commit 980c6786a419950816c67eb1b53e021ebdfe483c
from: Stefan Sperling <stsp@stsp.name>
date: Tue Jan 31 13:49:48 2023 UTC

make 'got rebase' work when the to-be-rebased branch has no parent commit

found by and ok op@, who also provided the test case

commit - faf5b56f3ad3ab701a16b6684c5f936210ff86f8
commit + 980c6786a419950816c67eb1b53e021ebdfe483c
blob - 5d94c4ade9d0584ccb4b04bf99cb1c7f8a4d8745
blob + 06e066fceda7062b02b365d0bb490cd359852ca7
--- got/got.c
+++ got/got.c
@@ -11165,12 +11165,12 @@ cmd_rebase(int argc, char *argv[])
 		error = got_commit_graph_find_youngest_common_ancestor(&yca_id,
 		    base_commit_id, branch_head_commit_id, 1, repo,
 		    check_cancelled, NULL);
-		if (error)
-			goto done;
-		if (yca_id == NULL) {
-			error = got_error_msg(GOT_ERR_ANCESTRY,
-			    "specified branch shares no common ancestry "
-			    "with work tree's branch");
+		if (error) {
+			if (error->code == GOT_ERR_ANCESTRY) {
+				error = got_error_msg(GOT_ERR_ANCESTRY,
+				    "specified branch shares no common "
+				    "ancestry with work tree's branch");
+			}
 			goto done;
 		}
 
@@ -11226,17 +11226,16 @@ cmd_rebase(int argc, char *argv[])
 
 	parent_ids = got_object_commit_get_parent_ids(commit);
 	pid = STAILQ_FIRST(parent_ids);
-	if (pid == NULL) {
-		error = got_error(GOT_ERR_EMPTY_REBASE);
-		goto done;
+	if (pid) {
+		error = collect_commits(&commits, commit_id, &pid->id,
+		    yca_id, got_worktree_get_path_prefix(worktree),
+		    GOT_ERR_REBASE_PATH, repo);
+		if (error)
+			goto done;
 	}
-	error = collect_commits(&commits, commit_id, &pid->id,
-	    yca_id, got_worktree_get_path_prefix(worktree),
-	    GOT_ERR_REBASE_PATH, repo);
+
 	got_object_commit_close(commit);
 	commit = NULL;
-	if (error)
-		goto done;
 
 	if (!continue_rebase) {
 		error = got_worktree_rebase_prepare(&new_base_branch,
blob - c951c76bc67d396a591c05f06bd362c98aa7f678
blob + 3fd06efcdadb789fef14e683086013ed87d5bfd9
--- include/got_error.h
+++ include/got_error.h
@@ -100,7 +100,7 @@
 #define GOT_ERR_BRANCH_EXISTS	83
 #define GOT_ERR_MODIFIED	84
 #define GOT_ERR_NOT_REBASING	85
-#define GOT_ERR_EMPTY_REBASE	86
+/* 86 is currently unused */
 #define GOT_ERR_REBASE_COMMITID	87
 #define GOT_ERR_REBASING	88
 #define GOT_ERR_REBASE_PATH	89
blob - 7e698531e6e75bd34bc4b2f0c280aded67f43de0
blob + 3c84ba7eeb9c88175a7652495f934263b6fd2328
--- lib/error.c
+++ lib/error.c
@@ -129,7 +129,6 @@ static const struct got_error got_errors[] = {
 	{ GOT_ERR_MODIFIED,	"work tree contains local changes; these "
 	    "changes must be committed or reverted first" },
 	{ GOT_ERR_NOT_REBASING,	"rebase operation not in progress" },
-	{ GOT_ERR_EMPTY_REBASE,	"no commits to rebase" },
 	{ GOT_ERR_REBASE_COMMITID,"rebase commit ID mismatch" },
 	{ GOT_ERR_REBASING,	"a rebase operation is in progress in this "
 	    "work tree and must be continued or aborted first" },
blob - f87f1d9e51fc63c6ebf7cc957f15ec52ddd15420
blob + fceaf181cd74c8b1810cfe97234af037bb77561c
--- regress/cmdline/rebase.sh
+++ regress/cmdline/rebase.sh
@@ -912,7 +912,11 @@ test_rebase_no_commits_to_rebase() {
 		return 1
 	fi
 
-	(cd $testroot/wt && got branch -n newbranch)
+	# Create an unrelated branch with 'got import'.
+	mkdir -p $testroot/newtree
+	echo "new file" > $testroot/newtree/newfile
+	got import -m new -b newbranch -r $testroot/repo \
+		$testroot/newtree > /dev/null
 
 	echo "modified alpha on master" > $testroot/wt/alpha
 	(cd $testroot/wt && got commit -m 'test rebase_no_commits_to_rebase' \
@@ -922,7 +926,9 @@ test_rebase_no_commits_to_rebase() {
 	(cd $testroot/wt && got rebase newbranch > $testroot/stdout \
 		2> $testroot/stderr)
 
-	echo "got: no commits to rebase" > $testroot/stderr.expected
+	echo -n "got: specified branch shares no common ancestry " \
+		> $testroot/stderr.expected
+	echo "with work tree's branch" >> $testroot/stderr.expected
 	cmp -s $testroot/stderr.expected $testroot/stderr
 	ret=$?
 	if [ $ret -ne 0 ]; then
@@ -1883,6 +1889,47 @@ test_rebase_out_of_date2() {
 		diff -u $testroot/stderr.expected $testroot/stderr
 	fi
 	test_done "$testroot" "$ret"
+}
+
+test_rebase_one_commit() {
+	local testroot=`test_init rebase_one_commit`
+
+	if ! got checkout $testroot/repo $testroot/wt >/dev/null; then
+		test_done "$testroot" 1
+		return 1
+	fi
+
+	(cd $testroot/wt && got branch newbranch) >/dev/null
+
+	echo "modified alpha on newbranch" >$testroot/wt/alpha
+	(cd $testroot/wt && got commit -m 'edit alpha') >/dev/null
+	(cd $testroot/wt && got update) >/dev/null
+	local commit=`git_show_branch_head $testroot/repo newbranch`
+
+	echo -n '' > $testroot/stderr.expected
+
+	(cd $testroot/wt && got rebase master >$testroot/stdout \
+		2> $testroot/stderr)
+	ret=$?
+	if [ $ret -ne 0 ]; then
+		echo "rebase comand failed unexpectedly" >&2
+		diff -u $testroot/stderr.expected $testroot/stderr
+		test_done "$testroot" "1"
+		return 1
+	fi
+
+	echo "Forwarding refs/heads/master to commit $commit" \
+		>$testroot/stdout.expected
+	echo "Switching work tree to refs/heads/master" \
+		>> $testroot/stdout.expected
+
+	if ! cmp -s $testroot/stdout.expected $testroot/stdout; then
+		diff -u $testroot/stdout.expected $testroot/stdout
+		test_done "$testroot" 1
+		return 1
+	fi
+
+	test_done "$testroot" 0
 }
 
 test_parseargs "$@"
@@ -1906,3 +1953,4 @@ run_test test_rebase_no_author_info
 run_test test_rebase_nonbranch
 run_test test_rebase_umask
 run_test test_rebase_out_of_date2
+run_test test_rebase_one_commit