git log -p -m: document -m and honor --first-parent

git log -p -m is used to show one merge entry per parent, with an
appropriate diff; this can be useful when examining histories where
full set of changes introduced by a merged branch is interesting, not
only the conflicts.

This patch properly documents the -m switch, which has so far been
mentioned only as a fairly special diff-tree flag.

It also makes the code show full patch entry only for the first parent
when --first-parent is used. Thus:

git log -p -m --first-parent

will show the history from the "main branch perspective", while also
including full diff of changes introduced by other merged in branches.

Signed-off-by: Petr Baudis <pasky@suse.cz>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/Documentation/diff-generate-patch.txt b/Documentation/diff-generate-patch.txt
index 0f25ba7e3857e6c4f18c3589b31f082b602df6dc..8f9a2412fd44c80f2bf8d63271e2897ebeb3ddeb 100644 (file)
--- a/Documentation/diff-generate-patch.txt
+++ b/Documentation/diff-generate-patch.txt
@@ -56,7 +56,8 @@ combined diff format
 
 "git-diff-tree", "git-diff-files" and "git-diff" can take '-c' or
 '--cc' option to produce 'combined diff'.  For showing a merge commit
 
 "git-diff-tree", "git-diff-files" and "git-diff" can take '-c' or
 '--cc' option to produce 'combined diff'.  For showing a merge commit

-with "git log -p", this is the default format.
+with "git log -p", this is the default format; you can force showing
+full diff with the '-m' option.

 A 'combined diff' format looks like this:
 
 ------------
 A 'combined diff' format looks like this:
 
 ------------

diff --git a/Documentation/git-log.txt b/Documentation/git-log.txt
index 0e39bb61eebfce5d1bff032c65bf04bb77f8ce62..fb184ba1863845797a5f296581ec74a1b31bef1a 100644 (file)
--- a/Documentation/git-log.txt
+++ b/Documentation/git-log.txt
@@ -118,6 +118,15 @@ git log master --not --remotes=*/master::
        Shows all commits that are in local master but not in any remote
        repository master branches.
 
        Shows all commits that are in local master but not in any remote
        repository master branches.
 

+git log -p -m --first-parent::
+
+       Shows the history including change diffs, but only from the
+       "main branch" perspective, skipping commits that come from merged
+       branches, and showing full diffs of changes introduced by the merges.
+       This makes sense only when following a strict policy of merging all
+       topic branches when staying on a single integration branch.
+
+

 Discussion
 ----------
 
 Discussion
 ----------
 

diff --git a/Documentation/rev-list-options.txt b/Documentation/rev-list-options.txt
index 6e9baf8b38be5fba5e3c82e617ab95d579731884..39a064b53354d162ab0820c4af293182b9ad997b 100644 (file)
--- a/Documentation/rev-list-options.txt
+++ b/Documentation/rev-list-options.txt
@@ -108,8 +108,8 @@ options may be given. See linkgit:git-diff-files[1] for more options.
 
 -c::
 
 
 -c::
 

-       This flag changes the way a merge commit is displayed.  It shows
-       the differences from each of the parents to the merge result
+       With this option, diff output for a merge commit
+       shows the differences from each of the parents to the merge result

        simultaneously instead of showing pairwise diff between a parent
        and the result one at a time. Furthermore, it lists only files
        which were modified from all parents.
        simultaneously instead of showing pairwise diff between a parent
        and the result one at a time. Furthermore, it lists only files
        which were modified from all parents.


@@ -121,6 +121,15 @@ options may be given. See linkgit:git-diff-files[1] for more options.
        the parents have only two variants and the merge result picks
        one of them without modification.
 
        the parents have only two variants and the merge result picks
        one of them without modification.
 

+-m::
+
+       This flag makes the merge commits show the full diff like
+       regular commits; for each merge parent, a separate log entry
+       and diff is generated. An exception is that only diff against
+       the first parent is shown when '--first-parent' option is given;
+       in that case, the output represents the changes the merge
+       brought _into_ the then-current branch.
+

 -r::
 
        Show recursive diffs.
 -r::
 
        Show recursive diffs.

diff --git a/log-tree.c b/log-tree.c
index 27afcf697238a48c01dd49996f5263cd72a52eac..d3ae969f608b50a469aa60b2e925558a6bb437e5 100644 (file)
--- a/log-tree.c
+++ b/log-tree.c
@@ -514,6 +514,16 @@ static int log_tree_diff(struct rev_info *opt, struct commit *commit, struct log
                        return 0;
                else if (opt->combine_merges)
                        return do_diff_combined(opt, commit);
                        return 0;
                else if (opt->combine_merges)
                        return do_diff_combined(opt, commit);

+               else if (opt->first_parent_only) {
+                       /*
+                        * Generate merge log entry only for the first
+                        * parent, showing summary diff of the others
+                        * we merged _in_.
+                        */
+                       diff_tree_sha1(parents->item->object.sha1, sha1, "", &opt->diffopt);
+                       log_tree_diff_flush(opt);
+                       return !opt->loginfo;
+               }

 
                /* If we show individual diffs, show the parent info */
                log->parent = parents->item;
 
                /* If we show individual diffs, show the parent info */
                log->parent = parents->item;