[PATCH v6 0/3] Add support for displaying submodules as a proper diff

From: Jacob Keller <jacob.keller@gmail.com>

This patch series adds support for displaying a submodule as a difference between the pre and post commits. This allows projects who frequently update submodule contents to view the submodule in the log as if it were just one squashed commit that updates all the files in the submodule together, even if you mix-match the submodule part with a regular part you just see a complete diff that shows all the changes.

To make this work, I also extended the graph-aware output with a --line-prefix option. This option extends both diff and log to show a prefix. It's a bit of a hack in someways, but it works for showing a prefix both when graph is enabled and when its not. I think it works quite well.

I added several tests to the line-prefix, and also a few tests for the new submodule format.

I welcome comments on how to improve the graph line-prefix code, as well as the actual submodule diff format.

Jacob Keller (2):
  graph: add support for --line-prefix on all graph-aware output
  diff: add SUBMODULE_DIFF format to display submodule diff

Junio C Hamano (1):
  diff.c: remove output_prefix_length field

 Documentation/diff-config.txt                      |   3 +-
 Documentation/diff-options.txt                     |  10 +-
 builtin/rev-list.c                                 |  70 +-
 diff.c                                             |  49 +-
 diff.h                                             |  11 +-
 graph.c                                            | 105 +--
 graph.h                                            |  22 +-
 log-tree.c                                         |   5 +-
 submodule.c                                        | 130 ++++
 submodule.h                                        |   6 +
 t/t4013-diff-various.sh                            |   6 +
 ...diff.diff_--line-prefix=abc_master_master^_side |  29 +
 t/t4013/diff.diff_--line-prefix_--cached_--_file0  |  15 +
 t/t4059-diff-submodule-option-diff-format.sh       | 738 +++++++++++++++++++++
 t/t4202-log.sh                                     | 323 +++++++++
 15 files changed, 1419 insertions(+), 103 deletions(-)
 create mode 100644 t/t4013/diff.diff_--line-prefix=abc_master_master^_side
 create mode 100644 t/t4013/diff.diff_--line-prefix_--cached_--_file0
 create mode 100755 t/t4059-diff-submodule-option-diff-format.sh