Re: "git add -p ." raises an unexpected "warning: empty strings as pathspecs will be made invalid in upcoming releases. please use . instead if you meant to match all paths"

Kevin Daudt [off-list ref] writes:

quoted

On Wed, Nov 30, 2016 at 12:31:49PM -0800, Peter Urda wrote:

quoted

After upgrading to version 2.11.0 I am getting a warning about empty
strings as pathspecs while using 'patch'

- Ran 'git add -p .' from the root of my git repository.

- I was able to normally stage my changes, but was presented with a
"warning: empty strings as pathspecs will be made invalid in upcoming
releases. please use . instead if you meant to match all paths"
message.

- I expected no warning message since I included a "." with my original command.

I believe that I should not be seeing this warning message as I
included the requested "." pathspec.

Yes, this seems to be caused by pathspec.c::prefix_pathspec()
overwriting the original pathspec "." into "".  The callchain
looks like this:

    builtin/add.c::interactive_add()
     -> parse_pathspec()
        passes argv[] that has "." to the caller,
        receives pathspec whose pathspec->items[].original
	is supposed to point at the unmolested original,
        but prefix_pathspec() munges "." into ""
     -> run_add_interactive()
        which runs "git add--interactive" with
	pathspec->items[].original as pathspecs


Perhaps this would work it around, but there should be a better way
to fix it (like, making sure that what we call "original" indeed
stays "original").

 builtin/add.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/builtin/add.c b/builtin/add.c
index e8fb80b36e..137097192d 100644
--- a/builtin/add.c
+++ b/builtin/add.c

@@ -167,9 +167,18 @@ int run_add_interactive(const char *revision, const char *patch_mode,
 	if (revision)
 		argv_array_push(&argv, revision);
 	argv_array_push(&argv, "--");
-	for (i = 0; i < pathspec->nr; i++)
+	for (i = 0; i < pathspec->nr; i++) {
 		/* pass original pathspec, to be re-parsed */
+		if (!*pathspec->items[i].original) {
+			/*
+			 * work around a misfeature in parse_pathspecs()
+			 * that munges "." into "".
+			 */
+			argv_array_push(&argv, ".");
+			continue;
+		}
 		argv_array_push(&argv, pathspec->items[i].original);
+	}
 
 	status = run_command_v_opt(argv.argv, RUN_GIT_CMD);
 	argv_array_clear(&argv);

@@ -180,7 +189,7 @@ int interactive_add(int argc, const char **argv, const char *prefix, int patch)
 {
 	struct pathspec pathspec;
 
-	parse_pathspec(&pathspec, 0,
+	parse_pathspec(&pathspec, 0,
 		       PATHSPEC_PREFER_FULL |
 		       PATHSPEC_SYMLINK_LEADING_PATH |
 		       PATHSPEC_PREFIX_ORIGIN,