[New-bugs-announce] [issue42950] Incorrect exception behavior in handling recursive call.

[Xinmeng Xia]

New submission from Xinmeng Xia <xiaxm at smail.nju.edu.cn>:

Seeing the following programs, we try to catch a recursive call error in exception handling.  The behaviors between Python 3.10.0a4 and older version are inconsistent. The outputs are attached in the end. The output on Python 3.10.0a4 is very weird. Two "print statements" lie in same "except" block to print "exception info" and a string "kk". "kk" is printed once while "exception info" is printed twice! I think a bug probably exists in Python 3.10.0a4 parser on handling stacks. 


=========================
def foo(c):
         try:
             c = c + 1
             print("ss"+str(c))
             foo(c)
         except Exception as e:
             print(str(e))
             print("kk")
         print(c)
c = 0
foo(c)
=========================

Output in Python 3.10.0a2 and older version(expected)
------------------------------------------------------------------------
ss1
ss2
....
ss996
maximum recursion depth exceeded while calling a Python object
kk
996
995
......
3
2
1
------------------------------------------------------------------------

Output in Python 3.10.0a4 (unexpected)
------------------------------------------------------------------------
ss1
ss2
....
ss996
maximum recursion depth exceeded while calling a Python object
maximum recursion depth exceeded while calling a Python object
kk
995
......
3
2
1
------------------------------------------------------------------------

----------
components: Interpreter Core
messages: 385170
nosy: xxm
priority: normal
severity: normal
status: open
title: Incorrect exception behavior in handling recursive call.
type: behavior
versions: Python 3.10

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue42950>
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