From 6109f54a5e238645438f5d210b7909777a2a2435 Mon Sep 17 00:00:00 2001
From: Martijn Dekker <martijn@inlv.org>
Date: Sun, 14 Jun 2020 10:24:05 +0200
Subject: [PATCH] Fix for no-argument use of 'cd' in .../fun/dirs

'cd' with no argument is supposed to go to your home directory, but
in this override function it produced an error due to an incorrect
use of $@ within another parameter substitution, preventing $@ from
expanding to zero words.

Ref.: https://groups.google.com/d/msgid/korn-shell/781ed34b-6860-5d47-dfe8-be21280a6b31%40inlv.org

src/cmd/ksh93/fun/dirs: _cd():
- Fix the bug by setting a positional parameter if needed,
  then using a normal and correct "$@" expansion for \cd.
- While we're here, restore a historic comment about using
  'command' to bypass aliases that exists in the listing of this
  function in the official 1995 KornShell book (pp. 274-276).
  Presumably, that comment was deleted when they decided to add the
  obnoxious and broken default alias command='command ', whenever
  that was. This branch got rid of that default alias in 61d9bca5.
---
 src/cmd/ksh93/fun/dirs | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/cmd/ksh93/fun/dirs b/src/cmd/ksh93/fun/dirs
index 0329970f3..a08a0ae55 100755
--- a/src/cmd/ksh93/fun/dirs
+++ b/src/cmd/ksh93/fun/dirs
@@ -55,7 +55,11 @@ function _cd
     case $dir in
     \~*)   dir=$HOME${dir#\~}
     esac
-    \cd "${dir:-$@}" >| /dev/null || return 1
+    # If there are no arguments, use $dir if non-empty.
+    (($#)) || set -- ${dir:+"$dir"}
+    # \cd prevents alias substitution.
+    # You can use command cd with 12/28/93 and newer.
+    \cd "$@" >| /dev/null || return 1
     dir=${OLDPWD#$HOME/}
     case $TERM in
     630)