kconfig: show sub-menu entries even if the prompt is hidden

Since commit f79dc03fe68c ("kconfig: refactor choice value
calculation"), when EXPERT is disabled, nothing within the "if INPUT"
... "endif" block in drivers/input/Kconfig is displayed. This issue
affects all command-line interfaces and GUI frontends.

The prompt for INPUT is hidden when EXPERT is disabled. Previously,
menu_is_visible() returned true in this case; however, it now returns
false, resulting in all sub-menu entries being skipped.

Here is a simplified test case illustrating the issue:

config A
bool "A" if X
default y

config B
bool "B"
depends on A

When X is disabled, A becomes unconfigurable and is forced to y.
B should be displayed, as its dependency is met.

This commit restores the necessary code, so menu_is_visible() functions
as it did previously.

Fixes: f79dc03fe68c ("kconfig: refactor choice value calculation")
Reported-by: Edmund Raile <[e-mail]>
Closes: https://lore.kernel.org/all/[e-mail]/
Signed-off-by: Masahiro Yamada <[e-mail]>

scripts/kconfig/menu.c

···
 
 bool menu_is_visible(struct menu *menu)
 {
+	struct menu *child;
 	struct symbol *sym;
 	tristate visible;
 
···
 	} else
 		visible = menu->prompt->visible.tri = expr_calc_value(menu->prompt->visible.expr);
 
-	return visible != no;
+	if (visible != no)
+		return true;
+
+	if (!sym || sym_get_tristate_value(menu->sym) == no)
+		return false;
+
+	for (child = menu->list; child; child = child->next)
+		if (menu_is_visible(child))
+			return true;
+
+	return false;
 }
 
 const char *menu_get_prompt(const struct menu *menu)