Add UNREACHABLE_CODE suppress, apply to bogus LTCG warning.

Author: evoskuil

include/bitcoin/system/allocator.hpp

@@ -118,7 +118,12 @@ class allocator
         auto ptr = allocate_object<Type>();
         construct_guard<Type> guard{ arena_, ptr };
         construct<Type>(ptr, std::forward<Args>(args)...);
+
+        // Bogus warning (under LTCG only).
+        BC_PUSH_WARNING(UNREACHABLE_CODE)
         guard.arena_ = nullptr;
+        BC_POP_WARNING()
+
         return ptr;
     }
 

include/bitcoin/system/warnings.hpp

@@ -44,6 +44,7 @@
         #define THROW_FROM_NOEXCEPT 4297
         #define TRUNCATED_CONSTANT 4310
         #define LOCAL_VARIABLE_NOT_INITIALIZED 4700
+        #define UNREACHABLE_CODE 4702
         #define NOT_INLINED 4714
         #define DISCARDING_NON_DISCARDABLE 4834