SL-20546: Merge branch 'DRTVWR-588-maint-W' into sl-20546.

1 files changed, 49 insertions, 0 deletions

diff --git a/indra/llcommon/function_types.h b/indra/llcommon/function_types.h
new file mode 100644
index 0000000000..3f42f6d640
--- /dev/null
+++ b/indra/llcommon/function_types.h
@@ -0,0 +1,49 @@
+/**
+ * @file   function_types.h
+ * @author Nat Goodspeed
+ * @date   2023-01-20
+ * @brief  Extend boost::function_types to examine boost::function and
+ *         std::function
+ * 
+ * $LicenseInfo:firstyear=2023&license=viewerlgpl$
+ * Copyright (c) 2023, Linden Research, Inc.
+ * $/LicenseInfo$
+ */
+
+#if ! defined(LL_FUNCTION_TYPES_H)
+#define LL_FUNCTION_TYPES_H
+
+#include <boost/function.hpp>
+#include <boost/function_types/function_arity.hpp>
+#include <functional>
+
+namespace LL
+{
+
+    template <typename F>
+    struct function_arity_impl
+    {
+        static constexpr auto value = boost::function_types::function_arity<F>::value;
+    };
+
+    template <typename F>
+    struct function_arity_impl<std::function<F>>
+    {
+        static constexpr auto value = function_arity_impl<F>::value;
+    };
+
+    template <typename F>
+    struct function_arity_impl<boost::function<F>>
+    {
+        static constexpr auto value = function_arity_impl<F>::value;
+    };
+
+    template <typename F>
+    struct function_arity
+    {
+        static constexpr auto value = function_arity_impl<typename std::decay<F>::type>::value;
+    };
+
+} // namespace LL
+
+#endif /* ! defined(LL_FUNCTION_TYPES_H) */