Format asm! macro calls

Configurations.md

@@ -1004,6 +1004,38 @@ macro_rules! foo {
 
 See also [`format_macro_matchers`](#format_macro_matchers).
 
+## `format_asm_macro`
+
+Format ``asm!`` macro calls.
+
+- **Default value**: `false`
+- **Possible values**: `true`, `false`
+- **Stable**: No (tracking issue: [#5210](https://github.com/rust-lang/rustfmt/issues/5210))
+
+#### `false` (default):
+
+```rust
+fn main() {
+    let x: u64;
+    unsafe {
+        asm!("mov {}, 5", out(reg) x);
+    }
+}
+```
+
+#### `true`:
+
+```rust
+fn main() {
+    let x: u64;
+    unsafe {
+        asm!(
+            "mov {}, 5",
+            out(reg) x
+        );
+    }
+}
+```
 
 ## `format_strings`
 

src/config/mod.rs

@@ -65,6 +65,7 @@ create_config! {
     normalize_doc_attributes: bool, false, false, "Normalize doc attributes as doc comments";
     license_template_path: String, String::default(), false,
         "Beginning of file must match license template";
+    format_asm_macro: bool, false, false, "Format asm! macro calls";
     format_strings: bool, false, false, "Format string literals where necessary";
     format_macro_matchers: bool, false, false,
         "Format the metavariable matching patterns in macros";
@@ -567,6 +568,7 @@ comment_width = 80
 normalize_comments = false
 normalize_doc_attributes = false
 license_template_path = ""
+format_asm_macro = false
 format_strings = false
 format_macro_matchers = false
 format_macro_bodies = true

src/expr.rs

@@ -1859,11 +1859,9 @@ pub(crate) enum RhsAssignKind<'ast> {
 
 impl<'ast> RhsAssignKind<'ast> {
     // TODO(calebcartwright)
-    // Preemptive addition for handling RHS with chains, not yet utilized.
     // It may make more sense to construct the chain first and then check
     // whether there are actually chain elements.
-    #[allow(dead_code)]
-    fn is_chain(&self) -> bool {
+    pub(crate) fn is_chain(&self) -> bool {
         match self {
             RhsAssignKind::Expr(kind, _) => {
                 matches!(