Fix #6351: "Hyperlink target is not referenced" message is shown even if referenced

CHANGES

@@ -96,6 +96,8 @@ Bugs fixed
 * commented term in glossary directive is wrongly recognized
 * #6299: rst domain: rst:directive directive generates waste space
 * #6331: man: invalid output when doctest follows rubric
+* #6351: "Hyperlink target is not referenced" message is shown even if
+  referenced
 
 Testing
 --------

sphinx/io.py

@@ -16,6 +16,7 @@ from docutils.io import FileInput, NullOutput
 from docutils.parsers.rst import Parser as RSTParser
 from docutils.readers import standalone
 from docutils.statemachine import StringList, string2lines
+from docutils.transforms.references import DanglingReferences
 from docutils.writers import UnfilteredWriter
 
 from sphinx.deprecation import RemovedInSphinx30Warning
@@ -64,7 +65,15 @@ class SphinxBaseReader(standalone.Reader):
 
     def get_transforms(self):
         # type: () -> List[Type[Transform]]
-        return super().get_transforms() + self.transforms
+        transforms = super().get_transforms() + self.transforms
+
+        # remove transforms which is not needed for Sphinx
+        unused = [DanglingReferences]
+        for transform in unused:
+            if transform in transforms:
+                transforms.remove(transform)
+
+        return transforms
 
     def new_document(self):
         # type: () -> nodes.document

sphinx/transforms/references.py

@@ -9,7 +9,7 @@
 """
 
 from docutils import nodes
-from docutils.transforms.references import Substitutions
+from docutils.transforms.references import DanglingReferences, Substitutions
 
 from sphinx.transforms import SphinxTransform
 
@@ -31,6 +31,22 @@ class SubstitutionDefinitionsRemover(SphinxTransform):
             node.parent.remove(node)
 
 
+class SphinxDanglingReferences(DanglingReferences):
+    """DanglingReferences transform which does not output info messages."""
+
+    def apply(self, **kwargs):
+        # type: (Any) -> None
+        try:
+            reporter = self.document.reporter
+            report_level = reporter.report_level
+
+            # suppress INFO level messages for a while
+            reporter.report_level = max(reporter.WARNING_LEVEL, reporter.report_level)
+            super().apply()
+        finally:
+            reporter.report_level = report_level
+
+
 class SphinxDomains(SphinxTransform):
     """Collect objects to Sphinx domains for cross references."""
     default_priority = 850
@@ -44,6 +60,7 @@ class SphinxDomains(SphinxTransform):
 def setup(app):
     # type: (Sphinx) -> Dict[str, Any]
     app.add_transform(SubstitutionDefinitionsRemover)
+    app.add_transform(SphinxDanglingReferences)
     app.add_transform(SphinxDomains)
 
     return {