The Python C API Exception Rule, When a C function returns to Python:
1. If the function returns NULL (indicating an error), there MUST be a Python exception set
2. If the function returns a non-NULL value (success), there MUST NOT be a Python exception set
Violating this rule causes SystemError.

 C function should own the exception it sets when returning NULL.

#!/usr/bin/env python3
"""
Minimal reproducer for Issue #865: SystemError when error_cb raises

This script is based on the exact reproducer from the GitHub issue.
It will try to connect to a non-existent broker, which will trigger
the error callback, which will raise an exception, which will cause
the SystemError.
"""

import sys
import os

# Use our locally built version with the fix
sys.path.insert(0, os.path.join(os.path.dirname(__file__), 'src'))

import confluent_kafka


def error_cb(error):
    """Error callback that raises an exception - this causes the SystemError"""
    # print(f"Error callback triggered: {error}")
    raise confluent_kafka.KafkaException(error)


def demo():
    """Main demo function that reproduces the SystemError"""
    consumer = confluent_kafka.Consumer({
        "bootstrap.servers": "nonexistent:9092",  # This will fail to resolve
        "group.id": "demo",
        "error_cb": error_cb,
    })
    
    consumer.subscribe(["test"])
    
    # This will trigger the error callback and cause SystemError
    return consumer.consume(1, timeout=1)


if __name__ == "__main__":
    print("Reproducing SystemError from Issue #865")
    print("=" * 50)
    print()
    
    print("This will attempt to connect to 'nonexistent:9092' which will fail.")
    print("The error_cb will be triggered and will raise a KafkaException.")
    print("You should see TWO exceptions:")
    print("1. Your KafkaException (the intended one)")
    print("2. A SystemError (the bug)")
    print()
    
    try:
        result = demo()
        print(f"Unexpected success: {result}")
    except Exception as e:
        print(f"Caught exception: {type(e).__name__}: {e}")
        print()
        
        # Print the full traceback to show both exceptions
        import traceback
        print("Full traceback showing the double exception:")
        print("-" * 50)
        traceback.print_exc()