New submission from Serhiy Storchaka <storchaka+cpyt...@gmail.com>:
There are several issues in ast.dump() with incompletely initialized node. Some
fields and attributes of AST nodes are optional, but creating an AST node
without them leads ast.dump() to fail or to produce incorrect result.
1. With annotate_fields=False ast.dump() outputs subnodes as positional
arguments of the node constructor.
>>> ast.dump(ast.Raise(exc=ast.Name(id='a', ctx=ast.Load()),
>>> cause=ast.Name(id='b', ctx=ast.Load())), annotate_fields=False)
"Raise(Name('a', Load()), Name('b', Load()))"
But if miss the optional exc field it outputs incorrect output:
>>> ast.dump(ast.Raise(cause=ast.Name(id='a', ctx=ast.Load())),
>>> annotate_fields=False)
"Raise(Name('a', Load()))"
which is not distinguished from the case when you pass only the exc field and
miss the cause field (both are optional):
>>> ast.dump(ast.Raise(exc=ast.Name(id='a', ctx=ast.Load())),
>>> annotate_fields=False)
"Raise(Name('a', Load()))"
2. The documentation of ast.dump() says that its result with
annotate_fields=True is impossible to evaluate, but this is not true, because
keyword arguments are supported by AST node constructors.
3. Attributes end_lineno and end_col_offset are optional, but if you miss them
ast.dump() with include_attributes=True will fail:
>>> ast.dump(ast.Raise(lineno=3, col_offset=4), include_attributes=True)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/home/serhiy/py/cpython3.8/Lib/ast.py", line 126, in dump
return _format(node)
File "/home/serhiy/py/cpython3.8/Lib/ast.py", line 118, in _format
rv += ', '.join('%s=%s' % (a, _format(getattr(node, a)))
File "/home/serhiy/py/cpython3.8/Lib/ast.py", line 118, in <genexpr>
rv += ', '.join('%s=%s' % (a, _format(getattr(node, a)))
AttributeError: 'Raise' object has no attribute 'end_lineno'
4. Even if you specify all attributes, the output looks weird if you do not
specify any field (note a space after "("):
>>> ast.dump(ast.Raise(lineno=3, col_offset=4, end_lineno=3,
>>> end_col_offset=24), include_attributes=True)
'Raise( lineno=3, col_offset=4, end_lineno=3, end_col_offset=24)'
----------
assignee: serhiy.storchaka
components: Library (Lib)
messages: 350506
nosy: serhiy.storchaka
priority: normal
severity: normal
status: open
title: ast.dump() with incomplete node
type: behavior
versions: Python 3.7, Python 3.8, Python 3.9
_______________________________________
Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue37950>
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