[PATCH 3/4] string-list: change "string_list_find_insert_index" return type to "size_t"

[shejialuo <shejialuo@gmail.com>]

As "string_list_find_insert_index" is a simple wrapper of
"get_entry_index", we could simply change its return type to "size_t".

Update all callers to use size_t variables for storing the return value.
The tricky fix is the loop condition in "mailmap.c" to properly handle
"size_t" underflow by changing from `0 <= --i` to `i-- > 0`.

Remove "DISABLE_SIGN_COMPARE_WARNINGS" from "mailmap.c" as it's no
longer needed with the proper unsigned types.

Signed-off-by: shejialuo <shejialuo@gmail.com>
---
 add-interactive.c | 2 +-
 mailmap.c         | 5 ++---
 refs.c            | 4 +---
 string-list.c     | 4 ++--
 string-list.h     | 4 ++--
 5 files changed, 8 insertions(+), 11 deletions(-)

diff --git a/add-interactive.c b/add-interactive.c
index 9a42b3b38b..2005f56b69 100644
--- a/add-interactive.c
+++ b/add-interactive.c
@@ -222,7 +222,7 @@ static void find_unique_prefixes(struct prefix_item_list *list)
 static ssize_t find_unique(const char *string, struct prefix_item_list *list)
 {
 	int exact_match;
-	int index = string_list_find_insert_index(&list->sorted, string, &exact_match);
+	size_t index = string_list_find_insert_index(&list->sorted, string, &exact_match);
 	struct string_list_item *item;
 
 	if (list->items.nr != list->sorted.nr)
diff --git a/mailmap.c b/mailmap.c
index 253517cdf6..0168342650 100644
--- a/mailmap.c
+++ b/mailmap.c
@@ -1,5 +1,4 @@
 #define USE_THE_REPOSITORY_VARIABLE
-#define DISABLE_SIGN_COMPARE_WARNINGS
 
 #include "git-compat-util.h"
 #include "environment.h"
@@ -244,7 +243,7 @@ static struct string_list_item *lookup_prefix(struct string_list *map,
 					      const char *string, size_t len)
 {
 	int exact_match;
-	int i = string_list_find_insert_index(map, string, &exact_match);
+	size_t i = string_list_find_insert_index(map, string, &exact_match);
 	if (exact_match) {
 		if (!string[len])
 			return &map->items[i];
@@ -266,7 +265,7 @@ static struct string_list_item *lookup_prefix(struct string_list *map,
 	 * overlong key would be inserted, which must come after the
 	 * real location of the key if one exists.
 	 */
-	while (0 <= --i && i < map->nr) {
+	while (i-- > 0 && i < map->nr) {
 		int cmp = strncasecmp(map->items[i].string, string, len);
 		if (cmp < 0)
 			/*
diff --git a/refs.c b/refs.c
index f1ff5bf846..a8f06b9a0a 100644
--- a/refs.c
+++ b/refs.c
@@ -1688,8 +1688,6 @@ const char *find_descendant_ref(const char *dirname,
 				const struct string_list *extras,
 				const struct string_list *skip)
 {
-	int pos;
-
 	if (!extras)
 		return NULL;
 
@@ -1699,7 +1697,7 @@ const char *find_descendant_ref(const char *dirname,
 	 * with dirname (remember, dirname includes the trailing
 	 * slash) and is not in skip, then we have a conflict.
 	 */
-	for (pos = string_list_find_insert_index(extras, dirname, NULL);
+	for (size_t pos = string_list_find_insert_index(extras, dirname, NULL);
 	     pos < extras->nr; pos++) {
 		const char *extra_refname = extras->items[pos].string;
 
diff --git a/string-list.c b/string-list.c
index 224bc182ff..e69923cd88 100644
--- a/string-list.c
+++ b/string-list.c
@@ -91,8 +91,8 @@ int string_list_has_string(const struct string_list *list, const char *string)
 	return exact_match;
 }
 
-int string_list_find_insert_index(const struct string_list *list, const char *string,
-				  int *exact_match)
+size_t string_list_find_insert_index(const struct string_list *list, const char *string,
+				     int *exact_match)
 {
 	return get_entry_index(list, string, exact_match);
 }
diff --git a/string-list.h b/string-list.h
index 03c7009472..f6be2bd5c7 100644
--- a/string-list.h
+++ b/string-list.h
@@ -173,8 +173,8 @@ void string_list_remove_empty_items(struct string_list *list, int free_util);
 
 /** Determine if the string_list has a given string or not. */
 int string_list_has_string(const struct string_list *list, const char *string);
-int string_list_find_insert_index(const struct string_list *list, const char *string,
-				  int *exact_match);
+size_t string_list_find_insert_index(const struct string_list *list, const char *string,
+				     int *exact_match);
 
 /**
  * Insert a new element to the string_list. The returned pointer can
-- 
2.51.0