Sometimes when I’m searching a GitHub repository, I end up with a ton of uninteresting results because there are, for example, tests or documentation in the repository that are not pertinent to what I’m searching for.
To search any subpath, just modify the search with the “path:” flag: “struct String” path:/stdlib. Six results, all pertinent to the actual implementation of “struct String”. Just what I was looking for.
There are lots of fancy constraints you can apply to GitHub searches, I simply hadn’t thought to look them up until now. Maybe some of them will make your exploration easier, too.