Undefined variables in function calls are not detected

[GaryJones]

Snippet:

<?php

if ( ! empty( $this->vars['video-id'] ) ) {
	echo $this->vars['video-id'];
}

With a default configuration (phpcs --standard=VariableAnalysis -s phpcs-test.php), then "Variable $this is undefined. (VariableAnalysis.CodeAnalysis.VariableAnalysis.UndefinedVariable)" is reported for line 4 (the echo line), but not for the $this in the empty().

Likewise:

<?php

if ( empty( $this->vars['video-id'] ) ) {
	return;
}

...doesn't give any violation at all.

If I remove the empty(), then the violation is reported.

<?php

if ( ! $this->vars['video-id'] ) {
	return;
}

Tested in VA 2.11.0.

[sirbrillig]

If the only function you tested with is empty(), then this is not a bug but a feature since empty() is allowed to contain undefined variables (since #204). This feature was added because both empty() and isset() are language constructs that are often used to detect the existence of variables (for example, no warning or error is thrown doing empty( $foo['bar']['baz'] ) if $foo does not exist, but will throw warnings for any other function like do_something( $foo['bar']['baz'] )).

Do you find this occurs with other functions as well?

[GaryJones]

That makes sense. I tried with current_user_can() as the wrapping function, and that correctly gave a violation, and then this was correctly silenced with the <property name="allowUndefinedVariablesInFileScope" value="true"/> line in the config file ✅