-There's one peculiarity of how constants work in PHP which it is useful -to note (this is not specific to SWIG though) - if you try to use an undeclared -constant, PHP will emit a warning (or a notice in PHP 7.1 and earlier) and then -expand the constant to a string version of the constant's name. Unfortunately -it is easy to miss the warning message if you're using PHP in a webserver as -it will probably end up in error.log or similar. Apparently this will throw -an Error in a future version of PHP, but until then it's something to be -aware of. +There's one peculiarity of how constants work in PHP prior to PHP 8 +which it is useful to note (this is not specific to SWIG though) - if you try +to use an undeclared constant, PHP will emit a warning (or a notice in PHP 7.1 +and earlier) and then expand the constant to a string version of the constant's +name. Unfortunately it is easy to miss the warning message if you're using PHP +in a webserver as it will probably end up in error.log or similar. PHP 8.0 +made this an error.