
1464 fn lorem<T : Eq>(t : T) {
1465 let lorem : Dolor = Lorem {
1472 See also: [`space_after_colon`](#space_after_colon).
1474 ## `struct_field_align_threshold`
1476 The maximum diff of width between struct fields to be aligned with each other.
1478 - **Default value** : 0
1479 - **Possible values**: any positive integer
1502 ## `spaces_around_ranges`
1504 Put spaces around the .., ..=, and ... range operators
1506 - **Default value**: `false`
1507 - **Possible values**: `true`, `false`
1510 #### `false` (default):
1538 let lorem = 0 .. 10;
1539 let ipsum = 0 ..= 10;
1558 ## `spaces_within_parens_and_brackets`
1560 Put spaces within non-empty generic arguments, parentheses, and square brackets
1562 - **Default value**: `false`
1563 - **Possible values**: `true`, `false`
1566 #### `false` (default):
1569 // generic arguments
1570 fn lorem<T: Eq>(t: T) {
1574 // non-empty parentheses
1575 fn lorem<T: Eq>(t: T) {
1576 let lorem = (ipsum, dolor);
1579 // non-empty square brackets
1580 fn lorem<T: Eq>(t: T) {
1581 let lorem: [usize; 2] = [ipsum, dolor];
1588 // generic arguments
1589 fn lorem< T: Eq >( t: T ) {
1593 // non-empty parentheses
1594 fn lorem< T: Eq >( t: T ) {
1595 let lorem = ( ipsum, dolor );
1598 // non-empty square brackets
1599 fn lorem< T: Eq >( t: T ) {
1600 let lorem: [ usize; 2 ] = [ ipsum, dolor ];
1604 ## `struct_lit_single_line`
1606 Put small struct literals on a single line
1608 - **Default value**: `true`
1609 - **Possible values**: `true`, `false`
1612 #### `true` (default):
1616 let lorem = Lorem { foo: bar, baz: ofo };
1631 See also: [`indent_style`](#indent_style).
1636 Number of spaces per tab
1638 - **Default value**: `4`
1639 - **Possible values**: any positive integer
1646 let ipsum = dolor();
1648 "amet consectetur adipiscing elit amet",
1649 "consectetur adipiscing elit amet consectetur.",
1658 let ipsum = dolor();
1660 "amet consectetur adipiscing elit amet",
1661 "consectetur adipiscing elit amet consectetur.",
1666 See also: [`hard_tabs`](#hard_tabs).
1671 How to handle trailing commas for lists
1673 - **Default value**: `"Vertical"`
1674 - **Possible values**: `"Always"`, `"Never"`, `"Vertical"`
1677 #### `"Vertical"` (default):
1681 let Lorem { ipsum, dolor, sit } = amet;
1697 let Lorem { ipsum, dolor, sit, } = amet;
1713 let Lorem { ipsum, dolor, sit } = amet;
1725 See also: [`match_block_trailing_comma`](#match_block_trailing_comma).
1727 ## `trailing_semicolon`
1729 Add trailing semicolon after break, continue and return
1731 - **Default value**: `true`
1732 - **Possible values**: `true`, `false`
1735 #### `true` (default):
1749 ## `type_punctuation_density`
1751 Determines if `+` or `=` are wrapped in spaces in the punctuation of types
1753 - **Default value**: `"Wide"`
1754 - **Possible values**: `"Compressed"`, `"Wide"`
1757 #### `"Wide"` (default):
1760 fn lorem<Ipsum: Dolor + Sit = Amet>() {
1765 #### `"Compressed"`:
1768 fn lorem<Ipsum: Dolor+Sit=Amet>() {
1773 ## `use_field_init_shorthand`
1775 Use field initialize shorthand if possible.
1777 - **Default value**: `false`
1778 - **Possible values**: `true`, `false`
1781 #### `false` (default):
1794 let a = Foo { x: x, y: y, z: z };
1811 let a = Foo { x, y, z };
1815 ## `use_try_shorthand`
1817 Replace uses of the try! macro by the ? shorthand
1819 - **Default value**: `false`
1820 - **Possible values**: `true`, `false`
1823 #### `false` (default):
1827 let lorem = try!(ipsum.map(|dolor| dolor.sit()));
1835 let lorem = ipsum.map(|dolor| dolor.sit())?;
1842 Break comments to fit on the line
1844 - **Default value**: `false`
1845 - **Possible values**: `true`, `false`
1848 #### `false` (default):
1851 // 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.
1857 // Lorem ipsum dolor sit amet, consectetur adipiscing elit,
1858 // sed do eiusmod tempor incididunt ut labore et dolore
1859 // magna aliqua. Ut enim ad minim veniam, quis nostrud
1860 // exercitation ullamco laboris nisi ut aliquip ex ea
1861 // commodo consequat.
1864 ## `match_arm_blocks`
1866 Wrap the body of arms in blocks when it does not fit on the same line with the pattern of arms
1868 - **Default value**: `true`
1869 - **Possible values**: `true`, `false`
1872 #### `true` (default):
1878 foooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo(x)
1880 false => println!("{}", sit),
1891 foooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo(x),
1892 false => println!("{}", sit),
1897 See also: [`match_block_trailing_comma`](#match_block_trailing_comma).
1901 What Write Mode to use when none is supplied: Replace, Overwrite, Display, Diff, Coverage
1903 - **Default value**: `"Overwrite"`
1904 - **Possible values**: `"Checkstyle"`, `"Coverage"`, `"Diff"`, `"Display"`, `"Overwrite"`, `"Plain"`, `"Replace"`
1907 ## `blank_lines_upper_bound`
1909 Maximum number of blank lines which can be put between items. If more than this number of consecutive empty
1910 lines are found, they are trimmed down to match this integer.
1912 - **Default value**: `1`
1913 - **Possible values**: *unsigned integer*
1964 See also: [`blank_lines_lower_bound`](#blank_lines_lower_bound)
1966 ## `blank_lines_lower_bound`
1968 Minimum number of blank lines which must be put between items. If two items have fewer blank lines between
1969 them, additional blank lines are inserted.
1971 - **Default value**: `0`
1972 - **Possible values**: *unsigned integer*
1976 Original Code (rustfmt will not change it with the default value of `0`):
2005 ## `remove_blank_lines_at_start_or_end_of_block`
2007 Remove blank lines at the start or the end of a block.
2009 - **Default value**: `true`
2010 - **Possible values**: `true`, `false`
2018 let mut str = String::new();
2019 str.push_str("hello, ");
2020 str.push_str("world!");
2023 println!("{}", msg);
2034 let mut str = String::new();
2035 str.push_str("hello, ");
2036 str.push_str("world!");
2040 println!("{}", msg);
2045 ## `required_version`
2047 Require a specific version of rustfmt. If you want to make sure that the
2048 specific version of rustfmt is used in your CI, use this option.
2050 - **Default value**: `CARGO_PKG_VERSION`
2051 - **Possible values**: any published version (e.g. `"0.3.8"`)
2054 ## `hide_parse_errors`
2056 Do not show parse errors if the parser failed to parse files.
2058 - **Default value**: `false`
2059 - **Possible values**: `true`, `false`
2064 Whether to use colored output or not.
2066 - **Default value**: `"Auto"`
2067 - **Possible values**: "Auto", "Always", "Never"
2070 ## `unstable_features`
2072 Enable unstable features on stable channel.
2074 - **Default value**: `false`
2075 - **Possible values**: `true`, `false`
2078 ## `license_template_path`
2080 Check whether beginnings of files match a license template.
2082 - **Default value**: `""``
2083 - **Possible values**: path to a license template file
2086 A license template is a plain text file which is matched literally against the
2087 beginning of each source file, except for `{}`-delimited blocks, which are
2088 matched as regular expressions. The following license template therefore
2089 matches strings like `// Copyright 2017 The Rust Project Developers.`, `//
2090 Copyright 2018 The Rust Project Developers.`, etc.:
2093 // Copyright {\d+} The Rust Project Developers.
2096 `\{`, `\}` and `\\` match literal braces / backslashes.
2100 Skip formatting the specified files and directories.
2102 - **Default value**: format every files
2103 - **Possible values**: See an example below
2108 If you want to ignore specific files, put the following to your config file:
2117 If you want to ignore every file under `examples/`, put the following to your config file: