Merge branch 'ex/deprecate-empty-pathspec-as-match-all'

An empty string used as a pathspec element has always meant
'everything matches', but it is too easy to write a script that
finds a path to remove in $path and run 'git rm "$paht"', which
ends up removing everything.  Start warning about this use of an
empty string used for 'everything matches' and ask users to use a
more explicit '.' for that instead.

The hope is that existing users will not mind this change, and
eventually the warning can be turned into a hard error, upgrading
the deprecation into removal of this (mis)feature.

* ex/deprecate-empty-pathspec-as-match-all:
  pathspec: warn on empty strings as pathspec

Author: gitster

pathspec.c

@@ -364,7 +364,7 @@ void parse_pathspec(struct pathspec *pathspec,
 {
 	struct pathspec_item *item;
 	const char *entry = argv ? *argv : NULL;
-	int i, n, prefixlen, nr_exclude = 0;
+	int i, n, prefixlen, warn_empty_string, nr_exclude = 0;
 
 	memset(pathspec, 0, sizeof(*pathspec));
 
@@ -402,8 +402,15 @@ void parse_pathspec(struct pathspec *pathspec,
 	}
 
 	n = 0;
-	while (argv[n])
+	warn_empty_string = 1;
+	while (argv[n]) {
+		if (*argv[n] == '\0' && warn_empty_string) {
+			warning(_("empty strings as pathspecs will be made invalid in upcoming releases. "
+				  "please use . instead if you meant to match all paths"));
+			warn_empty_string = 0;
+		}
 		n++;
+	}
 
 	pathspec->nr = n;
 	ALLOC_ARRAY(pathspec->items, n);

t/t3600-rm.sh

@@ -881,4 +881,9 @@ test_expect_success 'rm files with two different errors' '
 	test_i18ncmp expect actual
 '
 
+test_expect_success 'rm empty string should invoke warning' '
+	git rm -rf "" 2>output &&
+	test_i18ngrep "warning: empty strings" output
+'
+
 test_done

t/t3700-add.sh

@@ -331,6 +331,11 @@ test_expect_success 'git add --dry-run --ignore-missing of non-existing file out
 	test_i18ncmp expect.err actual.err
 '
 
+test_expect_success 'git add empty string should invoke warning' '
+	git add "" 2>output &&
+	test_i18ngrep "warning: empty strings" output
+'
+
 test_expect_success 'git add --chmod=[+-]x stages correctly' '
 	rm -f foo1 &&
 	echo foo >foo1 &&