When building on Ubuntu 16.04 using gcc5.4.0 (the stock compiler), after JDK-8233359 we get

/shared/projects/openjdk/jdk-jdk/source/src/hotspot/share/memory/operator_new.cpp:92:6: error: 'void operator delete(void*, size_t)' is a usual (non-placement) deallocation function in C++14 (or with -fsized-deallocation) [-Werror=c++14-compat]
 void operator delete(void* p, size_t size) throw() {
      ^
/shared/projects/openjdk/jdk-jdk/source/src/hotspot/share/memory/operator_new.cpp:96:6: error: 'void operator delete [](void*, size_t)' is a usual (non-placement) deallocation function in C++14 (or with -fsized-deallocation) [-Werror=c++14-compat]
 void operator delete [](void* p, size_t size) throw() {
      ^

-Wc++14-compat is enabled by -Wall, as is -Wc++11-compat (and Wc++17-compat in sufficiently recent versions of gcc).