1 files changed, 30 insertions, 15 deletions
diff --git a/compiler/rustc_parse/src/parser/attr_wrapper.rs b/compiler/rustc_parse/src/parser/attr_wrapper.rs
index 5fdafd187c6..34021c40ba9 100644
--- a/compiler/rustc_parse/src/parser/attr_wrapper.rs
+++ b/compiler/rustc_parse/src/parser/attr_wrapper.rs
@@ -442,23 +442,38 @@ fn make_token_stream(
         }
         token_and_spacing = iter.next();
     }
-    let mut final_buf = stack.pop().expect("Missing final buf!");
-    if break_last_token {
-        let last_token = final_buf.inner.pop().unwrap();
-        if let AttrTokenTree::Token(last_token, spacing) = last_token {
-            let unglued_first = last_token.kind.break_two_token_op().unwrap().0;
-
-            // An 'unglued' token is always two ASCII characters
-            let mut first_span = last_token.span.shrink_to_lo();
-            first_span = first_span.with_hi(first_span.lo() + rustc_span::BytePos(1));
-
-            final_buf
+    while let Some(FrameData { open_delim_sp, mut inner }) = stack.pop() {
+        // A former macro expansion could give us malformed tokens.
+        // In that case, manually close all open delimitors so downstream users
+        // don't ICE on them.
+        if let Some((delim, open_sp)) = open_delim_sp {
+            let dspan = DelimSpan::from_pair(open_sp, rustc_span::DUMMY_SP);
+            let stream = AttrTokenStream::new(inner);
+            let delimited = AttrTokenTree::Delimited(dspan, delim, stream);
+            stack
+                .last_mut()
+                .unwrap_or_else(|| panic!("Bottom token frame is missing for recovered token"))
                 .inner
-                .push(AttrTokenTree::Token(Token::new(unglued_first, first_span), spacing));
+                .push(delimited);
         } else {
-            panic!("Unexpected last token {:?}", last_token)
+            if break_last_token {
+                let last_token = inner.pop().unwrap();
+                if let AttrTokenTree::Token(last_token, spacing) = last_token {
+                    let unglued_first = last_token.kind.break_two_token_op().unwrap().0;
+
+                    // An 'unglued' token is always two ASCII characters
+                    let mut first_span = last_token.span.shrink_to_lo();
+                    first_span = first_span.with_hi(first_span.lo() + rustc_span::BytePos(1));
+
+                    inner
+                        .push(AttrTokenTree::Token(Token::new(unglued_first, first_span), spacing));
+                } else {
+                    panic!("Unexpected last token {:?}", last_token)
+                }
+            }
+            assert!(stack.is_empty(), "Stack should be empty: stack={:?}", stack);
+            return AttrTokenStream::new(inner);
         }
     }
-    assert!(stack.is_empty(), "Stack should be empty: final_buf={:?} stack={:?}", final_buf, stack);
-    AttrTokenStream::new(final_buf.inner)
+    panic!("Missing final buf!")
 }