Add Support for No Limit Queries to 'posts_per_rss' .

[ohryan]

Setting posts_per_rss = -1 will result in a query with LIMIT 0, -1.

[stevenkword]

Thank you for the report @ohryan.

As far as I'm aware, there isn't any document that states this query variable supports this value, but that doesn't mean it shouldn't. I simply wouldn't classify this as a bug and more like an enhancement.

I am in favor of supporting the functionality since the variable is passed on to posts_per_page in WP_Query. The problem seems to be more at the "LIMIT" filters which could be updated. This enhancement would require consideration for comment feeds as well.

Tests should be written against RSS and Atom and should work for all feeds endpoints (home, custom, comments, custom post types, etc.).

[mauteri]

Issue was that setting posts_per_page from posts_per_rss should be before checking nopaging and that post_per_page is equal to -1. included unit test in patch.

[jorbin]

The patch in the test should be updated to not use an anonymous function, and should be reworked in order to not need to be nested.

As mentioned by @stevenkword, comment feeds should also be tested.

[mauteri]

Fix unit test

[mauteri]

@jorbin @stevenkword I updated the diff and made the filter not a call to an anonymous function. As far as non-post feeds go, this is not related. The bug itself was a bug in get_posts and setting posts_per_page from posts_per_rss, which needed to be checked before nopaging and that post_per_page is equal to -1.

[mauteri]

Update to fix comment feed to support -1 plus unit test

[mauteri]

@jorbin @stevenkword updated to code. I was wrong, there was also a spot where this would fail for comments feed. I updated diff to fix this issue and added a unit test for it as well.