Fix deprecation warning when creating AST node without required fields

Python 3.13 added the warning which will become an error in Python 3.15
(see python/cpython#105880)

Author: cedk

genshi/template/astutil.py

@@ -802,7 +802,7 @@ def visit(self, node):
         return visitor(node)
 
     def _clone(self, node):
-        clone = node.__class__()
+        clone = construct_ast_class(node.__class__)
         for name in getattr(clone, '_attributes', ()):
             try:
                 setattr(clone, name, getattr(node, name))
@@ -887,3 +887,17 @@ def _clone(self, node):
     visit_Index = _clone
 
     del _clone
+
+
+def construct_ast_class(cls):
+    kwargs = {}
+    for name, typ in cls.__annotations__.items():
+        if typ is str:
+            kwargs[name] = 'foo'
+        elif typ is int:
+            kwargs[name] = 42
+        elif typ is object:
+            kwargs[name] = b'foo'
+        elif isinstance(typ, type) and issubclass(typ, _ast.AST):
+            kwargs[name] = construct_ast_class(typ)
+    return cls(**kwargs)

genshi/template/eval.py

@@ -20,7 +20,8 @@
 from six.moves import builtins
 
 from genshi.core import Markup
-from genshi.template.astutil import ASTTransformer, ASTCodeGenerator, parse
+from genshi.template.astutil import (
+    ASTTransformer, ASTCodeGenerator, parse, construct_ast_class)
 from genshi.template.base import TemplateRuntimeError
 from genshi.util import flatten
 
@@ -61,11 +62,9 @@ def __init__(self, source, filename=None, lineno=-1, lookup='strict',
                 'Expected string or AST node, but got %r' % source
             self.source = '?'
             if self.mode == 'eval':
-                node = _ast.Expression()
-                node.body = source
+                node = _ast.Expression(body=source)
             else:
-                node = _ast.Module()
-                node.body = [source]
+                node = _ast.Module(body=[source])
 
         self.ast = node
         self.code = _compile(node, self.source, mode=self.mode,
@@ -456,7 +455,7 @@ def _compile(node, source=None, mode='eval', filename=None, lineno=-1,
 
 
 def _new(class_, *args, **kwargs):
-    ret = class_()
+    ret = construct_ast_class(class_)
     for attr, value in zip(ret._fields, args):
         if attr in kwargs:
             raise ValueError('Field set both in args and kwargs')

pytest.ini

@@ -1,3 +1,6 @@
 [pytest]
 addopts = --doctest-modules
 doctest_optionflags = NORMALIZE_WHITESPACE ALLOW_UNICODE
+filterwarnings =
+    error
+    ignore:pkg_resources