RSS feeds have incorrect lastBuildDate when using alternate languages

[__jester]

When setting my site in English, the RSS feed says:
<lastBuildDate>Wed, 30 Nov 2016 15:47:34 +0000</lastBuildDate>

But when I set it up in Dutch, it says:
<lastBuildDate>wo, 30 nov 2016 15:47:34 +0000</lastBuildDate>

This date should be a valid RFC date. Otherwise feed validators won't validate the feed.

Possible fix:

<lastBuildDate><?php
date = get_lastpostmodified( 'GMT' );
echo $date ? mysql2date( 'D, d M Y H:i:s +0000', $date, false ) : date( 'D, d M Y H:i:s +0000'
}}}</lastBuildDate>
 

[swissspidy]

Was this working before? Doesn't seem like we changed the date format here. See #38027

[__jester]

Yes this was working differently in 4.6.1. It happens in the mysql2date function. The date get actually gets translated if you don't set the $translate parameter to false

[__jester]

In WP 4.6.1 is worked like this:

<lastBuildDate><?php echo mysql2date('D, d M Y H:i:s +0000', get_lastpostmodified('GMT'), false); ?></lastBuildDate>

[swissspidy]

You're right, thanks. Looks like the third parameter got lost in some files in [38925] or has always been. Seems like it has always been missing in wp-includes/feed-rss2-comments.php.

[stevenkword]

Do not translate mysql2date()

[stevenkword]

The translation doesn't seem to effect Atom feeds due to the 'Z' format, but I went ahead and added the parameter anyways for consistency.

[JxsDotNL]

While this is not fixed in the core yet, you can use this code to make the RSS feeds validate again:

<?php
add_filter('date_i18n','rssfeeds_date_donttranslate',10,4);
function rssfeeds_date_donttranslate($j, $req_format, $i, $gmt){
    if(is_feed())
        return date($req_format);
    else
        return $j;
}

[pento]

Unit tests would be helpful here, to avoid this bug being re-introduced in the future.

[dd32]

39141.unit-test.diff​ is an attempt at a unit test for this, unfortunately we have very little feed coverage right now. Testing the non-RSS2 feeds doesn't have much benefit either, as the date formats don't have any translated tokens.

If someone would like to extend 39141.unit-test.diff​ to cover the RSS2 Comments feed, please do.

[dd32]

Having taken another look at this, feed-rss2.php is the only RSS feed which actually had a date format which has any translatable components in it in the first place. Still makes sense to mark all of them as $translate = false though.

Digging into it further, the format D, d M Y H:i:s +0000 is the same as r - and as we don't need to translate it here we could probably just switch it back to that. It was changed back in r1041 (later follow up commits marked it as no-translate, this would be at least the 3rd time it's lost the no-translate flag).

[dd32]

In 39613:

Feeds: Do not translate the lastBuildDate field in RSS feeds.

Props stevenkword, dd32.
Fixes #39141

[dd32]

In 39614:

Feeds: Replace the RSS2 lastBuildDate date field with the r date specifier.

See #39141.

[dd32]

In 39615:

Feeds: Do not translate the lastBuildDate field in RSS feeds.

Props stevenkword.
Partial Merge of [39613] to the 4.7 branch.
Fixes #39141.

[dd32]

As only the main RSS feed was affected, I only backported that specific change to 4.7.1.

For 4.8+ I've added it for all feeds, and then converted it to the r date format anyway.

[dd32]

#39394 was marked as a duplicate.

[dd32]

#39434 was marked as a duplicate.