C++, properly reject functions as duplicates

Fixes sphinx-doc/sphinx#8270

CHANGES

@@ -19,6 +19,8 @@ Bugs fixed
 * #8188: C, add missing items to internal object types dictionary,
   e.g., preventing intersphinx from resolving them.
 * C, fix anon objects in intersphinx.
+* #8270, C++, properly reject functions as duplicate declarations if a
+  non-function declaration of the same name already exists.
 
 
 Testing

sphinx/domains/cpp.py

@@ -4360,6 +4360,11 @@ class Symbol:
             if Symbol.debug_lookup:
                 Symbol.debug_print("candId:", candId)
             for symbol in withDecl:
+                # but all existing must be functions as well,
+                # otherwise we declare it to be a duplicate
+                if symbol.declaration.objectType != 'function':
+                    handleDuplicateDeclaration(symbol, candSymbol)
+                    # (not reachable)
                 oldId = symbol.declaration.get_newest_id()
                 if Symbol.debug_lookup:
                     Symbol.debug_print("oldId: ", oldId)

tests/test_domain_cpp.py

@@ -1236,3 +1236,18 @@ def test_noindexentry(app):
     assert_node(doctree, (addnodes.index, desc, addnodes.index, desc))
     assert_node(doctree[0], addnodes.index, entries=[('single', 'f (C++ function)', '_CPPv41fv', '', None)])
     assert_node(doctree[2], addnodes.index, entries=[])
+
+
+def test_mix_decl_duplicate(app, warning):
+    # Issue 8270
+    text = (".. cpp:struct:: A\n"
+            ".. cpp:function:: void A()\n"
+            ".. cpp:struct:: A\n")
+    restructuredtext.parse(app, text)
+    ws = warning.getvalue().split("\n")
+    assert len(ws) == 5
+    assert "index.rst:2: WARNING: Duplicate C++ declaration, also defined in 'index'." in ws[0]
+    assert "Declaration is 'void A()'." in ws[1]
+    assert "index.rst:3: WARNING: Duplicate C++ declaration, also defined in 'index'." in ws[2]
+    assert "Declaration is 'A'." in ws[3]
+    assert ws[4] == ""