Merge branch 'kh/diff-tree'

* kh/diff-tree:
  Add test for diff-tree --stdin with two trees
  Teach git diff-tree --stdin to diff trees
  diff-tree: Note that the commit ID is printed with --stdin
  Refactoring: Split up diff_tree_stdin

1 files changed, 14 insertions, 5 deletions

diff --git a/Documentation/git-diff-tree.txt b/Documentation/git-diff-tree.txt
index 1fdf20dcc..5d48664e6 100644
--- a/Documentation/git-diff-tree.txt
+++ b/Documentation/git-diff-tree.txt
@@ -49,13 +49,22 @@ include::diff-options.txt[]
 --stdin::
 	When '--stdin' is specified, the command does not take
 	<tree-ish> arguments from the command line.  Instead, it
-	reads either one <commit> or a list of <commit>
-	separated with a single space from its standard input.
+	reads lines containing either two <tree>, one <commit>, or a
+	list of <commit> from its standard input.  (Use a single space
+	as separator.)
 +
-When a single commit is given on one line of such input, it compares
-the commit with its parents.  The following flags further affects its
-behavior.  The remaining commits, when given, are used as if they are
+When two trees are given, it compares the first tree with the second.
+When a single commit is given, it compares the commit with its
+parents.  The remaining commits, when given, are used as if they are
 parents of the first commit.
++
+When comparing two trees, the ID of both trees (separated by a space
+and terminated by a newline) is printed before the difference.  When
+comparing commits, the ID of the first (or only) commit, followed by a
+newline, is printed.
++
+The following flags further affects the behavior when comparing
+commits (but not trees).
 
 -m::
 	By default, 'git-diff-tree --stdin' does not show