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 <[email protected]> Change-Id: Iae4523142df563d208e20ab81dd47266b3f7dd27
openbmc · Jan 18, 2022 · b40dfec · b40dfec
1 parent 5770f51
commit b40dfec
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diff --git 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
@@ -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.