Fix static_string uninitialized warning

CHANGELOG.md

@@ -7,6 +7,7 @@ Version 191:
 * Use lean_tuple in bind_handler, bind_front_handler
 * Use mp11 in detail::variant
 * Fix buffers_cat uninitialized warning
+* Fix static_string uninitialized warning
 
 --------------------------------------------------------------------------------
 

include/boost/beast/core/detail/config.hpp

@@ -51,4 +51,13 @@
 #define BOOST_BEAST_DEPRECATION_STRING \
     "This is a deprecated interface, #define BOOST_BEAST_ALLOW_DEPRECATED to allow it"
 
+#ifndef BOOST_BEAST_ASSUME
+# ifdef BOOST_GCC
+#  define BOOST_BEAST_ASSUME(cond) \
+    do { if (!(cond)) __builtin_unreachable(); } while (0)
+# else
+#  define BOOST_BEAST_ASSUME(cond) do { } while(0)
+# endif
+#endif
+
 #endif

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

@@ -139,7 +139,9 @@ assign(static_string const& str) ->
     static_string&
 {
     n_ = str.n_;
-    Traits::copy(&s_[0], &str.s_[0], n_ + 1);
+    auto const n = n_ + 1;
+    BOOST_BEAST_ASSUME(n != 0);
+    Traits::copy(&s_[0], &str.s_[0], n);
     return *this;
 }