[PATCH] diff-cache/tree compatible output for show-diff (take 2).

This makes diff-tree-helper handle ("warn about") unmerged path entries

    U <path> <record-terminator>

This is emitted once per unmerged path, no matter how many unmerged
stages there are. 

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

diff-tree-helper.c

@@ -44,6 +44,9 @@ static int parse_oneside_change(const char *cp, struct diff_spec *one,
 	return 0;
 }
 
+#define PLEASE_WARN -1
+#define WARNED_OURSELVES -2
+ 
 static int parse_diff_tree_output(const char *buf,
 				  struct diff_spec *old,
 				  struct diff_spec *new,
@@ -52,6 +55,9 @@ static int parse_diff_tree_output(const char *buf,
 	int ch;
 
 	switch (*cp++) {
+	case 'U':
+		fprintf(stderr, "warning: unmerged path %s\n", cp+1);
+		return WARNED_OURSELVES;
 	case '+':
 		old->file_valid = 0;
 		return parse_oneside_change(cp, new, path);
@@ -61,7 +67,7 @@ static int parse_diff_tree_output(const char *buf,
 	case '*':
 		break;
 	default:
-		return -1;
+		return PLEASE_WARN;
 	}
 	
 	/* This is for '*' entries */
@@ -74,26 +80,26 @@ static int parse_diff_tree_output(const char *buf,
 		cp++;
 	}
 	if (strncmp(cp, "->", 2))
-		return -1;
+		return PLEASE_WARN;
 	cp += 2;
 	while ((ch = *cp) && ('0' <= ch && ch <= '7')) {
 		new->mode = (new->mode << 3) | (ch - '0');
 		cp++;
 	}
 	if (strncmp(cp, "\tblob\t", 6))
-		return -1;
+		return PLEASE_WARN;
 	cp += 6;
 	if (get_sha1_hex(cp, old->u.sha1))
-		return -1;
+		return PLEASE_WARN;
 	cp += 40;
 	if (strncmp(cp, "->", 2))
-		return -1;
+		return PLEASE_WARN;
 	cp += 2;
 	if (get_sha1_hex(cp, new->u.sha1))
-		return -1;
+		return PLEASE_WARN;
 	cp += 40;
 	if (*cp++ != '\t')
-		return -1;
+		return PLEASE_WARN;
 	strcpy(path, cp);
 	return 0;
 }
@@ -120,12 +126,15 @@ int main(int ac, char **av) {
 	/* the remaining parameters are paths patterns */
 
 	while (1) {
+		int status;
 		struct diff_spec old, new;
 		char path[PATH_MAX];
 		read_line(&sb, stdin, line_termination);
 		if (sb.eof)
 			break;
-		if (parse_diff_tree_output(sb.buf, &old, &new, path)) { 
+		status = parse_diff_tree_output(sb.buf, &old, &new, path);
+		if (status) {
+			if (status == PLEASE_WARN)
 				fprintf(stderr, "cannot parse %s\n", sb.buf);
 			continue;
 		}