How can I check a php file for undefined functions?

Question

Calling php -l checks the syntax of a php file.

Is there a way to check for undefined functions? I don't need it to work with functions defined at runtime nor with dynamic calls.

Calling the file obviously won't work: I need to check the whole file, not only the branch that gets executed. See the follwing example.

myfile.php:

function imhere () {}

main.php:

require_once 'myfile.php';

if (true) {
    imhere();
}
else {
    imnhothere(); // I need to get a warning about this
}

Answer 1

Checking for undefined functions is impossible in a dynamic language. Consider that undefined functions can manifest in lots of ways:

undefined();
array_filter('undefined', $array);
$prefix = 'un'; $f = $prefix.'defined'; $f();

This is in addition to the fact that there may be functions that are used and defined conditionally (through includes or otherwise). In the worst case, consider this scenario:

if(time() & 1) {
    function foo() {}
}

foo();

Does the above program call an undefined function?