environment: remove the global variable 'merge_log_config'

The global variable 'merge_log_config', set via the "merge.log" or
"merge.summary" settings, is only used in 'cmd_fmt_merge_msg()' and
'cmd_merge()' to adjust the 'shortlog_len' variable.

Remove 'merge_log_config' globally and localize it in
'cmd_fmt_merge_msg()' and 'cmd_merge()'. Set its value by passing it in
'fmt_merge_msg_config()' by passing its pointer to the function via the
callback parameter.

This change is part of an ongoing effort to eliminate global variables,
improve modularity and help libify the codebase.

Mentored-by: Christian Couder <christian.couder@gmail.com>
Mentored-by: Ghanshyam Thakkar <shyamthakkar001@gmail.com>
Signed-off-by: Ayush Chandekar <ayu.chandekar@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: ayu-ch

builtin/fmt-merge-msg.c

@@ -19,6 +19,7 @@ int cmd_fmt_merge_msg(int argc,
 	const char *message = NULL;
 	char *into_name = NULL;
 	int shortlog_len = -1;
+	int merge_log_config = -1;
 	struct option options[] = {
 		{
 			.type = OPTION_INTEGER,
@@ -53,7 +54,7 @@ int cmd_fmt_merge_msg(int argc,
 	int ret;
 	struct fmt_merge_msg_opts opts;
 
-	git_config(fmt_merge_msg_config, NULL);
+	git_config(fmt_merge_msg_config, &merge_log_config);
 	argc = parse_options(argc, argv, prefix, options, fmt_merge_msg_usage,
 			     0);
 	if (argc > 0)

builtin/merge.c

@@ -1316,6 +1316,7 @@ int cmd_merge(int argc,
 	struct commit_list *remoteheads = NULL, *p;
 	void *branch_to_free;
 	int orig_argc = argc;
+	int merge_log_config = -1;
 
 	show_usage_with_options_if_asked(argc, argv,
 					 builtin_merge_usage, builtin_merge_options);
@@ -1334,7 +1335,7 @@ int cmd_merge(int argc,
 		skip_prefix(branch, "refs/heads/", &branch);
 
 	init_diff_ui_defaults();
-	git_config(git_merge_config, NULL);
+	git_config(git_merge_config, &merge_log_config);
 
 	if (!branch || is_null_oid(&head_oid))
 		head_commit = NULL;

environment.c

@@ -67,7 +67,6 @@ int grafts_keep_true_parents;
 int core_apply_sparse_checkout;
 int core_sparse_checkout_cone;
 int sparse_expect_files_outside_of_patterns;
-int merge_log_config = -1;
 int precomposed_unicode = -1; /* see probe_utf8_pathname_composition() */
 unsigned long pack_size_limit_cfg;
 int max_allowed_tree_depth =

fmt-merge-msg.c

@@ -26,13 +26,15 @@ static struct string_list suppress_dest_patterns = STRING_LIST_INIT_DUP;
 int fmt_merge_msg_config(const char *key, const char *value,
 			 const struct config_context *ctx, void *cb)
 {
+	int *merge_log_config = cb;
+
 	if (!strcmp(key, "merge.log") || !strcmp(key, "merge.summary")) {
 		int is_bool;
-		merge_log_config = git_config_bool_or_int(key, value, ctx->kvi, &is_bool);
-		if (!is_bool && merge_log_config < 0)
+		*merge_log_config = git_config_bool_or_int(key, value, ctx->kvi, &is_bool);
+		if (!is_bool && *merge_log_config < 0)
 			return error("%s: negative length %s", key, value);
-		if (is_bool && merge_log_config)
-			merge_log_config = DEFAULT_MERGE_LOG_LEN;
+		if (is_bool && *merge_log_config)
+			*merge_log_config = DEFAULT_MERGE_LOG_LEN;
 	} else if (!strcmp(key, "merge.branchdesc")) {
 		use_branch_desc = git_config_bool(key, value);
 	} else if (!strcmp(key, "merge.suppressdest")) {

fmt-merge-msg.h

@@ -12,7 +12,6 @@ struct fmt_merge_msg_opts {
 	const char *into_name;
 };
 
-extern int merge_log_config;
 int fmt_merge_msg_config(const char *key, const char *value,
 			 const struct config_context *ctx, void *cb);
 int fmt_merge_msg(struct strbuf *in, struct strbuf *out,