Minor internal code tweaks

* mark all eligible classes Final
* new TableIndex strong type
* buildfixes for HAVE_DEBUGSPEW()
* overridden virtual destructors tagged as such

1 files changed, 1 insertions, 1 deletions

diff --git a/src/unique.hpp b/src/unique.hpp
index aec5610..06a4532 100644
--- a/src/unique.hpp
+++ b/src/unique.hpp
@@ -78,7 +78,7 @@ class [[nodiscard]] Unique<T, TAG, std::enable_if_t<!std::is_scalar_v<T>>>
     using self = Unique<T, TAG, void>;
     using type = T;
     using T::T;
-    explicit Unique(T const& b_)
+    constexpr explicit Unique(T const& b_)
     : T{ b_ }
     {
     }