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Description
Bug report
Bug description:
python 3.13 raises an RecursionError when I try to deepcopy the ast in the following example.
import ast import copy code=""" ('',) while i < n: if ch == '': ch = format[i] if ch == '': if freplace is None: '' % getattr(object) elif ch == '': if zreplace is None: if hasattr: offset = object.utcoffset() if offset is not None: if offset.days < 0: offset = -offset h = divmod(timedelta(hours=0)) if u: zreplace = '' % (sign,) elif s: zreplace = '' % (sign,) else: zreplace = '' % (sign,) elif ch == '': if Zreplace is None: Zreplace = '' if hasattr(object): s = object.tzname() if s is not None: Zreplace = s.replace('') newformat.append(Zreplace) else: push('') else: push(ch) """ tree=ast.parse(code) # add a back reference to the parent node for node in ast.walk(tree): for child in ast.iter_child_nodes(node): child.parent=node tree2=copy.deepcopy(tree) output (Python 3.13.0b1+):
Traceback (most recent call last): File "/home/frank/projects/cpython/../cpython_bugs/deep_copy_ast_with_parents.py", line 50, in <module> tree2=copy.deepcopy(tree) File "/home/frank/projects/cpython/Lib/copy.py", line 162, in deepcopy y = _reconstruct(x, memo, *rv) File "/home/frank/projects/cpython/Lib/copy.py", line 253, in _reconstruct y = func(*args) File "/home/frank/projects/cpython/Lib/copy.py", line 252, in <genexpr> args = (deepcopy(arg, memo) for arg in args) ~~~~~~~~^^^^^^^^^^^ File "/home/frank/projects/cpython/Lib/copy.py", line 136, in deepcopy y = copier(x, memo) File "/home/frank/projects/cpython/Lib/copy.py", line 196, in _deepcopy_list append(deepcopy(a, memo)) ~~~~~~~~^^^^^^^^^ ... File "/home/frank/projects/cpython/Lib/copy.py", line 162, in deepcopy y = _reconstruct(x, memo, *rv) File "/home/frank/projects/cpython/Lib/copy.py", line 259, in _reconstruct state = deepcopy(state, memo) File "/home/frank/projects/cpython/Lib/copy.py", line 136, in deepcopy y = copier(x, memo) File "/home/frank/projects/cpython/Lib/copy.py", line 221, in _deepcopy_dict y[deepcopy(key, memo)] = deepcopy(value, memo) ~~~~~~~~^^^^^^^^^^^^^ File "/home/frank/projects/cpython/Lib/copy.py", line 162, in deepcopy y = _reconstruct(x, memo, *rv) File "/home/frank/projects/cpython/Lib/copy.py", line 253, in _reconstruct y = func(*args) File "/home/frank/projects/cpython/Lib/copy.py", line 252, in <genexpr> args = (deepcopy(arg, memo) for arg in args) ~~~~~~~~^^^^^^^^^^^ File "/home/frank/projects/cpython/Lib/copy.py", line 136, in deepcopy y = copier(x, memo) RecursionError: maximum recursion depth exceededThe problem can be reproduced on the current main (5c02ea8)
I was able to bisect the problem down to ed4dfd8 (@JelleZijlstra may be you know more here)
The code in the example looks big but is already minimized.
I hope that this example is simple enough to find and fix the bug, I can try to find a smaller one if it is needed.
CPython versions tested on:
3.13, CPython main branch
Operating systems tested on:
No response