PyCode "Unparse": Added support for slice objects in subscriptions

CHANGES.rst

@@ -27,6 +27,8 @@ Features added
 * #11892: Improved performance when resolving cross references in cpp domain.
   Patch by Rouslan Korneychuk.
 
+* #11981: pycode "UnparseVisitor": Added support for slice objects in subscriptions
+
 Bugs fixed
 ----------
 

sphinx/pycode/ast.py

@@ -187,3 +187,9 @@ def visit_Tuple(self, node: ast.Tuple) -> str:
 
     def generic_visit(self, node: ast.AST) -> NoReturn:
         raise NotImplementedError('Unable to parse %s object' % type(node).__name__)
+
+    def visit_Slice(self, node: ast.Slice) -> str:
+        start = self.visit(node.lower) if node.lower else ""
+        stop = self.visit(node.upper) if node.upper else ""
+        step = self.visit(node.step) if node.step else ""
+        return f"{start}:{stop}:{step}"

tests/test_pycode/test_pycode_ast.py

@@ -51,6 +51,8 @@
      "lambda x=0, /, y=1, *args, z, **kwargs: ..."),  # posonlyargs
     ("0x1234", "0x1234"),                       # Constant
     ("1_000_000", "1_000_000"),                 # Constant
+    ("Tuple[:,:]", "Tuple[::, ::]"),            # Index, Subscript, Slice
+    ("Tuple[1:2:3]", "Tuple[1:2:3]"),           # Index, Subscript, Slice
 ])
 def test_unparse(source, expected):
     module = ast.parse(source)