From b40dfec619e0e917e21ccf2b56c0c75f43427d99 Mon Sep 17 00:00:00 2001
From: Patrick Williams <patrick@stwcx.xyz>
Date: Tue, 18 Jan 2022 10:59:44 -0600
Subject: [PATCH] util: variant: add static assert

The two variant utilities both have an 'Unused' template parameter pack
which is expected to be empty.  Add static assert to confirm the
parameter pack is indeed always empty.  (Generally the non-empty
parameter pack should match with a specialization.)

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Iae4523142df563d208e20ab81dd47266b3f7dd27
---
 include/sdbusplus/utility/dedup_variant.hpp  | 1 +
 include/sdbusplus/utility/merge_variants.hpp | 1 +
 2 files changed, 2 insertions(+)

diff --git a/include/sdbusplus/utility/dedup_variant.hpp b/include/sdbusplus/utility/dedup_variant.hpp
index bfffd20f..786f7ef4 100644
--- a/include/sdbusplus/utility/dedup_variant.hpp
+++ b/include/sdbusplus/utility/dedup_variant.hpp
@@ -25,6 +25,7 @@ template <typename T, typename... Unused>
 struct dedup_variant
 {
     using type = T;
+    static_assert(sizeof...(Unused) == 0);
 };
 
 /** Find the deduplicated variant type.
diff --git a/include/sdbusplus/utility/merge_variants.hpp b/include/sdbusplus/utility/merge_variants.hpp
index 89c55711..70796821 100644
--- a/include/sdbusplus/utility/merge_variants.hpp
+++ b/include/sdbusplus/utility/merge_variants.hpp
@@ -26,6 +26,7 @@ template <typename T, typename... Unused>
 struct merge_variants
 {
     using type = T;
+    static_assert(sizeof...(Unused) == 0);
 };
 
 /** Compute the merged variant type.