--incompatible_sandbox_hermetic_tmp breaks outputs materialized as a symlinks to source artifacts #21215
Description
Originally reported by @tyler-french in #20886 (but seems to be a separate issue).
Minimal repro (Linux):
.bazelversion
7.0.2
.bazelrc
build --noenable_bzlmod
repo.bzl
def _impl(rctx):
rctx.file("file.txt", "hello")
rctx.file("BUILD", """exports_files(["file.txt"])""")
repo = repository_rule(_impl)
WORSKPACE
load(":repo.bzl", "repo")
repo(name= "repo")
BUILD
genrule(
name = "gen",
outs = ["file.txt"],
srcs = ["@repo//:file.txt"],
cmd = "ln -s $< $@",
)
Result:
ERROR: /usr/local/google/home/tjgq/proj/dangling-symlink-repro/BUILD:1:8: declared output 'file.txt' is a dangling symbolic link
ERROR: /usr/local/google/home/tjgq/proj/dangling-symlink-repro/BUILD:1:8: Executing genrule //:gen failed: not all outputs were created or valid
I believe this is because we copy (actually, move) the symlink as-is out of the sandbox, so it ends up pointing to a location like /tmp/bazel-source-roots/1/file.txt, which only makes sense in the context of the sandbox.
Things to keep in mind when fixing this:
- Make sure that symlinks to the main repo (as opposed to an external repo) work as well
- Make sure that an indirection through multiple symlinks works as well