Fix backslash in RDoc monofont causing unwanted linking

When text in <tt> tags contains backslashes (e.g., <tt>.bar.hello(\)</tt>),
RDoc was incorrectly creating cross-reference links because the backslash
matched the escaped character pattern in CROSSREF_REGEXP.

This fix adds a check to prevent cross-referencing when the match is solely
due to escaped characters that don't represent valid method/class references.

Fixes #1390

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: st0012

lib/rdoc/markup/to_html_crossref.rb

@@ -94,6 +94,18 @@ def handle_regexp_CROSSREF(target)
       return name if name =~ /\A[a-z]*\z/
     end
 
+    # Check if the match is solely due to an escaped character pattern.
+    # If the text contains backslash escapes but doesn't match any
+    # valid cross-reference pattern (class, method, etc.), return as-is
+    if name =~ /\\/ && 
+       name !~ /\A#{CLASS_REGEXP_STR}(?:[.#]|::)#{METHOD_REGEXP_STR}\z/o &&
+       name !~ /\A\\?#{CLASS_REGEXP_STR}\z/o &&
+       name !~ /\A\\?\##{METHOD_REGEXP_STR}\z/o &&
+       name !~ /\A::#{METHOD_REGEXP_STR}\z/o &&
+       name !~ /\A\.\.\/|[-\/\w]+[_\/.][-\w\/.]+\z/ # filepath pattern
+      return name
+    end
+
     cross_reference name, rdoc_ref: false
   end
 
@@ -198,13 +210,29 @@ def convert_flow(flow)
           String === (str = flow[i]) and
           RDoc::Markup::AttrChanger === flow[i+1] and
           tt_tag?(flow[i+1].turn_off, true) and
-          (@options.hyperlink_all ? ALL_CROSSREF_REGEXP : CROSSREF_REGEXP).match?(str) and
-          (text = cross_reference str) != str
+          (@options.hyperlink_all ? ALL_CROSSREF_REGEXP : CROSSREF_REGEXP).match?(str)
         then
-          text = yield text, res if defined?(yield)
-          res << text
-          i += 2
-          next
+          # Check if the match is solely due to an escaped character pattern.
+          # If the text contains backslash escapes but doesn't match any
+          # valid cross-reference pattern (class, method, etc.), skip cross-referencing
+          if str =~ /\\/ && 
+             str !~ /\A#{CLASS_REGEXP_STR}(?:[.#]|::)#{METHOD_REGEXP_STR}\z/o &&
+             str !~ /\A\\?#{CLASS_REGEXP_STR}\z/o &&
+             str !~ /\A\\?\##{METHOD_REGEXP_STR}\z/o &&
+             str !~ /\A::#{METHOD_REGEXP_STR}\z/o &&
+             str !~ /\A\.\.\/|[-\/\w]+[_\/.][-\w\/.]+\z/ # filepath pattern
+            # Don't cross-reference, just output the text wrapped in code tags
+            text = "<code>#{CGI.escapeHTML(str)}</code>"
+            text = yield text, res if defined?(yield)
+            res << text
+            i += 2
+            next
+          elsif (text = cross_reference str) != str
+            text = yield text, res if defined?(yield)
+            res << text
+            i += 2
+            next
+          end
         end
         off_tags res, item
         on_tags res, item

test/rdoc/rdoc_markup_to_html_crossref_test.rb

@@ -33,6 +33,22 @@ def test_convert_CROSSREF
     assert_equal para("<code># :stopdoc:</code>:"), result
   end
 
+  def test_convert_CROSSREF_backslash_escapes_in_monofont
+    # Test that backslash escapes in monofont don't create unwanted links
+    result = @to.convert '<tt>.bar.hello(\)</tt>'
+    assert_equal para("<code>.bar.hello(\\)</code>"), result
+
+    result = @to.convert '<tt>.bar.hello(\\\\)</tt>'
+    assert_equal para("<code>.bar.hello(\\)</code>"), result
+
+    # Regular method references should still work
+    result = @to.convert '<tt>C1#m</tt>'
+    assert_equal para("<a href=\"C1.html#method-i-m\"><code>C1#m</code></a>"), result
+
+    result = @to.convert '<tt>C1.m</tt>'
+    assert_equal para("<a href=\"C1.html#method-c-m\"><code>C1.m</code></a>"), result
+  end
+
   def test_convert_CROSSREF_ignored_excluded_words
     @options.autolink_excluded_words = ['C1']