[issue42950] Incorrect exception behavior in handling recursive call.

[Mark Shannon]

Mark Shannon <mark at hotpy.org> added the comment:

If you make calls in an exception handler that is handling a RecursionError, without unwinding first, then it is likely that another RecursionError may occur.

What is strange is that the second RecursionError is raised after `print(str(e))` has printed the exception, which is weird and needs further investigation.

The following code, using `list.append` shows what happens without the additional RecursionError from print.
`list.append` is safe to use as it never raises a RecursionError.

    import sys
    sys.setrecursionlimit(100)
    events = []

    def foo(c):
        try:
            c = c + 1
            events.append("ss"+str(c))
            foo(c)
        except Exception as e:
            events.append(e)
            events.append("kk")
        events.append(c)

    c = 0
    foo(c)
    for ev in events:
        print(ev)


ss1
ss2
....
ss97
maximum recursion depth exceeded while getting the str of an object
kk
97
95
......
3
2
1

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