[PATCH 7/8] checkout: allow ignoring unmatched pathspec

[Thomas Gummerer <t.gummerer@gmail.com>]

Currently when 'git checkout -- <pathspec>...' is invoked with
multiple pathspecs, where one or more of the pathspecs don't match
anything, checkout errors out.

This can be inconvenient in some cases, such as when using git
checkout from a script.  Introduce a new --ignore-unmatched option,
which which allows us to ignore a non-matching pathspec instead of
erroring out.

In a subsequent commit we're going to start using 'git checkout' in
'git stash' and are going to make use of this feature.

Signed-off-by: Thomas Gummerer <t.gummerer@gmail.com>
---
 builtin/checkout.c        | 10 +++++++++-
 t/t2022-checkout-paths.sh |  9 +++++++++
 t/t9902-completion.sh     |  1 +
 3 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/builtin/checkout.c b/builtin/checkout.c
index 6ba85e9de5..7e7b5cd1d3 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -46,6 +46,7 @@ struct checkout_opts {
 	int show_progress;
 	int overlay_mode;
 	int cached;
+	int ignore_unmatched;
 	/*
 	 * If new checkout options are added, skip_merge_working_tree
 	 * should be updated accordingly.
@@ -358,7 +359,8 @@ static int checkout_paths(const struct checkout_opts *opts,
 			ce->ce_flags |= CE_MATCHED;
 	}
 
-	if (report_path_error(ps_matched, &opts->pathspec, opts->prefix)) {
+	if (!opts->ignore_unmatched &&
+	    report_path_error(ps_matched, &opts->pathspec, opts->prefix)) {
 		free(ps_matched);
 		return 1;
 	}
@@ -586,6 +588,11 @@ static int skip_merge_working_tree(const struct checkout_opts *opts,
 	 * not tested here
 	 */
 
+	/*
+	 * opts->ignore_unmatched cannot be used with switching branches so is
+	 * not tested here
+	 */
+
 	/*
 	 * If we aren't creating a new branch any changes or updates will
 	 * happen in the existing branch.  Since that could only be updating
@@ -1320,6 +1327,7 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
 		OPT_BOOL(0, "progress", &opts.show_progress, N_("force progress reporting")),
 		OPT_BOOL(0, "overlay", &opts.overlay_mode, N_("use overlay mode")),
 		OPT_BOOL(0, "cached", &opts.cached, N_("work on the index only")),
+		OPT_BOOL(0, "ignore-unmatched", &opts.ignore_unmatched, N_("don't error on unmatched pathspecs")),
 		OPT_END(),
 	};
 
diff --git a/t/t2022-checkout-paths.sh b/t/t2022-checkout-paths.sh
index fc3eb43b89..b44cdf7b63 100755
--- a/t/t2022-checkout-paths.sh
+++ b/t/t2022-checkout-paths.sh
@@ -78,4 +78,13 @@ test_expect_success 'do not touch files that are already up-to-date' '
 	test_cmp expect actual
 '
 
+test_expect_success 'checkout --ignore-unmatched' '
+	test_commit file1 &&
+	echo changed >file1.t &&
+	git checkout --ignore-unmatched -- file1.t unknown-file &&
+	echo file1 >expect &&
+	test_cmp expect file1.t
+
+'
+
 test_done
diff --git a/t/t9902-completion.sh b/t/t9902-completion.sh
index cbc304ace8..475debcf95 100755
--- a/t/t9902-completion.sh
+++ b/t/t9902-completion.sh
@@ -1438,6 +1438,7 @@ test_expect_success 'double dash "git checkout"' '
 	--no-... Z
 	--overlay Z
 	--cached Z
+	--ignore-unmatched Z
 	EOF
 '
 
-- 
2.20.0.405.gbc1bbc6f85