kconfig: turn missing prompt for choice members into error

Choice members must have a prompt; hence make it an error.

While I was here, I moved the check to the parser to slim down
_menu_finalize().
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

scripts/kconfig/menu.c

@@ -507,8 +507,6 @@ static void _menu_finalize(struct menu *parent, bool inside_choice)
 		    menu->sym && !sym_is_choice_value(menu->sym)) {
 			current_entry = menu;
 			menu->sym->flags |= SYMBOL_CHOICEVAL;
-			if (!menu->prompt)
-				menu_warn(menu, "choice value must have a prompt");
 			for (prop = menu->sym->prop; prop; prop = prop->next) {
 				if (prop->type == P_DEFAULT)
 					prop_warn(prop, "defaults for choice "

scripts/kconfig/parser.y

@@ -30,6 +30,8 @@ static bool zconf_endtoken(const char *tokenname,
 
 struct menu *current_menu, *current_entry;
 
+static bool inside_choice = false;
+
 %}
 
 %union
@@ -145,6 +147,14 @@ config_entry_start: T_CONFIG nonconst_symbol T_EOL
 
 config_stmt: config_entry_start config_option_list
 {
+	if (inside_choice) {
+		if (!current_entry->prompt) {
+			fprintf(stderr, "%s:%d: error: choice member must have a prompt\n",
+				current_entry->filename, current_entry->lineno);
+			yynerrs++;
+		}
+	}
+
 	printd(DEBUG_PARSE, "%s:%d:endconfig\n", cur_filename, cur_lineno);
 };
 
@@ -237,10 +247,14 @@ choice_entry: choice choice_option_list
 	}
 
 	$$ = menu_add_menu();
+
+	inside_choice = true;
 };
 
 choice_end: end
 {
+	inside_choice = false;
+
 	if (zconf_endtoken($1, "choice")) {
 		menu_end_menu();
 		printd(DEBUG_PARSE, "%s:%d:endchoice\n", cur_filename, cur_lineno);