Tentative built-in "git show"

This uses the "--no-walk" flag that I never actually implemented (but I'm
sure I mentioned it) to make "git show" be essentially the same thing as
"git whatchanged --no-walk".

It just refuses to add more interesting parents to the revision walking
history, so you don't actually get any history, you just get the commit
you asked for.

I was going to add "--no-walk" as a real argument flag to git-rev-list
too, but I'm not sure anybody actually needs it. Although it might be
useful for porcelain, so I left the door open.

[jc: ported to the unified option structure by Linus]

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

git.c

@@ -354,6 +354,23 @@ static int cmd_wc(int argc, const char **argv, char **envp)
 	return cmd_log_wc(argc, argv, envp, &rev);
 }
 
+static int cmd_show(int argc, const char **argv, char **envp)
+{
+	struct rev_info rev;
+
+	init_revisions(&rev);
+	rev.diff = 1;
+	rev.ignore_merges = 0;
+	rev.combine_merges = 1;
+	rev.dense_combined_merges = 1;
+	rev.abbrev = DEFAULT_ABBREV;
+	rev.commit_format = CMIT_FMT_DEFAULT;
+	rev.diffopt.recursive = 1;
+	rev.no_walk = 1;
+	argc = setup_revisions(argc, argv, &rev, "HEAD");
+	return cmd_log_wc(argc, argv, envp, &rev);
+}
+
 static int cmd_log(int argc, const char **argv, char **envp)
 {
 	struct rev_info rev;
@@ -377,6 +394,7 @@ static void handle_internal_command(int argc, const char **argv, char **envp)
 		{ "help", cmd_help },
 		{ "log", cmd_log },
 		{ "whatchanged", cmd_wc },
+		{ "show", cmd_show },
 	};
 	int i;
 

revision.c

@@ -380,6 +380,9 @@ static void add_parents_to_list(struct rev_info *revs, struct commit *commit, st
 	if (revs->prune_fn)
 		revs->prune_fn(revs, commit);
 
+	if (revs->no_walk)
+		return;
+
 	parent = commit->parents;
 	while (parent) {
 		struct commit *p = parent->item;
@@ -816,6 +819,8 @@ void prepare_revision_walk(struct rev_info *revs)
 		list = list->next;
 	}
 
+	if (revs->no_walk)
+		return;
 	if (revs->limited)
 		limit_list(revs);
 	if (revs->topo_order)

revision.h

@@ -26,6 +26,7 @@ struct rev_info {
 	/* Traversal flags */
 	unsigned int	dense:1,
 			no_merges:1,
+			no_walk:1,
 			remove_empty_trees:1,
 			lifo:1,
 			topo_order:1,