How to tell psalm that constants are configurable?

[AgentOak]

I'm using a php file with constants as configuration, like this (config.php):

<?php
/**
 * Enables debug mode, bla bla bla
 *
 * @var bool
 */
const DEBUG = false;

This file is required() from a bootstrap file before classes that make use of these constants are autoloaded.

In my psalm.xml I list <file name="config.php"> in <projectFiles>, but then psalm complains about UndefinedConstant violations in other files:

ERROR: UndefinedConstant - src/Templating/Template.php:29:29 - Const DEBUG is not defined (see https://psalm.dev/020)
        $options["debug"] = DEBUG;

I found #2644 where <stubs> are suggested. Adding config.php as a stub fixes these warnings, but now psalm also uses the predefined values of these constants for analysis and as a result finds violations like this:

ERROR: TypeDoesNotContainType - src/Templating/Template.php:30:29 - if (false) is impossible (see https://psalm.dev/056)
        $options["cache"] = DEBUG ? false : self::CACHE_DIR;

How to handle this case? I cannot define the constants without values because that is a syntax error. Thanks.

[ygottschalk]

As a workaround: Try including it as an autoloader

<psalm [...] autoloader="config.php">
    <projectFiles>
        [...]
    </projectFiles>
</psalm>

(maybe you'll additionally need to include the file <file name="config.php"> in <projectFiles>)
Hope this helps

[philstutz]

We use

define('DEBUG', /** @var bool $x */ $x = false);

in a stub - works.

https://psalm.dev/r/77d4facff4

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/77d4facff4

<?php

define('DEBUG', /** @var bool $x */ $x = false);

/** @psalm-trace DEBUG */

if (DEBUG) {
    echo 'x';
}

Psalm output (using commit 47a2545):

INFO: Trace - 7:1 - DEBUG: bool

[kkmuffme]

@philstutz this works for you in stubs? When I do that the DEBUG constant is treated as mixed, not bool.
Only works in actual code (or autoloader) but won't work in stubs.

EDIT: even in an autoloader.php it doesn't work? Always mixed

[philstutz]

@kkmuffme You're right, can't get that working with 4.17/4.18 (was the current version then) nor with latest. Only same file as in the snippet or direct requires work.

For our use case mixed seems to have been enough to get rid of the RedundantCondition and other findings.

[kkmuffme]

@philstutz I created a PR that will allow doing this in the stubs:

define('DEBUG', /** @var bool */ false);

[xPaw]

Do I understand correctly that this stub workaround does not work for class constants since define('Thing::DEBUG', ...) wouldn't work?

[kkmuffme]

Yes, it only works for define as per my PR