Auto merge of rust-lang#113225 - calebcartwright:sync-rustfmt, r=calebcartwright

Update Rustfmt (add let-else support)

Adds let-else formatting support

Bit more detail in: https://github.com/rust-lang/rustfmt/blob/master/CHANGELOG.md#160-2023-07-02
Accompanying blog post: rust-lang/blog.rust-lang.org#1117

I know we're getting close to tool week, however, there's been extensive discussion and testing of the changes in this between both t-style and t-rustfmt. Our confidence level is extremely high, and even if it's only on nightly for a few days, I'd still much prefer that and being able to get this out with 1.72 vs having to push to 1.73

Closes rust-lang/rustfmt#4914
cc `@rust-lang/style` for awareness

Author: bors

Cargo.lock

@@ -4264,7 +4264,7 @@ dependencies = [
 
 [[package]]
 name = "rustfmt-nightly"
-version = "1.5.3"
+version = "1.6.0"
 dependencies = [
  "annotate-snippets",
  "anyhow",

src/tools/rustfmt/CHANGELOG.md

@@ -2,6 +2,17 @@
 
 ## [Unreleased]
 
+
+## [1.6.0] 2023-07-02
+
+### Added
+
+- Support for formatting let-else statements [#5690]
+- New config option, `single_line_let_else_max_width`, that allows users to configure the maximum length of single line `let-else` statements. `let-else` statements that otherwise meet the requirements to be formatted on a single line will have their divergent`else` block formatted over multiple lines if they exceed this length [#5684]
+
+[#5690]: (https://github.com/rust-lang/rustfmt/pulls/5690)
+[#5684]: https://github.com/rust-lang/rustfmt/issues/5684
+
 ## [1.5.3] 2023-06-20
 
 ### Fixed

src/tools/rustfmt/Cargo.lock

@@ -481,9 +481,9 @@ dependencies = [
 
 [[package]]
 name = "proc-macro2"
-version = "1.0.56"
+version = "1.0.63"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2b63bdb0cd06f1f4dedf69b254734f9b45af66e4a031e42a7480257d9898b435"
+checksum = "7b368fba921b0dce7e60f5e04ec15e565b3303972b42bcfde1d0713b881959eb"
 dependencies = [
  "unicode-ident",
 ]
@@ -545,7 +545,7 @@ dependencies = [
 
 [[package]]
 name = "rustfmt-nightly"
-version = "1.5.3"
+version = "1.6.0"
 dependencies = [
  "annotate-snippets",
  "anyhow",

src/tools/rustfmt/Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 
 name = "rustfmt-nightly"
-version = "1.5.3"
+version = "1.6.0"
 description = "Tool to find and fix Rust formatting issues"
 repository = "https://github.com/rust-lang/rustfmt"
 readme = "README.md"

src/tools/rustfmt/Configurations.md

@@ -2392,6 +2392,78 @@ By default this option is set as a percentage of [`max_width`](#max_width) provi
 
 See also [`max_width`](#max_width) and [`use_small_heuristics`](#use_small_heuristics)
 
+## `single_line_let_else_max_width`
+
+Maximum line length for single line let-else statements.
+See the [let-else statement section of the Rust Style Guide](https://github.com/rust-lang/rust/blob/master/src/doc/style-guide/src/statements.md#else-blocks-let-else-statements) for more details on when a let-else statement may be written on a single line.
+A value of `0` (zero) means the divergent `else` block will always be formatted over multiple lines.
+Note this occurs when `use_small_heuristics` is set to `Off`.
+
+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_let_else_max_width` will take precedence.
+
+- **Default value**: `50`
+- **Possible values**: any positive integer that is less than or equal to the value specified for [`max_width`](#max_width)
+- **Stable**: Yes
+
+#### `50` (default):
+
+```rust
+fn main() {
+    let Some(w) = opt else { return Ok(()) };
+
+    let Some(x) = opt else { return };
+
+    let Some(y) = opt else {
+        return;
+    };
+
+    let Some(z) = some_very_very_very_very_long_name else {
+        return;
+    };
+}
+```
+
+#### `0`:
+
+```rust
+fn main() {
+    let Some(w) = opt else {
+        return Ok(());
+    };
+
+    let Some(x) = opt else {
+        return;
+    };
+
+    let Some(y) = opt else {
+        return;
+    };
+
+    let Some(z) = some_very_very_very_very_long_name else {
+        return;
+    };
+}
+```
+
+#### `100`:
+
+```rust
+fn main() {
+    let Some(w) = opt else { return Ok(()) };
+
+    let Some(x) = opt else { return };
+
+    let Some(y) = opt else {
+        return;
+    };
+
+    let Some(z) = some_very_very_very_very_long_name else { return };
+}
+```
+
+See also [`max_width`](#max_width) and [`use_small_heuristics`](#use_small_heuristics)
+
+
 ## `space_after_colon`
 
 Leave a space after the colon.
@@ -2804,6 +2876,7 @@ The ratios are:
 * [`array_width`](#array_width) - `60%`
 * [`chain_width`](#chain_width) - `60%`
 * [`single_line_if_else_max_width`](#single_line_if_else_max_width) - `50%`
+* [`single_line_let_else_max_width`](#single_line_let_else_max_width) - `50%`
 
 For example when `max_width` is set to `100`, the width settings are:
 * `fn_call_width=60`
@@ -2813,6 +2886,7 @@ For example when `max_width` is set to `100`, the width settings are:
 * `array_width=60`
 * `chain_width=60`
 * `single_line_if_else_max_width=50`
+* `single_line_let_else_max_width=50`
 
 and when `max_width` is set to `200`:
 * `fn_call_width=120`
@@ -2822,6 +2896,7 @@ and when `max_width` is set to `200`:
 * `array_width=120`
 * `chain_width=120`
 * `single_line_if_else_max_width=100`
+* `single_line_let_else_max_width=100`
 
 ```rust
 enum Lorem {
@@ -2891,6 +2966,7 @@ So if `max_width` is set to `200`, then all the width settings are also set to `
 * `array_width=200`
 * `chain_width=200`
 * `single_line_if_else_max_width=200`
+* `single_line_let_else_max_width=200`
 
 ```rust
 enum Lorem {
@@ -2918,6 +2994,7 @@ See also:
 * [`array_width`](#array_width)
 * [`chain_width`](#chain_width)
 * [`single_line_if_else_max_width`](#single_line_if_else_max_width)
+* [`single_line_let_else_max_width`](#single_line_let_else_max_width)
 
 ## `use_try_shorthand`
 

src/tools/rustfmt/config_proc_macro/Cargo.lock

@@ -4,9 +4,9 @@ version = 3
 
 [[package]]
 name = "proc-macro2"
-version = "1.0.56"
+version = "1.0.63"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2b63bdb0cd06f1f4dedf69b254734f9b45af66e4a031e42a7480257d9898b435"
+checksum = "7b368fba921b0dce7e60f5e04ec15e565b3303972b42bcfde1d0713b881959eb"
 dependencies = [
  "unicode-ident",
 ]

src/tools/rustfmt/rust-toolchain

@@ -1,3 +1,3 @@
 [toolchain]
-channel = "nightly-2023-06-19"
+channel = "nightly-2023-07-01"
 components = ["llvm-tools", "rustc-dev"]

src/tools/rustfmt/src/config/config_type.rs

@@ -121,6 +121,7 @@ macro_rules! create_config {
                     | "use_small_heuristics"
                     | "fn_call_width"
                     | "single_line_if_else_max_width"
+                    | "single_line_let_else_max_width"
                     | "attr_fn_like_width"
                     | "struct_lit_width"
                     | "struct_variant_width"
@@ -269,6 +270,7 @@ macro_rules! create_config {
                     | "use_small_heuristics"
                     | "fn_call_width"
                     | "single_line_if_else_max_width"
+                    | "single_line_let_else_max_width"
                     | "attr_fn_like_width"
                     | "struct_lit_width"
                     | "struct_variant_width"
@@ -407,6 +409,14 @@ macro_rules! create_config {
                     "single_line_if_else_max_width",
                 );
                 self.single_line_if_else_max_width.2 = single_line_if_else_max_width;
+
+                let single_line_let_else_max_width = get_width_value(
+                    self.was_set().single_line_let_else_max_width(),
+                    self.single_line_let_else_max_width.2,
+                    heuristics.single_line_let_else_max_width,
+                    "single_line_let_else_max_width",
+                );
+                self.single_line_let_else_max_width.2 = single_line_let_else_max_width;
             }
 
             fn set_heuristics(&mut self) {

src/tools/rustfmt/src/config/mod.rs

@@ -58,6 +58,9 @@ create_config! {
     chain_width: usize, 60, true, "Maximum length of a chain to fit on a single line.";
     single_line_if_else_max_width: usize, 50, true, "Maximum line length for single line if-else \
         expressions. A value of zero means always break if-else expressions.";
+    single_line_let_else_max_width: usize, 50, true, "Maximum line length for single line \
+        let-else statements. A value of zero means always format the divergent `else` block \
+        over multiple lines.";
 
     // Comments. macros, and strings
     wrap_comments: bool, false, false, "Break comments to fit on the line";
@@ -473,6 +476,9 @@ mod test {
             chain_width: usize, 60, true, "Maximum length of a chain to fit on a single line.";
             single_line_if_else_max_width: usize, 50, true, "Maximum line length for single \
                 line if-else expressions. A value of zero means always break if-else expressions.";
+            single_line_let_else_max_width: usize, 50, false, "Maximum line length for single \
+                line let-else statements. A value of zero means always format the divergent \
+                `else` block over multiple lines.";
 
             // Options that are used by the tests
             stable_option: bool, false, true, "A stable option";
@@ -619,6 +625,7 @@ struct_variant_width = 35
 array_width = 60
 chain_width = 60
 single_line_if_else_max_width = 50
+single_line_let_else_max_width = 50
 wrap_comments = false
 format_code_in_doc_comments = false
 doc_comment_code_block_width = 100

src/tools/rustfmt/src/config/options.rs

@@ -236,6 +236,9 @@ pub struct WidthHeuristics {
     // Maximum line length for single line if-else expressions. A value
     // of zero means always break if-else expressions.
     pub(crate) single_line_if_else_max_width: usize,
+    // Maximum line length for single line let-else statements. A value of zero means
+    // always format the divergent `else` block over multiple lines.
+    pub(crate) single_line_let_else_max_width: usize,
 }
 
 impl fmt::Display for WidthHeuristics {
@@ -255,6 +258,7 @@ impl WidthHeuristics {
             array_width: usize::max_value(),
             chain_width: usize::max_value(),
             single_line_if_else_max_width: 0,
+            single_line_let_else_max_width: 0,
         }
     }
 
@@ -267,6 +271,7 @@ impl WidthHeuristics {
             array_width: max_width,
             chain_width: max_width,
             single_line_if_else_max_width: max_width,
+            single_line_let_else_max_width: max_width,
         }
     }
 
@@ -288,6 +293,7 @@ impl WidthHeuristics {
             array_width: (60.0 * max_width_ratio).round() as usize,
             chain_width: (60.0 * max_width_ratio).round() as usize,
             single_line_if_else_max_width: (50.0 * max_width_ratio).round() as usize,
+            single_line_let_else_max_width: (50.0 * max_width_ratio).round() as usize,
         }
     }
 }