fix(tvix/eval): don't bubble up io errors from path_exists r/8416

path_exists was returning an error when certain common IO errors were
encountered. e.g. in the path "/dev/null/.", path_exists would throw
an error because the underlying call to Path::try_exists threw an
error because null isn't a directory. But if null isn't a directory,
then the path is invalid, so this should really be returning
false. That's what nix's behavior is and that's what makes sense.

The trait function isn't being changed because some other
implementers (e.g. tvix_store_io) have actual errors they can throw.

Fixes: b/411
Change-Id: I9e810e7a198bffe61365697c6d3d7e71f264c20b
Reviewed-on: https://cl.tvl.fyi/c/depot/+/12042
Tested-by: BuildkiteCI
Autosubmit: chickadee <matthewktromp@gmail.com>
Reviewed-by: aspen <root@gws.fyi>

1 files changed, 1 insertions, 0 deletions

diff --git a/tvix/eval/src/tests/tvix_tests/eval-okay-path-exists-child-of-file.nix b/tvix/eval/src/tests/tvix_tests/eval-okay-path-exists-child-of-file.nix
new file mode 100644
index 000000000000..8588f0bddfc1
--- /dev/null
+++ b/tvix/eval/src/tests/tvix_tests/eval-okay-path-exists-child-of-file.nix
@@ -0,0 +1 @@
+builtins.pathExists ("/dev/null/.")
\ No newline at end of file