Merge branch 'jk/diff-submodule-diff-inline'

The "git diff --submodule={short,log}" mechanism has been enhanced
to allow "--submodule=diff" to show the patch between the submodule
commits bound to the superproject.

* jk/diff-submodule-diff-inline:
  diff: teach diff to display submodule difference with an inline diff
  submodule: refactor show_submodule_summary with helper function
  submodule: convert show_submodule_summary to use struct object_id *
  allow do_submodule_path to work even if submodule isn't checked out
  diff: prepare for additional submodule formats
  graph: add support for --line-prefix on all graph-aware output
  diff.c: remove output_prefix_length field
  cache: add empty_tree_oid object and helper function

2 files changed, 18 insertions, 11 deletions

diff --git a/Documentation/diff-config.txt b/Documentation/diff-config.txt
index d5a5b17d50..0eded24034 100644
--- a/Documentation/diff-config.txt
+++ b/Documentation/diff-config.txt
@@ -122,10 +122,11 @@ diff.suppressBlankEmpty::
 
 diff.submodule::
 	Specify the format in which differences in submodules are
-	shown.  The "log" format lists the commits in the range like
-	linkgit:git-submodule[1] `summary` does.  The "short" format
-	format just shows the names of the commits at the beginning
-	and end of the range.  Defaults to short.
+	shown.  The "short" format just shows the names of the commits
+	at the beginning and end of the range. The "log" format lists
+	the commits in the range like linkgit:git-submodule[1] `summary`
+	does. The "diff" format shows an inline diff of the changed
+	contents of the submodule. Defaults to "short".
 
 diff.wordRegex::
 	A POSIX Extended Regular Expression used to determine what is a "word"
diff --git a/Documentation/diff-options.txt b/Documentation/diff-options.txt
index 705a873942..7805a0ccad 100644
--- a/Documentation/diff-options.txt
+++ b/Documentation/diff-options.txt
@@ -210,13 +210,16 @@ any of those replacements occurred.
 	of the `--diff-filter` option on what the status letters mean.
 
 --submodule[=<format>]::
-	Specify how differences in submodules are shown.  When `--submodule`
-	or `--submodule=log` is given, the 'log' format is used.  This format lists
-	the commits in the range like linkgit:git-submodule[1] `summary` does.
-	Omitting the `--submodule` option or specifying `--submodule=short`,
-	uses the 'short' format. This format just shows the names of the commits
-	at the beginning and end of the range.  Can be tweaked via the
-	`diff.submodule` configuration variable.
+	Specify how differences in submodules are shown.  When specifying
+	`--submodule=short` the 'short' format is used.  This format just
+	shows the names of the commits at the beginning and end of the range.
+	When `--submodule` or `--submodule=log` is specified, the 'log'
+	format is used.  This format lists the commits in the range like
+	linkgit:git-submodule[1] `summary` does.  When `--submodule=diff`
+	is specified, the 'diff' format is used.  This format shows an
+	inline diff of the changes in the submodule contents between the
+	commit range.  Defaults to `diff.submodule` or the 'short' format
+	if the config option is unset.
 
 --color[=<when>]::
 	Show colored diff.
@@ -569,5 +572,8 @@ endif::git-format-patch[]
 --no-prefix::
 	Do not show any source or destination prefix.
 
+--line-prefix=<prefix>::
+	Prepend an additional prefix to every line of output.
+
 For more detailed explanation on these common options, see also
 linkgit:gitdiffcore[7].