From e0772c12aeafb9b1b9274927024c15a9af1e9567 Mon Sep 17 00:00:00 2001
From: Michal Sojka <michal.sojka@cvut.cz>
Date: Thu, 31 Jul 2025 00:30:43 +0200
Subject: [PATCH] minimal/do: Do not fail with bash 5.3

When running "make test" with bash 5.3, it fails with:

    minimal/do: line 358: cd: null directory
    ./do: minimal/do test failed
    make: *** [Makefile:10: test] Error 42

The reason is that bash 5.3 implements the latest version of the POSIX
standard, which requires that "cd" with an empty string should fail.
Specifically, "If directory is an empty string, cd shall write a
diagnostic message to standard error and exit with non-zero status."
[1]. This is documented at [2].

Fix that by substituting an empty string with ".", which is already
being done at other places in the that script.

[1]: https://pubs.opengroup.org/onlinepubs/9799919799/utilities/cd.html
[2]: https://cgit.git.savannah.gnu.org/cgit/bash.git/tree/CHANGES?h=bash-5.3#n119.
---
 minimal/do | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/minimal/do b/minimal/do
index 557c433..7c165c8 100755
--- a/minimal/do
+++ b/minimal/do
@@ -355,7 +355,7 @@ _do()
 		fi
 		target=$PWD/$target
 		tmp=$PWD/$tmp
-		cd "$dodir" || return 99
+		cd "${dodir:-.}" || return 99
 		target=$(_relpath "$target" "$PWD") || return 98
 		tmp=$(_relpath "$tmp" "$PWD") || return 97
 		base=${target%$ext}