Fix a help message of empty_line_after_doc_comments for cases where the following item is nameless (rust-lang#14584)

Fixes rust-lang/rust-clippy#14515.

changelog: [`empty_line_after_doc_comments`]: Fix a help message for
cases where the following item is nameless.

Author: samueltardieu

clippy_lints/src/empty_line_after.rs

@@ -1,3 +1,5 @@
+use std::borrow::Cow;
+
 use clippy_utils::diagnostics::span_lint_and_then;
 use clippy_utils::source::{SpanRangeExt, snippet_indent};
 use clippy_utils::tokenize_with_text;
@@ -89,7 +91,7 @@ declare_clippy_lint! {
 #[derive(Debug)]
 struct ItemInfo {
     kind: &'static str,
-    name: Symbol,
+    name: Option<Symbol>,
     span: Span,
     mod_items: Option<NodeId>,
 }
@@ -315,8 +317,12 @@ impl EmptyLineAfter {
                     for stop in gaps.iter().flat_map(|gap| gap.prev_chunk) {
                         stop.comment_out(cx, &mut suggestions);
                     }
+                    let name = match info.name {
+                        Some(name) => format!("{} `{name}`", info.kind).into(),
+                        None => Cow::from("the following item"),
+                    };
                     diag.multipart_suggestion_verbose(
-                        format!("if the doc comment should not document `{}` comment it out", info.name),
+                        format!("if the doc comment should not document {name} then comment it out"),
                         suggestions,
                         Applicability::MaybeIncorrect,
                     );
@@ -381,13 +387,10 @@ impl EmptyLineAfter {
     ) {
         self.items.push(ItemInfo {
             kind: kind.descr(),
-            // FIXME: this `sym::empty` can be leaked, see
-            // https://github.com/rust-lang/rust/pull/138740#discussion_r2021979899
-            name: if let Some(ident) = ident { ident.name } else { kw::Empty },
-            span: if let Some(ident) = ident {
-                span.with_hi(ident.span.hi())
-            } else {
-                span.with_hi(span.lo())
+            name: ident.map(|ident| ident.name),
+            span: match ident {
+                Some(ident) => span.with_hi(ident.span.hi()),
+                None => span.shrink_to_lo(),
             },
             mod_items: match kind {
                 ItemKind::Mod(_, _, ModKind::Loaded(items, _, _, _)) => items
@@ -447,7 +450,7 @@ impl EarlyLintPass for EmptyLineAfter {
     fn check_crate(&mut self, _: &EarlyContext<'_>, krate: &Crate) {
         self.items.push(ItemInfo {
             kind: "crate",
-            name: kw::Crate,
+            name: Some(kw::Crate),
             span: krate.spans.inner_span.with_hi(krate.spans.inner_span.lo()),
             mod_items: krate
                 .items

tests/ui/empty_line_after/doc_comments.1.fixed

@@ -142,4 +142,9 @@ impl Foo for LineComment {
     fn bar() {}
 }
 
+//~v empty_line_after_doc_comments
+/// Docs for this item.
+// fn some_item() {}
+impl LineComment {} // or any other nameless item kind
+
 fn main() {}

tests/ui/empty_line_after/doc_comments.2.fixed

@@ -152,4 +152,10 @@ impl Foo for LineComment {
     fn bar() {}
 }
 
+//~v empty_line_after_doc_comments
+// /// Docs for this item.
+// fn some_item() {}
+
+impl LineComment {} // or any other nameless item kind
+
 fn main() {}

tests/ui/empty_line_after/doc_comments.rs

@@ -155,4 +155,10 @@ impl Foo for LineComment {
     fn bar() {}
 }
 
+//~v empty_line_after_doc_comments
+/// Docs for this item.
+// fn some_item() {}
+
+impl LineComment {} // or any other nameless item kind
+
 fn main() {}

tests/ui/empty_line_after/doc_comments.stderr

@@ -87,7 +87,7 @@ LL |       fn new_code() {}
    |       ----------- the comment documents this function
    |
    = help: if the empty line is unintentional, remove it
-help: if the doc comment should not document `new_code` comment it out
+help: if the doc comment should not document function `new_code` then comment it out
    |
 LL |     // /// docs for `old_code`
    |     ++
@@ -107,7 +107,7 @@ LL |       struct Multiple;
    |       --------------- the comment documents this struct
    |
    = help: if the empty lines are unintentional, remove them
-help: if the doc comment should not document `Multiple` comment it out
+help: if the doc comment should not document struct `Multiple` then comment it out
    |
 LL ~     // /// Docs
 LL ~     // /// for OldA
@@ -149,7 +149,7 @@ LL |       fn new_code() {}
    |       ----------- the comment documents this function
    |
    = help: if the empty line is unintentional, remove it
-help: if the doc comment should not document `new_code` comment it out
+help: if the doc comment should not document function `new_code` then comment it out
    |
 LL -     /**
 LL +     /*
@@ -167,7 +167,7 @@ LL |       fn new_code2() {}
    |       ------------ the comment documents this function
    |
    = help: if the empty line is unintentional, remove it
-help: if the doc comment should not document `new_code2` comment it out
+help: if the doc comment should not document function `new_code2` then comment it out
    |
 LL |     // /// Docs for `old_code2`
    |     ++
@@ -183,10 +183,26 @@ LL |       fn bar() {}
    |       ------ the comment documents this function
    |
    = help: if the empty line is unintentional, remove it
-help: if the doc comment should not document `bar` comment it out
+help: if the doc comment should not document function `bar` then comment it out
    |
 LL |     // /// comment on assoc item
    |     ++
 
-error: aborting due to 11 previous errors
+error: empty line after doc comment
+  --> tests/ui/empty_line_after/doc_comments.rs:159:1
+   |
+LL | / /// Docs for this item.
+LL | | // fn some_item() {}
+LL | |
+   | |_^
+LL |   impl LineComment {} // or any other nameless item kind
+   |   - the comment documents this implementation
+   |
+   = help: if the empty line is unintentional, remove it
+help: if the doc comment should not document the following item then comment it out
+   |
+LL | // /// Docs for this item.
+   | ++
+
+error: aborting due to 12 previous errors