kconfig: Clarify choice dependency propagation

[carl9170fw.git] / config / menu.c

diff --git a/config/menu.c b/config/menu.c
index 47bec3434fef16f1b0c46e0f8d908ee704aa57ca..dcf22008b2d6e4732d1e2785b0706395a8e1b071 100644 (file)
--- a/config/menu.c
+++ b/config/menu.c
@@ -323,6 +323,13 @@ void menu_finalize(struct menu *parent)
                                if (menu->sym && menu->sym->type == S_UNKNOWN)
                                        menu_set_type(sym->type);
                        }
+
+                       /*
+                        * Use the choice itself as the parent dependency of
+                        * the contained items. This turns the mode of the
+                        * choice into an upper bound on the visibility of the
+                        * choice value symbols.
+                        */
                        parentdep = expr_alloc_symbol(sym);
                } else if (parent->prompt)
                        parentdep = parent->prompt->visible.expr;
@@ -549,6 +556,15 @@ void menu_finalize(struct menu *parent)
                sym->flags |= SYMBOL_WARNED;
        }
 
+       /*
+        * For non-optional choices, add a reverse dependency (corresponding to
+        * a select) of '<visibility> && m'. This prevents the user from
+        * setting the choice mode to 'n' when the choice is visible.
+        *
+        * This would also work for non-choice symbols, but only non-optional
+        * choices clear SYMBOL_OPTIONAL as of writing. Choices are implemented
+        * as a type of symbol.
+        */
        if (sym && !sym_is_optional(sym) && parent->prompt) {
                sym->rev_dep.expr = expr_alloc_or(sym->rev_dep.expr,
                                expr_alloc_and(parent->prompt->visible.expr,