use SWAP macro

Apply the semantic patch swap.cocci to convert hand-rolled swaps to use
the macro SWAP.  The resulting code is shorter and easier to read, the
object code is effectively unchanged.

The patch for object.c had to be hand-edited in order to preserve the
comment before the change; Coccinelle tried to eat it for some reason.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/diff-tree.c

@@ -147,9 +147,7 @@ int cmd_diff_tree(int argc, const char **argv, const char *prefix)
 		tree1 = opt->pending.objects[0].item;
 		tree2 = opt->pending.objects[1].item;
 		if (tree2->flags & UNINTERESTING) {
-			struct object *tmp = tree2;
+			SWAP(tree2, tree1);
-			tree2 = tree1;
-			tree1 = tmp;
 		}
 		diff_tree_sha1(tree1->oid.hash,
 			       tree2->oid.hash,

builtin/diff.c

@@ -45,12 +45,9 @@ static void stuff_change(struct diff_options *opt,
 		return;
 
 	if (DIFF_OPT_TST(opt, REVERSE_DIFF)) {
-		unsigned tmp;
+		SWAP(old_mode, new_mode);
-		const unsigned char *tmp_u;
+		SWAP(old_sha1, new_sha1);
-		const char *tmp_c;
+		SWAP(old_name, new_name);
-		tmp = old_mode; old_mode = new_mode; new_mode = tmp;
-		tmp_u = old_sha1; old_sha1 = new_sha1; new_sha1 = tmp_u;
-		tmp_c = old_name; old_name = new_name; new_name = tmp_c;
 	}
 
 	if (opt->prefix &&

diff-no-index.c

@@ -186,9 +186,8 @@ static int queue_diff(struct diff_options *o,
 
 		if (DIFF_OPT_TST(o, REVERSE_DIFF)) {
 			unsigned tmp;
-			const char *tmp_c;
 			tmp = mode1; mode1 = mode2; mode2 = tmp;
-			tmp_c = name1; name1 = name2; name2 = tmp_c;
+			SWAP(name1, name2);
 		}
 
 		d1 = noindex_filespec(name1, mode1);

diff.c

@@ -5118,13 +5118,11 @@ void diff_change(struct diff_options *options,
 
 	if (DIFF_OPT_TST(options, REVERSE_DIFF)) {
 		unsigned tmp;
-		const unsigned char *tmp_c;
+		SWAP(old_mode, new_mode);
-		tmp = old_mode; old_mode = new_mode; new_mode = tmp;
+		SWAP(old_sha1, new_sha1);
-		tmp_c = old_sha1; old_sha1 = new_sha1; new_sha1 = tmp_c;
 		tmp = old_sha1_valid; old_sha1_valid = new_sha1_valid;
 			new_sha1_valid = tmp;
-		tmp = old_dirty_submodule; old_dirty_submodule = new_dirty_submodule;
+		SWAP(old_dirty_submodule, new_dirty_submodule);
-			new_dirty_submodule = tmp;
 	}
 
 	if (options->prefix &&

graph.c

@@ -997,7 +997,6 @@ static void graph_output_post_merge_line(struct git_graph *graph, struct strbuf
 static void graph_output_collapsing_line(struct git_graph *graph, struct strbuf *sb)
 {
 	int i;
-	int *tmp_mapping;
 	short used_horizontal = 0;
 	int horizontal_edge = -1;
 	int horizontal_edge_target = -1;
@@ -1132,9 +1131,7 @@ static void graph_output_collapsing_line(struct git_graph *graph, struct strbuf
 	/*
 	 * Swap mapping and new_mapping
 	 */
-	tmp_mapping = graph->mapping;
+	SWAP(graph->mapping, graph->new_mapping);
-	graph->mapping = graph->new_mapping;
-	graph->new_mapping = tmp_mapping;
 
 	/*
 	 * If graph->mapping indicates that all of the branch lines

line-range.c

@@ -269,8 +269,7 @@ int parse_range_arg(const char *arg, nth_line_fn_t nth_line_cb,
 		return -1;
 
 	if (*begin && *end && *end < *begin) {
-		long tmp;
+		SWAP(*end, *begin);
-		tmp = *end; *end = *begin; *begin = tmp;
 	}
 
 	return 0;

merge-recursive.c

@@ -1390,14 +1390,11 @@ static int process_renames(struct merge_options *o,
 			branch1 = o->branch1;
 			branch2 = o->branch2;
 		} else {
-			struct rename *tmp;
 			renames1 = b_renames;
 			renames2Dst = &a_by_dst;
 			branch1 = o->branch2;
 			branch2 = o->branch1;
-			tmp = ren2;
+			SWAP(ren2, ren1);
-			ren2 = ren1;
-			ren1 = tmp;
 		}
 
 		if (ren1->processed)

object.c

@@ -104,9 +104,7 @@ struct object *lookup_object(const unsigned char *sha1)
 		 * that we do not need to walk the hash table the next
 		 * time we look for it.
 		 */
-		struct object *tmp = obj_hash[i];
+		SWAP(obj_hash[i], obj_hash[first]);
-		obj_hash[i] = obj_hash[first];
-		obj_hash[first] = tmp;
 	}
 	return obj;
 }

pack-revindex.c

@@ -59,7 +59,6 @@ static void sort_revindex(struct revindex_entry *entries, unsigned n, off_t max)
 	 * be a no-op, as everybody lands in the same zero-th bucket.
 	 */
 	for (bits = 0; max >> bits; bits += DIGIT_SIZE) {
-		struct revindex_entry *swap;
 		unsigned i;
 
 		memset(pos, 0, BUCKETS * sizeof(*pos));
@@ -97,9 +96,7 @@ static void sort_revindex(struct revindex_entry *entries, unsigned n, off_t max)
 		 * Now "to" contains the most sorted list, so we swap "from" and
 		 * "to" for the next iteration.
 		 */
-		swap = from;
+		SWAP(from, to);
-		from = to;
-		to = swap;
 	}
 
 	/*

prio-queue.c

@@ -12,9 +12,7 @@ static inline int compare(struct prio_queue *queue, int i, int j)
 
 static inline void swap(struct prio_queue *queue, int i, int j)
 {
-	struct prio_queue_entry tmp = queue->array[i];
+	SWAP(queue->array[i], queue->array[j]);
-	queue->array[i] = queue->array[j];
-	queue->array[j] = tmp;
 }
 
 void prio_queue_reverse(struct prio_queue *queue)

strbuf.h

@@ -109,9 +109,7 @@ extern void strbuf_attach(struct strbuf *, void *, size_t, size_t);
  */
 static inline void strbuf_swap(struct strbuf *a, struct strbuf *b)
 {
-	struct strbuf tmp = *a;
+	SWAP(*a, *b);
-	*a = *b;
-	*b = tmp;
 }