Warning: strpos(): Empty delimiter in search_simplify_excerpt_match()

Problem/Motivation

When you enter some partially successful search query, dozens of the following warning raises:

Warning: strpos(): Empty delimiter in search_simplify_excerpt_match() (line 1315 of /www/modules/search/search.module).

There are some public examples indexed by google as well: http://www.google.com/search?gcx=c&ie=UTF-8&q=Empty+delimiter+in+search_...

The error message says that second parameter of the strpos is null. This happen only under certain circumstances. After further research I found that more than one search keyword is needed because the affected code is in the part which cares about marking keywords in the resulting items. So it happens only when some results are found and at least one keyword is null or empty array after simplification. So the following search queries trigger this error:

• keyword OR 0
• keyword AND _
• keyword AND _OR 0

Searching for the "empty keywords" individually results in "at least one positive keyword with 3 characters or more" form validation error so the bug doesn't appear.

Proposed resolution

Solution is skip the search_simplify_excerpt_match() when simplified keyword or text are empty.

Remaining tasks

• Write the test.
• Fix in Drupal 8. Fixed!
• Fix in Drupal 7. Fixed!

User interface changes

None.

API changes

None.