Symbol declared but not used for members read by variable name

[sfsaccone]

Describe the bug

A "symbol is declared but not used" error/warning is given for class members that are accessed in the code by using a variable for the member name where the variable is from a hard-coded array. I often do this in __get() methods to make private members readable. So, I get lots of these errors/warnings. Normally, these are very useful for cleaning up code. It would be great if they could be suppressed in this situation.

To Reproduce

<?php

class MyClass {
    private string $readOnlyMember;
    private string $otherReadOnlyMember;
    private string $totallyPrivateMember;

    public function __construct() {
        $this->readOnlyMember = 'a'; // Symbol '$readOnlyMember' is declared but not used
        $this->otherReadOnlyMember = 'b'; // Symbol '$otherReadOnlyMember' is declared but not used
        $this->totallyPrivateMember = 'c';
    }

    public function privateData() : string {
        return $this->totallyPrivateMember;
    }

    public function __get($name): mixed
    {
        $allowed = [
            'myReadOnlyMember',
            'otherReadOnlyMember'
        ];
        if (in_array($name, $allowed)) {
            return $this->$name;
        }
        throw new \Exception("Attempt to read private or unknown member $name");
    }
}

Expected behavior

No error messages or warnings.

Screenshots

The error messages/warnings shown in the inline comments.

Platform and version

• Windows 11
• Visual Studio Code 1.96.4
• Intelephense 1.12.6

[sfsaccone]

Oh, I see PHP 8.1 introduced the readonly keyword for this. There are no errors/warnings for the code below. Yay.

class MyClass {
    public readonly string $readOnlyMember;
    public readonly string $otherReadOnlyMember;
    private string $totallyPrivateMember;

    public function __construct() {
        $this->readOnlyMember = 'a';
        $this->otherReadOnlyMember = 'b';
        $this->totallyPrivateMember = 'c';
    }

    public function privateData() : string {
        return $this->totallyPrivateMember;
    }
}

[bmewburn]

You can suppress this on a case by case basis with an annotation above the statement /** @disregard P1003 */ . I'll close this as it seems like an edge case with a workaround or alternate way of implementing.

[sfsaccone]

Makes sense, thanks!

[sfsaccone]

My bad. The readonly keyword does not provide the same functionality as __get(). With the second class definition above using readonly, I can only assign readOnlyMember in the constructor. That's not what I want. Therefore, I'm back to the first class example using __get(). I tried @disregard but I still get the errors:

<?php

class MyClass {

    /** @disregard P1003 */
    private string $readOnlyMember; // Symbol '$readOnlyMember' is declared but not used
...

It would great if you could add a new feature that suppresses P1003 for a member declaration when the class has a __get() method returns a value rather than throws an exception when that member is given as the argument to the __get() method. If the @disregard would work that would be ok, but not ideal.

Sorry for the confusion.

[sfsaccone]

Alternatively, I could write the __get() like this (a Codeium suggestion):

public function __get($name): mixed
    {
        $allowed = [
            'readOnlyMember' => $this->readOnlyMember,
            'otherReadOnlyMember' => $this->otherReadOnlyMember,
        ];

        if (isset($allowed[$name])) {
            return $allowed[$name];
        }

        throw new \Exception("Attempt to read private or unknown member $name");
    }

It's just as readable as in the first block above and there are no P1003 errors. Works for me.

[bmewburn]

That looks like a good solution. I'll keep this ticket open to fix the @disregard.