x/pkgsite: add a special case to search ONLY within std / stdlib

[henderjon]

What is the URL of the page with the issue?

https://pkg.go.dev/std

What is your user agent?

Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/112.0.0.0 Safari/537.36

Screenshot

N/A

What did you do?

When I type something like NewReader it searches everything. I would like to see a way to confine my search to standard library. It's nice that stdlib results are labeled as such but either a special case or syntax addition to actual constrain my search would be very helpful.

[hyangah]

Looks like "Searching by symbol" supports an option to limit search with package path (so, module path too). However, standard library doesn't have a common package path name so we cannot utilize this option for stdlib. And, even when std or stdlib (pseudo module names used in vuln db or in the go project) is usable, they are too common. So, as @henderjon suggested we may need a special case or search syntax.

In the mean time, users may be able to search from the source repo (e.g. https://cs.opensource.google/search?q=NewReader&sq=&ss=go%2Fgo) or source code search services like sourcegraph, etc.

[seankhliao]

with CL 644676 "std/" is recognized as a prefix for the standard library, it should probably also be made to work with symbol search

cc @jba