[PATCH 1/1] Add a helper to reverse index_pos_to_insert_pos()

["Johannes Schindelin via GitGitGadget" <gitgitgadget@gmail.com>]

From: Johannes Schindelin <johannes.schindelin@gmx.de>

We have just introduced the helper `index_pos_to_insert_pos()` to help
avoiding underflows when returning `-1 - pos` for cases where we want to
return an insert position, using the ones' complement (as `int`).

As pointed out during the review of the patch series that introduced it,
this helper wants to be accompanied by a helper that reverse that ones'
complement, for clarity. This patch does exactly that.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 blame.c           | 5 +++--
 builtin/mv.c      | 2 +-
 cache.h           | 5 +++++
 merge-recursive.c | 4 ++--
 read-cache.c      | 2 +-
 rerere.c          | 2 +-
 sha1-name.c       | 2 +-
 submodule.c       | 2 +-
 unpack-trees.c    | 2 +-
 9 files changed, 16 insertions(+), 10 deletions(-)

diff --git a/blame.c b/blame.c
index 145eaf2faf..848355923d 100644
--- a/blame.c
+++ b/blame.c
@@ -109,8 +109,9 @@ static void verify_working_tree_path(struct repository *r,
 	pos = index_name_pos(r->index, path, strlen(path));
 	if (pos >= 0)
 		; /* path is in the index */
-	else if (-1 - pos < r->index->cache_nr &&
-		 !strcmp(r->index->cache[-1 - pos]->name, path))
+	else if (insert_pos_to_index_pos(pos) < r->index->cache_nr &&
+		 !strcmp(r->index->cache[insert_pos_to_index_pos(pos)]->name,
+			 path))
 		; /* path is in the index, unmerged */
 	else
 		die("no such path '%s' in HEAD", path);
diff --git a/builtin/mv.c b/builtin/mv.c
index be15ba7044..9ebb1ed0a2 100644
--- a/builtin/mv.c
+++ b/builtin/mv.c
@@ -102,7 +102,7 @@ static int index_range_of_same_dir(const char *src, int length,
 	if (first >= 0)
 		die(_("%.*s is in index"), len_w_slash, src_w_slash);
 
-	first = -1 - first;
+	first = insert_pos_to_index_pos(first);
 	for (last = first; last < active_nr; last++) {
 		const char *path = active_cache[last]->name;
 		if (strncmp(path, src_w_slash, len_w_slash))
diff --git a/cache.h b/cache.h
index 850e7b945a..8fb57db091 100644
--- a/cache.h
+++ b/cache.h
@@ -738,6 +738,11 @@ static inline int index_pos_to_insert_pos(uintmax_t pos)
 	return -1 - (int)pos;
 }
 
+static inline int insert_pos_to_index_pos(int pos)
+{
+	return -1 - pos;
+}
+
 #define ADD_CACHE_OK_TO_ADD 1		/* Ok to add */
 #define ADD_CACHE_OK_TO_REPLACE 2	/* Ok to replace file/directory */
 #define ADD_CACHE_SKIP_DFCHECK 4	/* Ok to skip DF conflict checks */
diff --git a/merge-recursive.c b/merge-recursive.c
index d2e380b7ed..8dca01a279 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -753,7 +753,7 @@ static int dir_in_way(struct index_state *istate, const char *path,
 	pos = index_name_pos(istate, dirpath.buf, dirpath.len);
 
 	if (pos < 0)
-		pos = -1 - pos;
+		pos = insert_pos_to_index_pos(pos);
 	if (pos < istate->cache_nr &&
 	    !strncmp(dirpath.buf, istate->cache[pos]->name, dirpath.len)) {
 		strbuf_release(&dirpath);
@@ -822,7 +822,7 @@ static int would_lose_untracked(struct merge_options *opt, const char *path)
 	int pos = index_name_pos(istate, path, strlen(path));
 
 	if (pos < 0)
-		pos = -1 - pos;
+		pos = insert_pos_to_index_pos(pos);
 	while (pos < istate->cache_nr &&
 	       !strcmp(path, istate->cache[pos]->name)) {
 		/*
diff --git a/read-cache.c b/read-cache.c
index ec13953a21..ac3b0f8e5c 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -641,7 +641,7 @@ static int index_name_pos_also_unmerged(struct index_state *istate,
 		return pos;
 
 	/* maybe unmerged? */
-	pos = -1 - pos;
+	pos = insert_pos_to_index_pos(pos);
 	if (pos >= istate->cache_nr ||
 			compare_name((ce = istate->cache[pos]), path, namelen))
 		return -1;
diff --git a/rerere.c b/rerere.c
index 17abb47321..122ebed5d8 100644
--- a/rerere.c
+++ b/rerere.c
@@ -154,7 +154,7 @@ static struct rerere_dir *find_rerere_dir(const char *hex)
 		rr_dir->status = NULL;
 		rr_dir->status_nr = 0;
 		rr_dir->status_alloc = 0;
-		pos = -1 - pos;
+		pos = insert_pos_to_index_pos(pos);
 
 		/* Make sure the array is big enough ... */
 		ALLOC_GROW(rerere_dir, rerere_dir_nr + 1, rerere_dir_alloc);
diff --git a/sha1-name.c b/sha1-name.c
index 49855ad24f..bee7ce39ee 100644
--- a/sha1-name.c
+++ b/sha1-name.c
@@ -98,7 +98,7 @@ static void find_short_object_filename(struct disambiguate_state *ds)
 		loose_objects = odb_loose_cache(odb, &ds->bin_pfx);
 		pos = oid_array_lookup(loose_objects, &ds->bin_pfx);
 		if (pos < 0)
-			pos = -1 - pos;
+			pos = insert_pos_to_index_pos(pos);
 		while (!ds->ambiguous && pos < loose_objects->nr) {
 			const struct object_id *oid;
 			oid = loose_objects->oid + pos;
diff --git a/submodule.c b/submodule.c
index 0f199c5137..4cab9100ea 100644
--- a/submodule.c
+++ b/submodule.c
@@ -37,7 +37,7 @@ int is_gitmodules_unmerged(const struct index_state *istate)
 {
 	int pos = index_name_pos(istate, GITMODULES_FILE, strlen(GITMODULES_FILE));
 	if (pos < 0) { /* .gitmodules not found or isn't merged */
-		pos = -1 - pos;
+		pos = insert_pos_to_index_pos(pos);
 		if (istate->cache_nr > pos) {  /* there is a .gitmodules */
 			const struct cache_entry *ce = istate->cache[pos];
 			if (ce_namelen(ce) == strlen(GITMODULES_FILE) &&
diff --git a/unpack-trees.c b/unpack-trees.c
index dab713203e..abb33ce259 100644
--- a/unpack-trees.c
+++ b/unpack-trees.c
@@ -553,7 +553,7 @@ static int locate_in_src_index(const struct cache_entry *ce,
 	int len = ce_namelen(ce);
 	int pos = index_name_pos(index, ce->name, len);
 	if (pos < 0)
-		pos = -1 - pos;
+		pos = insert_pos_to_index_pos(pos);
 	return pos;
 }
 
-- 
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