tree-walk.c: break circular dependency with unpack-trees

The unpack-trees API depends on the tree-walk API. But we've recently
introduced a dependency in tree-walk.c on MAX_UNPACK_TREES, which
doesn't otherwise care about unpack-trees at all.

Let's break that dependency by reversing the constants: we'll introduce
a new MAX_TRAVERSE_TREES which belongs to the tree-walk API. And then we
can define MAX_UNPACK_TREES in terms of that (since unpack-trees cannot
possibly work with more trees than it can traverse at once via
tree-walk).

The value for both will remain at 8. This is somewhat arbitrary and
probably more than is necessary, per ca885a4 (read-tree() and
unpack_trees(): use consistent limit, 2008-03-13), but there's not
really any pressing need to reduce it.

Suggested-by: Elijah Newren <[email protected]>
Signed-off-by: Jeff King <[email protected]>
Acked-by: Elijah Newren <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: peff

tree-walk.c

@@ -1,6 +1,5 @@
 #include "cache.h"
 #include "tree-walk.h"
-#include "unpack-trees.h"
 #include "dir.h"
 #include "object-store.h"
 #include "tree.h"
@@ -410,7 +409,7 @@ int traverse_trees(struct index_state *istate,
 		   struct traverse_info *info)
 {
 	int error = 0;
-	struct name_entry entry[MAX_UNPACK_TREES];
+	struct name_entry entry[MAX_TRAVERSE_TREES];
 	int i;
 	struct tree_desc_x tx[ARRAY_SIZE(entry)];
 	struct strbuf base = STRBUF_INIT;

tree-walk.h

@@ -3,6 +3,8 @@
 
 #include "cache.h"
 
+#define MAX_TRAVERSE_TREES 8
+
 /**
  * The tree walking API is used to traverse and inspect trees.
  */

unpack-trees.h

@@ -6,7 +6,7 @@
 #include "string-list.h"
 #include "tree-walk.h"
 
-#define MAX_UNPACK_TREES 8
+#define MAX_UNPACK_TREES MAX_TRAVERSE_TREES
 
 struct cache_entry;
 struct unpack_trees_options;