commit 75bbb53178bc07949826c81f52ea9f5f042b43e4
from: Stefan Sperling <stsp@stsp.name>
date: Mon May 06 08:45:14 2024 UTC

show hint about update -b if the user attempts to rebase a branch onto itself

Specifically, when 'gut send' suggests 'fetch and rebase required', new users
might try to use 'got fetch' directly followed by 'got rebase' without first
updating the work tree to newly fetched commits. Got would then say "main is
already based on main" without any hint for a way out. Hopefully, pointing
users at the update -b command will make them search the manual for details.

commit - ef4f8ddaffcf814c74e3e3d806e430aeea45d7e8
commit + 75bbb53178bc07949826c81f52ea9f5f042b43e4
blob - e00dd735e29a8c982aa31faed0b6cb120e11839e
blob + b32ea7c37a6e4abe3ed85220602e1e8e24af6dc0
--- got/got.c
+++ got/got.c
@@ -11654,9 +11654,19 @@ cmd_rebase(int argc, char *argv[])
 
 		if (got_object_id_cmp(base_commit_id, yca_id) == 0) {
 			struct got_pathlist_head paths;
-			printf("%s is already based on %s\n",
-			    got_ref_get_name(branch),
-			    got_worktree_get_head_ref_name(worktree));
+			const char *branch_name = got_ref_get_name(branch);
+			const char *base =
+			    got_worktree_get_head_ref_name(worktree);
+
+			if (strcmp(branch_name, base) == 0) {
+				error = got_error_fmt(GOT_ERR_WRONG_BRANCH,
+				    "cannot rebase %s onto itself",
+				    branch_name);
+				goto done;
+			} else {
+				printf("%s is already based on %s\n",
+				    branch_name, base);
+			}
 			error = switch_head_ref(branch, branch_head_commit_id,
 			    worktree, repo);
 			if (error)
blob - 591ee66b8e3d659624ea402adc5cac155bfd6e21
blob + 43420d51963fb8796ed7148130020e3b879a4c8a
--- 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
-/* 86 is currently unused */
+#define GOT_ERR_WRONG_BRANCH	86
 #define GOT_ERR_REBASE_COMMITID	87
 #define GOT_ERR_REBASING	88
 #define GOT_ERR_REBASE_PATH	89
blob - 711d2054736f85896487ec6f2e7ed54fa6a56048
blob + 3e65ec158b7f496672f8134c31836cb0f31eb628
--- lib/error.c
+++ lib/error.c
@@ -131,6 +131,7 @@ static const struct got_error got_errors[] = {
 	    "changes must be committed or reverted first" },
 	{ GOT_ERR_NOT_REBASING,	"rebase operation not in progress" },
 	{ GOT_ERR_REBASE_COMMITID,"rebase commit ID mismatch" },
+	{ GOT_ERR_WRONG_BRANCH, "update -b required" },
 	{ GOT_ERR_REBASING,	"a rebase operation is in progress in this "
 	    "work tree and must be continued or aborted first" },
 	{ GOT_ERR_REBASE_PATH,	"cannot rebase branch which contains "
blob - fae088133932111b4944a156b5ea1ac14d52df37
blob + fdc97d042d96cc880bf32dab15045285d6a80e27
--- regress/cmdline/rebase.sh
+++ regress/cmdline/rebase.sh
@@ -47,6 +47,19 @@ test_rebase_basic() {
 		return 1
 	fi
 
+	(cd $testroot/wt && got rebase master > $testroot/stdout \
+		2> $testroot/stderr)
+	echo -n "got: cannot rebase refs/heads/master onto itself: " \
+		> $testroot/stderr.expected
+	echo "update -b required" >> $testroot/stderr.expected
+	cmp -s $testroot/stderr.expected $testroot/stderr
+	ret=$?
+	if [ $ret -ne 0 ]; then
+		diff -u $testroot/stderr.expected $testroot/stderr
+		test_done "$testroot" "$ret"
+		return 1
+	fi
+
 	(cd $testroot/wt && got rebase newbranch > $testroot/stdout)
 
 	git -C $testroot/repo checkout -q newbranch