kconfig: Clarify choice dependency propagation

It's easy to miss that choices are special-cased to pass on their mode
as the parent dependency.

No functional changes. Only comments added.

Signed-off-by: Ulf Magnusson <ulfalizer@gmail.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/scripts/kconfig/menu.c b/scripts/kconfig/menu.c
index 7634d56..dcf2200 100644
--- a/scripts/kconfig/menu.c
+++ b/scripts/kconfig/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;