Closed
Description
Bug report
Checklist
- I am confident this is a bug in CPython, not a bug in a third-party project
- I have searched the CPython issue tracker,
and am confident this bug has not been reported before
CPython versions tested on:
3.12, CPython main branch
Operating systems tested on:
macOS
Output from running 'python -VV' on the command line:
Python 3.12.0b4 (v3.12.0b4:97a6a41816, Jul 11 2023, 11:19:02) [Clang 13.0.0 (clang-1300.0.29.30)] on darwin
A clear and concise description of the bug:
The ast.unparse Unparser doesn't seem to respect PEP701, for example, if you use double quotes in an f-string then unparse the AST it will use a backslash--
>>> import ast >>> code = 'f" something { my_dict["key"] } something else "' >>> tree = ast.parse(code) >>> ast.unparse(tree) 'f" something {my_dict[\'key\']} something else "'Furthermore, if you use the nested f-string example in the PEP, it crashes completely when unparsing the AST
>>> f"{f"{f"{f"{f"{f"{1+1}"}"}"}"}"}" '2' >>> code = 'f"{f"{f"{f"{f"{f"{1+1}"}"}"}"}"}"' >>> import ast >>> tree = ast.parse(code) >>> tree <ast.Module object at 0x10992fed0> >>> ast.unparse(tree) Traceback (most recent call last): File "<stdin>", line 1, in <module> File "/Library/Frameworks/Python.framework/Versions/3.12/lib/python3.12/ast.py", line 1777, in unparse return unparser.visit(ast_obj) ^^^^^^^^^^^^^^^^^^^^^^^ File "/Library/Frameworks/Python.framework/Versions/3.12/lib/python3.12/ast.py", line 859, in visit self.traverse(node) File "/Library/Frameworks/Python.framework/Versions/3.12/lib/python3.12/ast.py", line 850, in traverse super().visit(node) File "/Library/Frameworks/Python.framework/Versions/3.12/lib/python3.12/ast.py", line 407, in visit return visitor(node) ^^^^^^^^^^^^^ File "/Library/Frameworks/Python.framework/Versions/3.12/lib/python3.12/ast.py", line 874, in visit_Module self._write_docstring_and_traverse_body(node) File "/Library/Frameworks/Python.framework/Versions/3.12/lib/python3.12/ast.py", line 867, in _write_docstring_and_traverse_body self.traverse(node.body) File "/Library/Frameworks/Python.framework/Versions/3.12/lib/python3.12/ast.py", line 848, in traverse self.traverse(item) File "/Library/Frameworks/Python.framework/Versions/3.12/lib/python3.12/ast.py", line 850, in traverse super().visit(node) File "/Library/Frameworks/Python.framework/Versions/3.12/lib/python3.12/ast.py", line 407, in visit return visitor(node) ^^^^^^^^^^^^^ File "/Library/Frameworks/Python.framework/Versions/3.12/lib/python3.12/ast.py", line 889, in visit_Expr self.traverse(node.value) File "/Library/Frameworks/Python.framework/Versions/3.12/lib/python3.12/ast.py", line 850, in traverse super().visit(node) File "/Library/Frameworks/Python.framework/Versions/3.12/lib/python3.12/ast.py", line 407, in visit return visitor(node) ^^^^^^^^^^^^^ File "/Library/Frameworks/Python.framework/Versions/3.12/lib/python3.12/ast.py", line 1240, in visit_JoinedStr self._write_fstring_inner(value) File "/Library/Frameworks/Python.framework/Versions/3.12/lib/python3.12/ast.py", line 1268, in _write_fstring_inner self.visit_FormattedValue(node) File "/Library/Frameworks/Python.framework/Versions/3.12/lib/python3.12/ast.py", line 1281, in visit_FormattedValue raise ValueError( ValueError: Unable to avoid backslash in f-string expression part