Add runfiles example with more levels of indirection

[hofbi]

#3399 changed the behavior of runfiles. Due to this change a few cases no longer work with bazel run that did work before. I tried to create a more complex runfiles example since rules_rust does not have anyone yet + we can use it for discussing what should be the correct behavior.

# Everything with bazel test still works
bazel test //...

# bazel run no longer works for all cases that work with bazel test
bazel run //pkg_a:pkg_a_binary
bazel run //pkg_b:pkg_b_binary

I added a comment to the few cases that still work with bazel test but no longer work with bazel run. In particular, this happens when requesting a folder through runfiles instead of an individual file.

[scasagrande]

In particular, this happens when requesting a folder through runfiles instead of an individual file.

I recently noticed this as well. To get around this I adjusted some code to look for the BUILD.bazel file in the directory, and then trim off the file.

[hofbi]

In particular, this happens when requesting a folder through runfiles instead of an individual file.

I recently noticed this as well. To get around this I adjusted some code to look for the BUILD.bazel file in the directory, and then trim off the file.

Could you share an example?

[scasagrande]

Small correction, I just look for any specific file in the directory.

something along the lines of this should return the relative path to a/b/c/ . This would require a data dependency on a filegroup target under @a//b:c which at least contains the file somefile.txt.

        let target = "a/b/c/somefile.txt";
        let rf = runfiles::Runfiles::create()?;
        let path = runfiles::rlocation!(rf, target);
        let path = match path {
            Some(value) => value,
            None => {
                return Err(...)
            }
        };
        let path = match path.parent() {
            Some(value) => value,
            None => {
                return Err(...)
            }
        };

[hofbi]

Yes, getting the parent of a particular file is what I also used for a quick fix. But it feels a bit hacky.

[scasagrande]

Well yeah 😆