fastdebug builds of 8u and 11u result in the following warning when compiling with gcc 8.3:

/home/dbuck/backports/sanity/jdk11u-cpu/open/src/hotspot/share/classfile/classLoader.cpp: In static member function 'static void ClassLoader::compile_the_world_in(char*, Handle, Thread*)':
/home/dbuck/backports/sanity/jdk11u-cpu/open/src/hotspot/share/classfile/classLoader.cpp:2039:12: warning: 'char* strncpy(char*, const char*, size_t)' specified bound depends on the length of the source argument [-Wstringop-overflow=]
     strncpy(buffer, name, len - 6);
     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
/home/dbuck/backports/sanity/jdk11u-cpu/open/src/hotspot/share/classfile/classLoader.cpp:173:26: note: length computed here
   size_t str_len = strlen(str);
                    ~~~~~~^~~~~

This warning will cause builds to fail when warnings-as-errors is enabled (the default).

This code was removed in JDK 12 (see JDK-8213812), so JDK 11 and JDK 8 are the only LTS versions that need to be fixed. There are a number of similar issues elsewhere in 11u, but they can hopefully be addressed by backporting preexisting fixes from later releases.