From 82a1b00eb6d99bca1f4bc021a4c97ed7ccea16c8 Mon Sep 17 00:00:00 2001
From: dearblue <dearblue@users.osdn.me>
Date: Sun, 2 Jan 2022 14:59:55 +0900
Subject: Assert that `MRB_METHOD_CACHE_SIZE` is a power of 2

The `mrb_static_assert_powerof2()` macro has been introduced for this purpose.
---
 include/mruby.h | 3 +++
 1 file changed, 3 insertions(+)

(limited to 'include/mruby.h')

diff --git a/include/mruby.h b/include/mruby.h
index 806ceaff6..3e92021ac 100644
--- a/include/mruby.h
+++ b/include/mruby.h
@@ -109,6 +109,8 @@
     mrb_static_assert_expand(mrb_static_assert_selector(__VA_ARGS__, mrb_static_assert2, mrb_static_assert1, _)(__VA_ARGS__))
 #endif
 
+#define mrb_static_assert_powerof2(num) mrb_static_assert((num) > 0 && (num) == ((num) & -(num)), "need power of 2 for " #num)
+
 #include "mrbconf.h"
 
 #include <mruby/common.h>
@@ -208,6 +210,7 @@ struct mrb_context {
 
 #ifdef MRB_METHOD_CACHE_SIZE
 # undef MRB_NO_METHOD_CACHE
+mrb_static_assert_powerof2(MRB_METHOD_CACHE_SIZE);
 #else
 /* default method cache size: 256 */
 /* cache size needs to be power of 2 */
-- 
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