Add warning sub-type for duplicate equation label warnings (#13929)

Co-authored-by: Adam Turner <9087854+AA-Turner@users.noreply.github.com>

Author: jdillard

CHANGES.rst

@@ -120,6 +120,9 @@ Bugs fixed
   configuration variable ``doctest_test_doctest_blocks``.
 * #13885: Coverage builder: Fix TypeError when warning about missing modules.
   Patch by Damien Ayers.
+* #13929: Duplicate equation label warnings now have a new warning
+  sub-type, ``ref.equation``.
+  Patch by Jared Dillard.
 
 
 Testing

doc/usage/configuration.rst

@@ -1394,6 +1394,7 @@ Options for warning control
    * ``ref.any``
    * ``ref.citation``
    * ``ref.doc``
+   * ``ref.equation``
    * ``ref.footnote``
    * ``ref.keyword``
    * ``ref.numref``

sphinx/domains/math.py

@@ -74,6 +74,8 @@ def note_equation(self, docname: str, labelid: str, location: Any = None) -> Non
                 labelid,
                 other,
                 location=location,
+                type='ref',
+                subtype='equation',
             )
 
         self.equations[labelid] = (docname, self.env.new_serialno('eqno') + 1)

tests/roots/test-ext-math-duplicate-label/conf.py

@@ -0,0 +1 @@
+extensions = ['sphinx.ext.mathjax']

tests/roots/test-ext-math-duplicate-label/index.rst

@@ -0,0 +1,16 @@
+Test duplicate equation labels
+===============================
+
+First equation with label:
+
+.. math::
+   :label: duplicated
+
+   a^2 + b^2 = c^2
+
+Second equation with the same label:
+
+.. math::
+   :label: duplicated
+
+   e^{i\pi} + 1 = 0

tests/test_extensions/test_ext_math.py

@@ -566,3 +566,19 @@ def test_mathjax_is_installed_if_included_file_has_equations_singlehtml(
 
     content = (app.outdir / 'index.html').read_text(encoding='utf8')
     assert MATHJAX_URL in content
+
+
+@pytest.mark.sphinx(
+    'html',
+    testroot='ext-math-duplicate-label',
+    confoverrides={'extensions': ['sphinx.ext.mathjax'], 'show_warning_types': True},
+)
+def test_duplicate_equation_label_warning_type(app: SphinxTestApp) -> None:
+    """Test that duplicate equation labels emit warnings with type ref.equation."""
+    app.build(force_all=True)
+
+    from sphinx._cli.util.errors import strip_escape_sequences
+
+    warnings = strip_escape_sequences(app.warning.getvalue())
+    assert 'WARNING: duplicate label of equation duplicated' in warnings
+    assert '[ref.equation]' in warnings