Fix a spurious gcc warning

CHANGELOG.md

@@ -4,6 +4,7 @@ Version 187:
 * Fix warning in file tests
 * Fix uninitialized comparison in buffers iterator
 * Partial support for BOOST_NO_EXCEPTIONS
+* Fix a spurious gcc warning
 
 --------------------------------------------------------------------------------
 

include/boost/beast/core/impl/buffers_cat.ipp

@@ -34,6 +34,8 @@ class buffers_cat_view<Bn...>::const_iterator
 
     struct past_end
     {
+        char unused = 0; // make g++8 happy
+
         operator bool() const noexcept
         {
             return true;