Deleting last path component on Linux can result in URL with empty path

[ahoppen]

var url = URL(fileURLWithPath: "/whatever/test.swift")
print("'\(url.path)'") // prints '/whatever/test.swift'
url.deleteLastPathComponent()
print("'\(url.path)'") // prints '/whatever'
url.deleteLastPathComponent()
print("'\(url.path)'") // prints ''

url = URL(fileURLWithPath: "/test.swift")
print("'\(url.path)'") // prints '/test.swift'
url.deleteLastPathComponent()
print("'\(url.path)'") // prints '/'

Where it prints '' at the end of the first section, I think it should print /.

This is in a Swift 6.0 Linux docker image.

[jrflat]

This String.deletingLastPathComponent() bug was fixed in main by #897. The implementation was updated in main (still fixes the bug) in #927. Neither of those were cherry-picked to release/6.0, though.

@parkera Can we cherry-pick #927 (String+Path parsing performance improvements) to release/6.0, or should we just take the minimal fix from #897?

[parkera]

I think I'd rather take the full patch than attempt to cut it down.

[jrflat]

Resolved by #1013 in release/6.0, please verify with a recent 6.0 toolchain, thanks!