Fix rpath for binaries in external repositories

[fmeum]

The solib directory is located within the subdirectory of the runfiles
directory corresponding to the workspace. Thus, if a binary is contained
in an external repository, its $ORIGIN relative rpath has to first
ascend to the runfiles directory and then descend into the workspace
directory.

Fixes #16003

[fmeum]

@oquenchil This PR is similar to #14600, but resolves a different issue. I can rebase this PR onto #14600 if you should prefer to merge that one first.

[fmeum]

@bazel-io flag

[AustinSchuh]

Success, this fixes test in external repositories! Thanks @fmeum !

[ShreeM01]

@bazel-io fork 5.3.0

[ShreeM01]

@bazel-io fork 5.3.0

[fmeum]

@kshyanashree The command lacks the rc1.

[ShreeM01]

@bazel-io fork 5.3.0rc1

[fmeum]

@kshyanashree I don't know why, but the last command failed as well.

[coeuvre]

Assigning to @oquenchil since this is about cc rules.

[sgowroji]

@bazel-io fork 5.3.0

[ShreeM01]

Hi @fmeum, Is it possible for you to get the PR review done? Since we will be merging it under the release 5.3.0.

[fmeum]

@kshyanashree I don't know when @oquenchil will be able to review the change. It does fix a known Bazel 5 regression - is that sufficient to hold the release for it/up the priority?

[oquenchil]

LGTM

[pcjanzen]

Although this patch fixes the remote execution case, it breaks the local execution case.

In local execution, the runfiles tree contains symlinks to regular files in the output root; the $ORIGIN that the dynamic loader uses is the location of that regular file, not the symlink:

bazel-bin/external/other_repo/test/test.runfiles/other_repo/test/test -> bazel-bin/external/other_repo/test/test

and the solib directory is directly underneath bazel-bin, there is no subdirectory for the main workspace.

This causes the test to fail:

INFO: From Testing @other_repo//test:test:
==================== Test output for @other_repo//test:test:
/home/pauljanzen/.cache/bazel/_bazel_pauljanzen/ce3ed1e55900fb9d8cbdc1181abe7157/sandbox/processwrapper-sandbox/4/execroot/__main__/bazel-out/k8-fastbuild/bin/external/other_repo/test/test.runfiles/__main__/../other_repo/test/test: error while loading shared libraries: libexternal_Sother_Urepo_Slib_Sliblib.so: cannot open shared object file: No such file or directory
================================================================================

[fmeum]

CC @kshyanashree as a potential 5.3.0 regression.

@pcjanzen Would adding both rpaths fix this problem?

[pcjanzen]

Would adding both rpaths fix this problem?

I think so, but between this problem and #14600 there are starting to be kind of a lot of rpath entries and I can't honestly say I've thought through all the combinations.