If you search for an exact match you still get almost 600 results, see:
https://github.com/search?q=%22eval%28%24_GET%22&type=Code&r...
I would definitely expect the google pattern of doing exact match when in quotes. Throw in a regexp engine as well, because I tried using wildcards and that didn't do anything.
For example, if searching for vulnerabilities I would like to be able to do something like:
eval(.*$_[(GET|POST)].*)
I am seeing a pattern that most people would prefer the loose match over exact to get back more results, but with the exact matches (if any) at the top.
I will take this onboard and see if I can improve things.