From 5c9bd9c2b4fdca00410209d4c33edc3bebc63444 Mon Sep 17 00:00:00 2001
From: Aaron Hill <aa1ronham@gmail.com>
Date: Fri, 2 Jul 2021 11:30:20 -0500
Subject: [PATCH] Recover from a misplaced inner doc comment

Fixes #86781
---
 compiler/rustc_parse/src/parser/attr.rs               |  9 ++++++++-
 src/test/ui/proc-macro/issue-86781-bad-inner-doc.rs   | 11 +++++++++++
 .../ui/proc-macro/issue-86781-bad-inner-doc.stderr    | 11 +++++++++++
 3 files changed, 30 insertions(+), 1 deletion(-)
 create mode 100644 src/test/ui/proc-macro/issue-86781-bad-inner-doc.rs
 create mode 100644 src/test/ui/proc-macro/issue-86781-bad-inner-doc.stderr

diff --git a/compiler/rustc_parse/src/parser/attr.rs b/compiler/rustc_parse/src/parser/attr.rs
index 8b050389078..e9f0038b2d6 100644
--- a/compiler/rustc_parse/src/parser/attr.rs
+++ b/compiler/rustc_parse/src/parser/attr.rs
@@ -64,7 +64,14 @@ pub(super) fn parse_outer_attributes(&mut self) -> PResult<'a, AttrWrapper> {
                 }
                 self.bump();
                 just_parsed_doc_comment = true;
-                Some(attr::mk_doc_comment(comment_kind, attr_style, data, self.prev_token.span))
+                // Always make an outer attribute - this allows us to recover from a misplaced
+                // inner attribute.
+                Some(attr::mk_doc_comment(
+                    comment_kind,
+                    ast::AttrStyle::Outer,
+                    data,
+                    self.prev_token.span,
+                ))
             } else {
                 None
             };
diff --git a/src/test/ui/proc-macro/issue-86781-bad-inner-doc.rs b/src/test/ui/proc-macro/issue-86781-bad-inner-doc.rs
new file mode 100644
index 00000000000..8be1ae77738
--- /dev/null
+++ b/src/test/ui/proc-macro/issue-86781-bad-inner-doc.rs
@@ -0,0 +1,11 @@
+// aux-build:test-macros.rs
+
+#[macro_use]
+extern crate test_macros;
+
+//! Inner doc comment
+//~^ ERROR expected outer doc comment
+#[derive(Empty)]
+pub struct Foo;
+
+fn main() {}
diff --git a/src/test/ui/proc-macro/issue-86781-bad-inner-doc.stderr b/src/test/ui/proc-macro/issue-86781-bad-inner-doc.stderr
new file mode 100644
index 00000000000..0b2e612ee5b
--- /dev/null
+++ b/src/test/ui/proc-macro/issue-86781-bad-inner-doc.stderr
@@ -0,0 +1,11 @@
+error[E0753]: expected outer doc comment
+  --> $DIR/issue-86781-bad-inner-doc.rs:6:1
+   |
+LL | //! Inner doc comment
+   | ^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: inner doc comments like this (starting with `//!` or `/*!`) can only appear before items
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0753`.
-- 
2.44.0