From 7b5a01c90b240d126efc86f9f99100db918d452e Mon Sep 17 00:00:00 2001
From: Kees Cook <kees@outflux.net>
Date: Fri, 18 Nov 2022 09:48:08 -0800
Subject: Introduce ACPI_FLEX_ARRAY

Add helper to work around the pointless C99 requirement that flex array
members not be allowed in unions (nor alone in structs), which is not
actually a real-world problem.
---
 source/include/platform/acenv.h | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/source/include/platform/acenv.h b/source/include/platform/acenv.h
index 674c4c7d0..1cae95fd6 100644
--- a/source/include/platform/acenv.h
+++ b/source/include/platform/acenv.h
@@ -418,6 +418,17 @@
 #define ACPI_STRUCT_INIT(field, value)  value
 #endif
 
+/*
+ * Flexible array members are not allowed to be part of a union under
+ * C99, but this is not for any technical reason. Work around the
+ * limitation.
+ */
+#define ACPI_FLEX_ARRAY(TYPE, NAME)             \
+        struct {                                \
+                struct { } __Empty_ ## NAME;    \
+                TYPE NAME[];                    \
+        }
+
 /*
  * Configurable calling conventions:
  *
-- 
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