RE: [PATCH] pathspec: correct an empty string used as a pathspec element

From

rsbecker@nexbridge.com <rsbecker@nexbridge.com>

Date

May 29, 2022, 23:01 UTC

Message-ID

<032f01d873b0$008c1b50$01a451f0$@nexbridge.com>

In-Reply-To

<xmqqpmjwx8so.fsf_-_@gitster.g>

On May 29, 2022 6:40 PM, Junio C Hamano wrote:

>Pathspecs with only negative elements did not work with some commands that
>pass the pathspec along to a subprocess.  For instance,
>
>    $ git add -p -- ':!*.txt'
>
>should add everything except for paths ending in ".txt", but it gets

complaint from

>underlying "diff-index" and aborts.
>
>We used to error out when a pathspec with only negative elements in it,

like the

>one in the above example.  Later, 859b7f1d (pathspec:
>don't error out on all-exclusionary pathspec patterns, 2017-02-07) updated

the

>logic to add an empty string as an extra element.  The intention was to let

the

>extra element to match everything and let the negative ones given by the

user to

>subtract from it.
>
>At around the same time, we were migrating from "an empty string is a valid
>pathspec element that matches everything" to "either a dot or ":/" is used

to

>match all, and an empty string is rejected", between d426430e (pathspec:

warn on

>empty strings as pathspec,
>2016-06-22) and 9e4e8a64 (pathspec: die on empty strings as pathspec,

2017-06-

>06).  I think 9e4e8a64, which happened long after 859b7f1d happened, was

not

>careful enough to turn the empty string 859b7f1d added to either a dot or

":/".

>
>A care should be taken as the definition of "everything" depends on
>subcommand.  For the purpose of "add -p", adding a "." to add everything in

the

>current directory is the right thing to do.  But for some other commands,

":/" (i.e.

>really really everything, even things outside the current subdirectory) is

the right

>choice.
>
>We would break commands in a big way if we get this wrong, so add a handful

of

>test pieces to make sure the resulting code still excludes the paths that

are

>expected and includes "everything" else.