config.c: remove unused git_config_key_is_valid()

The git_config_key_is_valid() function got left behind in a
refactoring in a9bcf6586d (alias: use the early config machinery to
expand aliases, 2017-06-14),

It previously had two users when it was added in 9e9de18f1a (config:
silence warnings for command names with invalid keys, 2015-08-24), and
after 6a1e1bc0a1 (pager: use callbacks instead of configset,
2016-09-12) only one remained.

By removing it we can get rid of the "quiet" branches in this
function, as well as cases where "store_key" is NULL, for which there
are no other users.

Out of the 5 callers of git_config_parse_key() only one needs to pass
a non-NULL "size_t *baselen_", so we could remove the third parameter
from the public interface. I did not find that potential
simplification to be worthwhile.

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

config.c

@@ -425,7 +425,7 @@ static inline int iskeychar(int c)
  * baselen - pointer to size_t which will hold the length of the
  *           section + subsection part, can be NULL
  */
-static int git_config_parse_key_1(const char *key, char **store_key, size_t *baselen_, int quiet)
+int git_config_parse_key(const char *key, char **store_key, size_t *baselen_)
 {
 	size_t i, baselen;
 	int dot;
@@ -437,14 +437,12 @@ static int git_config_parse_key_1(const char *key, char **store_key, size_t *bas
 	 */
 
 	if (last_dot == NULL || last_dot == key) {
-		if (!quiet)
+		error(_("key does not contain a section: %s"), key);
-			error(_("key does not contain a section: %s"), key);
 		return -CONFIG_NO_SECTION_OR_NAME;
 	}
 
 	if (!last_dot[1]) {
-		if (!quiet)
+		error(_("key does not contain variable name: %s"), key);
-			error(_("key does not contain variable name: %s"), key);
 		return -CONFIG_NO_SECTION_OR_NAME;
 	}
 
@@ -455,8 +453,7 @@ static int git_config_parse_key_1(const char *key, char **store_key, size_t *bas
 	/*
 	 * Validate the key and while at it, lower case it for matching.
 	 */
-	if (store_key)
+	*store_key = xmallocz(strlen(key));
-		*store_key = xmallocz(strlen(key));
 
 	dot = 0;
 	for (i = 0; key[i]; i++) {
@@ -467,39 +464,24 @@ static int git_config_parse_key_1(const char *key, char **store_key, size_t *bas
 		if (!dot || i > baselen) {
 			if (!iskeychar(c) ||
 			    (i == baselen + 1 && !isalpha(c))) {
-				if (!quiet)
+				error(_("invalid key: %s"), key);
-					error(_("invalid key: %s"), key);
 				goto out_free_ret_1;
 			}
 			c = tolower(c);
 		} else if (c == '\n') {
-			if (!quiet)
+			error(_("invalid key (newline): %s"), key);
-				error(_("invalid key (newline): %s"), key);
 			goto out_free_ret_1;
 		}
-		if (store_key)
+		(*store_key)[i] = c;
-			(*store_key)[i] = c;
 	}
 
 	return 0;
 
 out_free_ret_1:
-	if (store_key) {
+	FREE_AND_NULL(*store_key);
-		FREE_AND_NULL(*store_key);
-	}
 	return -CONFIG_INVALID_KEY;
 }
 
-int git_config_parse_key(const char *key, char **store_key, size_t *baselen)
-{
-	return git_config_parse_key_1(key, store_key, baselen, 0);
-}
-
-int git_config_key_is_valid(const char *key)
-{
-	return !git_config_parse_key_1(key, NULL, NULL, 1);
-}
-
 static int config_parse_pair(const char *key, const char *value,
 			  config_fn_t fn, void *data)
 {

config.h

@@ -259,7 +259,6 @@ int git_config_set_gently(const char *, const char *);
 void git_config_set(const char *, const char *);
 
 int git_config_parse_key(const char *, char **, size_t *);
-int git_config_key_is_valid(const char *key);
 
 /*
  * The following macros specify flag bits that alter the behavior