Merge branch 'rs/swap'

Code clean-up.

* rs/swap:
  graph: use SWAP macro
  diff: use SWAP macro
  use SWAP macro
  apply: use SWAP macro
  add SWAP macro

14 files changed, 63 insertions, 65 deletions

diff --git a/apply.c b/apply.c
index 2ed808d429..0e2caeab9c 100644
--- a/apply.c
+++ b/apply.c
@@ -2187,29 +2187,20 @@ static int parse_chunk(struct apply_state *state, char *buffer, unsigned long si
 	return offset + hdrsize + patchsize;
 }
 
-#define swap(a,b) myswap((a),(b),sizeof(a))
-
-#define myswap(a, b, size) do {		\
-	unsigned char mytmp[size];	\
-	memcpy(mytmp, &a, size);		\
-	memcpy(&a, &b, size);		\
-	memcpy(&b, mytmp, size);		\
-} while (0)
-
 static void reverse_patches(struct patch *p)
 {
 	for (; p; p = p->next) {
 		struct fragment *frag = p->fragments;
 
-		swap(p->new_name, p->old_name);
-		swap(p->new_mode, p->old_mode);
-		swap(p->is_new, p->is_delete);
-		swap(p->lines_added, p->lines_deleted);
-		swap(p->old_sha1_prefix, p->new_sha1_prefix);
+		SWAP(p->new_name, p->old_name);
+		SWAP(p->new_mode, p->old_mode);
+		SWAP(p->is_new, p->is_delete);
+		SWAP(p->lines_added, p->lines_deleted);
+		SWAP(p->old_sha1_prefix, p->new_sha1_prefix);
 
 		for (; frag; frag = frag->next) {
-			swap(frag->newpos, frag->oldpos);
-			swap(frag->newlines, frag->oldlines);
+			SWAP(frag->newpos, frag->oldpos);
+			SWAP(frag->newlines, frag->oldlines);
 		}
 	}
 }
diff --git a/builtin/diff-tree.c b/builtin/diff-tree.c
index 806dd7a885..8ce00480cd 100644
--- a/builtin/diff-tree.c
+++ b/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;
-			tree2 = tree1;
-			tree1 = tmp;
+			SWAP(tree2, tree1);
 		}
 		diff_tree_sha1(tree1->oid.hash,
 			       tree2->oid.hash,
diff --git a/builtin/diff.c b/builtin/diff.c
index 7f91f6d226..3d64b85337 100644
--- a/builtin/diff.c
+++ b/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;
-		const unsigned char *tmp_u;
-		const char *tmp_c;
-		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;
+		SWAP(old_mode, new_mode);
+		SWAP(old_sha1, new_sha1);
+		SWAP(old_name, new_name);
 	}
 
 	if (opt->prefix &&
diff --git a/contrib/coccinelle/swap.cocci b/contrib/coccinelle/swap.cocci
new file mode 100644
index 0000000000..a0934d1fda
--- /dev/null
+++ b/contrib/coccinelle/swap.cocci
@@ -0,0 +1,28 @@
+@ swap_with_declaration @
+type T;
+identifier tmp;
+T a, b;
+@@
+- T tmp = a;
++ T tmp;
++ tmp = a;
+  a = b;
+  b = tmp;
+
+@ swap @
+type T;
+T tmp, a, b;
+@@
+- tmp = a;
+- a = b;
+- b = tmp;
++ SWAP(a, b);
+
+@ extends swap @
+identifier unused;
+@@
+  {
+  ...
+- T unused;
+  ... when != unused
+  }
diff --git a/diff-no-index.c b/diff-no-index.c
index f420786039..df762fd0f7 100644
--- a/diff-no-index.c
+++ b/diff-no-index.c
@@ -185,10 +185,8 @@ static int queue_diff(struct diff_options *o,
 		struct diff_filespec *d1, *d2;
 
 		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(mode1, mode2);
+			SWAP(name1, name2);
 		}
 
 		d1 = noindex_filespec(name1, mode1);
diff --git a/diff.c b/diff.c
index a79f3408da..051761be40 100644
--- a/diff.c
+++ b/diff.c
@@ -5118,14 +5118,10 @@ void diff_change(struct diff_options *options,
 		return;
 
 	if (DIFF_OPT_TST(options, REVERSE_DIFF)) {
-		unsigned tmp;
-		const unsigned char *tmp_c;
-		tmp = old_mode; old_mode = new_mode; new_mode = tmp;
-		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;
-			new_dirty_submodule = tmp;
+		SWAP(old_mode, new_mode);
+		SWAP(old_sha1, new_sha1);
+		SWAP(old_sha1_valid, new_sha1_valid);
+		SWAP(old_dirty_submodule, new_dirty_submodule);
 	}
 
 	if (options->prefix &&
diff --git a/git-compat-util.h b/git-compat-util.h
index f46d40e4a4..ef6d560e15 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -527,6 +527,16 @@ static inline int ends_with(const char *str, const char *suffix)
 	return strip_suffix(str, suffix, &len);
 }
 
+#define SWAP(a, b) do {						\
+	void *_swap_a_ptr = &(a);				\
+	void *_swap_b_ptr = &(b);				\
+	unsigned char _swap_buffer[sizeof(a)];			\
+	memcpy(_swap_buffer, _swap_a_ptr, sizeof(a));		\
+	memcpy(_swap_a_ptr, _swap_b_ptr, sizeof(a) +		\
+	       BUILD_ASSERT_OR_ZERO(sizeof(a) == sizeof(b)));	\
+	memcpy(_swap_b_ptr, _swap_buffer, sizeof(a));		\
+} while (0)
+
 #if defined(NO_MMAP) || defined(USE_WIN32_MMAP)
 
 #ifndef PROT_READ
diff --git a/graph.c b/graph.c
index 0649007704..8b9049dd2c 100644
--- a/graph.c
+++ b/graph.c
@@ -497,7 +497,6 @@ static void graph_update_width(struct git_graph *graph,
 static void graph_update_columns(struct git_graph *graph)
 {
 	struct commit_list *parent;
-	struct column *tmp_columns;
 	int max_new_columns;
 	int mapping_idx;
 	int i, seen_this, is_commit_in_columns;
@@ -510,11 +509,8 @@ static void graph_update_columns(struct git_graph *graph)
 	 * We'll re-use the old columns array as storage to compute the new
 	 * columns list for the commit after this one.
 	 */
-	tmp_columns = graph->columns;
-	graph->columns = graph->new_columns;
+	SWAP(graph->columns, graph->new_columns);
 	graph->num_columns = graph->num_new_columns;
-
-	graph->new_columns = tmp_columns;
 	graph->num_new_columns = 0;
 
 	/*
@@ -1031,7 +1027,6 @@ 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;
@@ -1166,9 +1161,7 @@ static void graph_output_collapsing_line(struct git_graph *graph, struct strbuf
 	/*
 	 * Swap mapping and new_mapping
 	 */
-	tmp_mapping = graph->mapping;
-	graph->mapping = graph->new_mapping;
-	graph->new_mapping = tmp_mapping;
+	SWAP(graph->mapping, graph->new_mapping);
 
 	/*
 	 * If graph->mapping indicates that all of the branch lines
diff --git a/line-range.c b/line-range.c
index de4e32f942..323399d16c 100644
--- a/line-range.c
+++ b/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;
-		tmp = *end; *end = *begin; *begin = tmp;
+		SWAP(*end, *begin);
 	}
 
 	return 0;
diff --git a/merge-recursive.c b/merge-recursive.c
index d327209443..b7ff1ada3c 100644
--- a/merge-recursive.c
+++ b/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;
-			ren2 = ren1;
-			ren1 = tmp;
+			SWAP(ren2, ren1);
 		}
 
 		if (ren1->processed)
diff --git a/object.c b/object.c
index 67d9a9e221..e680d881a4 100644
--- a/object.c
+++ b/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];
-		obj_hash[i] = obj_hash[first];
-		obj_hash[first] = tmp;
+		SWAP(obj_hash[i], obj_hash[first]);
 	}
 	return obj;
 }
diff --git a/pack-revindex.c b/pack-revindex.c
index 6bc7c94033..1b7ebd8d7e 100644
--- a/pack-revindex.c
+++ b/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;
-		from = to;
-		to = swap;
+		SWAP(from, to);
 	}
 
 	/*
diff --git a/prio-queue.c b/prio-queue.c
index e4365b00d6..17252d231b 100644
--- a/prio-queue.c
+++ b/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];
-	queue->array[i] = queue->array[j];
-	queue->array[j] = tmp;
+	SWAP(queue->array[i], queue->array[j]);
 }
 
 void prio_queue_reverse(struct prio_queue *queue)
diff --git a/strbuf.h b/strbuf.h
index 2262b12683..cf1b5409e7 100644
--- a/strbuf.h
+++ b/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;
-	*a = *b;
-	*b = tmp;
+	SWAP(*a, *b);
 }