Fix handling of attribute in enum

src/bin/main.rs

@@ -64,11 +64,17 @@ enum Operation {
     /// Print version information
     Version,
     /// Output default config to a file, or stdout if None
-    ConfigOutputDefault { path: Option<String> },
+    ConfigOutputDefault {
+        path: Option<String>,
+    },
     /// Output current config (as if formatting to a file) to stdout
-    ConfigOutputCurrent { path: Option<String> },
+    ConfigOutputCurrent {
+        path: Option<String>,
+    },
     /// No file specified, read from stdin
-    Stdin { input: String },
+    Stdin {
+        input: String,
+    },
 }
 
 /// Rustfmt operations errors.

src/items.rs

@@ -21,7 +21,9 @@ use crate::expr::{
     rewrite_assign_rhs_with_comments, rewrite_else_kw_with_comments, rewrite_let_else_block,
     RhsAssignKind, RhsTactics,
 };
-use crate::lists::{definitive_tactic, itemize_list, write_list, ListFormatting, Separator};
+use crate::lists::{
+    definitive_tactic, itemize_list, write_list, ListFormatting, ListItem, Separator,
+};
 use crate::macros::{rewrite_macro, MacroPosition};
 use crate::overflow;
 use crate::rewrite::{Rewrite, RewriteContext, RewriteError, RewriteErrorExt, RewriteResult};
@@ -643,8 +645,33 @@ impl<'a> FmtVisitor<'a> {
         let mut items: Vec<_> = itemize_list_with(self.config.struct_variant_width());
 
         // If one of the variants use multiple lines, use multi-lined formatting for all variants.
-        let has_multiline_variant = items.iter().any(|item| item.inner_as_ref().contains('\n'));
-        let has_single_line_variant = items.iter().any(|item| !item.inner_as_ref().contains('\n'));
+        let is_multi_line_variant = |item: &ListItem| -> bool {
+            let variant_str = item.inner_as_ref();
+            if self.config.style_edition() < StyleEdition::Edition2024 {
+                // Fall back to previous naive implementation (#5662) because of
+                // rustfmt's stability guarantees
+                return variant_str.contains('\n');
+            }
+
+            let mut first_line_is_read = false;
+            for line in variant_str.split('\n') {
+                if first_line_is_read {
+                    return false;
+                }
+
+                // skip rustdoc comments and macro attributes
+                let line = line.trim_start();
+                if line.starts_with("///") || line.starts_with("#") {
+                    continue;
+                } else {
+                    first_line_is_read = true;
+                }
+            }
+
+            true
+        };
+        let has_multiline_variant = items.iter().any(is_multi_line_variant);
+        let has_single_line_variant = items.iter().any(|item| !is_multi_line_variant(item));
         if has_multiline_variant && has_single_line_variant {
             items = itemize_list_with(0);
         }

src/modules.rs

@@ -77,10 +77,14 @@ pub struct ModuleResolutionError {
 pub(crate) enum ModuleResolutionErrorKind {
     /// Find a file that cannot be parsed.
     #[error("cannot parse {file}")]
-    ParseError { file: PathBuf },
+    ParseError {
+        file: PathBuf,
+    },
     /// File cannot be found.
     #[error("{file} does not exist")]
-    NotFound { file: PathBuf },
+    NotFound {
+        file: PathBuf,
+    },
     /// File a.rs and a/mod.rs both exist
     #[error("file for module found at both {default_path:?} and {secondary_path:?}")]
     MultipleCandidates {

tests/target/attribute-in-enum/horizontal-no-doc.rs

@@ -0,0 +1,7 @@
+// rustfmt-style_edition: 2024
+enum MyType {
+    A { field1: bool, field2: bool },
+    B { field1: bool, field2: bool },
+    C { field1: bool, field2: bool },
+    D { field1: bool, field2: bool },
+}

tests/target/attribute-in-enum/horizontal-with-doc.rs

@@ -0,0 +1,8 @@
+// rustfmt-style_edition: 2024
+enum MyType {
+    A { field1: bool, field2: bool },
+    B { field1: bool, field2: bool },
+    /// OMG a comment
+    C { field1: bool, field2: bool },
+    D { field1: bool, field2: bool },
+}

tests/target/attribute-in-enum/vertical-macro-one-line.rs

@@ -0,0 +1,14 @@
+// rustfmt-style_edition: 2024
+enum A {
+    B {
+        a: usize,
+        b: usize,
+        c: usize,
+        d: usize,
+    },
+
+    #[attr]
+    C {
+        a: usize,
+    },
+}

tests/target/attribute-in-enum/vertical-no-doc.rs

@@ -0,0 +1,13 @@
+// rustfmt-style_edition: 2024
+enum A {
+    B {
+        a: usize,
+        b: usize,
+        c: usize,
+        d: usize,
+    },
+
+    C {
+        a: usize,
+    },
+}

tests/target/attribute-in-enum/vertical-with-doc.rs

@@ -0,0 +1,14 @@
+// rustfmt-style_edition: 2024
+enum A {
+    B {
+        a: usize,
+        b: usize,
+        c: usize,
+        d: usize,
+    },
+
+    /// C
+    C {
+        a: usize,
+    },
+}