From: Ulf Magnusson <ulfalizer@gmail.com>
Date: Sun, 14 Jan 2018 09:56:20 +0000 (+0100)
Subject: kconfig: Document SYMBOL_OPTIONAL logic
X-Git-Url: https://jxself.org/git/?p=carl9170fw.git;a=commitdiff_plain;h=8feb6085df8ac5f420533fba818aad40d0ff0e09

kconfig: Document SYMBOL_OPTIONAL logic

Not obvious, especially if you don't already know how choices are
implemented.

No functional changes. Only comments added.

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

diff --git a/config/menu.c b/config/menu.c
index 47bec34..7634d56 100644
--- a/config/menu.c
+++ b/config/menu.c
@@ -549,6 +549,15 @@ 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,