get_the_category() returns incorrect value if called with no parameters

[norocketsurgeon]

While the wordpress codex say that if get_the_category is called without any parameters it should get the categories for the current post instead it returns an empty array if called with no parameters. This is due to the following code flow:

get_the_category() calls
get_the_terms( false ) calls
get_post ( false )

get_the_terms expects and integer and passing it to get_post without any checking. get_post expects the parameters passed to it to be an integer. If it is not an integer it returns null. This causes get_the_terms() to return false back to get_the_category() because of the following code in get_the_terms():

if ( ! $post = get_post( $post ) )
                return false;

This causes get_the_category() to return an empty array do to the following code:

if ( ! $categories || is_wp_error( $categories ) )
                $categories = array();

I have included a patch for this.

Steps to replicate this issue:
1) create wordpress site containing a page that has been assigned a category.
2) inside the loop section of your page.php add:
$categories = get_the_category();
print_r($categories);
3) browse to the page that has the category
4) witness the problem

[norocketsurgeon]

get_the_content patch

[norocketsurgeon]

Sorry guys, This was actually just a problem with the post-to-post plugin that I misinterpreted as a WordPress bug. I made the mistake of looking at the codex for get_post instead of the source for the function. Please ignore.