[PATCHv2 2/2] commit/status: show the index-worktree diff with -v -v

[Michael J Gruber <git@drmicha.warpmail.net>]

git commit and git status in long format show the diff between HEAD
and the index when given -v. This allows previewing a commit to be made.

They also list tracked files with unstaged changes, but without a diff.

Introduce '-v -v' which shows the diff between the index and the
worktree in addition to the HEAD index diff. This allows a review of unstaged
changes which might be missing from the commit.

Signed-off-by: Michael J Gruber <git@drmicha.warpmail.net>
---
 Documentation/git-commit.txt |  4 ++++
 t/t7508-status.sh            | 43 +++++++++++++++++++++++++++++++++++++++++++
 wt-status.c                  | 10 ++++++++++
 3 files changed, 57 insertions(+)

diff --git a/Documentation/git-commit.txt b/Documentation/git-commit.txt
index 1e74b75..f14d2ec 100644
--- a/Documentation/git-commit.txt
+++ b/Documentation/git-commit.txt
@@ -284,6 +284,10 @@ configuration variable documented in linkgit:git-config[1].
 	would be committed at the bottom of the commit message
 	template.  Note that this diff output doesn't have its
 	lines prefixed with '#'.
++
+If specified twice, show in addition the unified diff between
+what would be committed and the worktree files, i.e. the unstaged
+changes to tracked files.
 
 -q::
 --quiet::
diff --git a/t/t7508-status.sh b/t/t7508-status.sh
index 4989e98..6779195 100755
--- a/t/t7508-status.sh
+++ b/t/t7508-status.sh
@@ -139,6 +139,49 @@ test_expect_success 'status -v' '
 	test_cmp expect output
 '
 
+cat >expect <<\EOF
+On branch master
+Changes to be committed:
+  (use "git reset HEAD <file>..." to unstage)
+
+	new file:   dir2/added
+
+Changes not staged for commit:
+  (use "git add <file>..." to update what will be committed)
+  (use "git checkout -- <file>..." to discard changes in working directory)
+
+	modified:   dir1/modified
+
+Untracked files:
+  (use "git add <file>..." to include in what will be committed)
+
+	dir1/untracked
+	dir2/modified
+	dir2/untracked
+	expect
+	output
+	untracked
+
+diff --git HEAD=base-commit/dir2/added INDEX=staged-for-commit/dir2/added
+new file mode 100644
+index 0000000..00750ed
+--- /dev/null
++++ INDEX=staged-for-commit/dir2/added
+@@ -0,0 +1 @@
++3
+diff --git INDEX=staged-for-commit/dir1/modified WORKTREE=not-staged-for-commit/dir1/modified
+index e69de29..d00491f 100644
+--- INDEX=staged-for-commit/dir1/modified
++++ WORKTREE=not-staged-for-commit/dir1/modified
+@@ -0,0 +1 @@
++1
+EOF
+
+test_expect_success 'status -v -v' '
+	git status -v -v >output &&
+	test_cmp expect output
+'
+
 test_expect_success 'setup fake editor' '
 	cat >.git/editor <<-\EOF &&
 	#! /bin/sh
diff --git a/wt-status.c b/wt-status.c
index 29666d0..b6e9837 100644
--- a/wt-status.c
+++ b/wt-status.c
@@ -873,7 +873,17 @@ static void wt_status_print_verbose(struct wt_status *s)
 		rev.diffopt.use_color = 0;
 		wt_status_add_cut_line(s->fp);
 	}
+	if (s->verbose > 1) {
+		rev.diffopt.a_prefix = "HEAD=base-commit/";
+		rev.diffopt.b_prefix = "INDEX=staged-for-commit/";
+	} /* else use prefix as per user config */
 	run_diff_index(&rev, 1);
+	if (s->verbose > 1) {
+		setup_work_tree();
+		rev.diffopt.a_prefix = "INDEX=staged-for-commit/";
+		rev.diffopt.b_prefix = "WORKTREE=not-staged-for-commit/";
+		run_diff_files(&rev, 0);
+	}
 }
 
 static void wt_status_print_tracking(struct wt_status *s)
-- 
2.3.1.303.g5174db1