revision.h: store hidden refs in a `strvec`

In subsequent commits, it will be convenient to have a 'const char **'
of hidden refs (matching `transfer.hiderefs`, `uploadpack.hideRefs`,
etc.), instead of a `string_list`.

Convert spots throughout the tree that store the list of hidden refs
from a `string_list` to a `strvec`.

Note that in `parse_hide_refs_config()` there is an ugly const-cast used
to avoid an extra copy of each value before trimming any trailing slash
characters. This could instead be written as:

    ref = xstrdup(value);
    len = strlen(ref);
    while (len && ref[len - 1] == '/')
            ref[--len] = '\0';
    strvec_push(hide_refs, ref);
    free(ref);

but the double-copy (once when calling `xstrdup()`, and another via
`strvec_push()`) is wasteful.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/receive-pack.c

@@ -90,7 +90,7 @@ static struct object_id push_cert_oid;
 static struct signature_check sigcheck;
 static const char *push_cert_nonce;
 static const char *cert_nonce_seed;
-static struct string_list hidden_refs = STRING_LIST_INIT_DUP;
+static struct strvec hidden_refs = STRVEC_INIT;
 
 static const char *NONCE_UNSOLICITED = "UNSOLICITED";
 static const char *NONCE_BAD = "BAD";
@@ -2619,7 +2619,7 @@ int cmd_receive_pack(int argc, const char **argv, const char *prefix)
 		packet_flush(1);
 	oid_array_clear(&shallow);
 	oid_array_clear(&ref);
-	string_list_clear(&hidden_refs, 0);
+	strvec_clear(&hidden_refs);
 	free((void *)push_cert_nonce);
 	return 0;
 }

ls-refs.c

@@ -72,7 +72,7 @@ struct ls_refs_data {
 	unsigned symrefs;
 	struct strvec prefixes;
 	struct strbuf buf;
-	struct string_list hidden_refs;
+	struct strvec hidden_refs;
 	unsigned unborn : 1;
 };
 
@@ -155,7 +155,7 @@ int ls_refs(struct repository *r, struct packet_reader *request)
 	memset(&data, 0, sizeof(data));
 	strvec_init(&data.prefixes);
 	strbuf_init(&data.buf, 0);
-	string_list_init_dup(&data.hidden_refs);
+	strvec_init(&data.hidden_refs);
 
 	git_config(ls_refs_config, &data);
 
@@ -197,7 +197,7 @@ int ls_refs(struct repository *r, struct packet_reader *request)
 	packet_fflush(stdout);
 	strvec_clear(&data.prefixes);
 	strbuf_release(&data.buf);
-	string_list_clear(&data.hidden_refs, 0);
+	strvec_clear(&data.hidden_refs);
 	return 0;
 }
 

refs.c

@@ -1427,7 +1427,7 @@ char *shorten_unambiguous_ref(const char *refname, int strict)
 }
 
 int parse_hide_refs_config(const char *var, const char *value, const char *section,
-			   struct string_list *hide_refs)
+			   struct strvec *hide_refs)
 {
 	const char *key;
 	if (!strcmp("transfer.hiderefs", var) ||
@@ -1438,22 +1438,23 @@ int parse_hide_refs_config(const char *var, const char *value, const char *secti
 
 		if (!value)
 			return config_error_nonbool(var);
-		ref = xstrdup(value);
+
+		/* drop const to remove trailing '/' characters */
+		ref = (char *)strvec_push(hide_refs, value);
 		len = strlen(ref);
 		while (len && ref[len - 1] == '/')
 			ref[--len] = '\0';
-		string_list_append_nodup(hide_refs, ref);
 	}
 	return 0;
 }
 
 int ref_is_hidden(const char *refname, const char *refname_full,
-		  const struct string_list *hide_refs)
+		  const struct strvec *hide_refs)
 {
 	int i;
 
 	for (i = hide_refs->nr - 1; i >= 0; i--) {
-		const char *match = hide_refs->items[i].string;
+		const char *match = hide_refs->v[i];
 		const char *subject;
 		int neg = 0;
 		const char *p;

refs.h

@@ -814,7 +814,7 @@ int update_ref(const char *msg, const char *refname,
 	       unsigned int flags, enum action_on_err onerr);
 
 int parse_hide_refs_config(const char *var, const char *value, const char *,
-			   struct string_list *);
+			   struct strvec *);
 
 /*
  * Check whether a ref is hidden. If no namespace is set, both the first and
@@ -824,7 +824,7 @@ int parse_hide_refs_config(const char *var, const char *value, const char *,
  * the ref is outside that namespace, the first parameter is NULL. The second
  * parameter always points to the full ref name.
  */
-int ref_is_hidden(const char *, const char *, const struct string_list *);
+int ref_is_hidden(const char *, const char *, const struct strvec *);
 
 /* Is this a per-worktree ref living in the refs/ namespace? */
 int is_per_worktree_ref(const char *refname);

revision.c

@@ -1558,7 +1558,7 @@ void init_ref_exclusions(struct ref_exclusions *exclusions)
 void clear_ref_exclusions(struct ref_exclusions *exclusions)
 {
 	string_list_clear(&exclusions->excluded_refs, 0);
-	string_list_clear(&exclusions->hidden_refs, 0);
+	strvec_clear(&exclusions->hidden_refs);
 	exclusions->hidden_refs_configured = 0;
 }
 

revision.h

@@ -10,6 +10,7 @@
 #include "decorate.h"
 #include "ident.h"
 #include "list-objects-filter-options.h"
+#include "strvec.h"
 
 /**
  * The revision walking API offers functions to build a list of revisions
@@ -95,7 +96,7 @@ struct ref_exclusions {
 	 * Hidden refs is a list of patterns that is to be hidden via
 	 * `ref_is_hidden()`.
 	 */
-	struct string_list hidden_refs;
+	struct strvec hidden_refs;
 
 	/*
 	 * Indicates whether hidden refs have been configured. This is to
@@ -110,7 +111,7 @@ struct ref_exclusions {
  */
 #define REF_EXCLUSIONS_INIT { \
 	.excluded_refs = STRING_LIST_INIT_DUP, \
-	.hidden_refs = STRING_LIST_INIT_DUP, \
+	.hidden_refs = STRVEC_INIT, \
 }
 
 struct oidset;

upload-pack.c

@@ -69,7 +69,7 @@ struct upload_pack_data {
 	struct object_array have_obj;
 	struct oid_array haves;					/* v2 only */
 	struct string_list wanted_refs;				/* v2 only */
-	struct string_list hidden_refs;
+	struct strvec hidden_refs;
 
 	struct object_array shallows;
 	struct string_list deepen_not;
@@ -127,7 +127,7 @@ static void upload_pack_data_init(struct upload_pack_data *data)
 {
 	struct string_list symref = STRING_LIST_INIT_DUP;
 	struct string_list wanted_refs = STRING_LIST_INIT_DUP;
-	struct string_list hidden_refs = STRING_LIST_INIT_DUP;
+	struct strvec hidden_refs = STRVEC_INIT;
 	struct object_array want_obj = OBJECT_ARRAY_INIT;
 	struct object_array have_obj = OBJECT_ARRAY_INIT;
 	struct oid_array haves = OID_ARRAY_INIT;
@@ -162,7 +162,7 @@ static void upload_pack_data_clear(struct upload_pack_data *data)
 {
 	string_list_clear(&data->symref, 1);
 	string_list_clear(&data->wanted_refs, 1);
-	string_list_clear(&data->hidden_refs, 0);
+	strvec_clear(&data->hidden_refs);
 	object_array_clear(&data->want_obj);
 	object_array_clear(&data->have_obj);
 	oid_array_clear(&data->haves);
@@ -1170,7 +1170,7 @@ static void receive_needs(struct upload_pack_data *data,
 
 /* return non-zero if the ref is hidden, otherwise 0 */
 static int mark_our_ref(const char *refname, const char *refname_full,
-			const struct object_id *oid, const struct string_list *hidden_refs)
+			const struct object_id *oid, const struct strvec *hidden_refs)
 {
 	struct object *o = lookup_unknown_object(the_repository, oid);
 
@@ -1465,7 +1465,7 @@ static int parse_want(struct packet_writer *writer, const char *line,
 
 static int parse_want_ref(struct packet_writer *writer, const char *line,
 			  struct string_list *wanted_refs,
-			  struct string_list *hidden_refs,
+			  struct strvec *hidden_refs,
 			  struct object_array *want_obj)
 {
 	const char *refname_nons;