[PATCH v3 07/16] restore: reject invalid combinations with --staged

[Nguyễn Thái Ngọc Duy]

git-checkout rejects plenty of invalid option combinations. Since
git-checkout is equivalent of either

    git restore --source --staged --worktree

or

    git restore --worktree

that still leaves the new mode 'git restore --index' unprotected. Reject
some more invalid option combinations.

The other new mode 'restore --source --worktree' does not need anything
else.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclo...@gmail.com>
---
 builtin/checkout.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/builtin/checkout.c b/builtin/checkout.c
index e855c64cfe..71e2589340 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -433,6 +433,16 @@ static int checkout_paths(const struct checkout_opts *opts,
                die(_("'%s' must be used when '%s' is not specified"),
                    "--worktree", "--source");
 
+       if (opts->checkout_index && !opts->checkout_worktree &&
+           opts->writeout_stage)
+               die(_("'%s' or '%s' cannot be used with %s"),
+                   "--ours", "--theirs", "--staged");
+
+       if (opts->checkout_index && !opts->checkout_worktree &&
+           opts->merge)
+               die(_("'%s' or '%s' cannot be used with %s"),
+                   "--merge", "--conflict", "--staged");
+
        if (opts->patch_mode) {
                const char *patch_mode;
 
-- 
2.21.0.854.ge34a79f761