From f7bb9972194d3cea0cf03a1fabf32fa72c20ce04 Mon Sep 17 00:00:00 2001
From: "Stanislav (Stas) Katkov" <git@skatkov.com>
Date: Thu, 14 May 2026 16:07:38 +0200
Subject: [PATCH 1/2] Resolve markdown crash for invalid note reference

Issue originally reported here:
https://github.com/ruby/rdoc/issues/654
---
 lib/rdoc/markdown.kpeg          |  2 ++
 lib/rdoc/markdown.rb            |  2 ++
 test/rdoc/rdoc_markdown_test.rb | 10 ++++++++++
 3 files changed, 14 insertions(+)

diff --git a/lib/rdoc/markdown.kpeg b/lib/rdoc/markdown.kpeg
index 0e15a604f4..b9a0990e62 100644
--- a/lib/rdoc/markdown.kpeg
+++ b/lib/rdoc/markdown.kpeg
@@ -403,6 +403,8 @@
   # the note order list for proper display at the end of the document.
 
   def note_for ref
+    raise ParseError, "invalid note reference: #{ref}" unless @note_order
+
     @note_order << ref
 
     label = @note_order.length
diff --git a/lib/rdoc/markdown.rb b/lib/rdoc/markdown.rb
index c01cab0096..f6cfc9a24d 100644
--- a/lib/rdoc/markdown.rb
+++ b/lib/rdoc/markdown.rb
@@ -788,6 +788,8 @@ def note label
   # the note order list for proper display at the end of the document.
 
   def note_for ref
+    raise ParseError, "invalid note reference: #{ref}" unless @note_order
+
     @note_order << ref
 
     label = @note_order.length
diff --git a/test/rdoc/rdoc_markdown_test.rb b/test/rdoc/rdoc_markdown_test.rb
index 646f12a999..b73300f578 100644
--- a/test/rdoc/rdoc_markdown_test.rb
+++ b/test/rdoc/rdoc_markdown_test.rb
@@ -1002,6 +1002,16 @@ def test_parse_note_inline
     assert_equal expected, doc
   end
 
+  def test_parse_note_invalid_reference
+    @parser.notes = true
+
+    error = assert_raise RDoc::Markdown::ParseError do
+      parse "[[^0]\n"
+    end
+
+    assert_equal "invalid note reference: 0", error.message
+  end
+
   def test_parse_note_no_notes
     @parser.notes = false
 

From 2505a3a88f3ae56e7f8a8955ee7e7c4c2689f366 Mon Sep 17 00:00:00 2001
From: "Stanislav (Stas) Katkov" <git@skatkov.com>
Date: Thu, 14 May 2026 22:04:00 +0200
Subject: [PATCH 2/2] Ignore note references before note ordering

Note references can be parsed while Markdown references are being collected, before footnote ordering has started. Treat that early pass as a no-op so malformed reference labels and valid labels containing footnotes do not crash the parser.
---
 lib/rdoc/markdown.kpeg          |  2 +-
 lib/rdoc/markdown.rb            |  2 +-
 test/rdoc/rdoc_markdown_test.rb | 21 +++++++++++++++++----
 3 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/lib/rdoc/markdown.kpeg b/lib/rdoc/markdown.kpeg
index b9a0990e62..893204151f 100644
--- a/lib/rdoc/markdown.kpeg
+++ b/lib/rdoc/markdown.kpeg
@@ -403,7 +403,7 @@
   # the note order list for proper display at the end of the document.
 
   def note_for ref
-    raise ParseError, "invalid note reference: #{ref}" unless @note_order
+    return unless @note_order
 
     @note_order << ref
 
diff --git a/lib/rdoc/markdown.rb b/lib/rdoc/markdown.rb
index f6cfc9a24d..4326fb6549 100644
--- a/lib/rdoc/markdown.rb
+++ b/lib/rdoc/markdown.rb
@@ -788,7 +788,7 @@ def note label
   # the note order list for proper display at the end of the document.
 
   def note_for ref
-    raise ParseError, "invalid note reference: #{ref}" unless @note_order
+    return unless @note_order
 
     @note_order << ref
 
diff --git a/test/rdoc/rdoc_markdown_test.rb b/test/rdoc/rdoc_markdown_test.rb
index b73300f578..5d432c6cc5 100644
--- a/test/rdoc/rdoc_markdown_test.rb
+++ b/test/rdoc/rdoc_markdown_test.rb
@@ -1005,11 +1005,24 @@ def test_parse_note_inline
   def test_parse_note_invalid_reference
     @parser.notes = true
 
-    error = assert_raise RDoc::Markdown::ParseError do
-      parse "[[^0]\n"
-    end
+    assert_kind_of RDoc::Markup::Document, parse("[[^0]\n")
+  end
+
+  def test_parse_note_reference_in_reference_label
+    @parser.notes = true
+
+    doc = parse <<~MD
+      [foo[^1]bar]
 
-    assert_equal "invalid note reference: 0", error.message
+      [^1]: footnote
+    MD
+
+    expected = doc(
+      para("[foo{*1}[rdoc-label:foottext-1:footmark-1]bar]"),
+      rule(1),
+      para("{^1}[rdoc-label:footmark-1:foottext-1] footnote"))
+
+    assert_equal expected, doc
   end
 
   def test_parse_note_no_notes