Merge branch 'jc/blame-reverse'

It is a common mistake to say "git blame --reverse OLD path",
expecting that the command line is dwimmed as if asking how lines
in path in an old revision OLD have survived up to the current
commit.

* jc/blame-reverse:
blame: dwim "blame --reverse OLD" as "blame --reverse OLD.."
blame: improve diagnosis for "--reverse NEW"

diff --git a/Documentation/blame-options.txt b/Documentation/blame-options.txt
index 02cb6845cd96194b655c9898189c4d5f24ca6a92..2669b87c9d59a80e5e4f3d0ade1893ec8e5b3f30 100644 (file)
--- a/Documentation/blame-options.txt
+++ b/Documentation/blame-options.txt
@@ -28,12 +28,13 @@ include::line-range-format.txt[]
 -S <revs-file>::
        Use revisions from revs-file instead of calling linkgit:git-rev-list[1].
 
---reverse::
+--reverse <rev>..<rev>::
        Walk history forward instead of backward. Instead of showing
        the revision in which a line appeared, this shows the last
        revision in which a line has existed. This requires a range of
        revision like START..END where the path to blame exists in
-       START.
+       START.  `git blame --reverse START` is taken as `git blame
+       --reverse START..HEAD` for convenience.
 
 -p::
 --porcelain::

diff --git a/Documentation/git-blame.txt b/Documentation/git-blame.txt
index 9dccb3319b2f5faa0ca7fd36b365f30cce5d3e89..fdc3aea30a4cdb480d469455a66e51a76366be93 100644 (file)
--- a/Documentation/git-blame.txt
+++ b/Documentation/git-blame.txt
@@ -10,7 +10,7 @@ SYNOPSIS
 [verse]
 'git blame' [-c] [-b] [-l] [--root] [-t] [-f] [-n] [-s] [-e] [-p] [-w] [--incremental]
            [-L <range>] [-S <revs-file>] [-M] [-C] [-C] [-C] [--since=<date>]
-           [--progress] [--abbrev=<n>] [<rev> | --contents <file> | --reverse <rev>]
+           [--progress] [--abbrev=<n>] [<rev> | --contents <file> | --reverse <rev>..<rev>]
            [--] <file>
 
 DESCRIPTION

diff --git a/builtin/blame.c b/builtin/blame.c
index da44b36ff5eab12a442e5299ff8b98c2505b16f4..4ddfadb71f7ef93958e2f236e166212e8b6bda2b 100644 (file)
--- a/builtin/blame.c
+++ b/builtin/blame.c
@@ -2456,6 +2456,41 @@ static char *prepare_final(struct scoreboard *sb)
        return xstrdup_or_null(name);
 }
 
+static const char *dwim_reverse_initial(struct scoreboard *sb)
+{
+       /*
+        * DWIM "git blame --reverse ONE -- PATH" as
+        * "git blame --reverse ONE..HEAD -- PATH" but only do so
+        * when it makes sense.
+        */
+       struct object *obj;
+       struct commit *head_commit;
+       unsigned char head_sha1[20];
+
+       if (sb->revs->pending.nr != 1)
+               return NULL;
+
+       /* Is that sole rev a committish? */
+       obj = sb->revs->pending.objects[0].item;
+       obj = deref_tag(obj, NULL, 0);
+       if (obj->type != OBJ_COMMIT)
+               return NULL;
+
+       /* Do we have HEAD? */
+       if (!resolve_ref_unsafe("HEAD", RESOLVE_REF_READING, head_sha1, NULL))
+               return NULL;
+       head_commit = lookup_commit_reference_gently(head_sha1, 1);
+       if (!head_commit)
+               return NULL;
+
+       /* Turn "ONE" into "ONE..HEAD" then */
+       obj->flags |= UNINTERESTING;
+       add_pending_object(sb->revs, &head_commit->object, "HEAD");
+
+       sb->final = (struct commit *)obj;
+       return sb->revs->pending.objects[0].name;
+}
+
 static char *prepare_initial(struct scoreboard *sb)
 {
        int i;
@@ -2474,14 +2509,17 @@ static char *prepare_initial(struct scoreboard *sb)
                if (obj->type != OBJ_COMMIT)
                        die("Non commit %s?", revs->pending.objects[i].name);
                if (sb->final)
-                       die("More than one commit to dig down to %s and %s?",
+                       die("More than one commit to dig up from, %s and %s?",
                            revs->pending.objects[i].name,
                            final_commit_name);
                sb->final = (struct commit *) obj;
                final_commit_name = revs->pending.objects[i].name;
        }
+
+       if (!final_commit_name)
+               final_commit_name = dwim_reverse_initial(sb);
        if (!final_commit_name)
-               die("No commit to dig down to?");
+               die("No commit to dig up from?");
        return xstrdup(final_commit_name);
 }