Ignore format_code_in_doc_comments if doc is in the middle of comment

src/attr.rs

@@ -212,11 +212,60 @@ where
     &attrs[..len]
 }
 
+/// Attr is doc attr with doc.
+///
+/// ```ignore
+/// #[doc = "doc"]
+/// ```
+fn is_doc_eq_attr(attr: &ast::Attribute) -> bool {
+    match &attr.kind {
+        ast::AttrKind::Normal(normal) if normal.item.path == sym::doc => match normal.item.args {
+            ast::AttrArgs::Eq(..) => true,
+            _ => false,
+        },
+        _ => false,
+    }
+}
+
+/// Is there a `#[doc = "doc"]` attribute in the middle of doc comments.
+///
+/// If there's such attribute, we skip formatting, because the doc can point to an external file,
+/// and we don't know how that file may break the formatting.
+fn has_doc_eq_attr_in_the_middle_of_comments(attrs: &[ast::Attribute]) -> bool {
+    enum Stage {
+        Start,
+        SeenDocComment,
+        SeenDocAttr,
+    }
+    let mut stage = Stage::Start;
+    for attr in attrs {
+        match &stage {
+            Stage::Start => {
+                if attr.is_doc_comment() {
+                    stage = Stage::SeenDocComment;
+                }
+            }
+            Stage::SeenDocComment => {
+                if is_doc_eq_attr(attr) {
+                    stage = Stage::SeenDocAttr;
+                }
+            }
+            Stage::SeenDocAttr => {
+                if attr.is_doc_comment() {
+                    return true;
+                }
+            }
+        }
+    }
+    false
+}
+
 /// Rewrite the any doc comments which come before any other attributes.
 fn rewrite_initial_doc_comments(
     context: &RewriteContext<'_>,
     attrs: &[ast::Attribute],
     shape: Shape,
+    has_doc_attr_in_the_middle_of_comments: bool,
 ) -> Option<(usize, Option<String>)> {
     if attrs.is_empty() {
         return Some((0, None));
@@ -235,6 +284,7 @@ fn rewrite_initial_doc_comments(
                 &snippet,
                 shape.comment(context.config),
                 context.config,
+                has_doc_attr_in_the_middle_of_comments,
             )?),
         ));
     }
@@ -318,7 +368,12 @@ impl Rewrite for ast::Attribute {
     fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
         let snippet = context.snippet(self.span);
         if self.is_doc_comment() {
-            rewrite_doc_comment(snippet, shape.comment(context.config), context.config)
+            rewrite_doc_comment(
+                snippet,
+                shape.comment(context.config),
+                context.config,
+                false,
+            )
         } else {
             let should_skip = self
                 .ident()
@@ -347,6 +402,7 @@ impl Rewrite for ast::Attribute {
                             &doc_comment,
                             shape.comment(context.config),
                             context.config,
+                            false,
                         );
                     }
                 }
@@ -378,6 +434,9 @@ impl Rewrite for [ast::Attribute] {
         // or `#![rustfmt::skip::attributes(derive)]`
         let skip_derives = context.skip_context.attributes.skip("derive");
 
+        let has_doc_attr_in_the_middle_of_comments =
+            has_doc_eq_attr_in_the_middle_of_comments(attrs);
+
         // This is not just a simple map because we need to handle doc comments
         // (where we take as many doc comment attributes as possible) and possibly
         // merging derives into a single attribute.
@@ -387,8 +446,12 @@ impl Rewrite for [ast::Attribute] {
             }
 
             // Handle doc comments.
-            let (doc_comment_len, doc_comment_str) =
-                rewrite_initial_doc_comments(context, attrs, shape)?;
+            let (doc_comment_len, doc_comment_str) = rewrite_initial_doc_comments(
+                context,
+                attrs,
+                shape,
+                has_doc_attr_in_the_middle_of_comments,
+            )?;
             if doc_comment_len > 0 {
                 let doc_comment_str = doc_comment_str.expect("doc comments, but no result");
                 result.push_str(&doc_comment_str);

src/comment.rs

@@ -248,8 +248,20 @@ pub(crate) fn combine_strs_with_missing_comments(
     Some(result)
 }
 
-pub(crate) fn rewrite_doc_comment(orig: &str, shape: Shape, config: &Config) -> Option<String> {
-    identify_comment(orig, false, shape, config, true)
+pub(crate) fn rewrite_doc_comment(
+    orig: &str,
+    shape: Shape,
+    config: &Config,
+    has_doc_attr_in_the_middle_of_comments: bool,
+) -> Option<String> {
+    identify_comment(
+        orig,
+        false,
+        shape,
+        config,
+        true,
+        has_doc_attr_in_the_middle_of_comments,
+    )
 }
 
 pub(crate) fn rewrite_comment(
@@ -258,7 +270,7 @@ pub(crate) fn rewrite_comment(
     shape: Shape,
     config: &Config,
 ) -> Option<String> {
-    identify_comment(orig, block_style, shape, config, false)
+    identify_comment(orig, block_style, shape, config, false, false)
 }
 
 fn identify_comment(
@@ -267,6 +279,7 @@ fn identify_comment(
     shape: Shape,
     config: &Config,
     is_doc_comment: bool,
+    has_doc_attr_in_the_middle_of_comments: bool,
 ) -> Option<String> {
     let style = comment_style(orig, false);
 
@@ -365,7 +378,9 @@ fn identify_comment(
             && !(
                 // `format_code_in_doc_comments` should only take effect on doc comments,
                 // so we only consider it when this comment block is a doc comment block.
-                is_doc_comment && config.format_code_in_doc_comments()
+                is_doc_comment
+                    && config.format_code_in_doc_comments()
+                    && !has_doc_attr_in_the_middle_of_comments
             )
         {
             light_rewrite_comment(first_group, shape.indent, config, is_doc_comment)
@@ -377,6 +392,7 @@ fn identify_comment(
                 shape,
                 config,
                 is_doc_comment || style.is_doc_comment(),
+                has_doc_attr_in_the_middle_of_comments,
             )?
         };
     if rest.is_empty() {
@@ -388,6 +404,7 @@ fn identify_comment(
             shape,
             config,
             is_doc_comment,
+            has_doc_attr_in_the_middle_of_comments,
         )
         .map(|rest_str| {
             format!(
@@ -725,6 +742,7 @@ impl<'a> CommentRewrite<'a> {
         line: &'a str,
         has_leading_whitespace: bool,
         is_doc_comment: bool,
+        has_doc_attr_in_the_middle_of_comments: bool,
     ) -> bool {
         let num_newlines = count_newlines(orig);
         let is_last = i == num_newlines;
@@ -767,6 +785,7 @@ impl<'a> CommentRewrite<'a> {
                 let code_block = match self.code_block_attr.as_ref().unwrap() {
                     CodeBlockAttribute::Rust
                         if self.fmt.config.format_code_in_doc_comments()
+                            && !has_doc_attr_in_the_middle_of_comments
                             && !self.code_block_buffer.trim().is_empty() =>
                     {
                         let mut config = self.fmt.config.clone();
@@ -912,6 +931,7 @@ fn rewrite_comment_inner(
     shape: Shape,
     config: &Config,
     is_doc_comment: bool,
+    has_doc_attr_in_the_middle_of_comments: bool,
 ) -> Option<String> {
     let mut rewriter = CommentRewrite::new(orig, block_style, shape, config);
 
@@ -941,7 +961,14 @@ fn rewrite_comment_inner(
         });
 
     for (i, (line, has_leading_whitespace)) in lines.enumerate() {
-        if rewriter.handle_line(orig, i, line, has_leading_whitespace, is_doc_comment) {
+        if rewriter.handle_line(
+            orig,
+            i,
+            line,
+            has_leading_whitespace,
+            is_doc_comment,
+            has_doc_attr_in_the_middle_of_comments,
+        ) {
             break;
         }
     }

tests/source/doc-attr-in-the-middle-of-doc-comment.rs

@@ -0,0 +1,21 @@
+// rustfmt-format_code_in_doc_comments: true
+
+//! <details open>
+//!     <summary>Example 1</summary>
+//!
+//! ```
+#![doc = "test()"]
+//! ```
+//!
+//! </details>
+//!
+//! <details open>
+//!     <summary>Example 2</summary>
+//!
+//! ```
+//! example(2);
+//! ```
+//!
+//! </details>
+
+struct FooBar;

tests/target/doc-attr-in-the-middle-of-doc-comment.rs

@@ -0,0 +1,21 @@
+// rustfmt-format_code_in_doc_comments: true
+
+//! <details open>
+//!     <summary>Example 1</summary>
+//!
+//! ```
+#![doc = "test()"]
+//! ```
+//!
+//! </details>
+//!
+//! <details open>
+//!     <summary>Example 2</summary>
+//!
+//! ```
+//! example(2);
+//! ```
+//!
+//! </details>
+
+struct FooBar;