bpo-34967: Sphinx is deprecating add_description_unit, use add_object_type (GH-9827)

(cherry picked from commit e385d06)

Co-authored-by: Stéphane Wirtel <stephane@wirtel.be>

Author: miss-islington

Doc/tools/extensions/pyspecific.py

@@ -388,11 +388,9 @@ def setup(app):
     app.add_directive('deprecated-removed', DeprecatedRemoved)
     app.add_builder(PydocTopicsBuilder)
     app.add_builder(suspicious.CheckSuspiciousMarkupBuilder)
-    app.add_description_unit('opcode', 'opcode', '%s (opcode)',
-                             parse_opcode_signature)
-    app.add_description_unit('pdbcommand', 'pdbcmd', '%s (pdb command)',
-                             parse_pdb_command)
-    app.add_description_unit('2to3fixer', '2to3fixer', '%s (2to3 fixer)')
+    app.add_object_type('opcode', 'opcode', '%s (opcode)', parse_opcode_signature)
+    app.add_object_type('pdbcommand', 'pdbcmd', '%s (pdb command)', parse_pdb_command)
+    app.add_object_type('2to3fixer', '2to3fixer', '%s (2to3 fixer)')
     app.add_directive_to_domain('py', 'decorator', PyDecoratorFunction)
     app.add_directive_to_domain('py', 'decoratormethod', PyDecoratorMethod)
     app.add_directive_to_domain('py', 'coroutinefunction', PyCoroutineFunction)

Misc/NEWS.d/next/Documentation/2018-10-13-07-39-57.bpo-34967.E40tFP.rst

@@ -0,0 +1,2 @@
+Use app.add_object_type() instead of the deprecated Sphinx function
+app.description_unit()