For reference, in Go there's a core package called Path that contains a Join() method. Instead of passing an array, it's a variadic function, and it ignores empty strings too:

Join joins any number of path elements into a single path, adding a separating slash if necessary. The result is Cleaned; in particular, all empty strings are ignored.

func Join(elem ...string) string

Example:

package main

import (
	"fmt"
	"path"
)

func main() {
	fmt.Println(path.Join("a", "b", "c"))
	fmt.Println(path.Join("a", "b/c"))
	fmt.Println(path.Join("a/b", "c"))
	fmt.Println(path.Join("", ""))
	fmt.Println(path.Join("a", ""))
	fmt.Println(path.Join("", "a"))
}

a/b/c
a/b/c
a/b/c

a
a

If we decide to do the same, I propose this:

• Rename this function to Filesystem::joinPaths() because Filesystem::join() looks like you are joining files.
• Define this function as joinPaths(string ...$paths): string
• Clean up the result removing double slashes and empty segments
• Don't make any difference based on OS because PHP doesn't need that (as pointed by the original reporter) Update: Go defines a different package called filepath to take into account the differences between OS.

Let me know when you feel like it's ready and discussed enough for a PR.

This exists in node as well and is called path.join().
Would this function merge ../ (without using realpath)?

This also exists in python os.path.join('foo', 'bar') and would be useful to call this function statically too Filesystem::join()

Can we move forward on this ?
I feel that could be really useful.

I'll be happy to implement what @javiereguiluz proposed. I think that (at least in the first iteration) it shouldn't be too clever and merge ../ as @apfelbox suggested (would break SRP). Maybe there could be a extra function like resolveRelativePathSegments or even $fs->realpath() for things like this. But that's for further discussion. I noticed that there is already a SO question for this!

@tomasfejfar go for it (when you have time), if you need any help you can ask me !
If you want to initiate the thing and that someone help with tests or implem, same I'm ok to help you ;).

Thank you for this suggestion.
There has not been a lot of activity here for a while. Would you still like to see this feature?

+1 to this feature 👍

Thank you for this suggestion.
There has not been a lot of activity here for a while. Would you still like to see this feature?

Yes.

#30969 this one is much further...

Is there anyone up to take over that PR or create a new PR for this issue?
It doesn't make sense to keep feature requests stalled for more than 2 years.

If you need help with the contribution process, feel free to hop into the #contribs channel on Symfony Slack.

Ah, I see @theofidry restarted the PR himself. Thanks!