Online PHP editor | output for udA9Y

Output for 8.3.0 - 8.3.6: Fatal error: Uncaught Error: Undefined constant a::d in /in/udA9Y:9 Stack trace: #0 /in/udA9Y(13): [constant expression]() #1 {main} thrown in /in/udA9Y on line 9
Process exited with code 255.
Output for 8.2.0 - 8.2.18: Fatal error: Uncaught Error: Undefined constant a::d in /in/udA9Y:9 Stack trace: #0 {main} thrown in /in/udA9Y on line 9
Process exited with code 255.
Output for 8.0.0 - 8.0.30, 8.1.0 - 8.1.28: Fatal error: Uncaught Error: Undefined constant a::d in /in/udA9Y:13 Stack trace: #0 {main} thrown in /in/udA9Y on line 13
Process exited with code 255.
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: Fatal error: Uncaught Error: Undefined class constant 'a::d' in /in/udA9Y:13 Stack trace: #0 {main} thrown in /in/udA9Y on line 13
Process exited with code 255.
Output for 5.2.4 - 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: Fatal error: Undefined class constant 'a::d' in /in/udA9Y on line 13
Process exited with code 255.
Output for 5.0.0 - 5.0.5, 5.1.0 - 5.1.6, 5.2.0 - 5.2.3: Notice: Use of undefined constant a::d - assumed 'a::d' in /in/udA9Y on line 13 string(4) "a::d" string(4) "a::d" string(4) "a::d" string(4) "a::d"
Output for 4.4.2 - 4.4.9: Parse error: syntax error, unexpected T_CONST, expecting T_OLD_FUNCTION or T_FUNCTION or T_VAR or '}' in /in/udA9Y 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_CONST, expecting T_OLD_FUNCTION or T_FUNCTION or T_VAR or '}' in /in/udA9Y 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/udA9Y on line 4
Process exited with code 255.