Online PHP editor | output for S1TW8

Output for 7.0.0 - 7.0.20, 7.1.0 - 7.1.33, 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.18, 8.3.0 - 8.3.6: cuf: C::f invoke: C::f
Output for 5.2.2 - 5.2.17, 5.3.0 - 5.3.29, 5.4.0 - 5.4.45, 5.5.24 - 5.5.35, 5.6.8 - 5.6.28: cuf: C::f invoke: Fatal error: Call to undefined function C::f() in /in/S1TW8 on line 12
Process exited with code 255.
Output for 5.1.0 - 5.1.6, 5.2.0 - 5.2.1: cuf: Warning: call_user_func(C::f): Unable to call C::f() in /in/S1TW8 on line 9 invoke: Fatal error: Call to undefined function C::f() in /in/S1TW8 on line 12
Process exited with code 255.
Output for 5.0.0 - 5.0.5: cuf: Warning: call_user_func(C::f): First argument is expected to be a valid callback in /in/S1TW8 on line 9 invoke: Fatal error: Call to undefined function C::f() in /in/S1TW8 on line 12
Process exited with code 255.
Output for 4.4.2 - 4.4.9: Parse error: syntax error, unexpected T_STRING, expecting T_OLD_FUNCTION or T_FUNCTION or T_VAR or '}' in /in/S1TW8 on line 4
Process exited with code 255.
Output for 4.3.0 - 4.3.1, 4.3.5 - 4.3.11, 4.4.0 - 4.4.1: Parse error: parse error, unexpected T_STRING, expecting T_OLD_FUNCTION or T_FUNCTION or T_VAR or '}' in /in/S1TW8 on line 4
Process exited with code 255.
Output for 4.3.2 - 4.3.4: Parse error: parse error, expecting `T_OLD_FUNCTION' or `T_FUNCTION' or `T_VAR' or `'}'' in /in/S1TW8 on line 4
Process exited with code 255.