Calling function ast.parse() with large size can cause a segmentation fault in Python 3.5 -3.10. Please check the following two examples. The example 1 works as expected, while the second one triggers segmentation fault on Python 3.5,3.6,3.7,3.8,3.9,3.10. The primary difference between these two examples lay on the value of "n".



Example 1:
=========================================
import ast
mylist = []
n = 100000
print(ast.parse("mylist"+"+mylist"*n))
==========================================

The actual output: AST nodes on Python 3.5-3.10 (as expected)
# <_ast.Module object at 0x7f78d7b672e8>
 


Example 2:
===================================
import ast
mylist = []
n = 1000000
print(ast.parse("mylist"+"+mylist"*n))
# <_ast.Module object at 0x7f78d7b672e8>
===================================

The actual output: segmentation fault on Python 3.5 - 3.10 (not as expected)




My system information:

>> python3.10 -V
Python 3.10.0a2

>> python3.9 -V
Python 3.9.0rc1

>> python3.8 -V
Python 3.8.0

>> python3.7 -V
Python 3.7.3

>> python3.6 -V
Python 3.6.12

>> uname -v
#73~16.04.1-Ubuntu

PR: https://github.com/python/cpython/pull/23744 stops this from segfaulting.  It does however raise a RecursionError:

RecursionError: maximum recursion depth exceeded during compilation

As per https://bugs.python.org/issue42609#msg382910, Serhiy implies that the new recursion error is probably expected and acceptable.

fyi, Issue42712, Issue42712, Issue42714, Issue42715, Issue42716 all seem to be variants of the same underlying problem