Fix Issue 17634 - variadic overload of std.algorithm.searching.countUntil should return which needle was found

[wilzbach]

Thanks a lot to @MartinNowak for suggesting this solution on Slack.

CC @RazvanN7

[dlang-bot]

Thanks for your pull request, @wilzbach!

Bugzilla references

Auto-close	Bugzilla	Severity	Description
✓	8804	minor	countUntil warning on an infinite range
✓	17634	enhancement	variadic overload of std.algorithm.searching.countUntil should return which needle was found

Testing this PR locally

If you don't have a local development environment setup, you can use Digger to test this PR:

dub run digger -- build "master + phobos#5618"

[RazvanN7]

Awesome. Looks good to me.

[wilzbach]

Regardless, this is liable to break code - what with people using auto and all.

Yes in theory that's possible, but isn't this unlikely as the resulting type will behave as if it would be a ptrdiff_t?

How about just adding a new function countUntilWhich that takes a ref size_t as its second argument?

I would like to avoid introducing a new symbol for this seldom use-case. Hence, if we can't do the trick above, I think a template flag would be better e.g. countUntil!Yes.needleCount(haystack, needles). Also note that countUntil(haystack, needlePosition, needles) would be possible as well.