status: show more info than "currently not on any branch"

When a remote ref or a tag is checked out, HEAD is automatically
detached. There is no user-friendly way to find out what ref is
checked out in this case. This patch digs in reflog for this
information and shows "HEAD detached from origin/master" or "HEAD
detached at v1.8.0" instead of "currently not on any branch".

When it cannot figure out the original ref, it shows an abbreviated
SHA-1. "Currently not on any branch" would never display (unless
reflog is pruned to near empty that the last checkout entry is lost).

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 33 insertions, 19 deletions

diff --git a/t/t7512-status-help.sh b/t/t7512-status-help.sh
index 51ab89411..5adba4f5e 100755
--- a/t/t7512-status-help.sh
+++ b/t/t7512-status-help.sh
@@ -76,7 +76,7 @@ test_expect_success 'status when rebase in progress before resolving conflicts'
 	ONTO=$(git rev-parse --short HEAD^^) &&
 	test_must_fail git rebase HEAD^ --onto HEAD^^ &&
 	cat >expected <<-EOF &&
-	# Not currently on any branch.
+	# HEAD detached at $ONTO
 	# You are currently rebasing branch '\''rebase_conflicts'\'' on '\''$ONTO'\''.
 	#   (fix conflicts and then run "git rebase --continue")
 	#   (use "git rebase --skip" to skip this patch)
@@ -103,7 +103,7 @@ test_expect_success 'status when rebase in progress before rebase --continue' '
 	echo three >main.txt &&
 	git add main.txt &&
 	cat >expected <<-EOF &&
-	# Not currently on any branch.
+	# HEAD detached at $ONTO
 	# You are currently rebasing branch '\''rebase_conflicts'\'' on '\''$ONTO'\''.
 	#   (all conflicts fixed: run "git rebase --continue")
 	#
@@ -135,7 +135,7 @@ test_expect_success 'status during rebase -i when conflicts unresolved' '
 	ONTO=$(git rev-parse --short rebase_i_conflicts) &&
 	test_must_fail git rebase -i rebase_i_conflicts &&
 	cat >expected <<-EOF &&
-	# Not currently on any branch.
+	# HEAD detached at $ONTO
 	# You are currently rebasing branch '\''rebase_i_conflicts_second'\'' on '\''$ONTO'\''.
 	#   (fix conflicts and then run "git rebase --continue")
 	#   (use "git rebase --skip" to skip this patch)
@@ -161,7 +161,7 @@ test_expect_success 'status during rebase -i after resolving conflicts' '
 	test_must_fail git rebase -i rebase_i_conflicts &&
 	git add main.txt &&
 	cat >expected <<-EOF &&
-	# Not currently on any branch.
+	# HEAD detached at $ONTO
 	# You are currently rebasing branch '\''rebase_i_conflicts_second'\'' on '\''$ONTO'\''.
 	#   (all conflicts fixed: run "git rebase --continue")
 	#
@@ -187,9 +187,10 @@ test_expect_success 'status when rebasing -i in edit mode' '
 	export FAKE_LINES &&
 	test_when_finished "git rebase --abort" &&
 	ONTO=$(git rev-parse --short HEAD~2) &&
+	TGT=$(git rev-parse --short two_rebase_i) &&
 	git rebase -i HEAD~2 &&
 	cat >expected <<-EOF &&
-	# Not currently on any branch.
+	# HEAD detached from $TGT
 	# You are currently editing a commit while rebasing branch '\''rebase_i_edit'\'' on '\''$ONTO'\''.
 	#   (use "git commit --amend" to amend the current commit)
 	#   (use "git rebase --continue" once you are satisfied with your changes)
@@ -214,8 +215,9 @@ test_expect_success 'status when splitting a commit' '
 	ONTO=$(git rev-parse --short HEAD~3) &&
 	git rebase -i HEAD~3 &&
 	git reset HEAD^ &&
+	TGT=$(git rev-parse --short HEAD) &&
 	cat >expected <<-EOF &&
-	# Not currently on any branch.
+	# HEAD detached at $TGT
 	# You are currently splitting a commit while rebasing branch '\''split_commit'\'' on '\''$ONTO'\''.
 	#   (Once your working directory is clean, run "git rebase --continue")
 	#
@@ -243,10 +245,11 @@ test_expect_success 'status after editing the last commit with --amend during a
 	export FAKE_LINES &&
 	test_when_finished "git rebase --abort" &&
 	ONTO=$(git rev-parse --short HEAD~3) &&
+	TGT=$(git rev-parse --short three_amend) &&
 	git rebase -i HEAD~3 &&
 	git commit --amend -m "foo" &&
 	cat >expected <<-EOF &&
-	# Not currently on any branch.
+	# HEAD detached from $TGT
 	# You are currently editing a commit while rebasing branch '\''amend_last'\'' on '\''$ONTO'\''.
 	#   (use "git commit --amend" to amend the current commit)
 	#   (use "git rebase --continue" once you are satisfied with your changes)
@@ -276,7 +279,7 @@ test_expect_success 'status: (continue first edit) second edit' '
 	git rebase -i HEAD~3 &&
 	git rebase --continue &&
 	cat >expected <<-EOF &&
-	# Not currently on any branch.
+	# HEAD detached from $ONTO
 	# You are currently editing a commit while rebasing branch '\''several_edits'\'' on '\''$ONTO'\''.
 	#   (use "git commit --amend" to amend the current commit)
 	#   (use "git rebase --continue" once you are satisfied with your changes)
@@ -298,7 +301,7 @@ test_expect_success 'status: (continue first edit) second edit and split' '
 	git rebase --continue &&
 	git reset HEAD^ &&
 	cat >expected <<-EOF &&
-	# Not currently on any branch.
+	# HEAD detached from $ONTO
 	# You are currently splitting a commit while rebasing branch '\''several_edits'\'' on '\''$ONTO'\''.
 	#   (Once your working directory is clean, run "git rebase --continue")
 	#
@@ -325,7 +328,7 @@ test_expect_success 'status: (continue first edit) second edit and amend' '
 	git rebase --continue &&
 	git commit --amend -m "foo" &&
 	cat >expected <<-EOF &&
-	# Not currently on any branch.
+	# HEAD detached from $ONTO
 	# You are currently editing a commit while rebasing branch '\''several_edits'\'' on '\''$ONTO'\''.
 	#   (use "git commit --amend" to amend the current commit)
 	#   (use "git rebase --continue" once you are satisfied with your changes)
@@ -347,7 +350,7 @@ test_expect_success 'status: (amend first edit) second edit' '
 	git commit --amend -m "a" &&
 	git rebase --continue &&
 	cat >expected <<-EOF &&
-	# Not currently on any branch.
+	# HEAD detached from $ONTO
 	# You are currently editing a commit while rebasing branch '\''several_edits'\'' on '\''$ONTO'\''.
 	#   (use "git commit --amend" to amend the current commit)
 	#   (use "git rebase --continue" once you are satisfied with your changes)
@@ -370,7 +373,7 @@ test_expect_success 'status: (amend first edit) second edit and split' '
 	git rebase --continue &&
 	git reset HEAD^ &&
 	cat >expected <<-EOF &&
-	# Not currently on any branch.
+	# HEAD detached from $ONTO
 	# You are currently splitting a commit while rebasing branch '\''several_edits'\'' on '\''$ONTO'\''.
 	#   (Once your working directory is clean, run "git rebase --continue")
 	#
@@ -398,7 +401,7 @@ test_expect_success 'status: (amend first edit) second edit and amend' '
 	git rebase --continue &&
 	git commit --amend -m "d" &&
 	cat >expected <<-EOF &&
-	# Not currently on any branch.
+	# HEAD detached from $ONTO
 	# You are currently editing a commit while rebasing branch '\''several_edits'\'' on '\''$ONTO'\''.
 	#   (use "git commit --amend" to amend the current commit)
 	#   (use "git rebase --continue" once you are satisfied with your changes)
@@ -422,7 +425,7 @@ test_expect_success 'status: (split first edit) second edit' '
 	git commit -m "e" &&
 	git rebase --continue &&
 	cat >expected <<-EOF &&
-	# Not currently on any branch.
+	# HEAD detached from $ONTO
 	# You are currently editing a commit while rebasing branch '\''several_edits'\'' on '\''$ONTO'\''.
 	#   (use "git commit --amend" to amend the current commit)
 	#   (use "git rebase --continue" once you are satisfied with your changes)
@@ -447,7 +450,7 @@ test_expect_success 'status: (split first edit) second edit and split' '
 	git rebase --continue &&
 	git reset HEAD^ &&
 	cat >expected <<-EOF &&
-	# Not currently on any branch.
+	# HEAD detached from $ONTO
 	# You are currently splitting a commit while rebasing branch '\''several_edits'\'' on '\''$ONTO'\''.
 	#   (Once your working directory is clean, run "git rebase --continue")
 	#
@@ -477,7 +480,7 @@ test_expect_success 'status: (split first edit) second edit and amend' '
 	git rebase --continue &&
 	git commit --amend -m "h" &&
 	cat >expected <<-EOF &&
-	# Not currently on any branch.
+	# HEAD detached from $ONTO
 	# You are currently editing a commit while rebasing branch '\''several_edits'\'' on '\''$ONTO'\''.
 	#   (use "git commit --amend" to amend the current commit)
 	#   (use "git rebase --continue" once you are satisfied with your changes)
@@ -572,8 +575,9 @@ test_expect_success 'status when bisecting' '
 	git bisect start &&
 	git bisect bad &&
 	git bisect good one_bisect &&
-	cat >expected <<-\EOF &&
-	# Not currently on any branch.
+	TGT=$(git rev-parse --short two_bisect) &&
+	cat >expected <<-EOF &&
+	# HEAD detached at $TGT
 	# You are currently bisecting branch '\''bisect'\''.
 	#   (use "git bisect reset" to get back to the original branch)
 	#
@@ -596,7 +600,7 @@ test_expect_success 'status when rebase conflicts with statushints disabled' '
 	ONTO=$(git rev-parse --short HEAD^^) &&
 	test_must_fail git rebase HEAD^ --onto HEAD^^ &&
 	cat >expected <<-EOF &&
-	# Not currently on any branch.
+	# HEAD detached at $ONTO
 	# You are currently rebasing branch '\''statushints_disabled'\'' on '\''$ONTO'\''.
 	#
 	# Unmerged paths:
@@ -662,5 +666,15 @@ test_expect_success 'status when cherry-picking after resolving conflicts' '
 	test_i18ncmp expected actual
 '
 
+test_expect_success 'status showing detached from a tag' '
+	test_commit atag tagging &&
+	git checkout atag &&
+	cat >expected <<-\EOF
+	# HEAD detached at atag
+	nothing to commit (use -u to show untracked files)
+	EOF
+	git status --untracked-files=no >actual &&
+	test_i18ncmp expected actual
+'
 
 test_done