cocci & cache-tree.h: migrate "write_cache_as_tree" to "*_index_*"

Add a trivial rule for "write_cache_as_tree" to
"index-compatibility.cocci", and apply it. This was left out of the
rules added in 0e6550a2c6 (cocci: add a
index-compatibility.pending.cocci, 2022-11-19) because this
compatibility wrapper lived in "cache-tree.h", not "cache.h"

But it's like the other "USE_THE_INDEX_COMPATIBILITY_MACROS", so let's
migrate it too.

The replacement of "USE_THE_INDEX_COMPATIBILITY_MACROS" here with
"USE_THE_INDEX_VARIABLE" is a manual change on top, now that these
files only use "&the_index", and don't need any compatibility
macros (or functions).

The wrapping of some argument lists is likewise manual, as coccinelle
would otherwise give us overly long argument lists.

The reason for putting the "O" in the cocci rule on the "-" and "+"
lines is because I couldn't get correct whitespacing otherwise,
i.e. I'd end up with "oid,&the_index", not "oid, &the_index".

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

builtin/am.c

@@ -3,7 +3,7 @@
  *
  * Based on git-am.sh by Junio C Hamano.
  */
-#define USE_THE_INDEX_COMPATIBILITY_MACROS
+#define USE_THE_INDEX_VARIABLE
 #include "cache.h"
 #include "config.h"
 #include "builtin.h"
@@ -1655,7 +1655,7 @@ static void do_commit(const struct am_state *state)
 	if (!state->no_verify && run_hooks("pre-applypatch"))
 		exit(1);
 
-	if (write_cache_as_tree(&tree, 0, NULL))
+	if (write_index_as_tree(&tree, &the_index, get_index_file(), 0, NULL))
 		die(_("git write-tree failed to write a tree"));
 
 	if (!get_oid_commit("HEAD", &parent)) {
@@ -2063,7 +2063,7 @@ static int clean_index(const struct object_id *head, const struct object_id *rem
 	if (fast_forward_to(head_tree, head_tree, 1))
 		return -1;
 
-	if (write_cache_as_tree(&index, 0, NULL))
+	if (write_index_as_tree(&index, &the_index, get_index_file(), 0, NULL))
 		return -1;
 
 	index_tree = parse_tree_indirect(&index);

builtin/merge.c

@@ -706,7 +706,7 @@ static int read_tree_trivial(struct object_id *common, struct object_id *head,
 
 static void write_tree_trivial(struct object_id *oid)
 {
-	if (write_cache_as_tree(oid, 0, NULL))
+	if (write_index_as_tree(oid, &the_index, get_index_file(), 0, NULL))
 		die(_("git write-tree failed to write a tree"));
 }
 

builtin/stash.c

@@ -1,4 +1,4 @@
-#define USE_THE_INDEX_COMPATIBILITY_MACROS
+#define USE_THE_INDEX_VARIABLE
 #include "builtin.h"
 #include "config.h"
 #include "parse-options.h"
@@ -528,7 +528,8 @@ static int do_apply_stash(const char *prefix, struct stash_info *info,
 					 NULL, NULL, NULL))
 		return -1;
 
-	if (write_cache_as_tree(&c_tree, 0, NULL))
+	if (write_index_as_tree(&c_tree, &the_index, get_index_file(), 0,
+				NULL))
 		return error(_("cannot apply a stash in the middle of a merge"));
 
 	if (index) {
@@ -552,7 +553,8 @@ static int do_apply_stash(const char *prefix, struct stash_info *info,
 
 			discard_index(&the_index);
 			repo_read_index(the_repository);
-			if (write_cache_as_tree(&index_tree, 0, NULL))
+			if (write_index_as_tree(&index_tree, &the_index,
+						get_index_file(), 0, NULL))
 				return error(_("could not save index tree"));
 
 			reset_head();
@@ -1377,7 +1379,8 @@ static int do_create_stash(const struct pathspec *ps, struct strbuf *stash_msg_b
 
 	strbuf_addf(&commit_tree_label, "index on %s\n", msg.buf);
 	commit_list_insert(head_commit, &parents);
-	if (write_cache_as_tree(&info->i_tree, 0, NULL) ||
+	if (write_index_as_tree(&info->i_tree, &the_index, get_index_file(), 0,
+				NULL) ||
 	    commit_tree(commit_tree_label.buf, commit_tree_label.len,
 			&info->i_tree, parents, &info->i_commit, NULL, NULL)) {
 		if (!quiet)

builtin/write-tree.c

@@ -3,7 +3,7 @@
  *
  * Copyright (C) Linus Torvalds, 2005
  */
-#define USE_THE_INDEX_COMPATIBILITY_MACROS
+#define USE_THE_INDEX_VARIABLE
 #include "builtin.h"
 #include "cache.h"
 #include "config.h"
@@ -38,7 +38,8 @@ int cmd_write_tree(int argc, const char **argv, const char *cmd_prefix)
 	argc = parse_options(argc, argv, cmd_prefix, write_tree_options,
 			     write_tree_usage, 0);
 
-	ret = write_cache_as_tree(&oid, flags, tree_prefix);
+	ret = write_index_as_tree(&oid, &the_index, get_index_file(), flags,
+				  tree_prefix);
 	switch (ret) {
 	case 0:
 		printf("%s\n", oid_to_hex(&oid));

cache-tree.h

@@ -55,11 +55,6 @@ void prime_cache_tree(struct repository *, struct index_state *, struct tree *);
 int cache_tree_matches_traversal(struct cache_tree *, struct name_entry *ent, struct traverse_info *info);
 
 #ifdef USE_THE_INDEX_COMPATIBILITY_MACROS
-static inline int write_cache_as_tree(struct object_id *oid, int flags, const char *prefix)
-{
-	return write_index_as_tree(oid, &the_index, get_index_file(), flags, prefix);
-}
-
 static inline int update_main_cache_tree(int flags)
 {
 	if (!the_index.cache_tree)

contrib/coccinelle/index-compatibility.cocci

@@ -135,3 +135,14 @@ identifier ACT = active_cache_tree;
   ...
 + , NULL, NULL, NULL
   )
+
+@@
+expression O;
+@@
+- write_cache_as_tree
++ write_index_as_tree
+  (
+- O,
++ O, &the_index, get_index_file(),
+  ...
+  )