1 files changed, 97 insertions, 0 deletions
diff --git a/src/tools/rustfmt/Configurations.md b/src/tools/rustfmt/Configurations.md
index 49e7e4e64..ac5747800 100644
--- a/src/tools/rustfmt/Configurations.md
+++ b/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`
 
@@ -2997,6 +3074,10 @@ See also [`brace_style`](#brace_style), [`control_brace_style`](#control_brace_s
 
 Break comments to fit on the line
 
+Note that no wrapping will happen if:
+1. The comment is the start of a markdown header doc comment
+2. An URL was found in the comment
+
 - **Default value**: `false`
 - **Possible values**: `true`, `false`
 - **Stable**: No (tracking issue: [#3347](https://github.com/rust-lang/rustfmt/issues/3347))
@@ -3011,6 +3092,11 @@ Break comments to fit on the line
 // commodo consequat.
 
 // 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.
+
+// Information on the lorem ipsum can be found at the following url: https://en.wikipedia.org/wiki/Lorem_ipsum. Its text is: 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.
+
+/// # This doc comment is a very long header (it starts with a '#'). Had it not been a header it would have been wrapped. But because it is a header, it will not be. That is because wrapping a markdown header breaks it.
+struct Foo {}
 ```
 
 #### `true`:
@@ -3021,6 +3107,17 @@ Break comments to fit on the line
 // magna aliqua. Ut enim ad minim veniam, quis nostrud
 // exercitation ullamco laboris nisi ut aliquip ex ea
 // commodo consequat.
+
+// 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.
+
+// Information on the lorem ipsum can be found at the following url: https://en.wikipedia.org/wiki/Lorem_ipsum. Its text is: 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.
+
+/// # This doc comment is a very long header (it starts with a '#'). Had it not been a header it would have been wrapped. But because it is a header, it will not be. That is because wrapping a markdown header breaks it.
+struct Foo {}
 ```
 
 # Internal Options