Throw notice on array offset access of null/bool/int/etc

[nikic]

This is a followup to #2031 for RFC https://wiki.php.net/rfc/notice-for-non-valid-array-container.

This implements the dead-simple variant of throwing a notice for array accesses on null/bool/int/float/resource (everything but array, string and object), while excluding list(), for which we did not reach an agreement on #2031. It does not try to suppress duplicate notices on nested accesses, because the additional complexity is not worthwhile.

[nikic]

Merged as c42b7dd and 26431d1.

[ondrejmirtes]

Unfortunately this is still allowed after this PR :/

$null = null;
$null['foo'] = 1; // $null is an array now

[carusogabriel]

@ondrejmirtes Indeed: https://3v4l.org/eLmFq. Thanks for the heads up, we'll take a look.

[claudepache]

@ondrejmirtes @carusogabriel The behaviour is expected, and falls outside the scope of the relevant RFC. This is a feature I take sometimes advantage of; that is, instead of writing:

if (!isset($foo[$bar]))
    $foo[$bar] = [ ];
$foo[$bar][] = $baz;

I just write:

$foo[$bar][] = $baz;

for the same effect. I expect that much existing code relies on that implicit creation of array.

As user, I have no strong feeling on whether it is a good feature for a new language, but I would be quite displeased if perfectly valid code started to throw warnings for unclear benefit.