Xinmeng Xia <xi...@smail.nju.edu.cn> added the comment:
Sorry, my description is a little confusing. My points lie on function
'compile' and 'exec'. Yes, I agree. AST can be modified and don't correspond to
valid programs. But I don't think this invaild program can be compiled and
exec without any check. It's dangerous.
See the following program: For "compile" and "exec", no error is reported on
Python 3.5-3.8 while error messages are reported on Python 3.9 and 3.10
======================================
import ast
class RewriteName(ast.NodeTransformer):
def visit_Name(self, node):
if node.id != "print":
node.id = str(False)
print(type(node.id))
return node
code = "a = 2;print(a)"
myast = ast.parse(code)
transformer = RewriteName()
newast = transformer.visit(myast)
c = compile(newast,'','exec')
exec(c)
=====================================
Error message on Python 3.9 and 3.10.
-------------------------------------
<class 'str'>
<class 'str'>
Traceback (most recent call last):
File "/home/xxm/Desktop/nameChanging/report/test1.py", line 574, in <module>
c = compile(newast,'','exec')
ValueError: Name node can't be used with 'False' constant
-------------------------------------
In fact, in class RewriteName, when "node.id" is assigned, the parser will
check whether the identifier is a "str". If not,"TypeError: AST identifier must
be of type str" will be reported. However, it's not enough. In Python,
identifier names have their own naming rules. "str" could be "+","1","False",
but these are not legally id. So the above error could be reported.
----------
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Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue42889>
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