PHPDoc type for context is too narrow

[derrabus]

I'm using PHPStan on my project as a static code analyzer. After the changes of #15, it is impossible for me to perform assertions on the context of log records without PHPStan complaining about accessing undefined keys.

self::assertSame($expectedFoo, $logger->records[0]['context']['foo']);

Output:

Offset 'foo' does not exist on array{exception?: Throwable}.

According to PSR-3, the context array can contains virtually anything. The exception key is mentioned in the standard for storing logged exceptions, but the standard also says,

Implementors MUST still verify that the 'exception' key is actually an Exception before using it as such, as it MAY contain anything.

Because of that, I'd like to propose that the type of the context is reverted to mixed[].

[sasezaki]

Looking back at the issue, with #15 update, "Offset 'foo' does not exist" will result in a level 5 error in phpstan as offsetAccess.notFound.

In previous versions, it would result in a level 10 error as offsetAccess.nonOffsetAccessible.

https://phpstan.org/r/5b1c42bc-3fcc-4b10-98cf-295491291b15

<?php declare(strict_types = 1);

/** @var array $records110 */
$records110[0]['context']['foo']; // Cannot access offset 'foo' on mixed.

/** @var list<array{context: array{exception?: \Throwable}}> $records120 */
$records120[0]['context']['foo']; // Offset 'foo' does not exist on array{exception?: Throwable}.

If defined as array{context: array<array-key, mixed>} ,

"Offset 'foo' might not exist on array.This error would be reported if the reportPossiblyNonexistentGeneralArrayOffset: true" would be appeared at level 7

[derrabus]

All of the errors happen with way more strict settings and can be healed by checking for the existance of the key first, e.g.

assert(isset($logger->records[0]['context']['foo']));

However, with the current annotation, even that check raises issues because I'm checking for a key that must not be there:

Call to function assert() with false will always evaluate to false.
Offset 'foo' on array{exception?: Throwable} in isset() does not exist.

Moreover, if I followed the PSR-3 specification on the context array which states,

Implementors MUST still verify that the 'exception' key is actually an Exception before using it as such, as it MAY contain anything.

then I would write a piece of code like this:

if (isset($logger->records[0]['context']['exception'])
    && $logger->records[0]['context']['exception'] instanceof \Throwable
) {
    // do something
}

This again produces a PHPStan error because I'm checking a tautology:

Instanceof between Throwable and Throwable will always evaluate to true.

So, I really think that mixed[] is the best we can do here for the context array shape.

[derrabus]

I've opened #21 to fix this issue.