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<?php function function_with_a_byref_nonnull_default_parameter(&$a = 123) { echo $a; } function_with_a_byref_nonnull_default_parameter();
Output for 5.0.0 - 5.0.5, 5.1.0 - 5.1.6, 5.2.0 - 5.2.17, 5.3.0 - 5.3.29, 5.4.0 - 5.4.45, 5.5.24 - 5.5.35, 5.6.7 - 5.6.28, 7.0.0 - 7.0.20, 7.1.0 - 7.1.10, 7.2.0 - 7.2.33, 7.3.16 - 7.3.32, 7.4.0 - 7.4.25, 8.0.0 - 8.0.12, 8.1rc1 - rc3
123
Output for 4.4.2 - 4.4.9
Parse error: syntax error, unexpected '=', expecting ')' in /in/eQ6e4 on line 3
Process exited with code 255.
Output for 4.3.1, 4.3.5 - 4.3.11, 4.4.0 - 4.4.1
Parse error: parse error, unexpected '=', expecting ')' in /in/eQ6e4 on line 3
Process exited with code 255.
Output for 4.3.2 - 4.3.4
Parse error: parse error, expecting `')'' in /in/eQ6e4 on line 3
Process exited with code 255.

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