object-store: move lookup_replace_object to replace-object.h

lookup_replace_object is a low-level function that most users of the
object store do not need to use directly.

Move it to replace-object.h to avoid a dependency loop in an upcoming
change to its inline definition that will make use of repository.h.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/mktag.c

@@ -1,5 +1,6 @@
 #include "builtin.h"
 #include "tag.h"
+#include "replace-object.h"
 
 /*
  * A signature file has a very simple fixed format: four lines

cache.h

@@ -1191,25 +1191,6 @@ static inline void *read_object_file(const struct object_id *oid, enum object_ty
 	return read_object_file_extended(oid, type, size, 1);
 }
 
-/*
- * This internal function is only declared here for the benefit of
- * lookup_replace_object().  Please do not call it directly.
- */
-extern const struct object_id *do_lookup_replace_object(const struct object_id *oid);
-
-/*
- * If object sha1 should be replaced, return the replacement object's
- * name (replaced recursively, if necessary).  The return value is
- * either sha1 or a pointer to a permanently-allocated value.  When
- * object replacement is suppressed, always return sha1.
- */
-static inline const struct object_id *lookup_replace_object(const struct object_id *oid)
-{
-	if (!check_replace_refs)
-		return oid;
-	return do_lookup_replace_object(oid);
-}
-
 /* Read and unpack an object file into memory, write memory to an object file */
 extern int oid_object_info(const struct object_id *, unsigned long *);
 

object.c

@@ -1,5 +1,6 @@
 #include "cache.h"
 #include "object.h"
+#include "replace-object.h"
 #include "blob.h"
 #include "tree.h"
 #include "commit.h"

replace-object.h

@@ -1,9 +1,31 @@
 #ifndef REPLACE_OBJECT_H
 #define REPLACE_OBJECT_H
 
+#include "oidmap.h"
+#include "repository.h"
+
 struct replace_object {
 	struct oidmap_entry original;
 	struct object_id replacement;
 };
 
+/*
+ * This internal function is only declared here for the benefit of
+ * lookup_replace_object().  Please do not call it directly.
+ */
+extern const struct object_id *do_lookup_replace_object(const struct object_id *oid);
+
+/*
+ * If object sha1 should be replaced, return the replacement object's
+ * name (replaced recursively, if necessary).  The return value is
+ * either sha1 or a pointer to a permanently-allocated value.  When
+ * object replacement is suppressed, always return sha1.
+ */
+static inline const struct object_id *lookup_replace_object(const struct object_id *oid)
+{
+	if (!check_replace_refs)
+		return oid;
+	return do_lookup_replace_object(oid);
+}
+
 #endif /* REPLACE_OBJECT_H */

sha1_file.c

@@ -23,6 +23,7 @@
 #include "sha1-lookup.h"
 #include "bulk-checkin.h"
 #include "repository.h"
+#include "replace-object.h"
 #include "streaming.h"
 #include "dir.h"
 #include "list.h"

streaming.c

@@ -5,6 +5,7 @@
 #include "streaming.h"
 #include "repository.h"
 #include "object-store.h"
+#include "replace-object.h"
 #include "packfile.h"
 
 enum input_source {