Remove nullable type after calling `HeaderBag::has` is breaking logic

[icanhazstring]

With the latest release 1.2.17 removing nullable from HeaderBag::get is not working correctly.
The header can still exist but the value can be null. If that happens we now can't check for null values.

Commit in question: 7389207

foreach ($this->supportHeaders as $name) {
    if (!$request->headers->has($name)) {
        continue;
    }

    $headerValue = $request->headers->get($name);
    if ($headerValue === null) { // this will be reported as "always false" but shouldn't
        continue;
    }

    $list[] = new Attribute($name, $headerValue);
}

[ondrejmirtes]

How does the HTTP request look like if the header is set, but the value is null?

[icanhazstring]

It doesn't have to come through the means of HTTP only.
It could be set using code directly as well, in that case, a null value is possible.

Edit:
As symfony itself inside the Request object while creating the HeaderBag is allowing null values either way it could always be possible.

[icanhazstring]

It happens in these lines:

public function get(string $key, string $default = null)
{
    $headers = $this->all($key);

    if (!$headers) {
        return $default;
    }

// Right here is the problem
    if (null === $headers[0]) {
        return null;
    }

    return (string) $headers[0];
}

[ondrejmirtes]

Alright, reverting. Thanks!

[ondrejmirtes]

Fixed by 3178f15.

/cc @franmomu

[franmomu]

didn't know it allows null, thanks for reporting 👍 and fixing it

[icanhazstring]

I think the extension from you is not completely wrong. But it would behave a little different:

• if ::has($a) is true
• ::get($a) will return a nullable value

But the difference is in the default value type:

• if ::has($a) is false
• ::get($a, 1) will return int
• checking value against anything other than string is always false

[github-actions]

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