config: fix sign comparison warnings

There are a couple of -Wsign-compare warnings in "config.c":

  - `prepare_include_condition_pattern()` is returns a signed integer,
    where it either returns a negative error code or the index of the
    last dir separator in a path. That index will always be a
    non-negative number, but we cannot just change the return type to a
    `size_t` due to it being re-used as error code. This is fixed by
    splitting up concerns: the return value is only used as error code,
    and the prefix is now returned via an out-pointer. This fixes a sign
    comparison warning when comparing `text.len < prefix`,

  - We treat `struct config_store_data::seen` as signed integer in
    several places even though it's unsigned.

  - There are multiple trivial sign comparison warnings where we use a
    signed loop index to iterate through an unsigned number of items.

Fix all of these issues and drop the `DISABLE_SIGN_COMPARE_WARNINGS`
macro.

Signed-off-by: Patrick Steinhardt <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: pks-t

config.c

@@ -6,8 +6,6 @@
  *
  */
 
-#define DISABLE_SIGN_COMPARE_WARNINGS
-
 #include "git-compat-util.h"
 #include "abspath.h"
 #include "date.h"
@@ -198,11 +196,12 @@ static void add_trailing_starstar_for_dir(struct strbuf *pat)
 }
 
 static int prepare_include_condition_pattern(const struct key_value_info *kvi,
-					     struct strbuf *pat)
+					     struct strbuf *pat,
+					     size_t *out)
 {
 	struct strbuf path = STRBUF_INIT;
 	char *expanded;
-	int prefix = 0;
+	size_t prefix = 0;
 
 	expanded = interpolate_path(pat->buf, 1);
 	if (expanded) {
@@ -229,8 +228,10 @@ static int prepare_include_condition_pattern(const struct key_value_info *kvi,
 
 	add_trailing_starstar_for_dir(pat);
 
+	*out = prefix;
+
 	strbuf_release(&path);
-	return prefix;
+	return 0;
 }
 
 static int include_by_gitdir(const struct key_value_info *kvi,
@@ -239,7 +240,8 @@ static int include_by_gitdir(const struct key_value_info *kvi,
 {
 	struct strbuf text = STRBUF_INIT;
 	struct strbuf pattern = STRBUF_INIT;
-	int ret = 0, prefix;
+	size_t prefix;
+	int ret = 0;
 	const char *git_dir;
 	int already_tried_absolute = 0;
 
@@ -250,12 +252,11 @@ static int include_by_gitdir(const struct key_value_info *kvi,
 
 	strbuf_realpath(&text, git_dir, 1);
 	strbuf_add(&pattern, cond, cond_len);
-	prefix = prepare_include_condition_pattern(kvi, &pattern);
-
-again:
-	if (prefix < 0)
+	ret = prepare_include_condition_pattern(kvi, &pattern, &prefix);
+	if (ret < 0)
 		goto done;
 
+again:
 	if (prefix > 0) {
 		/*
 		 * perform literal matching on the prefix part so that
@@ -724,7 +725,6 @@ int git_config_from_parameters(config_fn_t fn, void *data)
 	if (env) {
 		unsigned long count;
 		char *endp;
-		int i;
 
 		count = strtoul(env, &endp, 10);
 		if (*endp) {
@@ -736,18 +736,18 @@ int git_config_from_parameters(config_fn_t fn, void *data)
 			goto out;
 		}
 
-		for (i = 0; i < count; i++) {
+		for (unsigned long i = 0; i < count; i++) {
 			const char *key, *value;
 
-			strbuf_addf(&envvar, "GIT_CONFIG_KEY_%d", i);
+			strbuf_addf(&envvar, "GIT_CONFIG_KEY_%lu", i);
 			key = getenv_safe(&to_free, envvar.buf);
 			if (!key) {
 				ret = error(_("missing config key %s"), envvar.buf);
 				goto out;
 			}
 			strbuf_reset(&envvar);
 
-			strbuf_addf(&envvar, "GIT_CONFIG_VALUE_%d", i);
+			strbuf_addf(&envvar, "GIT_CONFIG_VALUE_%lu", i);
 			value = getenv_safe(&to_free, envvar.buf);
 			if (!value) {
 				ret = error(_("missing config value %s"), envvar.buf);
@@ -1614,13 +1614,13 @@ int config_with_options(config_fn_t fn, void *data,
 
 static void configset_iter(struct config_set *set, config_fn_t fn, void *data)
 {
-	int i, value_index;
+	int value_index;
 	struct string_list *values;
 	struct config_set_element *entry;
 	struct configset_list *list = &set->list;
 	struct config_context ctx = CONFIG_CONTEXT_INIT;
 
-	for (i = 0; i < list->nr; i++) {
+	for (size_t i = 0; i < list->nr; i++) {
 		entry = list->items[i].e;
 		value_index = list->items[i].value_index;
 		values = &entry->value_list;
@@ -2470,10 +2470,11 @@ static ssize_t write_pair(int fd, const char *key, const char *value,
  */
 static void maybe_remove_section(struct config_store_data *store,
 				 size_t *begin_offset, size_t *end_offset,
-				 int *seen_ptr)
+				 unsigned *seen_ptr)
 {
 	size_t begin;
-	int i, seen, section_seen = 0;
+	int section_seen = 0;
+	unsigned int i, seen;
 
 	/*
 	 * First, ensure that this is the first key, and that there are no
@@ -2716,7 +2717,8 @@ int repo_config_set_multivar_in_file_gently(struct repository *r,
 	} else {
 		struct stat st;
 		size_t copy_begin, copy_end;
-		int i, new_line = 0;
+		unsigned i;
+		int new_line = 0;
 		struct config_options opts;
 
 		if (!value_pattern)