m_option: add a way for aliases to use sub option prefix

Previously, using m_option_type_alias required that the alias have the
full name of the option value. This is limited if you are reusing the
same opts struct in different sub options. Fix this by add an additional
field to m_option to signal whether or not prefixes should be taken into
account for the alias option. Instead of blindly using whatever is
stored in opt->priv as the name, we can construct the desired option
name for either case (using the prefix or not).

options/m_config_core.c

@@ -227,6 +227,19 @@ const char *m_config_shadow_get_opt_name(struct m_config_shadow *shadow,
                            g->group->opts[opt_index].name);
 }
 
+const char *m_config_shadow_get_alias_from_opt(struct m_config_shadow *shadow, int32_t id,
+                                               char *buf, size_t buf_size)
+{
+    int group_index, opt_index;
+    get_opt_from_id(shadow, id, &group_index, &opt_index);
+
+    struct m_config_group *g = &shadow->groups[group_index];
+    const struct m_option *opt = &shadow->groups[group_index].group->opts[opt_index];
+    if (opt->alias_use_prefix)
+        return concat_name_buf(buf, buf_size, g->prefix, (const char *)opt->priv);
+    return (const char *)opt->priv;
+}
+
 const void *m_config_shadow_get_opt_default(struct m_config_shadow *shadow,
                                             int32_t id)
 {

options/m_config_core.h

@@ -175,6 +175,10 @@ const struct m_option *m_config_shadow_get_opt(struct m_config_shadow *shadow,
 const char *m_config_shadow_get_opt_name(struct m_config_shadow *shadow,
                                          int32_t id, char *buf, size_t buf_size);
 
+// Resolve alias mapping from opt.
+const char *m_config_shadow_get_alias_from_opt(struct m_config_shadow *shadow, int32_t id,
+                                               char *buf, size_t buf_size);
+
 // Pointer to default value, using m_option.type. NULL if option without data.
 // id must be a valid option ID as returned by m_config_shadow_get_next_opt() or
 // m_config_cache_get_next_opt().

options/m_config_frontend.c

@@ -302,7 +302,9 @@ static struct m_config_option *m_config_get_co_any(const struct m_config *config
 
     const char *prefix = config->is_toplevel ? "--" : "";
     if (co->opt->type == &m_option_type_alias) {
-        const char *alias = (const char *)co->opt->priv;
+        char buf[M_CONFIG_MAX_OPT_NAME_LEN];
+        const char *alias = m_config_shadow_get_alias_from_opt(config->shadow, co->opt_id,
+                                                               buf, sizeof(buf));
         if (co->opt->deprecation_message && !co->warning_was_printed) {
             if (co->opt->deprecation_message[0]) {
                 MP_WARN(config, "Warning: option %s%s was replaced with "
@@ -881,8 +883,12 @@ void m_config_print_option_list(const struct m_config *config, const char *name)
             MP_INFO(config, " [file]");
         if (opt->deprecation_message)
             MP_INFO(config, " [deprecated]");
-        if (opt->type == &m_option_type_alias)
+        if (opt->type == &m_option_type_alias) {
-            MP_INFO(config, " for %s", (char *)opt->priv);
+            char buf[M_CONFIG_MAX_OPT_NAME_LEN];
+            const char *alias = m_config_shadow_get_alias_from_opt(config->shadow, co->opt_id,
+                                                                   buf, sizeof(buf));
+            MP_INFO(config, " for %s", alias);
+        }
         if (opt->type == &m_option_type_cli_alias)
             MP_INFO(config, " for --%s (CLI/config files only)", (char *)opt->priv);
         MP_INFO(config, "\n");

options/m_option.h

@@ -389,6 +389,9 @@ struct m_option {
     // Always force an option update even if the written value does not change.
     bool force_update;
 
+    // If the option is an alias, use the prefix of sub option.
+    bool alias_use_prefix;
+
     int offset;
 
     // Most numeric types restrict the range to [min, max] if min<max (this

player/command.c

@@ -7187,7 +7187,10 @@ void command_init(struct MPContext *mpctx)
         };
 
         if (co->opt->type == &m_option_type_alias) {
-            prop.priv = co->opt->priv;
+            char buf[M_CONFIG_MAX_OPT_NAME_LEN];
+            const char *alias = m_config_shadow_get_alias_from_opt(mpctx->mconfig->shadow, co->opt_id,
+                                                                   buf, sizeof(buf));
+            prop.priv = talloc_strdup(ctx, alias);
 
             prop.call = co->opt->deprecation_message ?
                             mp_property_deprecated_alias : mp_property_alias;
@@ -7198,8 +7201,9 @@ void command_init(struct MPContext *mpctx)
             // be set as property.
             struct m_config_option *co2 = co;
             while (co2 && co2->opt->type == &m_option_type_alias) {
-                const char *alias = (const char *)co2->opt->priv;
+                const char *co2_alias = m_config_shadow_get_alias_from_opt(mpctx->mconfig->shadow, co2->opt_id,
-                co2 = m_config_get_co_raw(mpctx->mconfig, bstr0(alias));
+                                                                           buf, sizeof(buf));
+                co2 = m_config_get_co_raw(mpctx->mconfig, bstr0(co2_alias));
             }
             if (!co2)
                 continue;