built-in diff: assorted updates.

"git diff(n)" without --base, --ours, etc. defaults to --cc,
which usually is the same as -p unless you are in the middle of
a conflicted merge, just like the shell script version.

"git diff(n) blobA blobB path" complains and dies.

"git diff(n) tree0 tree1 tree2...treeN" does combined diff that
shows a merge of tree1..treeN to result in tree0.

Giving "-c" option to any command that defaults to "--cc" turns
off dense-combined flag.

Signed-off-by: Junio C Hamano <junkio@cox.net>

1 files changed, 30 insertions, 17 deletions

diff --git a/combine-diff.c b/combine-diff.c
index ca36f5d5e7..8a8fe3863a 100644
--- a/combine-diff.c
+++ b/combine-diff.c
@@ -831,15 +831,16 @@ void show_combined_diff(struct combine_diff_path *p,
 	}
 }
 
-void diff_tree_combined_merge(const unsigned char *sha1,
-			     int dense, struct rev_info *rev)
+void diff_tree_combined(const unsigned char *sha1,
+			const unsigned char parent[][20],
+			int num_parent,
+			int dense,
+			struct rev_info *rev)
 {
 	struct diff_options *opt = &rev->diffopt;
-	struct commit *commit = lookup_commit(sha1);
 	struct diff_options diffopts;
-	struct commit_list *parents;
 	struct combine_diff_path *p, *paths = NULL;
-	int num_parent, i, num_paths;
+	int i, num_paths;
 	int do_diffstat;
 
 	do_diffstat = (opt->output_format == DIFF_FORMAT_DIFFSTAT ||
@@ -849,17 +850,8 @@ void diff_tree_combined_merge(const unsigned char *sha1,
 	diffopts.with_stat = 0;
 	diffopts.recursive = 1;
 
-	/* count parents */
-	for (parents = commit->parents, num_parent = 0;
-	     parents;
-	     parents = parents->next, num_parent++)
-		; /* nothing */
-
 	/* find set of paths that everybody touches */
-	for (parents = commit->parents, i = 0;
-	     parents;
-	     parents = parents->next, i++) {
-		struct commit *parent = parents->item;
+	for (i = 0; i < num_parent; i++) {
 		/* show stat against the first parent even
 		 * when doing combined diff.
 		 */
@@ -867,8 +859,7 @@ void diff_tree_combined_merge(const unsigned char *sha1,
 			diffopts.output_format = DIFF_FORMAT_DIFFSTAT;
 		else
 			diffopts.output_format = DIFF_FORMAT_NO_OUTPUT;
-		diff_tree_sha1(parent->object.sha1, commit->object.sha1, "",
-			       &diffopts);
+		diff_tree_sha1(parent[i], sha1, "", &diffopts);
 		diffcore_std(&diffopts);
 		paths = intersect_paths(paths, i, num_parent);
 
@@ -907,3 +898,25 @@ void diff_tree_combined_merge(const unsigned char *sha1,
 		free(tmp);
 	}
 }
+
+void diff_tree_combined_merge(const unsigned char *sha1,
+			     int dense, struct rev_info *rev)
+{
+	int num_parent;
+	const unsigned char (*parent)[20];
+	struct commit *commit = lookup_commit(sha1);
+	struct commit_list *parents;
+
+	/* count parents */
+	for (parents = commit->parents, num_parent = 0;
+	     parents;
+	     parents = parents->next, num_parent++)
+		; /* nothing */
+
+	parent = xmalloc(num_parent * sizeof(*parent));
+	for (parents = commit->parents, num_parent = 0;
+	     parents;
+	     parents = parents->next, num_parent++)
+		memcpy(parent + num_parent, parents->item->object.sha1, 20);
+	diff_tree_combined(sha1, parent, num_parent, dense, rev);
+}