[PATCH] Detect renames in diff family.

This rips out the rename detection engine from diff-helper and moves it
to the diff core, and updates the internal calling convention used by
diff-tree family into the diff core.  In order to give the same option
name to diff-tree family as well as to diff-helper, I've changed the
earlier diff-helper '-r' option to '-M' (stands for Move; sorry but the
natural abbreviation 'r' for 'rename' is already taken for 'recursive').

Although I did a fair amount of test with the git-diff-tree with
existing rename commits in the core GIT repository, this should still be
considered beta (preview) release.  This patch depends on the diff-delta
infrastructure just committed.

This implements almost everything I wanted to see in this series of
patch, except a few minor cleanups in the calling convention into diff
core, but that will be a separate cleanup patch.

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

Documentation/git-diff-cache.txt

@@ -9,7 +9,7 @@ git-diff-cache - Compares content and mode of blobs between the cache and reposi
 
 SYNOPSIS
 --------
-'git-diff-cache' [-p] [-r] [-z] [-m] [--cached] <tree-ish>
+'git-diff-cache' [-p] [-r] [-z] [-m] [-M] [--cached] <tree-ish>
 
 DESCRIPTION
 -----------
@@ -33,6 +33,9 @@ OPTIONS
 -z::
 	\0 line termination on output
 
+-M::
+	Detect renames; implies -p.
+
 --cached::
 	do not consider the on-disk file at all
 

Documentation/git-diff-files.txt

@@ -9,7 +9,7 @@ git-diff-files - Compares files in the working tree and the cache
 
 SYNOPSIS
 --------
-'git-diff-files' [-p] [-q] [-r] [-z] [<pattern>...]
+'git-diff-files' [-p] [-q] [-r] [-z] [-M] [<pattern>...]
 
 DESCRIPTION
 -----------
@@ -26,6 +26,9 @@ OPTIONS
 -q::
 	Remain silent even on nonexisting files
 
+-M::
+	Detect renames; implies -p.
+
 -r::
 	This flag does not mean anything.  It is there only to match
 	git-diff-tree.  Unlike git-diff-tree, git-diff-files always looks

Documentation/git-diff-helper.txt

@@ -9,7 +9,7 @@ git-diff-helper - Generates patch format output for git-diff-*
 
 SYNOPSIS
 --------
-'git-diff-helper' [-z] [-R] [-r]
+'git-diff-helper' [-z] [-R] [-M]
 
 DESCRIPTION
 -----------
@@ -31,7 +31,7 @@ OPTIONS
 	would show a diff to bring the working file back to what
 	is in the <tree>.
 
--r::
+-M::
 	Detect renames.
 
 

Documentation/git-diff-tree.txt

@@ -9,7 +9,7 @@ git-diff-tree - Compares the content and mode of blobs found via two tree object
 
 SYNOPSIS
 --------
-'git-diff-tree' [-p] [-r] [-z] [--stdin] [-m] [-s] [-v] <tree-ish> <tree-ish> [<pattern>]\*
+'git-diff-tree' [-p] [-r] [-z] [--stdin] [-M] [-m] [-s] [-v] <tree-ish> <tree-ish> [<pattern>]\*
 
 DESCRIPTION
 -----------
@@ -33,6 +33,9 @@ OPTIONS
 	generate patch (see section on generating patches).  For
 	git-diff-tree, this flag implies '-r' as well.
 
+-M::
+	Detect renames; implies -p, in turn implying also '-r'.
+
 -r::
 	recurse
 

diff-cache.c

@@ -5,6 +5,7 @@ static int cached_only = 0;
 static int generate_patch = 0;
 static int match_nonexisting = 0;
 static int line_termination = '\n';
+static int detect_rename = 0;
 
 /* A file entry went away or appeared */
 static void show_file(const char *prefix, struct cache_entry *ce, unsigned char *sha1, unsigned int mode)
@@ -165,13 +166,14 @@ static void mark_merge_entries(void)
 }
 
 static char *diff_cache_usage =
-"git-diff-cache [-p] [-r] [-z] [-m] [--cached] <tree sha1>";
+"git-diff-cache [-p] [-r] [-z] [-m] [-M] [--cached] <tree-ish>";
 
 int main(int argc, char **argv)
 {
 	unsigned char tree_sha1[20];
 	void *tree;
 	unsigned long size;
+	int ret;
 
 	read_cache();
 	while (argc > 2) {
@@ -186,6 +188,10 @@ int main(int argc, char **argv)
 			generate_patch = 1;
 			continue;
 		}
+		if (!strcmp(arg, "-M")) {
+			generate_patch = detect_rename = 1;
+			continue;
+		}
 		if (!strcmp(arg, "-z")) {
 			line_termination = '\0';
 			continue;
@@ -204,6 +210,9 @@ int main(int argc, char **argv)
 	if (argc != 2 || get_sha1(argv[1], tree_sha1))
 		usage(diff_cache_usage);
 
+	if (generate_patch)
+		diff_setup(detect_rename, 0, 0, 0, 0);
+
 	mark_merge_entries();
 
 	tree = read_object_with_reference(tree_sha1, "tree", &size, 0);
@@ -212,5 +221,8 @@ int main(int argc, char **argv)
 	if (read_tree(tree, size, 1))
 		die("unable to read tree object %s", argv[1]);
 
-	return diff_cache(active_cache, active_nr);
+	ret = diff_cache(active_cache, active_nr);
+	if (generate_patch)
+		diff_flush();
+	return ret;
 }

diff-files.c

@@ -7,10 +7,11 @@
 #include "diff.h"
 
 static const char *diff_files_usage =
-"diff-files [-p] [-q] [-r] [-z] [paths...]";
+"diff-files [-p] [-q] [-r] [-z] [-M] [paths...]";
 
 static int generate_patch = 0;
 static int line_termination = '\n';
+static int detect_rename = 0;
 static int silent = 0;
 
 static int matches_pathspec(struct cache_entry *ce, char **spec, int cnt)
@@ -79,6 +80,9 @@ int main(int argc, char **argv)
 			; /* no-op */
 		else if (!strcmp(argv[1], "-z"))
 			line_termination = 0;
+		else if (!strcmp(argv[1], "-M")) {
+			detect_rename = generate_patch = 1;
+		}
 		else
 			usage(diff_files_usage);
 		argv++; argc--;
@@ -92,6 +96,9 @@ int main(int argc, char **argv)
 		exit(1);
 	}
 
+	if (generate_patch)
+		diff_setup(detect_rename, 0, 0, 0, 0);		
+
 	for (i = 0; i < entries; i++) {
 		struct stat st;
 		unsigned int oldmode, mode;
@@ -132,5 +139,7 @@ int main(int argc, char **argv)
 		show_modified(oldmode, mode, ce->sha1, null_sha1,
 			      ce->name);
 	}
+	if (generate_patch)
+		diff_flush();
 	return 0;
 }