Empty string entry in CDPATH completes from /

[jmou]

Describe the bug

CDPATH entries may be empty, which according to the bash documentation is equivalent to .; however it is slightly different in practice because . will echo the directory name while the empty string will not.

When CDPATH includes an empty string (e.g., CDPATH=:~/cdpath) the completion includes directories under the root directory /.

This appears to be a working one-line fix:

diff --git a/completions/cd b/completions/cd
index 8de903a6..51692079 100644
--- a/completions/cd
+++ b/completions/cd
@@ -38,6 +38,7 @@ _comp_cmd_cd__compgen_cdpath()
     local paths dirs _d
     _comp_split -F : paths "$CDPATH"
     for _p in "${paths[@]}"; do
+        _p="${_p:-.}"
         # create an array of matched subdirs
         _comp_compgen -v dirs -c "$_p/$cur" -- -d
         for _d in "${dirs[@]}"; do

To reproduce

$ env -i bwrap --ro-bind / / --dev /dev --ro-bind /etc/skel $HOME bash
[joe@doughboy joe]$ ls
[joe@doughboy joe]$ CDPATH=:$HOME
[joe@doughboy joe]$ cd s[TAB][TAB]
sbin/  srv/   sys/   

This is basically a default empty home directory with CDPATH set to :/home/joe.

Expected behavior

The current home directory is empty so there should be no completions.

Versions (please complete the following information)

• Operating system name/distribution and version: Fedora 43
• bash version, echo "$BASH_VERSION": 5.3.0(1)-release (x86_64-redhat-linux-gnu)
• bash-completion version, (IFS=.; echo "${BASH_COMPLETION_VERSINFO[*]}"): 2 16 0 (also reproduced at commit e8a3d33)

Additional context

Debug trace

[scop]

Thanks! Would you mind submitting a PR for this, along with an amendment to the test suite (test/t/test_cd.py)?

[jmou]

Done! #1529