cocci & cache.h: remove "USE_THE_INDEX_COMPATIBILITY_MACROS"

Have the last users of "USE_THE_INDEX_COMPATIBILITY_MACROS" use the
underlying *_index() variants instead. Now all previous users of
"USE_THE_INDEX_COMPATIBILITY_MACROS" have been migrated away from the
wrapper macros, and if applicable to use the "USE_THE_INDEX_VARIABLE"
added in [1].

Let's leave the "index-compatibility.cocci" in place, even though it
won't be doing anything on "master". It will benefit any out-of-tree
code that need to use these compatibility macros. We can eventually
remove it.

1. bdafeae0b9 (cache.h & test-tool.h: add & use
   "USE_THE_INDEX_VARIABLE", 2022-11-19)

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/commit.c

@@ -5,7 +5,7 @@
  * Based on git-commit.sh by Junio C Hamano and Linus Torvalds
  */
 
-#define USE_THE_INDEX_COMPATIBILITY_MACROS
+#define USE_THE_INDEX_VARIABLE
 #include "cache.h"
 #include "config.h"
 #include "lockfile.h"
@@ -992,8 +992,8 @@ static int prepare_to_commit(const char *index_file, const char *prefix,
 		const char *parent = "HEAD";
 
 		if (!the_index.cache_nr) {
-			discard_cache();
-			if (read_cache() < 0)
+			discard_index(&the_index);
+			if (repo_read_index(the_repository) < 0)
 				die(_("Cannot read index"));
 		}
 

builtin/merge.c

@@ -6,7 +6,7 @@
  * Based on git-merge.sh by Junio C Hamano.
  */
 
-#define USE_THE_INDEX_COMPATIBILITY_MACROS
+#define USE_THE_INDEX_VARIABLE
 #include "cache.h"
 #include "config.h"
 #include "parse-options.h"
@@ -390,8 +390,8 @@ static void restore_state(const struct object_id *head,
 	run_command(&cmd);
 
 refresh_cache:
-	discard_cache();
-	if (read_cache() < 0)
+	discard_index(&the_index);
+	if (repo_read_index(the_repository) < 0)
 		die(_("could not read index"));
 }
 

cache.h

@@ -449,15 +449,8 @@ typedef int (*must_prefetch_predicate)(const struct cache_entry *);
 void prefetch_cache_entries(const struct index_state *istate,
 			    must_prefetch_predicate must_prefetch);
 
-#if defined(USE_THE_INDEX_COMPATIBILITY_MACROS) || defined(USE_THE_INDEX_VARIABLE)
+#ifdef USE_THE_INDEX_VARIABLE
 extern struct index_state the_index;
-
-#ifndef USE_THE_INDEX_VARIABLE
-#ifdef USE_THE_INDEX_COMPATIBILITY_MACROS
-#define read_cache() repo_read_index(the_repository)
-#define discard_cache() discard_index(&the_index)
-#endif
-#endif
 #endif
 
 #define TYPE_BITS 3

contrib/coccinelle/index-compatibility.cocci

@@ -23,6 +23,9 @@ identifier ACT = active_cache_tree;
 @@
 @@
 (
+- read_cache
++ repo_read_index
+|
 - read_cache_unmerged
 + repo_read_index_unmerged
 |
@@ -97,6 +100,9 @@ identifier ACT = active_cache_tree;
 |
 - update_main_cache_tree
 + cache_tree_update
+|
+- discard_cache
++ discard_index
 )
   (
 + &the_index,

contrib/coccinelle/index-compatibility.pending.cocci

@@ -1,21 +0,0 @@
-// "the_repository" simple cases
-@@
-@@
-(
-- read_cache
-+ repo_read_index
-)
-  (
-+ the_repository,
-  ...)
-
-// "the_index" simple cases
-@@
-@@
-(
-- discard_cache
-+ discard_index
-)
-  (
-+ &the_index,
-  ...)