Resolve __DIR__ / __FILE__ when const/variable is used for include

[tomasz-kusy]

Fixes #7584

[orklah]

Thanks! Congrats for your first PR!

[weirdan]

Thanks!

[VincentLanglet]

Now __DIR__ is resolved, I ends with multiple errors similar to the issue
#3886 with the code

if (file_exists($file = __DIR__.'/custom_bootstrap.php')) {
    require_once $file;
}

Wouldn't it be possible for psalm to not report an error in this situation ?

Since the file with the code is autogenerated, and sometimes there is a custom_bootstrap, sometimes there isn't, I cannot add a psalm-suppress comment (because it will sometimes be reported as unused).
Any recommendation in this situation @orklah ?

[orklah]

Probably related to #3241 and #4788

If the expression is too complex, Psalm can't see you're requiring the same thing.

If you have control over the code generation, consider introducing a local variable before the file_exists, this may help