cd with empty argument does not conform to POSIX.1-2024 (Was: inherit OLDPWD from environment variable)

[Lawrence Velázquez <larryv@xxxxxxx>]

On Fri, Jul 19, 2024, at 10:46 PM, Lawrence Velázquez wrote:
> If we're going to begin importing OLDPWD from the environment, we
> might as well align with other shells for consistency, which means
> accepting a zero-length value as is.

Speaking of zero-length values vis-à-vis cd:

	% cd ""

The current behavior is to do nothing and exit with a zero status.
This is allowed by POSIX.1-2018 [1]:

	If _directory_ is an empty string, the results are unspecified.

However, it is not allowed by the newly released POSIX.1-2024 [2]:

	If _directory_ is an empty string, _cd_ shall write a
	diagnostic message to standard error and exit with non-zero
	status.

I don't have strong feelings about changing the default behavior,
but it would be useful to update POSIX_CD at least (and thus ksh/sh
emulation).

[1]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/cd.html
[2]: https://pubs.opengroup.org/onlinepubs/9799919799/utilities/cd.html

-- 
vq