sequencer: implement save_autostash()

Extract common functionality of apply_autostash() into
apply_save_autostash() and use it to implement save_autostash(). This
function will be used in a future commit.

The difference between save_autostash() and apply_autostash() is that
the former does not try to apply the stash. It skips that step and
just stores the created entry in the stash reflog.

This is useful in the case where we abort an operation when an autostash
is present but we don't want to dirty the worktree with the application
of the stash. For example, in a future commit, we will implement
`git merge --autostash`. Since merges can be aborted using
`git reset --hard`, we'd make use of save_autostash() to save the
autostash entry instead of applying it to the worktree thus keeping the
worktree undirtied.

Signed-off-by: Denton Liu <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: Denton-L

sequencer.c

@@ -3707,7 +3707,7 @@ void create_autostash(struct repository *r, const char *path,
 	strbuf_release(&buf);
 }
 
-int apply_autostash(const char *path)
+static int apply_save_autostash(const char *path, int attempt_apply)
 {
 	struct strbuf stash_oid = STRBUF_INIT;
 	struct child_process child = CHILD_PROCESS_INIT;
@@ -3720,13 +3720,17 @@ int apply_autostash(const char *path)
 	}
 	strbuf_trim(&stash_oid);
 
-	child.git_cmd = 1;
-	child.no_stdout = 1;
-	child.no_stderr = 1;
-	argv_array_push(&child.args, "stash");
-	argv_array_push(&child.args, "apply");
-	argv_array_push(&child.args, stash_oid.buf);
-	if (!run_command(&child))
+	if (attempt_apply) {
+		child.git_cmd = 1;
+		child.no_stdout = 1;
+		child.no_stderr = 1;
+		argv_array_push(&child.args, "stash");
+		argv_array_push(&child.args, "apply");
+		argv_array_push(&child.args, stash_oid.buf);
+		ret = run_command(&child);
+	}
+
+	if (attempt_apply && !ret)
 		fprintf(stderr, _("Applied autostash.\n"));
 	else {
 		struct child_process store = CHILD_PROCESS_INIT;
@@ -3742,17 +3746,30 @@ int apply_autostash(const char *path)
 			ret = error(_("cannot store %s"), stash_oid.buf);
 		else
 			fprintf(stderr,
-				_("Applying autostash resulted in conflicts.\n"
+				_("%s\n"
 				  "Your changes are safe in the stash.\n"
 				  "You can run \"git stash pop\" or"
-				  " \"git stash drop\" at any time.\n"));
+				  " \"git stash drop\" at any time.\n"),
+				attempt_apply ?
+				_("Applying autostash resulted in conflicts.") :
+				_("Autostash exists; creating a new stash entry."));
 	}
 
 	unlink(path);
 	strbuf_release(&stash_oid);
 	return ret;
 }
 
+int save_autostash(const char *path)
+{
+	return apply_save_autostash(path, 0);
+}
+
+int apply_autostash(const char *path)
+{
+	return apply_save_autostash(path, 1);
+}
+
 static const char *reflog_message(struct replay_opts *opts,
 	const char *sub_action, const char *fmt, ...)
 {

sequencer.h

@@ -193,6 +193,7 @@ void commit_post_rewrite(struct repository *r,
 
 void create_autostash(struct repository *r, const char *path,
 		      const char *default_reflog_action);
+int save_autostash(const char *path);
 int apply_autostash(const char *path);
 
 #define SUMMARY_INITIAL_COMMIT   (1 << 0)