Merge branch 'jc/diff'

* jc/diff:
  git-diff-tree --stdin: show all parents.
  combine-diff: remove misguided --show-empty hack.

combine-diff.c

@@ -608,7 +608,7 @@ static void reuse_combine_diff(struct sline *sline, unsigned long cnt,
 }
 
 int show_combined_diff(struct combine_diff_path *elem, int num_parent,
-		       int dense, const char *header, int show_empty)
+		       int dense, const char *header)
 {
 	unsigned long size, cnt, lno;
 	char *result, *cp, *ep;
@@ -742,8 +742,7 @@ int show_combined_diff(struct combine_diff_path *elem, int num_parent,
 }
 
 int diff_tree_combined_merge(const unsigned char *sha1,
-			     const char *header,
-			     int show_empty_merge, int dense)
+			     const char *header, int dense)
 {
 	struct commit *commit = lookup_commit(sha1);
 	struct diff_options diffopts;
@@ -777,12 +776,11 @@ int diff_tree_combined_merge(const unsigned char *sha1,
 		if (p->len)
 			num_paths++;
 	}
-	if (num_paths || show_empty_merge) {
+	if (num_paths) {
 		for (p = paths; p; p = p->next) {
 			if (!p->len)
 				continue;
-			if (show_combined_diff(p, num_parent, dense, header,
-					       show_empty_merge))
+			if (show_combined_diff(p, num_parent, dense, header))
 				header = NULL;
 		}
 	}

diff-files.c

@@ -160,7 +160,7 @@ int main(int argc, const char **argv)
 			if (combine_merges && num_compare_stages == 2) {
 				show_combined_diff(&combine.p, 2,
 						   dense_combined_merges,
-						   NULL, 0);
+						   NULL);
 				free(combine.p.path);
 				continue;
 			}

diff-tree.c

@@ -6,7 +6,6 @@ static int show_root_diff = 0;
 static int no_commit_id = 0;
 static int verbose_header = 0;
 static int ignore_merges = 1;
-static int show_empty_combined = 0;
 static int combine_merges = 0;
 static int dense_combined_merges = 0;
 static int read_stdin = 0;
@@ -101,23 +100,15 @@ static const char *generate_header(const unsigned char *commit_sha1,
 	return this_header;
 }
 
-static int diff_tree_commit(const unsigned char *commit_sha1)
+static int diff_tree_commit(struct commit *commit)
 {
-	struct commit *commit;
 	struct commit_list *parents;
-	char name[50];
-	unsigned char sha1[20];
+	unsigned const char *sha1 = commit->object.sha1;
 
-	sprintf(name, "%s^0", sha1_to_hex(commit_sha1));
-	if (get_sha1(name, sha1))
-		return -1;
-	name[40] = 0;
-	commit = lookup_commit(sha1);
-	
 	/* Root commit? */
 	if (show_root_diff && !commit->parents) {
 		header = generate_header(sha1, NULL, commit);
-		diff_root_tree(commit_sha1, "");
+		diff_root_tree(sha1, "");
 	}
 
 	/* More than one parent? */
@@ -127,7 +118,6 @@ static int diff_tree_commit(const unsigned char *commit_sha1)
 		else if (combine_merges) {
 			header = generate_header(sha1, sha1, commit);
 			return diff_tree_combined_merge(sha1, header,
-							show_empty_combined,
 							dense_combined_merges);
 		}
 	}
@@ -135,7 +125,7 @@ static int diff_tree_commit(const unsigned char *commit_sha1)
 	for (parents = commit->parents; parents; parents = parents->next) {
 		struct commit *parent = parents->item;
 		header = generate_header(sha1, parent->object.sha1, commit);
-		diff_tree_sha1_top(parent->object.sha1, commit_sha1, "");
+		diff_tree_sha1_top(parent->object.sha1, sha1, "");
 		if (!header && verbose_header) {
 			header_prefix = "\ndiff-tree ";
 			/*
@@ -147,28 +137,49 @@ static int diff_tree_commit(const unsigned char *commit_sha1)
 	return 0;
 }
 
+static int diff_tree_commit_sha1(const unsigned char *sha1)
+{
+	struct commit *commit = lookup_commit_reference(sha1);
+	if (!commit)
+		return -1;
+	return diff_tree_commit(commit);
+}
+
 static int diff_tree_stdin(char *line)
 {
 	int len = strlen(line);
-	unsigned char commit[20], parent[20];
-	static char this_header[1000];
-	int abbrev = diff_options.abbrev;
+	unsigned char sha1[20];
+	struct commit *commit;
 
 	if (!len || line[len-1] != '\n')
 		return -1;
 	line[len-1] = 0;
-	if (get_sha1_hex(line, commit))
+	if (get_sha1_hex(line, sha1))
+		return -1;
+	commit = lookup_commit(sha1);
+	if (!commit || parse_commit(commit))
 		return -1;
-	if (isspace(line[40]) && !get_sha1_hex(line+41, parent)) {
-		line[40] = 0;
-		line[81] = 0;
-		sprintf(this_header, "%s (from %s)\n",
-			diff_unique_abbrev(commit, abbrev),
-			diff_unique_abbrev(parent, abbrev));
-		header = this_header;
-		return diff_tree_sha1_top(parent, commit, "");
+	if (isspace(line[40]) && !get_sha1_hex(line+41, sha1)) {
+		/* Graft the fake parents locally to the commit */
+		int pos = 41;
+		struct commit_list **pptr, *parents;
+
+		/* Free the real parent list */
+		for (parents = commit->parents; parents; ) {
+			struct commit_list *tmp = parents->next;
+			free(parents);
+			parents = tmp;
+		}
+		commit->parents = NULL;
+		pptr = &(commit->parents);
+		while (line[pos] && !get_sha1_hex(line + pos, sha1)) {
+			struct commit *parent = lookup_commit(sha1);
+			if (parent) {
+				pptr = &commit_list_insert(parent, pptr)->next;
+			}
+			pos += 41;
+		}
 	}
-	line[40] = 0;
 	return diff_tree_commit(commit);
 }
 
@@ -278,7 +289,6 @@ int main(int argc, const char **argv)
 
 	if (combine_merges) {
 		diff_options.output_format = DIFF_FORMAT_PATCH;
-		show_empty_combined = !ignore_merges;
 		ignore_merges = 0;
 	}
 
@@ -291,7 +301,7 @@ int main(int argc, const char **argv)
 			usage(diff_tree_usage);
 		break;
 	case 1:
-		diff_tree_commit(sha1[0]);
+		diff_tree_commit_sha1(sha1[0]);
 		break;
 	case 2:
 		diff_tree_sha1_top(sha1[0], sha1[1], "");

diff.h

@@ -68,9 +68,9 @@ struct combine_diff_path {
 };
 
 int show_combined_diff(struct combine_diff_path *elem, int num_parent,
-		       int dense, const char *header, int show_empty);
+		       int dense, const char *header);
 
-extern int diff_tree_combined_merge(const unsigned char *sha1, const char *, int, int);
+extern int diff_tree_combined_merge(const unsigned char *sha1, const char *, int);
 
 extern void diff_addremove(struct diff_options *,
 			   int addremove,