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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"The error messages of `def func(*args='Hello'): pass` and `def func(**kwargs='Hello'): pass` should explain more clearly","articleBody":"# Bug report\n\n### Bug description:\n\n`*args` and `**kwargs` have an empty tuple and dictionary respectively as default values as shown below:\n\n```python\ndef func(*args):\n    print(args, type(args))\n\nfunc()\n# () \u003cclass 'tuple'\u003e\n```\n\n```python\ndef func(**kwargs):\n    print(kwargs, type(kwargs))\n\nfunc()\n{} \u003cclass 'dict'\u003e\n```\n\nThen, setting a default value to `*args` and `**kwargs` gets the error messages as shown below. I think the error messages should explain more clearly because Python doc doesn't explain `*args` and `**kwargs` are the optional parameters which have the immutable default values `()` and `{}` respectively and `var-keyword argument` and `var-keyword argument` should be `var-keyword parameter` and `var-keyword parameter`:\n\n```python\ndef func(*args='Hello'):\n    pass\n# Error\n```\n\n\u003e SyntaxError: var-positional argument cannot have default value\n\n```python\ndef func(**kwargs='Hello'):\n    pass\n# Error\n```\n\n\u003e SyntaxError: var-keyword argument cannot have default value\n\nSo, the error messages should be like belolw:\n\n\u003e SyntaxError: var-positional parameter's default value cannot be changed because it has the immutable default value `()`\n\n\u003e SyntaxError: var-keyword parameter's default value cannot be changed because it has the immutable default value `{}`\n\n### CPython versions tested on:\n\n3.12\n\n### Operating systems tested on:\n\nWindows\n\n\u003c!-- gh-linked-prs --\u003e\n### Linked PRs\n* gh-137793\n\u003c!-- /gh-linked-prs --\u003e\n","author":{"url":"https://github.com/hyperkai","@type":"Person","name":"hyperkai"},"datePublished":"2025-08-14T22:23:14.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":9},"url":"https://github.com/137786/cpython/issues/137786"}