Support unary subtraction in annotation parsing (sphinx-doc#11904)

Author: jayaddison

sphinx/domains/python/_annotations.py

@@ -109,6 +109,8 @@ def unparse(node: ast.AST) -> list[Node]:
             return unparse(node.value)
         if isinstance(node, ast.Invert):
             return [addnodes.desc_sig_punctuation('', '~')]
+        if isinstance(node, ast.USub):
+            return [addnodes.desc_sig_punctuation('', '-')]
         if isinstance(node, ast.List):
             result = [addnodes.desc_sig_punctuation('', '[')]
             if node.elts:

tests/roots/test-domain-py/module.rst

@@ -58,3 +58,9 @@ module
 .. py:module:: object
 
 .. py:function:: sum()
+
+.. py:data:: test
+    :type: typing.Literal[2]
+
+.. py:data:: test2
+    :type: typing.Literal[-2]

tests/test_domains/test_domain_py.py

@@ -133,7 +133,9 @@ def assert_refnode(node, module_name, class_name, target, reftype=None,
     assert_refnode(refnodes[13], False, False, 'list', 'class')
     assert_refnode(refnodes[14], False, False, 'ModTopLevel', 'class')
     assert_refnode(refnodes[15], False, False, 'index', 'doc', domain='std')
-    assert len(refnodes) == 16
+    assert_refnode(refnodes[16], False, False, 'typing.Literal', 'obj', domain='py')
+    assert_refnode(refnodes[17], False, False, 'typing.Literal', 'obj', domain='py')
+    assert len(refnodes) == 18
 
     doctree = app.env.get_doctree('module_option')
     refnodes = list(doctree.findall(pending_xref))