- Switched from `rustc-ap-*` crates to `rustc_private` for consumption model of rustc internals
-`annotate-snippets` updated to v0.8 [PR #4762](https://github.com/rust-lang/rustfmt/pull/4762)
- Greatly improved the performance of `cargo fmt` in large workspaces utilizing the `--all` flag by updating to a newer version of `cargo_metadata` that leverages updated `cargo` output from v1.51+ [PR #4997](https://github.com/rust-lang/rustfmt/pull/4997)
- Improved formatting of long slice patterns [#4530](https://github.com/rust-lang/rustfmt/issues/4530)
- **Note you must have `version = Two` in your configuration to take advantage of the new formatting**
- Various improvements to the configuration documentation website [https://rust-lang.github.io/rustfmt/?version=v1.4.38]([https://rust-lang.github.io/rustfmt/?version=v1.4.38])
- Addressed various clippy and rustc warnings
### Fixed
- Resolved issue where specious whitespace would be inserted when a block style comment was terminated within string literal processing [#4312](https://github.com/rust-lang/rustfmt/issues/4312)
- Nested out-of-line mods are again parsed and formatted [#4874](https://github.com/rust-lang/rustfmt/issues/4874)
- Accepts `2021` for edition value from rustfmt command line [PR #4847](https://github.com/rust-lang/rustfmt/pull/4847)
- Unstable command line options are no longer displayed in `--help` text on stable [PR #4798](https://github.com/rust-lang/rustfmt/issues/4798)
- Stopped panicking on patterns in match arms which start with non-ascii characters [#4868](https://github.com/rust-lang/rustfmt/issues/4868)
- Stopped stripping defaults on const params [#4816](https://github.com/rust-lang/rustfmt/issues/4816)
- Fixed issue with dropped content with GAT aliases with self bounds in impls [#4911](https://github.com/rust-lang/rustfmt/issues/4911)
- Stopped removing generic args on associated type constraints [#4943](https://github.com/rust-lang/rustfmt/issues/4943)
- Stopped dropping visibility on certain trait and impl items [#4960](https://github.com/rust-lang/rustfmt/issues/4960)
- Fixed dropping of qualified paths in struct patterns [#4908](https://github.com/rust-lang/rustfmt/issues/4908) and [#5005](https://github.com/rust-lang/rustfmt/issues/5005)
- Fixed bug in line width calculation that was causing specious formatting of certain patterns [#4031](https://github.com/rust-lang/rustfmt/issues/4031)
- **Note that this bug fix may cause observable formatting changes in cases where code had been formatted with prior versions of rustfmt that contained the bug**
- Fixed bug where rustfmt would drop parameter attributes if they were too long in certain cases [#4579](https://github.com/rust-lang/rustfmt/issues/4579)
- Resolved idempotency issue with extern body elements [#4963](https://github.com/rust-lang/rustfmt/issues/4963)
- rustfmt will now handle doc-style comments on function parameters, since they could appear with certain macro usage patterns even though it's generally invalid syntax [#4936](https://github.com/rust-lang/rustfmt/issues/4936)
- Fixed bug in `match_block_trailing_comma` where commas were not added to the blocks of bodies whose arm had a guard that did not fit on the same line as the pattern [#4998](https://github.com/rust-lang/rustfmt/pull/4998)
- Fixed bug in cases where derive attributes started with a block style comment [#4984](https://github.com/rust-lang/rustfmt/issues/4984)
- Fixed issue where the struct rest could be lost when `struct_field_align_threshold` was enabled [#4926](https://github.com/rust-lang/rustfmt/issues/4926)
- Handles cases where certain control flow type expressions have comments between patterns/keywords and the pattern ident contains the keyword [#5009](https://github.com/rust-lang/rustfmt/issues/5009)
- Handles tuple structs that have explicit visibilities and start with a block style comment [#5011](https://github.com/rust-lang/rustfmt/issues/5011)
- Handles leading line-style comments in certain types of macro calls [#4615](https://github.com/rust-lang/rustfmt/issues/4615)
### Added
- Granular width heuristic options made available for user control [PR #4782](https://github.com/rust-lang/rustfmt/pull/4782). This includes the following:
Note this hit the rustup distributions prior to the v1.4.38 release as part of an out-of-cycle updates, but is listed in this version because the feature was not in the other v1.4.37 releases. See also the `use_small_heuristics` section on the configuration site for more information
- New `One` variant added to `imports_granularity` configuration option which can be used to reformat all imports into a single use statement [#4669](https://github.com/rust-lang/rustfmt/issues/4669)
- rustfmt will now skip files that are annotated with `@generated` at the top of the file [#3958](https://github.com/rust-lang/rustfmt/issues/3958)
- New configuration option `hex_literal_case` that allows user to control the casing utilized for hex literals [PR #4903](https://github.com/rust-lang/rustfmt/pull/4903)
See the section on the configuration site for more information
-`cargo fmt` now directly supports the `--check` flag, which means it's now possible to run `cargo fmt --check` instead of the more verbose `cargo fmt -- --check` [#3888](https://github.com/rust-lang/rustfmt/issues/3888)
- **Build from source** - [Tag v1.4.38](https://github.com/rust-lang/rustfmt/tree/v1.4.38), see instructions for how to [install rustfmt from source][install-from-source]
- Resolve idempotence issue related to indentation of macro defs that contain or-patterns with inner comments ([#4603](https://github.com/rust-lang/rustfmt/issues/4603))
- **Build from source** - [Tag v1.4.37](https://github.com/rust-lang/rustfmt/tree/v1.4.37), see instructions for how to [install rustfmt from source][install-from-source]
- **Build from source** - [Tag v1.4.36](https://github.com/rust-lang/rustfmt/tree/v1.4.36), see instructions for how to [install rustfmt from source][install-from-source]
- **Build from source** - [Tag v1.4.35](https://github.com/rust-lang/rustfmt/tree/v1.4.35), see instructions for how to [install rustfmt from source][install-from-source]
- **Build from source** - [Tag v1.4.34](https://github.com/rust-lang/rustfmt/tree/v1.4.34), see instructions for how to [install rustfmt from source][install-from-source]
-`merge_imports` configuration has been deprecated in favor of the new `imports_granularity` option. Any existing usage of `merge_imports` will be automatically mapped to the corresponding value on `imports_granularity` with a warning message printed to encourage users to update their config files.
### Added
- New `imports_granularity` option has been added which succeeds `merge_imports`. This new option supports several additional variants which allow users to merge imports at different levels (crate or module), and even flatten imports to have a single use statement per item. ([PR #4634](https://github.com/rust-lang/rustfmt/pull/4634), [PR #4639](https://github.com/rust-lang/rustfmt/pull/4639))
See the section on the configuration site for more information
- Idempotence issue on blocks containing only empty statements ([#4627](https://github.com/rust-lang/rustfmt/issues/4627) and [#3868](https://github.com/rust-lang/rustfmt/issues/3868))
- Fix issue with semicolon placement on required functions that have a trailing comment that ends in a line-style comment before the semicolon ([#4646](https://github.com/rust-lang/rustfmt/issues/4646))
- Avoid shared interned cfg_if symbol since rustfmt can re-initialize the rustc_ast globals on multiple inputs ([#4656](https://github.com/rust-lang/rustfmt/issues/4656))
- **Build from source** - [Tag v1.4.33](https://github.com/rust-lang/rustfmt/tree/v1.4.33), see instructions for how to [install rustfmt from source][install-from-source]
- Indentation now correct on first bound in cases where the generic bounds are multiline formatted and the first bound itself is multiline formatted ([#4636](https://github.com/rust-lang/rustfmt/issues/4636))
- **Build from source** - [Tag v1.4.32](https://github.com/rust-lang/rustfmt/tree/v1.4.32), see instructions for how to [install rustfmt from source][install-from-source]
- **Build from source** - [Tag v1.4.31](https://github.com/rust-lang/rustfmt/tree/v1.4.31), see instructions for how to [install rustfmt from source][install-from-source]
- Last character in derive no longer erroneously stripped when `indent_style` is overridden to `Visual`. ([#4584](https://github.com/rust-lang/rustfmt/issues/4584))
- Brace wrapping of closure bodies maintained in cases where the closure has an explicit return type and the body consists of a single expression statement. ([#4577](https://github.com/rust-lang/rustfmt/issues/4577))
- No more panics on invalid code with `err` and `typeof` types ([#4357](https://github.com/rust-lang/rustfmt/issues/4357), [#4586](https://github.com/rust-lang/rustfmt/issues/4586))
- **Build from source** - [Tag v1.4.30](https://github.com/rust-lang/rustfmt/tree/v1.4.30), see instructions for how to [install rustfmt from source][install-from-source]
- **Build from source** - [Tag v1.4.29](https://github.com/rust-lang/rustfmt/tree/v1.4.29), see instructions for how to [install rustfmt from source][install-from-source]
- In the event of an invalid inner attribute on a `cfg_if` condition, rustfmt will now attempt to continue and format the imported modules. Previously rustfmt would emit the parser error about an inner attribute being invalid in this position, but for rustfmt's purposes the invalid attribute doesn't prevent nor impact module formatting.
### Added
- [`group_imports`][group-imports-config-docs] - a new configuration option that allows users to control the strategy used for grouping imports ([#4107](https://github.com/rust-lang/rustfmt/issues/4107))
- Formatting of malformed derived attributes is no longer butchered. ([#3898](https://github.com/rust-lang/rustfmt/issues/3898), [#4029](https://github.com/rust-lang/rustfmt/issues/4029), [#4115](https://github.com/rust-lang/rustfmt/issues/4115), [#4545](https://github.com/rust-lang/rustfmt/issues/4545))
- Correct indentation used in macro branches when `hard_tabs` is enabled. ([#4152](https://github.com/rust-lang/rustfmt/issues/4152))
- Comments between the visibility modifier and item name are no longer dropped. ([#2781](https://github.com/rust-lang/rustfmt/issues/2781))
- Comments preceding the assignment operator in type aliases are no longer dropped. ([#4244](https://github.com/rust-lang/rustfmt/issues/4244))
- Comments between {`&` operator, lifetime, `mut` kw, type} are no longer dropped. ([#4245](https://github.com/rust-lang/rustfmt/issues/4245))
- Comments between type bounds are no longer dropped. ([#4243](https://github.com/rust-lang/rustfmt/issues/4243))
- Function headers are no longer dropped on foreign function items. ([#4288](https://github.com/rust-lang/rustfmt/issues/4288))
- Foreign function blocks are no longer dropped. ([#4313](https://github.com/rust-lang/rustfmt/issues/4313))
-`where_single_line` is no longer incorrectly applied to multiline function signatures that have no `where` clause. ([#4547](https://github.com/rust-lang/rustfmt/issues/4547))
-`matches!` expressions with multiple patterns and a destructure pattern are now able to be formatted. ([#4512](https://github.com/rust-lang/rustfmt/issues/4512))
- **Build from source** - [Tag v1.4.28](https://github.com/rust-lang/rustfmt/tree/v1.4.28), see instructions for how to [install rustfmt from source][install-from-source]
- Leading comments in an extern block are no longer dropped (a bug that exists in v1.4.26). ([#4528](https://github.com/rust-lang/rustfmt/issues/4528))
- **Build from source** - [Tag v1.4.27](https://github.com/rust-lang/rustfmt/tree/v1.4.27), see instructions for how to [install rustfmt from source][install-from-source]
- Original comment indentation for trailing comments within an `if` is now taken into account when determining the indentation level to use for the trailing comment in formatted code. This does not modify any existing code formatted with rustfmt; it simply gives the programmer discretion to specify whether the comment is associated to the `else` block, or if the trailing comment is just a member of the `if` block. ([#1575](https://github.com/rust-lang/rustfmt/issues/1575), [#4120](https://github.com/rust-lang/rustfmt/issues/4120), [#4506](https://github.com/rust-lang/rustfmt/issues/4506))
In this example the `// else comment` refers to the `else`:
```rust
// if comment
if cond {
"if"
// else comment
} else {
"else"
}
```
Whereas in this case the `// continue` comments are members of their respective blocks and do not refer to the `else` below.
```rust
if toks.eat_token(Token::Word("modify"))? && toks.eat_token(Token::Word("labels"))? {
if toks.eat_token(Token::Colon)? {
// ate the token
} else if toks.eat_token(Token::Word("to"))? {
// optionally eat the colon after to, e.g.:
// @rustbot modify labels to: -S-waiting-on-author, +S-waiting-on-review
toks.eat_token(Token::Colon)?;
} else {
// It's okay if there's no to or colon, we can just eat labels
// afterwards.
}
1 + 2;
// continue
} else if toks.eat_token(Token::Word("label"))? {
// continue
} else {
return Ok(None);
}
```
### Fixed
- Formatting of empty blocks with attributes which only contained comments is no longer butchered.([#4475](https://github.com/rust-lang/rustfmt/issues/4475), [#4467](https://github.com/rust-lang/rustfmt/issues/4467), [#4452](https://github.com/rust-lang/rustfmt/issues/4452#issuecomment-705886282), [#4522](https://github.com/rust-lang/rustfmt/issues/4522))
- Indentation of trailing comments in non-empty extern blocks is now correct. ([#4120](https://github.com/rust-lang/rustfmt/issues/4120#issuecomment-696491872))
- **Build from source** - [Tag v1.4.26](https://github.com/rust-lang/rustfmt/tree/v1.4.26), see instructions for how to [install rustfmt from source][install-from-source]
- Semicolons are no longer automatically inserted on trailing expressions in macro definition arms ([#4507](https://github.com/rust-lang/rustfmt/pull/4507)). This gives the programmer control and discretion over whether there should be semicolons in these scenarios so that potential expansion issues can be avoided.
- **Build from source** - [Tag v1.4.25](https://github.com/rust-lang/rustfmt/tree/v1.4.25), see instructions for how to [install rustfmt from source][install-from-source]
- Block wrapped match arm bodies containing a single macro call expression are no longer flattened ([#4496](https://github.com/rust-lang/rustfmt/pull/4496)). This allows programmer discretion so that the block wrapping can be preserved in cases where needed to prevent issues in expansion, such as with trailing semicolons, and aligns with updated [Style Guide guidance](https://github.com/rust-dev-tools/fmt-rfcs/blob/master/guide/expressions.md#macro-call-expressions) for such scenarios.
### Fixed
- Remove useless `deprecated` attribute on a trait impl block in the rustfmt lib, as these now trigger errors ([rust-lang/rust/#78626](https://github.com/rust-lang/rust/pull/78626))
- **Build from source** - [Tag v1.4.24](https://github.com/rust-lang/rustfmt/tree/v1.4.24), see instructions for how to [install rustfmt from source][install-from-source]
- **Build from source** - [Tag v1.4.23](https://github.com/rust-lang/rustfmt/tree/v1.4.23), see instructions for how to [install rustfmt from source][install-from-source]
- Add `inline_attribute_width` configuration option to write an item and its attribute on the same line if their combined width is below a threshold #3409
- Support `const` generics f0c861b
- Support path clarity module #3448
### Changed
- Align loop and while formatting 7d9a2ef
- Support `EmitMode::ModifiedLines` with stdin input #3424
- Update `rustc-ap-*` crates to 407.0.0
- Remove trailing whitespaces in missing spans 2d5bc69
### Fixed
- Do not remove comment in the case of no arg 8e3ef3e
- Fix `Ident of macro+ident gets duplicated` error 40ff078
- Format the if expression at the end of the block in a single line 5f3dfe6
- Add a [section](https://github.com/rust-lang/rustfmt/blob/ae331be/Contributing.md#version-gate-formatting-changes) to the Contributing.md file about version-gating formatting changes 36e2cb0
- Allow specifying package with `-p` CLI option a8d2591
- Support `rustfmt::skip` on imports #3289
- Support global `rustfmt.toml` to be written in user config directory #3280
- Format visibility on trait alias 96a3df3
### Changed
- Do not modify original source code inside macro call #3260
- Recognize strings inside comments in order to avoid indenting them baa62c6
- Use Unicode-standard char width to wrap comments or strings a01990c
- Change new line point in the case of no args #3294
- Use the same formatting rule between functions and macros #3298
- Update rustc-ap-rustc_target to 366.0.0, rustc-ap-syntax to 366.0.0, and rustc-ap-syntax_pos to 366.0.0
### Fixed
- rewrite_comment: fix block fallback when failing to rewrite an itemized block ab7f4e1
- Catch possible tokenizer panics #3240
- Fix macro indentation on Windows #3266
- Fix shape when formatting return or break expr on statement position #3259
- rewrite_comment: fix block fallback when failing to rewrite an itemized block
- Keep leading double-colon to respect the 2018 edition of rust's paths a2bfc02
- Fix glob and nested global imports 2125ad2
- Do not force trailing comma when using mixed layout #3306
- Prioritize `single_line_fn` and `empty_item_single_line` over `brace_style`#3308
- Fix `internal error: left behind trailing whitespace` with long lines c2534f5
- Fix attribute duplication #3325
- Fix formatting of strings within a macro 813aa79
- Handle a macro argument with a single keyword 9a7ea6a
