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_imported_names = true
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-options` 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):
84 See also: [`control_brace_style`](#control_brace_style).
86 ### Function arguments
88 #### `"Block"` (default):
93 fn lorem(ipsum: usize) {}
113 fn lorem(ipsum: usize) {}
115 fn lorem(ipsum: usize,
128 #### `"Block"` (default):
162 #### `"Block"` (default):
170 Adipiscing: Eq = usize,
171 Consectetur: Eq = usize,
178 adipiscing: Adipiscing,
179 consectetur: Consectetur,
189 fn lorem<Ipsum: Eq = usize,
193 Adipiscing: Eq = usize,
194 Consectetur: Eq = usize,
200 adipiscing: Adipiscing,
201 consectetur: Consectetur,
210 #### `"Block"` (default):
225 let lorem = Lorem { ipsum: dolor,
230 See also: [`struct_lit_single_line`](#struct_lit_single_line), [`indent_style`](#indent_style).
234 #### `"Block"` (default):
237 fn lorem<Ipsum, Dolor, Sit, Amet>() -> T
251 fn lorem<Ipsum, Dolor, Sit, Amet>() -> T
261 ## `use_small_heuristics`
263 Whether to use different formatting for items and expressions if they satisfy a heuristic notion of 'small'.
265 - **Default value**: `true`
266 - **Possible values**: `true`, `false`
269 #### `true` (default):
275 Sit { amet: Consectetur, adipiscing: Elit },
293 let lorem = Lorem { ipsum: dolor };
295 let lorem = if ipsum { dolor } else { sit };
312 lorem("lorem", "ipsum", "dolor", "sit", "amet", "consectetur", "adipiscing");
319 let lorem = if ipsum {
329 Where to put a binary operator when a binary expression goes multiline.
331 - **Default value**: `"Front"`
332 - **Possible values**: `"Front"`, `"Back"`
335 #### `"Front"` (default):
339 let or = foofoofoofoofoofoofoofoofoofoofoofoofoofoofoofoo
340 || barbarbarbarbarbarbarbarbarbarbarbarbarbarbarbar;
342 let sum = 123456789012345678901234567890 + 123456789012345678901234567890
343 + 123456789012345678901234567890;
345 let range = aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
346 ..bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb;
354 let or = foofoofoofoofoofoofoofoofoofoofoofoofoofoofoofoo ||
355 barbarbarbarbarbarbarbarbarbarbarbarbarbarbarbar;
357 let sum = 123456789012345678901234567890 + 123456789012345678901234567890 +
358 123456789012345678901234567890;
360 let range = aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa..
361 bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb;
365 ## `combine_control_expr`
367 Combine control expressions with function calls.
369 - **Default value**: `true`
370 - **Possible values**: `true`, `false`
373 #### `true` (default):
385 foo!(if let Some(..) = x {
398 foo!(while let Some(..) = x {
432 if let Some(..) = x {
449 while let Some(..) = x {
475 Maximum length of comments. No effect unless`wrap_comments = true`.
477 - **Default value**: `80`
478 - **Possible values**: any positive integer
481 **Note:** A value of `0` results in [`wrap_comments`](#wrap_comments) being applied regardless of a line's width.
483 #### `80` (default; comments shorter than `comment_width`):
485 // Lorem ipsum dolor sit amet, consectetur adipiscing elit.
488 #### `60` (comments longer than `comment_width`):
490 // Lorem ipsum dolor sit amet,
491 // consectetur adipiscing elit.
494 See also [`wrap_comments`](#wrap_comments).
496 ## `condense_wildcard_suffixes`
498 Replace strings of _ wildcards by a single .. in tuple patterns
500 - **Default value**: `false`
501 - **Possible values**: `true`, `false`
504 #### `false` (default):
508 let (lorem, ipsum, _, _) = (1, 2, 3, 4);
509 let (lorem, ipsum, ..) = (1, 2, 3, 4);
517 let (lorem, ipsum, ..) = (1, 2, 3, 4);
521 ## `control_brace_style`
523 Brace style for control flow constructs
525 - **Default value**: `"AlwaysSameLine"`
526 - **Possible values**: `"AlwaysNextLine"`, `"AlwaysSameLine"`, `"ClosingNextLine"`
529 #### `"AlwaysSameLine"` (default):
541 #### `"AlwaysNextLine"`:
556 #### `"ClosingNextLine"`:
569 ## `disable_all_formatting`
571 Don't reformat anything
573 - **Default value**: `false`
574 - **Possible values**: `true`, `false`
577 ## `error_on_line_overflow`
579 Error if unable to get all lines within `max_width`
581 - **Default value**: `true`
582 - **Possible values**: `true`, `false`
585 See also [`max_width`](#max_width).
587 ## `error_on_line_overflow_comments`
589 Error if unable to get all comment lines within `comment_width`.
591 - **Default value**: `true`
592 - **Possible values**: `true`, `false`
595 See also [`comment_width`](#comment_width).
599 Argument density in functions
601 - **Default value**: `"Tall"`
602 - **Possible values**: `"Compressed"`, `"Tall"`, `"Vertical"`
605 #### `"Tall"` (default):
609 fn lorem(ipsum: Ipsum, dolor: Dolor, sit: Sit, amet: Amet);
611 fn lorem(ipsum: Ipsum, dolor: Dolor, sit: Sit, amet: Amet) {
620 consectetur: Consectetur,
621 adipiscing: Adipiscing,
630 consectetur: Consectetur,
631 adipiscing: Adipiscing,
643 fn lorem(ipsum: Ipsum, dolor: Dolor, sit: Sit, amet: Amet);
645 fn lorem(ipsum: Ipsum, dolor: Dolor, sit: Sit, amet: Amet) {
650 ipsum: Ipsum, dolor: Dolor, sit: Sit, amet: Amet, consectetur: Consectetur,
651 adipiscing: Adipiscing, elit: Elit,
655 ipsum: Ipsum, dolor: Dolor, sit: Sit, amet: Amet, consectetur: Consectetur,
656 adipiscing: Adipiscing, elit: Elit,
688 consectetur: Consectetur,
689 adipiscing: Adipiscing,
698 consectetur: Consectetur,
699 adipiscing: Adipiscing,
710 Brace style for items
712 - **Default value**: `"SameLineWhere"`
713 - **Possible values**: `"AlwaysNextLine"`, `"PreferSameLine"`, `"SameLineWhere"`
718 #### `"SameLineWhere"` (default):
725 fn lorem(ipsum: usize) {
729 fn lorem<T>(ipsum: T)
731 T: Add + Sub + Mul + Div,
737 #### `"AlwaysNextLine"`:
745 fn lorem(ipsum: usize)
750 fn lorem<T>(ipsum: T)
752 T: Add + Sub + Mul + Div,
758 #### `"PreferSameLine"`:
765 fn lorem(ipsum: usize) {
769 fn lorem<T>(ipsum: T)
771 T: Add + Sub + Mul + Div, {
776 ### Structs and enums
778 #### `"SameLineWhere"` (default):
793 #### `"AlwaysNextLine"`:
809 #### `"PreferSameLine"`:
824 ## `empty_item_single_line`
826 Put empty-body functions and impls on a single line
828 - **Default value**: `true`
829 - **Possible values**: `true`, `false`
832 #### `true` (default):
850 See also [`brace_style`](#brace_style), [`control_brace_style`](#control_brace_style).
855 Put single-expression functions on a single line
857 - **Default value**: `false`
858 - **Possible values**: `true`, `false`
861 #### `false` (default):
864 fn lorem() -> usize {
868 fn lorem() -> usize {
877 fn lorem() -> usize { 42 }
879 fn lorem() -> usize {
885 See also [`control_brace_style`](#control_brace_style).
888 ## `where_single_line`
890 To force single line where layout
892 - **Default value**: `false`
893 - **Possible values**: `true`, `false`
896 #### `false` (default):
911 where Option<T>: Ipsum
917 See also [`brace_style`](#brace_style), [`control_brace_style`](#control_brace_style).
920 ## `force_explicit_abi`
922 Always print the abi for extern items
924 - **Default value**: `true`
925 - **Possible values**: `true`, `false`
928 **Note:** Non-"C" ABIs are always printed. If `false` then "C" is removed.
930 #### `true` (default):
934 pub static lorem: c_int;
942 pub static lorem: c_int;
948 Format string literals where necessary
950 - **Default value**: `false`
951 - **Possible values**: `true`, `false`
954 #### `false` (default):
959 "ipsum dolor sit amet consectetur adipiscing elit lorem ipsum dolor sit amet consectetur adipiscing";
967 "ipsum dolor sit amet consectetur \
968 adipiscing elit lorem ipsum dolor sit";
971 See also [`max_width`](#max_width).
975 Use tab characters for indentation, spaces for alignment
977 - **Default value**: `false`
978 - **Possible values**: `true`, `false`
981 #### `false` (default):
984 fn lorem() -> usize {
985 42 // spaces before 42
992 fn lorem() -> usize {
997 See also: [`tab_spaces`](#tab_spaces).
1002 Indent style of imports
1004 - **Default Value**: `"Visual"`
1005 - **Possible values**: `"Block"`, `"Visual"`
1008 #### `"Visual"` (default):
1026 See also: [`imports_layout`](#imports_layout).
1030 Item layout inside a imports block
1032 - **Default value**: "Mixed"
1033 - **Possible values**: "Horizontal", "HorizontalVertical", "Mixed", "Vertical"
1036 #### `"Mixed"` (default):
1039 use foo::{xxx, yyy, zzz};
1041 use foo::{aaa, bbb, ccc,
1045 #### `"Horizontal"`:
1047 **Note**: This option forces all imports onto one line and may exceed `max_width`.
1050 use foo::{xxx, yyy, zzz};
1052 use foo::{aaa, bbb, ccc, ddd, eee, fff};
1055 #### `"HorizontalVertical"`:
1058 use foo::{xxx, yyy, zzz};
1084 ## `match_block_trailing_comma`
1086 Put a trailing comma after a block based match arm (non-block arms are not affected)
1088 - **Default value**: `false`
1089 - **Possible values**: `true`, `false`
1092 #### `false` (default):
1099 Lorem::Dolor => println!("dolor"),
1110 Lorem::Dolor => println!("dolor"),
1114 See also: [`trailing_comma`](#trailing_comma), [`match_arm_blocks`](#match_arm_blocks).
1118 Maximum width of each line
1120 - **Default value**: `100`
1121 - **Possible values**: any positive integer
1124 See also [`error_on_line_overflow`](#error_on_line_overflow).
1128 Merge multiple derives into a single one.
1130 - **Default value**: `true`
1131 - **Possible values**: `true`, `false`
1134 #### `true` (default):
1137 #[derive(Eq, PartialEq, Debug, Copy, Clone)]
1144 #[derive(Eq, PartialEq)]
1146 #[derive(Copy, Clone)]
1150 ## `force_multiline_blocks`
1152 Force multiline closure and match arm bodies to be wrapped in a block
1154 - **Default value**: `false`
1155 - **Possible values**: `false`, `true`
1158 #### `false` (default):
1161 result.and_then(|maybe_value| match maybe_value {
1168 println!("Hello World");
1178 result.and_then(|maybe_value| {
1188 println!("Hello World");
1198 Unix or Windows line endings
1200 - **Default value**: `"Unix"`
1201 - **Possible values**: `"Native"`, `"Unix"`, `"Windows"`
1204 ## `normalize_comments`
1206 Convert /* */ comments to // comments where possible
1208 - **Default value**: `false`
1209 - **Possible values**: `true`, `false`
1212 #### `false` (default):
1216 fn dolor() -> usize {}
1219 fn adipiscing() -> usize {}
1226 fn dolor() -> usize {}
1229 fn adipiscing() -> usize {}
1232 ## `reorder_imported_names`
1234 Reorder lists of names in import statements alphabetically
1236 - **Default value**: `false`
1237 - **Possible values**: `true`, `false`
1240 #### `false` (default):
1243 use super::{lorem, ipsum, dolor, sit};
1249 use super::{dolor, ipsum, lorem, sit};
1252 See also [`reorder_imports`](#reorder_imports).
1254 ## `reorder_imports`
1256 Reorder import statements alphabetically
1258 - **Default value**: `false`
1259 - **Possible values**: `true`, `false`
1262 #### `false` (default):
1280 See also [`reorder_imported_names`](#reorder_imported_names), [`reorder_imports_in_group`](#reorder_imports_in_group).
1282 ## `reorder_imports_in_group`
1284 Reorder import statements in group
1286 - **Default value**: `false`
1287 - **Possible values**: `true`, `false`
1290 **Note:** This option takes effect only when [`reorder_imports`](#reorder_imports) is set to `true`.
1292 #### `false` (default):
1316 See also [`reorder_imports`](#reorder_imports).
1318 ## `reorder_extern_crates`
1320 Reorder `extern crate` statements alphabetically
1322 - **Default value**: `true`
1323 - **Possible values**: `true`, `false`
1326 #### `true` (default):
1344 See also [`reorder_extern_crates_in_group`](#reorder_extern_crates_in_group).
1346 ## `reorder_extern_crates_in_group`
1348 Reorder `extern crate` statements in group
1350 - **Default value**: `true`
1351 - **Possible values**: `true`, `false`
1354 **Note:** This option takes effect only when [`reorder_imports`](#reorder_imports) is set to `true`.
1356 #### `true` (default):
1380 See also [`reorder_extern_crates`](#reorder_extern_crates).
1384 Report `TODO` items in comments.
1386 - **Default value**: `"Never"`
1387 - **Possible values**: `"Always"`, `"Unnumbered"`, `"Never"`
1390 Warns about any comments containing `TODO` in them when set to `"Always"`. If
1391 it contains a `#X` (with `X` being a number) in parentheses following the
1392 `TODO`, `"Unnumbered"` will ignore it.
1394 See also [`report_fixme`](#report_fixme).
1398 Report `FIXME` items in comments.
1400 - **Default value**: `"Never"`
1401 - **Possible values**: `"Always"`, `"Unnumbered"`, `"Never"`
1404 Warns about any comments containing `FIXME` in them when set to `"Always"`. If
1405 it contains a `#X` (with `X` being a number) in parentheses following the
1406 `FIXME`, `"Unnumbered"` will ignore it.
1408 See also [`report_todo`](#report_todo).
1413 Don't reformat out of line modules
1415 - **Default value**: `false`
1416 - **Possible values**: `true`, `false`
1419 ## `space_after_colon`
1421 Leave a space after the colon.
1423 - **Default value**: `true`
1424 - **Possible values**: `true`, `false`
1427 #### `true` (default):
1430 fn lorem<T: Eq>(t: T) {
1431 let lorem: Dolor = Lorem {
1441 fn lorem<T:Eq>(t:T) {
1442 let lorem:Dolor = Lorem {
1449 See also: [`space_before_colon`](#space_before_colon).
1451 ## `space_before_colon`
1453 Leave a space before the colon.
1455 - **Default value**: `false`
1456 - **Possible values**: `true`, `false`
1459 #### `false` (default):
1462 fn lorem<T: Eq>(t: T) {
1463 let lorem: Dolor = Lorem {
1473 fn lorem<T : Eq>(t : T) {
1474 let lorem : Dolor = Lorem {
1481 See also: [`space_after_colon`](#space_after_colon).
1483 ## `struct_field_align_threshold`
1485 The maximum diff of width between struct fields to be aligned with each other.
1487 - **Default value** : 0
1488 - **Possible values**: any positive integer
1511 ## `spaces_around_ranges`
1513 Put spaces around the .. and ... range operators
1515 - **Default value**: `false`
1516 - **Possible values**: `true`, `false`
1519 #### `false` (default):
1528 let lorem = 0 .. 10;
1531 ## `spaces_within_parens_and_brackets`
1533 Put spaces within non-empty generic arguments, parentheses, and square brackets
1535 - **Default value**: `false`
1536 - **Possible values**: `true`, `false`
1539 #### `false` (default):
1542 // generic arguments
1543 fn lorem<T: Eq>(t: T) {
1547 // non-empty parentheses
1548 fn lorem<T: Eq>(t: T) {
1549 let lorem = (ipsum, dolor);
1552 // non-empty square brackets
1553 let lorem: [usize; 2] = [ipsum, dolor];
1559 // generic arguments
1560 fn lorem< T: Eq >(t: T) {
1564 // non-empty parentheses
1565 fn lorem<T: Eq>( t: T ) {
1566 let lorem = ( ipsum, dolor );
1569 // non-empty square brackets
1570 let lorem: [ usize; 2 ] = [ ipsum, dolor ];
1573 ## `struct_lit_single_line`
1575 Put small struct literals on a single line
1577 - **Default value**: `true`
1578 - **Possible values**: `true`, `false`
1581 #### `true` (default):
1584 let lorem = Lorem { ipsum: dolor, sit: amet };
1596 See also: [`indent_style`](#indent_style).
1601 Number of spaces per tab
1603 - **Default value**: `4`
1604 - **Possible values**: any positive integer
1611 let ipsum = dolor();
1613 "amet consectetur adipiscing elit."
1622 let ipsum = dolor();
1624 "amet consectetur adipiscing elit."
1629 See also: [`hard_tabs`](#hard_tabs).
1634 How to handle trailing commas for lists
1636 - **Default value**: `"Vertical"`
1637 - **Possible values**: `"Always"`, `"Never"`, `"Vertical"`
1640 #### `"Vertical"` (default):
1643 let Lorem { ipsum, dolor, sit } = amet;
1657 let Lorem { ipsum, dolor, sit, } = amet;
1671 let Lorem { ipsum, dolor, sit } = amet;
1682 See also: [`match_block_trailing_comma`](#match_block_trailing_comma).
1684 ## `trailing_semicolon`
1686 Add trailing semicolon after break, continue and return
1688 - **Default value**: `true`
1689 - **Possible values**: `true`, `false`
1692 #### `true` (default):
1706 ## `type_punctuation_density`
1708 Determines if `+` or `=` are wrapped in spaces in the punctuation of types
1710 - **Default value**: `"Wide"`
1711 - **Possible values**: `"Compressed"`, `"Wide"`
1714 #### `"Wide"` (default):
1717 fn lorem<Ipsum: Dolor + Sit = Amet>() {
1722 #### `"Compressed"`:
1725 fn lorem<Ipsum: Dolor+Sit=Amet>() {
1730 ## `use_try_shorthand`
1732 Replace uses of the try! macro by the ? shorthand
1734 - **Default value**: `false`
1735 - **Possible values**: `true`, `false`
1738 #### `false` (default):
1741 let lorem = try!(ipsum.map(|dolor|dolor.sit()));
1747 let lorem = ipsum.map(|dolor| dolor.sit())?;
1753 Break comments to fit on the line
1755 - **Default value**: `false`
1756 - **Possible values**: `true`, `false`
1759 #### `false` (default):
1762 // 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.
1768 // Lorem ipsum dolor sit amet, consectetur adipiscing elit,
1769 // sed do eiusmod tempor incididunt ut labore et dolore
1770 // magna aliqua. Ut enim ad minim veniam, quis nostrud
1771 // exercitation ullamco laboris nisi ut aliquip ex ea
1772 // commodo consequat.
1775 ## `match_arm_blocks`
1777 Wrap the body of arms in blocks when it does not fit on the same line with the pattern of arms
1779 - **Default value**: `true`
1780 - **Possible values**: `true`, `false`
1783 #### `true` (default):
1788 foooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo(x)
1790 false => println!("{}", sit),
1799 foooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo(x),
1800 false => println!("{}", sit),
1804 See also: [`match_block_trailing_comma`](#match_block_trailing_comma).
1808 What Write Mode to use when none is supplied: Replace, Overwrite, Display, Diff, Coverage
1810 - **Default value**: `"Overwrite"`
1811 - **Possible values**: `"Checkstyle"`, `"Coverage"`, `"Diff"`, `"Display"`, `"Overwrite"`, `"Plain"`, `"Replace"`
1814 ## `blank_lines_upper_bound`
1816 Maximum number of blank lines which can be put between items. If more than this number of consecutive empty
1817 lines are found, they are trimmed down to match this integer.
1819 - **Default value**: `1`
1820 - **Possible values**: *unsigned integer*
1869 See also: [`blank_lines_lower_bound`](#blank_lines_lower_bound)
1871 ## `blank_lines_lower_bound`
1873 Minimum number of blank lines which must be put between items. If two items have fewer blank lines between
1874 them, additional blank lines are inserted.
1876 - **Default value**: `0`
1877 - **Possible values**: *unsigned integer*
1881 Original Code (rustfmt will not change it with the default value of `0`):