add tests and config spec for new option remove_nested_blocks

Author: karolzwolak

Diff for: Configurations.md

@@ -2227,6 +2227,39 @@ fn main() {
 }
 ```
 
+## `remove_nested_blocks`
+
+Works similarly to [`remove_nested_parens`](#remove_nested_parens), but removes nested blocks.
+
+- **Default value**: `false`,
+- **Possible values**: `true`, `false`
+- **Stable**: No
+
+
+#### `true`:
+```rust
+fn main() {
+    {
+        foo();
+    }
+}
+```
+
+#### `false` (default):
+```rust
+fn main() {
+    {
+        {
+            {
+                {
+                    foo();
+                }
+            }
+        }
+    }
+}
+```
+
 
 ## `reorder_impl_items`
 

Diff for: src/config/mod.rs

@@ -117,6 +117,7 @@ create_config! {
 
     // Misc.
     remove_nested_parens: RemoveNestedParens, true, "Remove nested parens";
+    remove_nested_blocks: RemoveNestedBlocks, false, "Remove nested blocks";
     combine_control_expr: CombineControlExpr, false, "Combine control expressions with function \
         calls";
     short_array_element_width_threshold: ShortArrayElementWidthThreshold, true,
@@ -796,6 +797,7 @@ space_after_colon = true
 spaces_around_ranges = false
 binop_separator = "Front"
 remove_nested_parens = true
+remove_nested_blocks = false
 combine_control_expr = true
 short_array_element_width_threshold = 10
 overflow_delimited_expr = false
@@ -887,6 +889,7 @@ space_after_colon = true
 spaces_around_ranges = false
 binop_separator = "Front"
 remove_nested_parens = true
+remove_nested_blocks = false
 combine_control_expr = true
 short_array_element_width_threshold = 10
 overflow_delimited_expr = true

Diff for: src/config/options.rs

@@ -658,6 +658,7 @@ config_option_with_style_edition_default!(
 
     // Misc.
     RemoveNestedParens, bool, _ => true;
+    RemoveNestedBlocks, bool, _ => false;
     CombineControlExpr, bool, _ => true;
     ShortArrayElementWidthThreshold, usize, _ => 10;
     OverflowDelimitedExpr, bool, Edition2024 => true, _ => false;

Diff for: tests/source/remove_nested_blocks.rs

@@ -0,0 +1,102 @@
+// rustfmt-remove_nested_blocks: true
+fn foo() {}
+
+// The way it is implemented right now, only 'naked' blocks are removed.
+// This means unsafe blocks, const blocks, blocks with labels and attributes,
+// blocks belonging to other constructs such as loops are not removed.
+fn main() {
+    {
+        {
+            {
+                foo();
+            }
+        }
+    }
+    // The next block will be removed
+    {
+        {
+            // Blocks with comments are not removed
+            {
+                {
+                    /* second comment */
+                    {
+                        foo();
+                    }
+                }
+            }
+        }
+    }
+    {
+        {
+            /*
+             * multi-line comment
+             */
+            foo();
+        }
+    }
+    {{{{{{{foo();}}}}}}}
+    {{/*comment*/{{{foo();}}}}}
+    {{/*comment*/{{/*comment*/{foo();}}}}}
+    {
+        const { const {} }
+    }
+    const { const {} }
+    unsafe { unsafe {} }
+    // As const and unsafe blocks are not 'naked' blocks, they are not removed.
+    unsafe {
+        unsafe {
+            {
+                const {
+                    const {
+                        {
+                            foo();
+                        }
+                    }
+                }
+            }
+        }
+    }
+    const {
+        unsafe {
+            {
+                unsafe {
+                    const {
+                        {
+                            foo();
+                        }
+                    }
+                }
+            }
+        }
+    }
+    {
+        'label1: {
+            'label2: {
+                foo();
+            }
+        }
+    }
+    'outer: loop {
+        {
+            'inner: loop {
+                {
+                    foo();
+                }
+            }
+        }
+    }
+    if let Some(x) = 5f64.map(|x| Ok(x)) {
+        {
+            if let Some(x) = 5f64.map(|x| Ok(x)) {
+                foo();
+            }
+        }
+    }
+    if false {
+        { {} }
+    }
+    #[cfg(debug)]
+    {
+        { {} }
+    }
+}

Diff for: tests/target/remove_nested_blocks.rs

@@ -0,0 +1,99 @@
+// rustfmt-remove_nested_blocks: true
+fn foo() {}
+
+// The way it is implemented right now, only 'naked' blocks are removed.
+// This means unsafe blocks, const blocks, blocks with labels and attributes,
+// blocks belonging to other constructs such as loops are not removed.
+fn main() {
+    {
+        foo();
+    }
+    // The next block will be removed
+    {
+        // Blocks with comments are not removed
+        {
+            /* second comment */
+            {
+                foo();
+            }
+        }
+    }
+    {
+        /*
+         * multi-line comment
+         */
+        foo();
+    }
+    {
+        foo();
+    }
+    {
+        /*comment*/
+        {
+            foo();
+        }
+    }
+    {
+        /*comment*/
+        {
+            /*comment*/
+            {
+                foo();
+            }
+        }
+    }
+    const { const {} }
+    const { const {} }
+    unsafe { unsafe {} }
+    // As const and unsafe blocks are not 'naked' blocks, they are not removed.
+    unsafe {
+        unsafe {
+            const {
+                const {
+                    {
+                        foo();
+                    }
+                }
+            }
+        }
+    }
+    const {
+        unsafe {
+            unsafe {
+                const {
+                    {
+                        foo();
+                    }
+                }
+            }
+        }
+    }
+    'label1: {
+        'label2: {
+            foo();
+        }
+    }
+    'outer: loop {
+        {
+            'inner: loop {
+                {
+                    foo();
+                }
+            }
+        }
+    }
+    if let Some(x) = 5f64.map(|x| Ok(x)) {
+        {
+            if let Some(x) = 5f64.map(|x| Ok(x)) {
+                foo();
+            }
+        }
+    }
+    if false {
+        {}
+    }
+    #[cfg(debug)]
+    {
+        {}
+    }
+}